DESCRIPTION RECORDING METHOD Technical Field The present invention relates to an ink jet recording method excellent in image durability, including image stability under high humidity conditions.

The present invention relates to a recording ink (preferably an ink for ink jet recording) and a recording method (preferably an ink jet recording method) which can provide an image having an excellent hue and excellent storage properties under severe conditions.

Background Art In recent years, with the spread of computers, ink jet printers have been widely used to print on paper, film, cloth, etc, at offices as well as at home.

Examples of ink jet recording method include a method which allows a piezoelectric element to give pressure that causes a droplet to be ejected, a method which comprises heating the ink to generate bubbles, causing a droplet to be ejected, a method involving the use of ultrasonic wave, and a method which uses electrostatic force to suck and discharge a droplet. As inks for these ink jet recording methods there are used aqueous inks, oil-based inks and solid (melt type) inks. Among these inks, aqueous inks are mainly used from the standpoint of producibility, handleability, odor, safety, etc.

The dyes to be incorporated in these inks for ink jet recording are required to exhibit a high solubility in solvents, allow a high density recording and have a good hue and an excellent fastness to light, heat, air, water and chemical, a good fixability to recording materials (image-receiving materials), difficulty in running, an excellent preservability, no toxicity and a high purity and be available at a low cost. However, it is extremely difficult to seek dyes meeting these requirements to a high extent. In particular, dyes having a good cyan hue and an excellent weathering resistance have been keenly desired. Various dyes and pigments have been already proposed for ink jet recording and have been actually used. However, no dyes meeting all these requirements have been found yet. Known dyes and pigments provided with color index (C. I. ) can difficultly satisfy both the hue and fastness requirements for inks for ink jet recording. To date, fast dyes having a good hue have been studied and excellent dyes have been developed as ink jet recording coloring materials.

However, all compounds which are water-soluble dyes have water-soluble groups as substituents. It was found disadvantageous in that when the number of water-soluble groups is increased to enhance the stability of the ink, the image thus formed can easily undergo bleeding under high humidity conditions.

On the other hand, it is important to remove finely divided bubbles from the ink during the preparation of the ink. When the removal of finely divided bubbles from the ink is insufficiently conducted, it is disadvantageous in that the stability of ejection of the ink can be impaired. For example, the ink can clog the ink jet head. It is often practiced to incorporate a surface active agent in the ink for the purpose of adjusting the physical properties of the ink and enhancing the capability of the ink of penetrating paper. However, the surface active agent is one of factors causing the generation of bubbles. Thus, the removal of bubbles is more important.

JP-A-6-24123, JP-A-6-152905 and JP-A-3-33298 describe a recording method in which spreading of dots is prevented when recording is performed to standard paper.

Disclosure of the Invention A first aim of the invention is to provide an ink jet recording method which is little subject to image bleeding even under high humidity conditions.

It is therefore a second aim of the invention to provide a recording method (preferably an ink jet recording method) which exhibits a high ejection stability and can provide a high quality image having an excellent hue and excellent storage properties. It is another aim of the invention to provide a recording method (preferably an ink jet recording method) which exhibits a good ejection stability under severe conditions over an extended period of time and can provide an image having high storage properties.

The aforementioned first aim of the invention is accomplished by the following six constitutions of ink jet recording method.

1) An ink jet recording method comprising printing an ink with an ink on an image-receiving material, according to an image data, so as to form an image, wherein the ink includes: an anionic dye ; and at least one of water and a water-soluble organic solvent, and wherein the anionic dye has three or more hydrogen-bonding functional groups.

2) The ink jet recording method as described in Clause (1), wherein a printing surface of the image- receiving material contains a compound having four or more hydrogen-bonding functional groups.

3) The ink jet recording method as described in Clause (1) or (2), wherein a printing surface of the image-receiving material contains a mordant.

4) The ink jet recording method as described in any one of Clauses (1) to (3), wherein as the anionic dye there is used at least one compound having an oxidation potential of more positive than 1.0 V.

5) The ink jet recording method as described in any one of Clauses (1) to (4), wherein as the anionic dye there is used at least one of the compounds represented by the following general formulae (1-1) to (1-4): general formula (1-1) : (All-N=N-Blz) ri L wherein All and BI, each independently represents a heterocyclic group which may be substituted; n represents an integer 1 or 2; and L represents a substituent bonded to All or Bu at arbitrary position, with the proviso that when n is 1, L represents a hydrogen atom or monovalent substituent and when n is 2, L represents a mere bond or divalent connecting group; general formula (1-2): wherein X21, X22, X23 and X24 each independently represents -SO-Z2, -SO2-Z2, -SO2NR21R22, sulfo group,- CONR2lR22 or-COOR21 in which Z2's each independently represents a substituted or unsubstituted alkyl, cycloalkyl, alkenyl, aralkyl, aryl or heterocyclic group and RZ, and R22 each independently represents a hydrogen atom or substituted or unsubstituted alkyl, cycloalkyl, alkenyl, aralkyl, aryl or heterocyclic group; Y21, Y22, Y23 and Y24 each independently represents a monovalent substituent; a21 to a24 and b21 to b24 represent the number of the substituents X21 to X24 and Y21 to Y24, respectively; azl to a24 each independently represents a number of from 0 to 4 and at least one of a21 to a24 is not zero; b21 to b24 each independently represents a number of from 0 to 4, with the proviso that when a21 to a24 and b21 to b24 each represent a number of 2 or more, the plurality of X2l's to X24's and Y2,'s to Y24's may be the same or different ; and M represents a hydrogen atom, metal atom or oxide, hydroxide or halide thereof ; general formula (1-3): wherein A31 represents a 5-membered heterocyclic group; B31 and B32 each represents =CR31-or-CR32= or one of B31 and B32 represents a nitrogen atom and the other represents =CR31-or-CR32= ; R35 and R36 each independently represents a hydrogen atom or an aliphatic group, aromatic group, heterocyclic group, acyl group, alkoxycarbonyl group, aryloxycarbonyl group, carbamoyl group, alkylsulfonyl group, arylsulfonyl group or sulfamoyl group which may further have substituents ; G3, R21 and R32 each independently represents a hydrogen atom, a halogen atom or an aliphatic group, aromatic group, heterocyclic group, cyano group, carboxyl group, carbamoyl group, alkoxycarbonyl group, aryloxycarbonyl group, heterocyclic oxycarbonyl group, acyl group, hydroxyl group, alkoxy group, aryloxy group, heterocyclic oxy group, silyloxy group, acyloxy group, carbamoyloxy group, alkoxycarbonyloxy group, aryloxycarbonyloxy group, amino group (including arylamino group and heterocyclic amino group), acylamino group, ureido group, sulfamonylamino group, alkoxycarbonylamino group, aryloxycarbonylamino group, alkylsulfonylamino group, arylsulfonylamino group, heterocyclic sulfonylamino group, nitro group, alkylthio group, arylthio group, alkylsulfonyl group, arylsulfonyl group, heterocyclic sulfonyl group, alkylsulfinyl group, arylsulfinyl group ; heterocyclic sulfinyl group, sulfamoyl group, sulfo group or heterocyclic thio group which may be further substituted; R31 and R3s or R3s and R36 may be connected to each other to form a 5-or 6-membered ring; and general formula (1-4): A41-N=N-B41-N=N-C41 wherein A41, B41 and C41 each independently represent an aromatic or heterocyclic group which may be substituted. m is 1 or 2, and n is an integer of 0 or more.

6) The ink jet recording method as defined in any one of Clauses (1) to (4), wherein the anionic dye represented by the general formula (1-2) is one represented by the following general formula (1-5) : general formula (1-5): wherein X51 to X54, Ysl to Y5s and Ml have the same meaning as Xl to X24, Y21 to Y24 and M in the general formula (1-2); and ase to as each independently represent an integer of 1 or 2.

The second aim of the invention is accomplished by the following constitutions (7) to (16).

(7) A recording method which comprises ejecting ink drops onto a recording material (receiving material) according to a recording signal, the recording material comprising a support and an ink-receptive layer provided on the support, by using at least two color inks comprising a yellow ink and a magenta ink, so as to record an image on the recording material, wherein the percent bleeding of the recorded image upon storage of the recorded image under high humidity (defined in Clause (8)) is 30% or less.

(8) The recording method as defined in Clause (7), wherein, supposing that an gray image having a 10 mm square and a reflection density of 1. 5 (neutral color according to CIE) is prepared using a plurality of color inks according to a neutral gray data outputted to a color printer, the gray image comprising a white line having a width of 0.2 mm extending through the center of the 10 mm square, the percent bleeding is represented by the following equation: % Bleeding = (DC-Db) /Da x 100 where Da represents a density of the gray image which has been just printed; Db represents a density of the white line which has been just printed; and Dc represents a density of the white line which has been allowed to stand at 23°C and 90% RH for 7 days shortly after printing.

(9) The ink jet recording method as defined in Clause (7) or (8), wherein the yellow and magenta inks each further comprise a surface active agent and the surface active agent is a betaine-based surface active agent.

(10) The ink jet recording method as defined in any one of Clauses (7) to (9), wherein the betaine-based surface active agent is represented by the following general formula (2-1) : (R) p-N-[L-(COOM3q] r.. (2-l) wherein R represents a hydrogen atom, alkyl group, aryl group or heterocyclic group; L represents a divalent connecting group; M represents a hydrogen atom, alkaline metal atom, ammonium group, protonated organic amine, protonated nitrogen-containing heterocyclic group or quaternary ammonium ion, with the proviso that if one"COO"of at least one (COOM) group is a counter ion of ammonium ion formed by nitrogen atoms in the molecule represented by the general formula (2-1), corresponding M of the"COO"represents a group which does not exist as a cation; q represents an integer of 1 or more; r represents an integer of 1 or more and 4 or less; and p represents an integer of from 0 to 4, with the proviso that: the sum of p and r is 3 or 4; when the sum of p and r is 4, the nitrogen atom is a protonated ammonium atom (=N+=) ; when q is 2 or more, the plurality of COOM groups may be the same or different; when r is 2 or more, the plurality of [L- (COOM) q] groups may be the same or different; and when p is 2 or more, the plurality of R's may be the same or different.

(11) The recording method as defined in any one of Clauses (7) to (10), wherein the yellow and magenta inks each further contain a water-miscible organic solvent and the water-miscible organic solvent is selected from the group consisting of triethylene glycol monobutyl ether, diethylene glycol monobutyl ether, tripropylene glycol monomethyl ether and dipropylene glycol monomethyl ether.

(12) The recording method as defined in any one of Clauses (7) to (11), wherein at least one of the dyes is a dye having an oxidation potential of more positive than 1. 0 V (vs SCE).

(13) The recording method as defined in any one of Clauses (7) to (12), wherein the dye for yellow ink is a yellow dye represented by the following general formula (2-2): (AII-N=N-BII) n-L... (2-2) wherein A, I and B, I each independently represents a heterocyclic group which may be substituted; n represents an integer 1 or 2; and L represents a hydrogen atom, mere bond or divalent connecting group, with the proviso that: when n is 1, L represents a hydrogen atom and both An and Bu are a monovalent heterocyclic group; and when n is 2, L represents a mere bond or divalent connecting group, one of All and BI, is a monovalent heterocyclic group and the other is a divalent connecting group, and two All's and Bll's each may be the same or different.

(14) The recording method as defined in any one of Clauses (7) to (13), wherein the dye for magenta ink is a magenta dye represented by the following general formula (Ml): wherein A31 represents a 5-membered heterocyclic group; B31 and B32 represent =CRi-and-CR2=, respectively, or one of B31 and B32 represents nitrogen atom and the other represents =CRI-or-CR2= ; Rs and R6 each independently represents a hydrogen atom or substituent ; and G3', Rl and W each independently represents a hydrogen atom or substituent.

(15) The recording method as defined in any one of Clauses (7) to (14), wherein the ink-receptive layer comprises an inorganic white particulate material.

(16) The recording method as defined in any one of Clauses (7) to (15), which is adapted for ink jet recording.

Best Mode For Carrying Out the Invention [First Embodiment] The first embodiment of the invention will be further described hereinafter. The invention discloses a technique of preventing image bleeding.

According to the first embodiment of the invention, there is provided an ink jet recording method comprising: printing, on an image-receiving material, an ink that includes: an anionic dye; and at least one of water and a water-soluble organic solvent, according to an image data to form an image, wherein the anionic dye has three or more hydrogen-bonding functional groups.

There are various ink jet recording methods. As previously mentioned, the ink jet recording method involving the use of an aqueous ink comprising a water-soluble dye dissolved in an aqueous solvent is mainly used both at home and office. The reason for this trend is that the aqueous dye which can be merely dissolved in water to form a uniform solution has a long history and thus can be used with techniques which have been accumulated on various molecular designs. Further, the aqueous ink jet recording method involves the use of an ink free of solid content such as pigment that forms a uniform solution and thus is most suitable for maintenance of desired ejection stability of nozzle, which is the greatest assignment in ink jet recording.

Further, the aqueous solvent has a high safety and a higher handleability than volatile solvent.

However, since the aqueous ink jet method involves recording a water-soluble dye on an image- receiving material with a water-soluble solvent left in the ink, image bleeding is observed when the image thus printed is stored under high humidity conditions despite the coexistence of a dye fixing material (e. g. , mordant).

It was found that this problem becomes remarkable with a dye having a high water solubility.

In the invention, a mutual interaction between dye and image-receiving material for dye fixing having a different mechanism from that of ordinary mordant is introduced.

In the invention, it was found that the introduction of a bonding group comprising a plurality of hydrogen bonds in combination is effective for this purpose.

Hydrogen bond is developed when a hydrogen atom connected to an atom having a high polarity present in an organic functional group forms a false bond while being oriented among polar atoms present in the molecule or foreign molecules. For the details of the concept of this hydrogen bond, reference can be made to Motohiro Nishio,"Yuki Kagaku no Tameno Bunshikanryoku Nyumon (Introduction of Intermolecular Force for Organic Chemistry) ", Scientific, Kodansha, 2000, pp. 21-25.

The term"polar atom"as used herein is meant to indicate an atom having a high electronegativity than that of carbon atom as calculated in terms of value proposed by L. Pauling. Examples of such a polar atom include oxygen atom, sulfur atom, selenium atom, nitrogen atom, and phosphorus atom.

Examples of functional groups on the part of hydrogen donor capable of developing hydrogen bond include hydroxyl groups (including both alcoholic hydroxyl group and phenolic hydroxyl group), thio groups (including both alkylthio group and arylthio group), carboxyl groups, phosphoric acid groups, phosphone groups, carbonamide groups, sulfonamide groups, alkylcarbonamide groups, arylcarbonamide groups, allcylsulfonamide groups, arylsulfonamide groups, carbamoyl groups, sulfamoyl groups, alkylcarbamoyl groups, arylcarbamoyl groups, alkylsulfamoyl groups, arylsulfamoyl groups, phosphonamide groups, amino groups, heterocyclic groups having N-H bond (e. g. , pyrazole group, imidazole group, triazole group, tetrazole group, condensed pyrazole group, condensed imidazole group), and thiocarboxyl groups.

On the other hand, as functional groups on the part of hydrogen atom acceptor there may be used groups containing polar atom except hydrogen atom. Examples of these functional groups include ether groups, thioether groups, carbonyl groups, thiocarbonyl groups, amino groups, and nitrogen atom, oxygen atom and sulfur atom contained in heterocyclic group.

In the invention, 4 or more, preferably 5 or more, more preferably 8 or more, particularly 10 or more such hydrogen-donating functional groups capable of developing hydrogen bonding properties are contained in one molecule.

Particularly preferred examples of hydrogen-bonding functional groups (hydrogen-bonding groups) to be contained in the molecule include amide-based groups (e. g. , carbonamide group, sulfonamide group, aklcarbonamide group, arylcarbonamide group, alkylsulfonamide group, arylsulfonamide group, carbamoyl group, sulfamoyl group, alkylcarbamoyl group, arylcarbamoyl group, alkylsulfamoyl group, arylsulfamoyl group, phosphonamide group), and heterocyclic groups having N-H bond (e. g. , pyrazole group, imidazole group, triazole group, tetrazole group, condensed pyrazole group, condensed imidazole group).

In the invention, for the purpose of fixing dye, mordant mutual interaction, too, acts besides the hydrogen-bonding mutual interaction. Referring to the mordant mutual interaction, a compound containing a group having a charge having a sign opposite that of the dissociative group of dye is used to cause ionic mutual interaction (coulombic mutual interaction) and hydrophobic mutual interaction in combination, whereby the dye molecule is fixed. This mutual interaction is a technique known in the art of imaging, particularly photography (especially dye diffusion transferring color photographic material) and is widely used in the art of ink jet recording.

In general, most dyes have an anionic dissociative group. Thus, cationic compounds are often used on the part of mordant. Examples of cationic compounds include compounds having aminic nitrogen atom (e. g., primary amine, secondary amine, tertiary amine, quaternary ammonium salt, nitrogen-containing heterocyclic compound), and metal salt compounds.

It is preferred that the mordant be contained in the coloring material-receiving layer. Preferred examples of inorganic mordants include polyvalent water-soluble metal salts and hydrophobic metal salt compounds.

Specific examples of the inorganic mordants include salts or complexes of metal selected from the group consisting of magnesium, aluminum, calcium, scandium, titanium, vanadium, manganese, iron, nickel, copper, zinc, gallium, germanium, strontium, yttrium, zirconium, molybdenum, indium, barium, lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, dysprosium, erbium, ytterbium, hafnium, tungsten and bismuth.

Specific examples of these metal salts or complexes include calcium acetate, calcium chloride, calcium formate, calcium sulfate, barium acetate, barium sulfate, barium phosphate, manganese chloride, manganese acetate, manganese formate dihydrate, manganese ammonium sulfate hexahydrate, cupric chloride, cupric ammonium chloride (II) dihydrate, copper sulfate, cobalt chloride, cobalt thiocyanate, cobalt sulfate, nickel sulfate hexahydrate, nickel chloride hexahydrate, nickel acetate tetrahydrate, nickel ammonium sulfate hexahydrate, nickel amide sulfate tetrahydrate, aluminum sulfate, aluminum alum, basic polyaluminum hydroxide, aluminum sulfite, aluminum thiosulfate, polyaluminum chloride, aluminum nitrate nonahydrate, aluminum chloride hexahydrate, ferrous bromide, ferrous chloride, ferric chloride, ferrous sulfate, ferric sulfate, zinc phenolsulfonate, zinc bromide, zinc chloride, zinc nitrate hexahydrate, zinc sulfate, titanium tetrachloride, tetraisopropyl titanate, titanium acetyl acetonate, titanium lactate, zirconium acetyl acetonate, zirconyl octylate, zirconyl acetate, zirconyl sulfate, zirconium ammonium carbonate, zirconyl stearate, zirconyl octylate, zirconyl nitrate, zirconium oxychloride, zirconium hydroxychloride, chromium acetate, chromium sulfate, magnesium sulfate, magnesium chloride hexahydrate, magnesium citrate nonahydrate, sodium phosphotungstate, sodium tungsten citrate, dodecatungstophosphoric n-hydrate, dodecatugstosilicic 26-hydrate, molybdenum chloride, dodecamolybdophosphoric n-hydrate, gallium nitrate, germanium nitrate, strontium nitrate, yttrium acetate, yttrium chloride, yttrium nitrate, indium nitrate, lanthanum nitrate, lanthanum chloride, lanthanum acetate, lanthanum benzoate, cerium chloride, cerium sulfate, cerium octylate, praseodymium nitrate, neodymium nitrate, samarium nitrate, europium nitrate, gadolinium nitrate, dysprosium nitrate, erbium nitrate, ytterbium nitrate, hafnium chloride, and bismuth nitrate.

Preferred examples of the inorganic mordants employable herein include aluminum-containing compounds, titanium-containing compounds, zirconium-containing compounds, and compounds (salts or complexes) of metal belonging to the group IIIB of the periodic table.

In the invention, the amount of the aforementioned mordant to be contained in the coloring material- receiving layer is preferably from 0. 01 g/m2 to 5 g/nr', more preferably from 0. 1 g/rn to 3 g/m2.

In the invention, in the case where the aforementioned hydrogen-bonding group is connected to the dye, it can be introduced as a water-soluble moiety of the dye molecule, can be introduced via a connecting group or can be separately introduced as a part of the molecule.

In the case where as the dyes there are used dyes other than the dye of the invention in combination of the dye of the invention, the amount of the dye of the invention to be used is preferably from 20 to 100% by weight, more preferably from 30 to 100% by weight based on the total weight of the dyes to be incorporated in the ink.

In order to intensify the hydrogen bond, the image-receiving material preferably comprises a compound having a structure having a hydrogen-bonding group that induces hydrogen bond.

This compound may be separately added in the form of a special compound or may be previously contained in other materials (either low molecular compound or polymer) which are then incorporated in the image-receiving material.

Preferably, this compound is introduced in other polymer materials. It is particularly preferred that such a substituent be introduced in the structure of the mordant.

The content of the polymer, if contained in the mordant, is from 0. 01 to 90%, preferably from 0. 1 to 70% by mol.

The effect of the invention is exerted between the dye substituted stereospecifically by a plurality of hydrogen-bonding dissociative groups and the image-receiving material comprising a dye-fixing material having a dye-accepting structure in its molecule. It is further preferred that an image-receiving material comprising an organic amine-based mordant as a mordant be used.

Specific examples of these organic amine-based mordants will be given below, but the invention is not limited thereto.

The dyes to be used in the invention, including those represented by the general formulae (1-1) to (1-4), will be described hereinafter.

In the invention, a dye having an oxidation potential of more positive than 1. 0 V (more preferably more positive than 1. 1 V, particularly more positive than 1.15 V) is preferably used. The use of a dye having an oxidation potential of more positive than 1.0 V makes it possible to obtain an image excellent in durability, particularly ozone resistance.

The oxidation potential (Eox) can be easily measured by those skilled in the art. For the details of the method for measuring the oxidation potential, reference can be made to P. Delahay,"New Instrumental Methods in Electrochemistry", 1954, Interscience Publishers, A. J. Bard et al, "Electrochemical Methods", 1980, John Wiley & Sons, and Akiya Fujishima, "Denki Kagaku Sokuteiho (Electrochemical Measuring Methods) ", 1984, Gihodo Shuppansha.

In some detail, the measurement of oxidation potential is carried out by dissolving the test specimen in a solvent such as dimethylformamide and acetonitrile containing a supporting electrolyte such as sodium perchlorate and tetrapropylammonium perchlorate in a concentration of from 1 x 10-2 to 1 x 10-6 mol/1, and then measuring the test solution for oxidation potential with respect to SCE (saturated calomel electrode) using cyclic voltammetry. This value may deviate by scores of millivolts due to the effect of difference in potential between solutions or resistivity of test solution. However, the incorporation of a standard specimen (e. g., hydroquinone) makes it possible to assure the reproducibility of potential. In order to unequivocally define potential, the potential (vs SCE) measured in dimethylformamide containing 0. 1 mol dns 3 of tetrapropylammonium perchlorate as a supporting electrolyte (concentration of dye: 0. 001 mol die) is defined as oxidation potential of dye. There are some cases where a water-soluble dye can be difficultly dissolved directly in N, N-dimethyl formamide. In this case, water is used in an amount as small as possible to dissolve the dye. The dye solution is diluted with N, N-dimethylformamide so that the water content is 2% or less, and then measured.

The value of oxidation potential Eox indicates the transferability of electrons from the specimen to the electrode. The greater this value is (the more positive the oxidation potential is), the more difficultly can be transferred electrons from the specimen to the electrode, i. e. , the more difficultly can be oxidized the specimen.

With regard to the structure of the compound, the incorporation of electron-withdrawing group causes the oxidation potential to be more positive while the incorporation of electron-donative group causes the oxidation potential to be more negative.

Examples of dyes having the aforementioned properties include azo dyes (yellow dye, magenta dye, black dye) and phthalocyanine dyes (cyan dye) having specific properties and structures. These dyes will be described hereinafter.

[Yellow dye] The yellow dye to be used in the invention preferably has an oxidation potential of more positive than 1. 0 V (vs SCE), more preferably more positive than 1. 1 V (vs SCE), particularly more positive than 1. 15 V (vs SCE) from the standpoint of fastness, particularly to ozone gas. As such a yellow dye, an azo dye satisfying the aforementioned requirements is particularly preferred.

As a dye satisfying these oxidation potential and absorption characteristics there is preferably used one represented by the following general formula (1-1). general formula (l-l) : (Azz-N=N-Bll) n-L In the general formula (1-1), All and Bil each independently represent a heterocyclic group which may be substituted. The heterocyclic group is preferably a heterocyclic group formed by a 5-membered or 6- membered ring. The heterocyclic group may have a monocyclic structure or a polycyclic structure formed by the condensation of two or more rings or may be an aromatic heterocyclic group or non-aromatic heterocyclic group. As hetero atoms constituting the aforementioned heterocyclic group there are preferably used nitrogen, oxygen and sulfur atoms. The suffix n represents an integer 1 or 2, preferably 2. L represents a substituent bonded to All or Bll at arbitrary position, with the proviso that when n is 1, L represents a hydrogen atom or monovalent substituent and when n is 2, L represents a mere bond or divalent connecting group.

Preferred examples of the heterocyclic group represented by All in the general formula (1-1) include 5- pyrazolone, pyrazole, triazole, oxazolone, isooxazolone, barbituric acid, pyridone, pyridine, rhodanine, pyrazolinedione, pyrazolopyridone, Meldrum's acid, and condensed heterocyclic group having an aromatic hydrocarbon ring or heterocyclic group condensed to these heterocyclic groups. Preferred among these heterocyclic groups are 5-pyrazolone, 5-aminopyrazole, pyridone, 2,6-diaminopyridine, and pyrazoloazoles.

Particularly preferred among these heterocyclic groups are 5-aminopyrazole, 2-hydroxy-6-pyridone, 2,6- diaminopyridine, and pyrazoloazoles.

Examples of the heterocyclic group represented by B, I include pyridine, pyrazine, pyrimidine, pyridazine, triazine, quinoline, isoquinoline, quinazoline, cinnoline, phthaladine, quinoxaline, pyrrole, indole, furane, benzofurane, thiophene, benzothiophene, pyrazole, imidazole, benzoimidazole, triazole, oxazole, isoxazole, benzoxazole, thiazole, benzothiazole, benzothiazole, isothiazole, benzoisothiazole, thiadiazole, benzoisoxazole, pyrrolidine, piperidine, piperazine, imidazolidine, and thiazoline. Preferred among these heterocyclic groups are pyridine, quinoline, thiophene, pyrazole, imidazole, benzoimidazole, triazole, oxazole, isoxazole, benzoxazole, thiazole, benzothiazole, isothiazole, benzoisothiazole, thiadiazole, and benzoisoxazole.

More desirable among these heterocyclic groups are quinoline, thiophene, pyrazole, benzoxazole, benzoisoxazole, isothiazole, imidazole, benzothiazole, and thiadiazole. Particularly preferred among these heterocyclic groups are pyrazole, benzoxazole, benzoxazole, imidazole, 1,2, 4-thiadiazole, and 1,3, 4-thiadiazole.

Examples of the substituents on An and Bu include halogen atoms, alkyl groups, cycloalkyl groups, aralkyl groups, alkenyl groups, alkinyl groups, aryl groups, heterocyclic groups, cyano groups, hydroxyl groups, nitro groups, alkoxy groups, aryloxy groups, silyloxy groups, heterocyclic oxy groups, acyloxy groups, carbamoyloxy groups, alkoxycarbonyloxy groups, aryloxycarbonyloxy groups, amino groups, acylamino groups, aminocarbonylamino groups, alkoxycarbonylamino groups, aryloxycarbonylamino groups, sulfamoylamino groups, alkylsulfonylamino groups, arylsulfonylamino groups, mercapto groups, alkylthio groups, arylthio groups, heterocyclic thio groups, sulfamoyl groups, alkylsulfinyl groups, arylsulfinyl groups, alkylsulfonyl groups, arylsulfonyl groups, acyl groups, aryloxycarbonyl groups, alkoxycarbonyl groups, carbamoyl groups, imide groups, phosphino groups, phosphinyl groups, phosphinyloxy groups, phosphinylamino groups, silyl groups, and the following ionic hydrophilic groups.

Examples of the monovalent substituent represented by L include the aforementioned substituents on An and Bm, and the following ionic hydrophilic groups. Examples of the divalent connecting group represented by L include alkylen group, arylene group, heterocyclic residue,-CO-,-SOn- (in which n is 0,1 or 2),-NR- (in which R represents a hydrogen atom, alkyl group or aryl group),-0-, and divalent group comprising these groups in combination. These groups may have substituents exemplified with reference to the substituents on A1 i and Bi i or the following ionic hydrophilic groups.

The dye of the general formula (1-1), if used as a water-soluble dye, preferably has at least one ionic hydrophilic group incorporated therein per molecule. Examples of the ionic hydrophilic group include sulfo groups, carboxyl groups, phosphono groups, and quaternary ammonium groups. Preferred among these ionic hydrophilic groups are carboxyl groups, phosphono groups, and sulfo groups. Particularly preferred among these ionic hydrophilic groups are carboxyl groups and sulfo groups. The carboxyl groups, phosphono groups and sulfo groups may be in the form of salt. Examples of the counter ion forming the salt include ammonium ion, alkaline metal ion (e. g. , lithium ion, sodium ion, potassium ion), and organic cation (e. g., tetramethylammonium ion, tetramethylguanidium ion, tetramethylphosphonium ion). Preferred among these counter ions are alkaline metal salts.

Preferred among the dyes represented by the general formula (1-1) are those having All-N=N-B moiety corresponding to the general formula (1-A), (1-B) or (1-C). general formula (1-A) wherein R, and R3 each represent a hydrogen atom, cyano group, alkyl group, cycloalkyl group, aralkyl group, alkoxy group, alkylthio group, arylthio group, aryl group or ionic hydrophilic group; R2 represents a hydrogen atom, alkyl group, cycloalkyl group, aralkyl group, carbamoyl group, acyl group, aryl group or heterocyclic group ; and R4 represents a heterocyclic group. general formula (1-B) wherein Rs represents a hydrogen atom, cyano group, alkyl group, cycloalkyl group, aralkyl group, alkoxy group, alkylthio group, arylthio group, aryl group or ionic hydrophilic group; Za represents-N=,-NH-or- C (RI) =; Zb and Zc each independently represent-N= or-C (Rl) in which R, 1 represents a hydrogen atom or non-metallic substituent; and R6 represents a heterocyclic group. general formula (1-C) wherein R ? and Rg each independently represent a hydrogen atom, cyano group, alkyl group, cycloalkyl group, aralkyl group, aryl group, alkylthio group, aryltllio group, alkoxycarbonyl. group, carbamoyl group or ionic hydrophilic group; Rs represents a hydrogen atom, halogen atom, alkyl group, alkoxy group, aryl group, aryloxy group, cyano group, acylamino group, sulfonylamino group, alkoxycarbonylamino group, ureido group, alkylthio group, arylthio group, alkoxycarbonyl group, carbamoyl group, sulfamoyl group, alkylsulfonyl group, arylsulfonyl group, acyl group, amino group, hydroxy group or ionic hydrophilic group; and Rio represents a heterocyclic group.

In the general formulae (1-A), (1-B) and (1-C), the alkyl groups represented by Rl, R2, R3, R5, R7, Rs and Rg contain a substituted or unsubstituted alkyl group. These alkyl groups each preferably have from 1 to 20 carbon atoms. Examples of the aforementioned substituents include hydroxyl groups, alkoxy groups, cyano groups, halogen atoms, and ionic hydrophilic groups. Examples of the aLkyl groups include methyl, ethyl, butyl, isopropyl, t-butyl, hydroxyethyl, methoxyethyl, cyanoethyl, trifluoromethyl, 3-sulfopropyl, and 4-sulfobutyl.

The cycloalkyl groups represented by Rl, R2, R3, R5, R7, R8 and Rg include a substituted or unsubstituted, cycloalkyl group. These cycloalkyl groups each preferably have from 5 to 12 carbon atoms.

Examples of the substituents on the cycloalkyl group include ionic hydrophilic groups. Examples of the cycloalkyl group include cyclohexyl groups. Examples of the aralkyl groups represented by Rl, R2, R3, R5, R7, and Rg include substituted and unsubstituted araLkyl groups. These aralkyl groups each preferably have from 7 to 20 carbon atoms. Examples of the substituents on the aralkyl group include ionic hydrophilic groups.

Examples of the aralkyl group include benzyl, and 2-phenethyl.

Examples of the aryl groups represented by Rl, R2, R3, R5, R7, Rs and Rg include substituted and unsubstituted aryl groups. These aryl groups each preferably have from 6 to 20 carbon atoms. Examples of the substituents on the aryl group include alkyl groups, alkoxy groups, halogen atoms, alkylamino groups, and ionic hydrophilic groups. Examples of the aryl group include phenyl, p-tollyl, p-methoxyphenyl, o-chlorophenyl, and m- (3-sulfopropylamino) phenyl.

Examples of the alkylthio groups represented by Rl, R2, R3, R5, R7, RS and Rg include substituted and unsubstituted alkylthio groups. These alkylthio groups each preferably have from 1 to 20 carbon atoms.

Examples of the substituents on the alkylthio group include ionic hydrophilic groups. Examples of the alkylthio group include methylthio, and ethylthio group. Examples of the arylthio groups represented by Ri, R2, R3, R5, R7, Rs and Rg include substituted and unsubstituted arylthio groups. These arylthio groups each preferably have from 6 to 20 carbon atoms. Examples of the substituents on the arylthio group include alkyl groups, and ionic hydrophilic groups. Examples of the arylthio group include phenylthio, and p-tolylthio group.

The heterocyclic group represented by R2 preferably is a 5-or 6-membered heterocyclic group which may be further condensed. Preferred examples of the hetero atoms constituting the heterocyclic group include nitrogen, sulfur and oxygen atoms. The heterocyclic groups may be aromatic or non-aromatic. These heterocyclic groups may be further substituted. Examples of the substituents on the heterocyclic group include those listed with reference to the aryl group described later. Preferred examples of the heterocyclic groups include a 6-membered nitrogen-containing aromatic heterocyclic group. Particularly preferred examples of such a 6-membered nitrogen-containing aromatic heterocyclic group include triazine, pyrimidine, and phthaladine.

Examples of the halogen atom represented by Rs include fluorine atom, chlorine atom, and bromine atom.

Examples of the alkoxy groups represented by Rl, R3, R5 and Rs include substituted and unsubstituted alkoxy groups. These alkoxy groups each preferably have from 1 to 20 alkoxy groups. Examples of the substituents include hydroxyl groups, and ionic hydrophilic groups. Examples of the alkoxy groups include methoxy, ethoxy, isopropoxy, methoxyethoxy, hydroxyethoxy, and 3-carboxypropoxy.

Examples of the aryloxy group represented by Rs include substituted and unsubstituted aryloxy groups.

These aryloxy groups each preferably have from 6 to 20 carbon atoms. Examples of the substituents on the aryloxy group include alkoxy groups, and ionic hydrophilic groups. Examples of the aryloxy groups include phenoxy, p-methoxyphenoxy, and o-methoxyphenoxy.

Examples of the acylamino group represented by Rs include substituted and unsubstituted acylamino groups. These acylamino groups each preferably have from 2 to 20 carbon atoms. Examples of the substituents on the acylamino group include ionic hydrophilic groups. Examples of the acylamino group include acetamid, propionamide, benzamid, and 3, 5-disulfobenzamide.

Examples of the sulfonylamino group represented by Rs include alkylsulfonylamino group, arylsulfonyl group, and heterocyclic sulfonylamino group. The alkyl moiety, aryl moiety and heterocyclic moiety of these sulfonylamino groups may have substituents. Examples of the aforementioned substituents include those exemplified with reference to the aryl group. These sulfonylamino groups each preferably have from 1 to 20 carbon atoms. Examples of the sulfonylamino group include methylsulfonylamino, and ediylsulfbnylamino.

Examples of the alkoxycarbonylamino group represented by Rs include substituted and unsubstituted alkoxycarbonylamino groups. These alkoxycarbonylamino groups each preferably have from 2 to 20 carbon atoms. Examples of the substituents on the alkoxycarbonylamino group include ionic hydrophilic groups.

Examples of the alkoxycarbonylamino group include ethoxycarbonylamino.

Examples of the ureido group represented by Rs include substituted and unsubstituted ureido groups.

These ureido groups each preferably have from 1 to 20 carbon atoms. Examples of the substituents on the ureido group include alkyl groups, and aryl groups. Examples of the ureido group include 3-methylureido group, 3, 3-dimethylureido group, and 3-phenylureido group.

Examples of the alkoxycarbonyl groups represented by Rv, R8 and R9 include substituted and unsubstituted alkoxycarbonyl groups. These alkoxycarbonyl groups each preferably have from 2 to 20 carbon atoms. Examples of the substituents on the alkoxycarbonyl group include ionic hydrophilic groups. Examples of the alkoxycarbonyl group include methoxycarbonyl, and ethoxycarbonyl.

Examples of the carbamoyl groups represented by R2, R7, R8 and R9 include substituted and unsubstituted carbamoyl groups. Examples of the substituents on the carbamoyl group include alkyl groups.

Examples of the carbamoyl group include methylcarbamoyl group, and dimethylcarbamoyl group.

Examples of the sulfamoyl group represented by Rg include substituted and unsubstituted sulfamoyl groups. Examples of the substituents on the sulfamoyl group include alkyl groups. Examples of the sulfamoyl group include dimethylsulfamoyl group, and di- (2-hydroxyethyl) sulfamoyl group.

Examples of the alkylsulfonyl group represented by Rs include alkylsulfonyl group, arylsulfonyl group and heterocyclic sulfonyl group which may further have substituents. Examples of these substituents include ionic hydrophilic groups. Examples of these sulfonyl groups include methylsulfonyl, and phenylsulfonyl.

Examples of the acyl groups represented by R2 and Rs include substituted and unsubstituted acyl groups. These acyl groups each preferably have from 1 to 20 carbon atoms.

Examples of the substituents on the acyl group include ionic hydrophilic groups. Examples of the acyl group include acetyl, and benzoyl.

Examples of the amino group represented by R8 include substituted and unsubstituted amino groups.

Examples of the substituents on the amino group include alkyl groups, aryl groups, and heterocyclic groups.

Examples of the amino group include methylamino, diethylamino, anilino, and 2-chloroanilino.

The heterocyclic groups represented by R4, R6 and RIO are the same as the heterocyclic groups represented by Bn in the general formula (1-1) which may be substituted. Preferred examples of the heterocyclic groups include those listed with reference to Bol in the general formula (1-1). Even more desirable examples of the heterocyclic groups include those listed with reference to Bll in the general formula (1-1).

Particularly preferred examples of the heterocyclic groups include those listed with reference to Bol in the general formula (1-1). Examples of the substituents on the heterocyclic group include ionic hydrophilic groups, Cl-C12 alkyl, aryl and arylthio groups, halogen atoms, cyano groups, sulfamoyl groups, sulfonamide groups, carbamoyl groups, and acylamino groups. These allyl and aryl groups may further contain substituents.

In the general formula (1-B), Za represents-N=,-NH-or-C (Ri) =. Zb and Zc each independently represent-N= or-C (Ru) = in which R, I represents a hydrogen atom or non-metallic substituent Preferred examples of the non-metallic substituent represented by Ru include cyano groups, cycloalkyl groups, araLkyl groups, aryl groups, alkylthio groups, arylthio groups, and ionic hydrophilic groups. These substituents each have the same meaning as those represented by Ri. Preferred examples of these substituents include those listed with reference to RI. Examples of the skeleton of the heterocyclic group composed of two 5-membered rings contained in the general formula (1-B) will be given below.

Examples of the substituents on the aforementioned substituents which may further have substituents include substituents which may substitute the heterocyclic groups All and BI, in the general formula (1-1).

Preferred among the dyes of the general formulae (1-A), (1-B) and (1-C) are those represented by the general formula (1-A). Particularly preferred among the dyes of the general formula (1-A) is one represented by the following general formula (1-Al). general formula (1-Al) : wherein R2'and R23 each represent a hydrogen atom, alkyl group, cycloalkyl group, alkoxy group or aryl group; R2 represents an aryl group or heterocyclic group ; and one of X and Y represents a nitrogen atom and the other represents-CR24 in which R24 represents a hydrogen or halogen atom or a cyano, alkyl, alkylthio, alkylsulfonyl, alkylsulfinyl, alkyloxycarbonyl, carbamoyl, alkoxy, aryl, arylthio, arylsulfonyl, arylsulfinyl, aryloxy or acylamino group. Preferred among these substituents are hydrogen atom, alkyl group, arylthio group, and aryl group. Particularly preferred among these substituents are hydrogen atom, alkylthio group, and aryl group.

These substituents each may be further substituted.

Preferred examples of the dye to be used in the invention include those disclosed in Japanese Patent Application No. 2003-286844, Japanese Patent Application No. 2002-211683, Japanese Patent Application No.

2002-124832, JP-A-2003-128953, and JP-A-2003-41160. Preferred among these dyes are those exemplified below. The dyes employable herein are not limited to these examples. These compounds can be synthesized according to JP-A-2-24191 and JP-A-2001-279145. H-N N-N t-CH9 N=N--, SL-s--N=N CdFle-t Dye H H ry Z, Dye L M Dye L M 1 SCH2CH2H Na 2-SCH2CH2s-Li 3-SCH2CH2CH2S-Na 4 SCH2CHzCH2S K 5-SCH2CH2CH2S- 6-SCHzCH2CH2S-NH4 - SCH2CHCHZS-HN (E t) s 8-SCH2yHS-Na 8 CH3 Na 3 9-SCH2CH20CH2CH2S-Na 10 8H Na 10-SCH2HCHZS- OH CHQH ll SCH2CHS Na cana -SCH2CHS 13 Na 14- -NHCONH- -Na R N=NX VLX VN=N R hd s s H NH2 H2N N i i Ar Ar Dye Ar L R 15 -SCH2CH2CH2S-t-C4H9 c02Na COa 16. -SCHCHS-t-Cg- Na0a5 NaO2 N^N COZNe 17 ! N\N/'WN-SCH2CH2CH2S-t-C4H9 H Na02C'C02Na a ; CDNA --SCH2CH2S- t-C4H9 H H Na02C C02Ne NaOlC NON C02Na 19 N CH2CH2CH2CH2 tC4Hg H H NaO2C CO2Na Na02G HN COiNe S5- 20 XN<NlNt N+N tC4Hg \-/H H \y i us H < NHC2H*SO3Na NaO2C CO2Na 21 ß SCH2CH2CH2S Ph NaO2C C02Na 22 < SCH2CH2CH2S t-C4H9- niHNH NC8HI7 _ - SCHzCHzS--t-C4H9 1 (C4Hg) 2N N N (G4H) 2 -IrLYN t-C, H, N=M- ! ! h -N=M C-t I 1 s l \ INC v \I, W r Na02 CO2Na NaOzC \ COzNa Dye L 24-SCH2CH2CH2S- 25 R N=N-Ar R N=N-Ar N N. NH2 N NH2 I L L L L Dye Ar L R S% Ha N-N SDAK $ Sonna N-N SK N sou S03K SOa 28 SN, v t'4Hs so, re so, a 29, N c"=c4i Hg7 soe - nua Su, mua SU, K so s 31 SC. H, -n t-C4HO7 s 32 s N t-C4H97 32 s J" N t-C, H.,- (C"M"MHC, H, NHN-"N (C, H R N=N-Ar R N=N-Ar N NH2 $NH2 I i L Dye Ar L R pp NN COK I N''"2"N "2 T-kHz N Dye COIK NaOzC N^N COzHe N. N CZNa -SCH3 N-j-N :--NH-NH-z*N-KN H NaOzC COzNa C02Na N NHC NH t-C zu S N N \ NaO2C 2M N (CH2C02Na) 2 3S s N » \9NHG2H4NH< t C4H R1 N=N-Ar /ruz NuN NH2 N'l-N N'N N=N-AR N R1 Dye Ar R 1 R2 cozy 36-JN t-C, H,---Q cl, K CO ; K SCCOa 37 j/N t-C4H9-NHC2H4S03Na s, N M-K 38 vs} Ph NHCl2H259 s t-C4H9 N=N-Ar I NH N z IJL H2 C4Hg-t - C, hot Dye Ar R 39 <) N {So ; ¢Na SOJNa - nu Somma Ph GOIK SONa Ph 40, -NH 40 N NH s'02K 41 -SCH2C02Na-NHC2H4S03Na S CON 42-NH02H4SO3Na CN CH2C02Na GO, AA 43 s--SCH, C0, Na NH-0 S 002NO C02Na N-N 4--S-SCHC02Na- NH Ph CO2Na CORNA pu 45 S C2H5 $ S t-C4H9 N=N-Ar N,, N NH2 R (N1R M-N N'\ N I Dye Ar R 46 As/N NHC2H4S03Na SU 47 4°7 S C02K Cl, K 48 NH-- S S03f ( 49-N N-N (CH2C02Na) z s Ph oh 50/NJ 1\-NH cana Na CDa 51 CNCOa - na N Corna CN Co2Na - nu 52 CON CH2C02Na sO2Na 53 ~<S) <COIN : ¢ C02Na 02nua 53 Colza C02Na 54 -NH S C02Na tZ4Hg N=NAr oN NH2 N""--N A NR DyeArR D e Ar R C02Na CO2Na 55 N-N-NH S -CO, Na CO2Na N-N 57 CO, Na'A=/ COa COzNa C02Na 57 N-N- ti8 -SCH2cHme2 COTA corna N-N cota zu S corna S03L I S0. i S soi C02'NH N-N 60--- SCH2CHMe2-NH J S C02 NH N-N 61- JSCHCHMe-NHCgH. n S y-N (CHC), S'N zHs COH, CO2C6H13 63/N-N-NHC6Hya R1 N=N-Ar NoN) NH2 2 R2 Dye Ar R 1 R2 N-\-/ 64 N t-C4H9-/\ S COjK SC2H4SONa So, Na 65 N 1N//\ S somma Pu Ph sane t C H9/ S SOYA NNT' N-N so3Ha 67 AS) t-C4H9-a No CH3 S03Na HC CH3 so3ta 68 t-C4Hg S SO, Na 69 S02NHCJZHZ $ N-N 70 H t-C4Hg-CON (C4Hg) 2 Ph CON (C4HO) 2 CON (C4H9) z 71 N t-04H97 coN (c H) Asz H/" 72 t-04Hg- S zeHn The content of the yellow dye represented by the general formula (1-1) in the ink is preferably from 0.2 to 20% by weight, more preferably from 0.5 to 15% by weight.

[Cyan dye] The phthalocyanine dye which is a cyan dye will be further described hereinafter.

The phthalocyanine dye to be used in the invention preferably is excellent in both light-resistance and ozone resistance and has little change of hue and surface conditions (little bronzing and dye precipitation).

Referring to light-resistance, it is desired that the ink show a light-resistance of not smaller than 90% as calculated in terms of percent dye remaining in 3 days when exposed to light from a Xenon lamp at Xe: 1.1 W/m (intermittent) through a TAC filter to a site on a PM photographic image-receiving paper produced by EPSON CO. , LTD (reflection density after irradiation/initial concentration x 100) where the reflection density OD is 1.0. It is also desired that the ink show a percent dye remaining of not smaller than 85% in 14 days.

The measure of change of hue and surface conditions is the amount of Cu ions present as phthalate after the decomposition of phthalocyanine dye. The amount of Cu compounds present on the actual print is preferably predetermined to be 10 mg/rn or less as calculated in terms of Cu ion. Referring to the amount of Cu ions to be eluted from the print, the amount of Cu ions to be eluted with water from a solid image containing Cu compounds in an amount of 20 mg/m2 or less as calculated in terms of Cu ion which has been stored in 5 ppm ozone atmosphere for 24 hours to undergo ozone fading is preferably 20% or less. All Cu compounds are trapped by the image-receiving material before fading.

A phthalocyanine dye having the aforesaid physical properties is obtained by 1) raising the oxidation potential, 2) enhancing the associatiability, 3) introducing an association-accelerating group or strengthening hydrogen bond during ir-7i stacking, 4) avoiding the introduction of substituents in a-position, i. e. , facilitating stacking, or by other methods.

The structural characteristic of the phthalocyanine dye to be used in the ink composition is that a phthalocyanine dye the number and position of substituents on which can be predetermined is used while the phthalocyanine dye which has been used in the related art inks is a mixture the number and position of substituents on which cannot be predetermined because it is derived by sulfonation of unsubstituted phthalocyanine.

A first structural characteristic is that the phthalocyanine dye of the present invention is a phthalocyanine dye obtained without sulfonation of unsubstituted phthalocyanine. A second structural characteristic is introduction of electron-withdrawing group into ¢-position of benzene rings of phthalocyanine, particularly into all benzene rings. In some detail, those substituted on sulfonyl group (JP-A-2002-249677, JP- A-2003-119415), those substituted on all sulfamoyl groups (JP-A-2002-302623, JP-A-2003-3109), those substituted on heterocyclic sulfamoyl group (JP-A-2002-294097, JP-A-2003-3086), those substituted on heterocyclic sulfonyl group (JP-A-2002-275386, JP-A-2003-3099), those substituted on specific sulfamoyl group (JP-A-2002-256167), those substituted on carbonyl group (JP-A-2003-213153), and those having specific substituents for enhancing solubility and ink stability and preventing bronzing are preferred, and in more detail, those having asymmetric carbon (JP-A-2003-213168), and those in the form of Li salt (JP-A-2003-213167).

Further, a first physical characteristic of the phthalocyanine dye of the present invention is that it has a high oxidation potential (more positive than 1.0 V). A second physical characteristic of the phthalocyanine dye of the present invention is that the phthalocyanine dye of the present invention has a strong associatiability.

Specific examples of such a phthalocyanine dye include those having a specified associatiability of oil-soluble dye (JP-A-2001-342373), and those having a specified associatiability of water-soluble dye (JP-A-2002- 309118).

Referring to the relationship between the number and properties (ink absorbance) of associatiable groups, the introduction of associatiable groups makes it more likely that the drop of absorbance can occur and kmax can appear in shorter wavelength range even in a dilute solution. Further, referring to the relationship between the number and properties (reflection density OD on PM920 image-receiving paper produced by EPSON CO., LTD.) of associatiable groups, the more the number of associatiable groups is, the lower is the reflection density OD at the same ion intensity. In other words, it is thought that association proceeds on the image-receiving paper. Referring to the relationship between the number and properties (ozone resistance, light-resistance) of associatiable groups, the more the number of associatiable groups is, the better is ozone resistance. A dye having many associatiable groups tends to have improved light-resistance as well. In order to provide ozone resistance, it is necessary that the benzene rings of phthalocyanine be provided with substituents.

Since there is a trade-off relation between reflection density OD and fastness, it is necessary that light-resistance be raised without weakening associatiability.

Preferred embodiments of the cyan ink of the present invention comprising a phthalocyanine dye having the aforesaid characteristics are as follows.

1) Cyan ink having a percent dye remaining of 90% or more as measured after 3 days of irradiation with xenon light (Xe: 1.1 W/m (intermittent) through TAC filter at the site on an image printed on a PM photographic image-receiving paper produced by EPSON Co. , Ltd. where the reflection density OD is 1. 0.

2) Cyan ink having a percent dye remaining of 60% or more (preferably 80% or more) as measured after 24 hours of storage in 5 ppm atmosphere at the site where printing has been made such that the reflection density is from 0.9 to 1.1 as measured through a status A filter.

3) Cyan ink which allows Cu ions to be eluted with water in an amount of 20% or less based on the total amount of dyes after ozone fading under the conditions of Clause 2.

4) Cyan ink which can penetrate a specific image-receiving paper to a depth of up to 30% of the upper portion of image-receiving layer.

As a dye having the aforementioned characteristics there may be used a phthalocyanine dye represented by the aforesaid general formula (1-2).

A phthalocyanine dye has been known as a fast dye but is known to have a poor fastness to ozone gas when used as an ink jet recording dyestuff.

In the present invention, it is preferred that an electrophilic group be introduced into the phthalocyanine skeleton to make the oxidation potential more positive than 1.0 V (vs SCE) as previously mentioned. Thus, the introduction of a substituent having a great Hammett's substituent constant op (a measure of the electrophilicity or electron-donating properties of substituents) such as sulfinyl group, sulfonyl group and sulfamoyl group makes it possible to make the oxidation potential more positive.

For the reason of potential adjustment, too, a phthalocyanine dye represented by the aforesaid general formula (1-2) is preferably used.

The phthalocyanine dye represented by the aforementioned general formula (1-2) will be further described hereinafter.

In the general formula (1-2), X21, X22, X23 and X24 each independently represent-SO-Z2,-SO2-Zz,- SO2NR2IRzz, sulfo group,-CONR2lR22 or-CO2R21. Preferred among these substituents are-SO-Z2,-SOz-Zz,- SO2NR21R22, and-CONR2lR22, particularly-SO2-Z2 and-SOzNRziRzz, most preferably-SOz-Z2. Herein, in the case where any one of a21 to a24 represents an integer of 2 or more, X2l to X24, if they are plural, may be the same or different and each independently represent any of the aforesaid groups. Further, X21, X22, X23 and X24 may be the same substituent or may all be the same but partially different substituents such as-SO2-Z2 in which Z2 is different among X21 to X24 or may be different substituents, e. g.,-SO2-Zz and-SO2NR21R22.

The aforesaid groups Z2 each independently represent substituted or unsubstituted alkyl group, substituted or unsubstituted cycloalkyl group, substituted or unsubstituted alkenyl group, substituted or unsubstituted aralkyl group, substituted or unsubstituted aryl group and substituted or unsubstituted heterocyclic group. Preferred among these groups are substituted or unsubstituted alkyl group, substituted or unsubstituted aryl group and substituted or unsubstituted heterocyclic group, and particularly preferred among these groups are substituted alkyl group, substituted aryl group and substituted heterocyclic group. 0 The aforesaid groups R2, and R22 each independently represent a hydrogen atom, substituted or unsubstituted alkyl group, substituted or unsubstituted cycloaLkyl group, substituted or unsubstituted alkenyl group, substituted or unsubstituted aralkyl group, substituted or unsubstituted aryl group or substituted or unsubstituted heterocyclic group. Preferred among these groups are hydrogen atom, substituted or unsubstituted alkyl group, substituted or unsubstituted aryl group or substituted or unsubstituted heterocyclic group, and particularly preferred among these groups are hydrogen atom, substituted alkyl group, substituted aryl group or substituted heterocyclic group. However, it is not preferred that R21 and R22 are a hydrogen atom at the same time.

The substituted or unsubstituted alkyl group represented by R21, R22 or Zz is preferably a C1-C30 aLkyl group. Particularly from the reason of enhancement of dye solubility or ink stability, the alkyl group is preferably branched, and it is particularly preferred that the alkyl group have asymmetric carbons (used in racemate form). Examples of the substituents on the alkyl group include those listed with reference to the case where Z2, R21, R22, Y21, Y22, Y23 and Y24 are able to have further substituents as described later. Particularly preferred among these substituents are hydroxyl group, ether group, ester group, cyano group, amide group and sulfonamide group because they enhance the association of dyes and hence the fastness thereof. Alternatively, the alkyl group may have a halogen atom or ionic hydrophilic group. The number of carbon atoms in the alkyl group does not include that of carbon atoms in the substituents. This can apply to other groups.

The substituted or unsubstituted cycloalkyl group represented by Rzi, R22 or Z2 is preferably a C5-C3o cycloalkyl group. Particularly from the reason of enhancement of dye solubility or ink stability, it is particularly preferred that the cycloalkyl group have asymmetric carbons (used in racemate form). Examples of the substituents on the cycloalkyl group include those listed with reference to the case where Z2, R21, R22, Y21, Y22, Y23 and Y24 are able to have further substituents as described later. Particularly preferred among these substituents are hydroxyl group, ether group, ester group, cyano group, amide group and sulfonamide group because they enhance the association of dyes and hence the fastness thereof. Alternatively, the cycloalkyl group may have a halogen atom or ionic hydrophilic group.

The substituted or unsubstituted alkenyl group represented by R2,, R22 or Zz is preferably a C2-C30 alkenyl group. Particularly from the reason of enhancement of dye solubility or ink stability, the alkenyl group is preferably branched. It is particularly preferred that the alkenyl group have asymmetric carbons (used in racemate form). Examples of the substituents on the alkenyl group include those listed with reference to the case where Z2, R21, R22, Y21, Y22, Y23 and Y24 are able to have further substituents as described later.

Particularly preferred among these substituents are hydroxyl group, ether group, ester group, cyano group, amide group and sulfonamide group because they enhance the association of dyes and hence the fastness thereof. Alternatively, the alkenyl group may have a halogen atom or ionic hydrophilic group.

The substituted or unsubstituted aralkyl group represented by Rzi, R22 or Z2 is preferably a C7-C30 aralkyl group. Particularly from the reason of enhancement of dye solubility or ink stability, the araLkyl group is preferably branched. It is particularly preferred that the aralkyl group have asymmetric carbons (used in racemate form). Examples of the substituents on the aralkyl group include those listed with reference to the case where Z2, R21, Rzz, Yzi, Yzz, Y23 and Yz4 are able to have further substituents as described later.

Particularly preferred among these substituents are hydroxyl group, ether group, ester group, cyano group, amide group and sulfonamide group because they enhance the association of dyes and hence the fastness thereof. Alternatively, the aralkyl group may have a halogen atom or ionic hydrophilic group.

The substituted or unsubstituted aryl group represented by R21, R22 or Zz is preferably a C6-C30 aryl group. Examples of the substituents on the aryl group include those listed with reference to the case where Z2, R21, R22, Y21, Y22, Y23 and Y24 are able to have further substituents as described later. In particular, en electron- withdrawing group is preferred because it causes the oxidation potential of the dye to be higher and thus enhances the fastness thereof. Examples of the electron-withdrawing group include those having a positive Hammett's substituent constant op. Preferred examples of the electron-withdrawing group include halogen atom, heterocyclic group, cyano group, carboxyl group, acylamino group, sulfonamide group, sulfamoyl group, carbamoyl group, sulfonyl group, imide group, acyl group, sulfo group, and quaternary ammonium group.

Particularly preferred among these electron-withdrawing groups are cyano group, carboxyl group, sulfamoyl group, carbamoyl group, sulfonyl group, imide group, acyl group, sulfo group, and quaternary ammonium group.

The heterocyclic group represented by R21, Raz or Z2 is preferably a 5-or 6-membered heterocyclic group which may be further condensed. The heterocyclic group may be an aromatic heterocyclic group or non- aromatic heterocyclic group. The heterocyclic group represented by R21, R22 or Z2 will be exemplified in the form of heterocyclic ring with its substitution position omitted, but the substitution position is not limited and, for example, pyridine may have substituents on the 2-, 3-or 4-position. Examples of the heterocyclic ring include pyridine, pyrazine, pyrimidine, pyridazine, triazine, quinoline, isoquinoline, quinazoline, cinnoline, phthaladine, quinoxaline, pyrrole, indole, furane, benzofurane, thiophene, benzothiophene, pyrazole, imidazole, benzimidazole, triazole, oxazole, benzoxaole, thiazole, benzothiazole, isothiazole, benzisothiazole, thiadiazole, isooxazole, benzisooxazole, pyrrolidine, piperidine, piperazine, imidazolidine, and thiazoline. In particular, aromatic heterocyclic groups are preferred. Preferred examples of the aromatic heterocyclic groups include pyridine, pyrazine, pyrimidine, pyridazine, triazine, pyrazole, imidazole, benzimidazole, triazole, thiazole, benzothiazole, isothiazole, benzisothiazole, and thiadiazole. These aromatic heterocyclic groups may have substituents, and examples of the substituents on the aromatic heterocyclic group include those listed with reference to the case where Z2, R21, R22, Y21, Y22, Y23 and Y24 are able to have further substituents as described later. Preferred examples of the substituents include those listed with reference to the aforementioned aryl group, and even more desirable examples of the substituents include those listed with reference to the aforementioned aryl group.

Y2i, Y22, Y23 and Y24 each independently represent a hydrogen atom, halogen atom, alkyl group, cycloalkyl group, alkenyl group, aralkyl group, aryl group, heterocyclic group, cyano group, hydroxyl group, nitro group, amino group, alkylamino group, alkoxy group, aryloxy group, acylamino group, arylamino group, ureido group, sulfamoyl group, alkylthio group, arylthio group, alkoxycarbonylamino group, sulfonamide group, carbamoyl group, sulfamoyl group, sulfonyl group, alkoxycarbonyl group, heterocyclic oxy group, azo group, acyloxy group, carbamoyloxy group, silyloxy group, aryloxycarbonyl group, aryloxycarbonylamino group, imide group, heterocyclic thio group, phosphoryl group, acyl group, carboxyl group or sulfo group which may further have substituents.

Preferred among these groups are hydrogen atom, halogen atom, alkyl group, aryl group, cyano group, alkoxy group, amide group, ureido group, sulfonamide group, carbamoyl group, sulfamoyl group, alkoxycarbonyl group, carboxyl group and sulfo group, particularly hydrogen atom, halogen atom, cyano group, carboxyl group and sulfo group, most preferably hydrogen atom.

In the case where Z2, Rzi, R22, Y21, Y22, Y23 and Y24 may further have substituents, they may further have the following substituents.

Examples of the substituents on Z2, R21, R22, Y21, Y22, Y23 and Y24 include Cl-CI2 straight-chain or branched alkyl group, Cy-Cjg straight-chain or branched aralkyl group, C2-CI2 straight-chain or branched alkenyl group, C2-CI2 straight-chain or branched alkinyl group, C3-C12 straight-chain or branched cycloalkyl group, C3- C, 2 straight-chain or branched cycloalkenyl group (These groups each preferably have branches for the reason of dye solubility or ink stability. It is particularly preferred that these groups have asymmetric carbons. Specific examples of these groups include methyl group, ethyl group, propyl group, isopropyl group, sec-butyl group, t- butyl group, 2-ethylhexyl group, 2-methylsulfonylethyl group, 3-phenoxypropyl group, trifluoromethyl group, and cyclopentyl group), halogen atom (e. g. , chlorine atom, bromine atom), aryl group (e. g. , phenyl group, 4-t- butylphenyl group, 2,4-di-t-amylphenyl group), heterocyclic group (e. g., imidazolyl group, pyrazolyl group, triazolyl group, 2-furyl group, 2-thienyl group, 2-pyrimidinyl group, 2-benzothiazolyl group), cyano group, hydroxyl group, nitro group, carboxy group, amino group, alkyloxy group (e. g. , methoxy group, ethoxy group, 2-methoxyethoxy group, 2-methanesulfohykethoxy group), aryloxy group (e. g., phenoxy group, 2- methylphenoxy group, 4-t-butylphenoxy group, 3-nitrophenoxy group, 3-t-butyloxycarbamoylphenoxy group, 3- methoxy carbamoyl group), acylamino group (e. g. , acetamide group, benzamide group, 4- (3-t-butyl-4- hydroxyphenoxy) butanamide group), alkylamino group (e. g., methylamino group, butylamino group, diethylamino group, methylbutylamino group), anilino group (e. g., phenylamino group, 2-chloroanilino group), ureido group (e. g. , phenylureido group, memylureido group, N, N-dibutylureido group), sulfamoylamino group (e. g., N, N-dipropylsulfamoylamino group), alkylthio group (e. g. , methylthio group, octylthio group, 2- phenoxyethylthio group), arylthio group (e. g. , phenylthio group, 2-butoxy-5-t-octylphenylthio group, 2- carboxyphenylthio group), alkyloxy carbonylamino group (e. g., methoxycarbonylamino group), sulfonamide group (e. g., methanesulfonamide group, benzenesulfonamide group, p-toluenesulfonamide group), carbamoyl group (e. g. , N-ethylcarbamoyl group, N, N-dibutylcarbamoyl group), sulfamoyl group (e. g., N-ethylsulfamoyl group, N, N-dipropyl sulfamoyl group, N-phenylsulfamoyl group), sulfonyl group (e. g., methanesulfonyl group, octanesulfonyl group, benzenesulfonyl group, toluenesulfonyl group), alkyloxycaibonyl group (e. g., methoxycarbonyl group, butyloxycarbonyl group), heterocyclic oxy group (e. g., l-phenyltetrazole-5-oxy group, 2-tetrahydropyranyloxy group), azo group (e. g. , phenylazo group, 4-methoxyphenylazo group, 4- pivaloylaiuinophenylazo group, 2-hydroxy-4-propanoylphenylazo group), acyloxy group (e. g. , acetoxy group), carbamoyloxy group (e. g. , N-methylcarbamoyloxy group, N-phenylcarbamoyloxy group), silyloxy group (e. g., trimethylsilyloxy group, dibutylmethylsilyloxy group), aryloxycarbonylamino group (e. g., phenoxycarbonylamino group), imide group (e. g. , N-succinimide group, N-phthalimide group), heterocyclic thio group (e. g. , 2-benzothiazolylthio group, 2, 4-di-phenoxy-1, 3,5-triazole-6-thio group, 2-pyridylthio group), sulfinyl group (e. g., 3-phenoxypropylsulfinyl group), phosphonyl group (e. g., phenoxyphosphonyl group, octyloxyphosphonyl group, phenylphosphonyl group), aryloxycarbonyl group (e. g. , phenoxycarbonyl group), acyl group (e. g. , acetyl group, 3-phenylpropanoyl group, benzoyl group), and ionic hydrophilic group (e. g., carboxyl group, sulfo group, phosphono group, quaternary ammonium group).

The phthalocyanine dye represented by the general formula (1-2), if it is water-soluble, preferably has an ionic hydrophilic group. Examples of the ionic hydrophilic group include sulfo group, carboxyl group, phosphono group, and quaternary ammonium group. Preferred among these ionic hydrophilic groups are carboxyl group, phosphono group, and sulfo group, and particularly preferred among these ionic hydrophilic groups are carboxyl group and sulfo group. The carboxyl group, phosphono group and sulfo group may be used in the form of salt, and examples of the counter ion forming the salt include ammonium ion, alkaline metal ion (e. g., lithium ion, sodium ion, potassium ion), and organic cation (e. g. , tetramethylammonium ion, tetramethylguanidium ion, tetramethylphosphonium ion). Preferred among these counter ions are alkaline metal ions, and particularly preferred among these counter ions is lithium ion because it enhances the dye solubility and hence the ink stability.

The number of ionic hydrophilic groups is preferably at least 2 per molecule of phthalocyanine-based dye, and it is particularly preferred that there be contained at least two sulfo groups and/or carboxyl groups in the phthalocyanine-based dye.

In the general formula (1-2), the suffixes azl to a24 and b21 to b24 represent the number of the substituents X21 to X24 and Y21 to Y24, respectively. The suffixes aa, to a24 each independently represent an integer of from 0 to 4, with the proviso that the suffixes a21 to a24 are not 0 at the same time. The suffixes b2l to b24 each independently represent an integer of from 0 to 4. When any of a21 to a24 and b21 to b24 is an integer of 2 or more, there are a plurality of any of X21's to X24's and Y2l's to Y24's and they may be the same or different.

The suffixes azi and b21 satisfy the equation a21 + b21 = 4. In a particularly preferred combination, a21 represents 1 or 2 while b21 represents 3 or 2, and in the best combination, a21 represents 1 while b21 represents 3.

The combinations a22 and b22, a23 and b23, and a24 and b24 are similar to the combination of a21 and b21, and preferred examples of the combinations a22 and b22, a23 and b23, and a24 and b24 are also similar to that of the combination of a21 and b21.

M represents a hydrogen atom, metal element or oxide, hydroxide or halide thereof.

Preferred examples of M other than hydrogen atom include metal elements such as Li, Na, K, Mg, Ti, Zr, V, Nb, Ta, Cr, Mo, W, Mn, Fe, Co, Ni, Ru, Rh, Pd, Os, Ir, Pt, Cu, Ag, Au, Zn, Cd, Hg, Al, Ga, In, Si, Ge, Sn, Pb, Sb and Bi.

Preferred examples of metal oxide include VO, and GeO.

Preferred examples of metal hydroxide include Si (OH) 2, Cr (OH)2, and Sn (OH) 2.

Examples of metal halide include AICI, SiC12, VCI, VClz, VOCl, FeCl, GaCl, and ZrCl.

Preferred among these metal elements are Cu, Ni, Zn, and Al, most preferably Cu.

In the phthalocyanine dye represented by the general formula (1-2), Pc (phthalocyanine ring) may form a dimer (e. g. , Pc-M-L-M-Pc) or trimer with L (divalent connecting group) interposed therebetween, and in this case, M's may be the same or different.

Preferred examples of the divalent connecting group represented by L include oxy group-0-, thio group-S-, carbonyl group-CO-, sulfonyl group -SO2-, imino group-NH-, methylene group-CH2-, and group formed by combining these groups.

Referring to preferred combination of substituents on the compound represented by the general formula (1-2), the compound of the general formula (1-2) preferably has various substituents at least one of which is one of the preferred groups listed above, and more preferably, more of the various substituents are the preferred groups listed above, and most preferably, all of the various substituents are the preferred groups listed above.

Preferred among the phthalocyanine dyes represented by the general formula (1-2) is a phthalocyanine dye having the structure represented by the aforesaid general formula (1-5). The phthalocyanine dye represented by the general formula (1-5) of the invention will be described in detail hereinafter.

In the aforesaid general formula (1-5), Xsl to X54 and Ysl to Yss have the same meaning as X21 to X24 and Yzi to Y24 in the general formula (1-2) and preferred examples of X5, to X54 and Ysl to Yss are the same as those in the general formula (1-2). Further, Ml has the same meaning as M in the general formula (1-2) and preferred examples of M, are the same as those in the general formula (1-2).

In the general formula (1-5), ase to a54 each independently represent an integer of 1 or 2, and preferably, the sum of a51, a52, a53 and a54 is equal to or smaller than 4 and equal to or greater than 6, and it is particularly preferred that a5l, asz, as3 and ase each are 1.

Xsi, Xs2, Xs3 and Xs4 may be the same substituent, or Xsi, Xs2, X53 and X54 each may be a substituent of the same kind but partially different, e. g.,-SOz-Zz in which Z2 differs among X51, Xsz, Xs3 and X54, or XslS Xs27 Xs3 and Xs4 may be different substituents, e. g., -SO2-Z2 and -SO2NR21R22.

Particularly preferred examples of the combination of substituents among the phthalocyanine dyes represented by the general formula (1-5) will be given below.

Preferably, X51 to Xs4 each independently represent-SO-Z2,-SO2-Z2,-SO2NR2iR22 or-CONR2lR22, particularly-SO2-Z2 or-S02NR21R22, most preferably-SO2-Z2.

Zz's each represent a substituted or unsubstituted alkyl group, substituted or unsubstituted aryl group or substituted or unsubstituted heterocyclic group, and most desirable among these groups are substituted alkyl group, substituted aryl and substituted heterocyclic group. Particularly for the reason of enhancement of dye solubility or ink stability, it is preferred that the substituents have asymmetric carbons (used in racemate form).

Further, for the reason of enhancement of association and hence fastness, it is preferred that the substituents have a hydroxyl group, ether group, ester group, cyano group, amide group or sulfonamide group incorporated therein.

R21 and R22 each independently represent a hydrogen atom, substituted or unsubstituted aLkyl group, substituted or unsubstituted aryl group or substituted or unsubstituted heterocyclic group, particularly a hydrogen atom, substituted alkyl group, substituted aryl group or substituted heterocyclic group. However, it is not preferred that R ? l and R22 each are a hydrogen atom at the same time. Particularly for the reason of enhancement, of dye solubility or ink stability, it is preferred that the substituents have asymmetric carbons (used in racemate form). Further, for the reason of enhancement of association and hence fastness, it is preferred that the substituents have a hydroxyl group, ether group, ester group, cyano group, amide group or sulfonamide group incorporated therein.

Ysl to Ys8 each independently represent a hydrogen atom, halogen atom, alkyl group, aryl group, cyano group, alkoxy group, amide group, ureido group, sulfonamide group, carbamoyl group, sulfamoyl group, alkoxycarbonyl group, carboxyl group or sulfo group, particularly hydrogen atom, halogen atom, cyano group, carboxyl group or sulfo group, most preferably hydrogen atom.

The suffixes a51 to as4 each independently represent 1 or 2, and it is particularly preferred that as, to a54 each be 1 at the same time.

Ml represents a hydrogen atom, metal element or oxide, hydroxide or halide thereof, particularly Cu, Ni, Zn or Al, most preferably Cu.

The phthalocyanine dye represented by the general formula (1-5), if it is water-soluble, preferably has an ionic hydrophilic group. Examples of the ionic hydrophilic group include sulfo group, carboxyl group, phosphono group, and quaternary ammonium group. Preferred among these ionic hydrophilic groups are carboxyl group, phosphono group, and sulfo group, and particularly preferred among these ionic hydrophilic groups are carboxyl group and sulfo group. The carboxyl group, phosphono group and sulfo group may be used in the form of salt, and examples of the counter ion forming the salt include ammonium ion, alkaline metal ion (e. g. , lithium ion, sodium ion, potassium ion), and organic cation (e. g., tetramethylammonium ion, tetramethyl guanidium ion, tetramethylphosphonium ion). Preferred among these counter ions are alkaline metal ions, and particularly preferred among these counter ions is lithium ion because it enhances the dye solubility and hence the ink stability.

The number of ionic hydrophilic groups is preferably at least 2 per molecule of phthalocyanine-based dye, and it is particularly preferred that there be contained at least two sulfo groups and/or carboxyl groups in the phthalocyanine-based dye.

Referring to preferred combination of substituents on the compound represented by the general formula (5), the compound of the general formula (1-5) preferably has various substituents at least one of which is one of the preferred groups listed above, and more preferably, more of the various substituents are the preferred groups listed above, and most preferably, all of the various substituents are the preferred groups listed above.

Referring to the chemical structure of the phthalocyanine dye represented by the general formula (1-5), it is preferred that at least one electron-withdrawing group such as sulfinyl group, sulfonyl group and sulfamoyl group be incorporated in each of four benzene rings in the phthalocyanine such that op value of the substituents in the entire phthalocyanine skeleton totals not smaller than 1. 6.

The Hammett's substituent constant op will be described hereinafter. Hammett's rule is an empirical rule which L. P. Hammett proposed in 1935 to quantitatively discuss the effect of substituents on the reaction or equilibrium of benzene derivatives, and the validity of this empirical rule has been widely accepted today.

Substituent constants required in Hammett's rule are op value and am value, and these values are found in many general literatures, and for the details of these values, reference can be made to J. A. Dean,"Lange's Handbook of Chemistry", 12th ed. , 1979 (Mc Graw-Hill), and"Kagaku no Ryoiki (Region of Chemistry)", extra edition, No. 122, pp. 96-103,1979 (Nankodo). In the present invention, these substituents are defined or described by Hammett's substituent constant op, but this does not mean that the known values found in the aforementioned literatures are not limited to certain substituents and it goes without saying that even if the values are unknown in literatures, they contain substituents which may fall within the defined range when measured according to Hammett's rule. Further, the compounds of the present invention contain those which are not benzene derivatives, and as a measure for indicating the electron effect of substituents there is used op value regardless of substitution position. In the present invention, op value is used in this sense.

The phthalocyanine derivative represented by the general formula (1-2) is normally a mixture of analogues which are unavoidably different in introduction sites of substituents Xn (n = 1 to 4) and Ym (m = 1 to 4) and introduced number of these substituents by synthesis method. Accordingly, the general formula of the phthalocyanine dye is mostly a statistically averaged representation of these analogous mixtures. In the invention, it was found that the classification of these analogous mixtures into the following three classes gives a specific mixture which is particularly preferred. In other words, mixtures of phthalocyanine-based dye analogues represented by the general formula (1-2) or (1-5) are classified into the following classes for definition. In the general formula (1-5), Y51, Ys2, Ys3, Y ; ; 4, Y, Ys, Ysy and Ysg are in 1-, 4-, 5-, 8-, 9-, 12-, 13- and 16-positions, respectively.

(1) (3-position substitution type: Phthalocyanine dye having a specific substituent on 2-and/or 3-position, 6- and/or 7-position, 10-and/or 11-position, or 14-and/or 15-position (2) a-position substitution type: Phthalocyanine dye having a specific substituent on 1-and/or 4-position, 5- and/or 8-position, 9-and/or 12-position, or 13-and/or 16-position (3) a, p-position mixed substitution type: Phthalocyanine dye having a specific substituent irregularly on 1-to 16-position In the present specification, in order to describe phthalocyanine dye derivatives having different structures (particularly different substitution positions), the aforementioned p-position substitution type, a- position substitution type and a, p-position mixed substitution type are used.

The phthalocyanine derivative to be used in the invention can be synthesized by, e. g. , methods described or cited in Shirai and Kobayashi,"Phthalocyanine-Chemistry and Function-", IPC Co. , Ltd. , pp. 1 to 62, C. C. Leznoff-A. B. P. Lever, "Phthalocyanines-Properties and Applications", VCH, pp. 1-54, etc. or analogous methods in combination.

The phthalocyanine compound represented by the general formula (1-2) to be used in the invention can be synthesized by, e. g., sulfonation reaction, sulfonylchloration reaction and amidation reaction of unsubstituted phthalocyanine compound as disclosed in WO00/17275, 00/08103,00/08101 and 98/41853 and JP-A-10-36471.

In this case, since sulfonation can occur on any position of the phthalocyanine nucleus, it is difficult to control the sulfonate number of substituents. Accordingly, when sulfo groups are incorporated under such a reaction condition, the position and number of sulfo groups incorporated in the reaction product cannot be predetermined, unavoidably giving a mixture of products having different numbers of substituents or substitution positions. Thus, since when this mixture is used as a starting material to synthesize the compound of the invention, an a, p-mixed substitution type mixture comprising some compounds having different numbers of substituents or substitution positions is obtained as a phthalocyanine dye because the number of heterocyclic group-substituted sulfamoyl groups or the substitution position cannot be predetermined.

As previously mentioned, when many electron-withdrawing groups such as sulfamoyl group are incorporated in the phthalocyanine nucleus, the phthalocyanine dye is provided with a more positive oxidation potential and hence an enhanced ozone fastness. When synthesized according to the aforementioned method, it is unavoidable that the reaction mixture contains a phthalocyanine dye having a small number of electron- withdrawing groups incorporated therein, i. e. , more negative oxidation potential. Accordingly, in order to enhance the ozone fastness of the phthalocyanine dye, a synthesis method capable of inhibiting the production of a compound having a more negative oxidation potential is preferably employed.

The phthalocyanine compound represented by the general formula (1-5) of the invention can be derived from a tetrasulfophthalocyanine compound obtained by, e. g. , reacting a phthalonitrile derivative (compound P) represented by the following general formula and/or a diiminoisoindoline derivative (compound Q) represented by the following general formula with a metal derivative represented by the general formula (1-6) or reacting a 4-sulfophthalocyanine derivative (compound R) represented by the following general formula with a metal derivative represented by the general formula (1-6). "P . CN Iq N N N q s M-(Y) d N X-X X General Formula P qt N N N yq T o M- (d &/or yq N N yq NH yq'yq NU v N-H P NH General Formula (5) General Formula I SO3Na q 103Na yq /'q\/ -q N N t (Y) q N N N Yq NaO3S N-M-N 03Na NaOaS-tJ N-M-N j-SONa General Formula FZ N q N yq' yq'yq S03Na In these general formulae, Xp corresponds to X51, X52, X53 or X54 in the general formula (1-5). Yq and Yq'each correspond to Y51, Y52, Y53, Y54, Y55, Y56, Y57 or Y58 in the general formula (1-5). In the compound R, M'represents a cation.

Examples of the cation represented by M'include alkaline metal ions such as Li, Na and K ions and organic cations such as triethylammonium ion and pyridinium ion.

General formula (1-6): M- (Y) d wherein M has the same meaning as M in the general formulae (1-2) or Ml in the general formula (1-5) ; Y represents a monovalent or divalent ligand such as halogen atom, acetate anion, acetyl acetonate and oxygen ; and d represents an integer of from 1 to 4.

In other words, when synthesized according to the aforementioned method, desired substituents can be incorporated by a predetermined number. In particular, in order to introduce many electron-withdrawing groups to make the oxidation potential more positive as in the present invention, the aforementioned synthesis method can be used because it is extremely excellent as compared with the aforementioned method for synthesis of the phthalocyanine compound of the general formula (1-2).

The phthalocyanine compound represented by the general formula (1-5) thus obtained is a mixture of compounds represented by the following general formulae (a)-l to (a) -4 which are isomeric with the substitution position on Xp, i. e., p-position substitution type mixture.

General Formula (a) 1 General Formula (a) 2 General Formula (a) General Formula (jazz In the foregoing synthesis method, when the same compound is used as Xp, a (3-position substitution type phthalocyanine dye wherein Xsi, X52, X53 and X54 are the same substituent can be obtained. On the contrary, when different materials are used in combination as Xp, a dye having substituents of the same kind but partially different or a dye having different substituents can be synthesized. Among the dyes of the general formula (1-5), these dyes having different electron-withdrawing substituents are particularly desirable because they can adjust the solubility and association of the dye, the age stability of the ink, etc.

In the invention, it was found very important for the enhancement of fastness that any of these substitution types has an oxidation potential of more positive than 1.0 V (vs SCE). The degree of this effect could not be expected from the related art. Although its mechanism is not known in detail, a tendency was given that (3-position substitution type is obviously better than a, ¢-position mixed substitution type in hue, light fastness, ozone fastness, etc.

Specific examples of the phthalocyanine dyes represented by the general formula (1-2) or (1-5) (exemplary compounds I-1 to I-12 and exemplary compounds 101 to 190) will be given below, but the phthalocyanine dye to be used in the present invention is not limited thereto. example compound In the table, specific examples are shown in random order independently in each of sets (X1,X2), (Y11,Y12),(Y13,Y14), (Y15,Y16)and(Y17,Y18). Compd. No. M xi X2 Yll, Y12 Y13, Y14 Y15, Y16 Y17, Y18 101 Cu-S02-NH-CH2-CH2-S03Li-H-H,-H-H,-H-H,-H-H,-H OH 102 Cu-S2 NH-CHZ-CH-CO-NH-CH2CH2-S03Na-H-CI,-H-CI,-H-CI,-H-CI,-H OH OH 103 Cu I-H-H,-H-H,-H-H,-H-H,-H . SO2NHCH2CH2CH2SO2NHCH2CHSO3Li. 104 Cu SO2NH vSO2NHCH2CH2SO3Li-H-H,-H-H,-H-H,-H-H,-H CH2-COONa 105 N-SO2 NH-CHz-CH2-CO-NH-CH-COONa-H-Cl,-H-Cl,-H-CI,-H-Cl,-H 106 Cu-S02-NH-CH2-CH2-S02-NH-CH2-COONa-CN-H,-H-H,-H-H,-H-H,-H CH2-OH 107 Cu so I-H-H,-H-H,-H-H,-H-H,-H - Cu-S02 CH2-CH2-CH2-S02-NH-CH-COOLi-H-H,-H-H,-H-H,-H-H,-H 108 Cu-SO2-CH2-CH2-CH2-S03Li-H-H,-H-H,-H-H,-H-H,-H 109 Cu-S02-CH2-CH2-CH2-SO3K-H-H,-H-H,-H-H,-H-H,-H 110 Cu-S02- (CH2) 6-C02K-H-H,-H-H,-H-H,-H-H,-H In the table, specific examples are shown in random order independently in each of sets (X1,X2), (Y11,Y12),(Y13,Y14), (Y15,Y16)and(Y17,Y18). Compd. No. M X1 X2 Y11, Y12 Y13, Y14 Y15, Y16 Y17, Y18 OH 111 Cu _S2-NH-CH2-CH2-CH2-S02-NH-CHZCH-CHZ S03Li H-H,-H-H,-H-H,-H-H,-H OH OH 112 ou I-SO3Li-H,-H-H,-H-H,-H-H,-H - SOs-CHz-CH-CHoSOsK 113 Cu--t-H-H.-H-H.-H-H.-H-H.-H OH OH 114 Cu I-SO3Li-H-H-H,-H-H,-H-H,-H -SO2-CH2-CH-CH CH3 115 Cu-s02NH (CH2) 3N (CH2CH20H) 2-CH3 C So38-H-H,-H-H,-H-H,-H-H,-H OH 116 Cu I-H-H,-H-H,-H-H,-H-H,-H COOLS T _ C O O L i 117 Cu I-H-H,-H-H,-H-H,-H-H,-H -CO-NH-CH-CH2CH2SO3Li In the table, specific examples are shown in random order independently in each of sets (X1,X2), (Y11,Y12),(Y13,Y14), (Y15,Y16)and(Y17,Y18). Compd. No. M X1 X2 Y11, Y12 Y13, Y14 Y15, Y16 Y17, Y18 CHs 118 Cu SO2CH2CH2CH uSO3Li-H-H,-H-H,-H-H,-H-H,-H SH OH 119 Cu I-H-H,-H-H,-H-H,-H-H,-H CH3 120 Cu I-H-H,-H-H,-H-H,-H-H,-H - SOZ-CHZ-CHZ CH-COOLi - S02 (CH2) 3S02NHCH2-CH-CH2-S03Li OH 121 Cu I-H-H,-H-H,-H-H,-H-H,-H OH OH 122 Cu I-H-H,-H-H,-H-H,-H-H,-H - C02CH2CH2CH2S02-NH-CH2-CH-CH2-S03Li 123 Cu-S02NH-C8H7 (t)-H-H,-H-H,-H-H,-H-H,-H CH2CH3 124 Cu I-H-H,-H-H,-H-H,-H-H,-H - S02-NH-CH2-CH-CH2CHCH2-CH3 In the table, specific examples are shown in random order independently in each of sets (X1,X2), (Y11,Y12),(Y13,Y14), (Y15,Y16)and(Y17,Y18). Compd. No. M X1 X2 Y11, Y12 Y13, Y14 Y15, Y16 Y17, Yl8 CH3 125 Cu I-H-H,-H-H,-H-H,-H-H,-H - S02CH2CH2CH2S02-NH-CH2-CH-CH2-CH3 CH3 126 Cu-SOZ_CH2-CHz-CHZ C02-CH-CHz-O-CH3-H-H,-H-H,-H-H,-H-H,-H CH3 127 Cu-S02CH2CH2CH2SO2NHCH2CH2CH20-CHCH3-H-H,-H-H,-H-H,-H-H,-H '-CH3 O-CH3 128 Zn I-CN-H,-H-H,-H-H,-H-H,-H - S02-CH2-CH-CH2-O-CH2 CH2CH3 129 Cu I-H-Cl,-H-Cl,-H-Cl,-H-Cl,-H - CO-NH-CH2-CH-CH2-CH2-CH2CH3 CH3 130 Cu I-H-H,-H-H,-H-H,-H-H,-H 2 2-4 9(t) CH3 S03Li CH3 S 131 Cu-S02-CH2-CH2-CH-S02-NH -H-H,-H-H,-H-H,-H-H,-H S03Li In the table, specific examples are shown in random order independently in each of sets (X1,X2), (Y11,Y12),(Y13,Y14), (Y15,Y16)and(Y17,Y18). Compd. No. M X1 X2 Y11, Y12 Y13, Y14 Y15, Y16 Y17, Y18 c°2C6H13 (n) 132 Cu-S02NH f -H-H,-H-H,-H-H,-H-H,-H C SO2NH4OCH2CH20CH3 133 Cu C2H5-H-H,-H-H,-H-H,-H-H,-H . SO2NHCH2CHX H --C4H9 CH2CH3 134 Cu-gp2NH S02-NH-CH2-CH-CH2CH2-CH2-CH3-H-H,-H-H,-H-H,-H-H,-H 135 Cu S2-H-H,-H-H,-H-H,-H-H,-H C02Na /C4Hg (n) 136 Cu-H-H,-H-H,-H-H,-H-H,-H AJJ In the table, specific examples are shown in random order independently in each of sets (X1,X2), (Y11,Y12),(Y13,Y14), (Y15,Y16)and(Y17,Y18). Compd. No. M X1 X2 Y11, Y12 Y13. Y14 Y15, Y16 Y17, Y18 s S03Li 137 CU-S02-, x-H-H,-H-H,-H-H,-H-H,-H N CH3 CHs - SOsNH 138 Cu S03Li-H-H,-H-H,-H-H,-H-H,-H Si Lis COzLi 139 Cu-S02 (CH2) 3-NH-C C02Li-C-H,-H-H,-H-H,-H-H,-H 0 O NH-CH2-CH2-CH-S03Li N-\ CH3 140 Cu-C02-CH2CH2CH2-NH--, N CH-H-H,-H-H,-H-H,-H-H,-H Nez NH-CH2-CH2-CH-S03Li In the table, specific examples are shown in random order independently in each of sets (X1,X2), (Y11,Y12),(Y13,Y14), (Y15,Y16)and(Y17,Y18). Compd. No. M X1 X2 Y11, Y12 Y13, Y14 Y15, Y16 Y17, Y18 COONa 141 Cu I-H-H,-H-H,-H-H,-H-H,-H - S02NH-CH-CH2-CO-N- (CH2CH20H) 2 SO2NH SO3Li 142 Cu NHC 4-H-H,-H-H,-H-H,-H-H,-H NHC I I O OH COOK 143 Cu I I-H-H,-H-H,-H-H,-H-H,-H - CO-NH-CH2-CH-CO-NH-CH-CH2CH2-S03K COOL) 144 Cu-gp2-CH2CH2CHz-NH-CO CO-NH-CH-CH2-COOLi-H-H,-H-H,-H-H,-H-H,-H 145 Cu-S02CH2CH20CH2CH20CH2CH2S03Li-H-H,-H-H,-H-H,-H-H,-H MPc (XPZ In the table, substituents (Xpi) and (Xp2) are random in the order of introducing positions ins-position substituent Compd. No. M Spi m Xp2 n OH S02-NH-CH2-CH-SOL : l S02-NH-CH2-CH-CF6 OH 147 Cu-S02-NH-CHp-CHQSO'Li 3 1 1 CH3 ;"2- L ; ri-urb CF6 148 Cu _S2__CH2-CH-S03Li. 3-SOzNH-CH2-CH2-CH2-SOz-NH-CH2-CHi-O-CHt-CH2 OH 1 S02-NH-CH2-CH-SOaLi 149 Cu _S__CH2-CH-SLi -S--Cti-Ci-f-CI-I-CO-N-CI--Ct-I-aH2 2 C 150 Gu-SOz-NH-CH2-CHz-SO2-NH-CH=CH2-COONa 3 _Sp2_CH-CI-iOH- OU 151 Cu-gp2_SNH-CH2 CN-S03Li 3-SazNH-CHt-CH=-0-CHt-CHz-OH 1 - 152 Cu-S02-CH2-CHZ-CH-S03Li. 25-SO2-CH2-CH2-O-CHi-CH2-OH 1. 5 S02-uM-ut-t2-uH-SC) ZLI- 1 2-SO-C6-CI42.-Cii2-CO-N-+Cti-CF6-oq 2 OH OH 154 Cu-SO= CHZ-CHZ-CHz-S03Li 3-gp2-CH-CI-tz-CH2-SO2-NH-CH2-CH-CI- ! OH t55 Cu-SO2-CHz-CH2-CI-I-COOK 2 2 OH OH 156 Cu-S02-CHz-CHz CHz-S3Li 3-S02-Ch4j-CH-CH2-803LI OH 157 Cu-SOt-CHt-CH :-0-CH-CHt-SO, L ! 2.. gpz-CHz-CHz-CHz-CC-CHz-CHz-CH-CHz-COOK M-Pc (p)-(xp2 w In the table, substituents (Xp1) and (Xp2) are random in the order of introducing positions ins-position substituent Compd. No M Xp1 m Xp2 n OH OH 158 Cu SO2CH2CHCHzBO3U 3 SOzC*<} S02NHCH2-CHCWOH 1 OH _ 159 Cu-SO=NHCHiCH2-S09Li 3-gp2-CFi-CH2-CH2-SO2-tl-CH2-CH-CI- CH2-CH2-COONa 160 Cu-SO2-CH2-CHi O-CH2-CH2-0-CH2-CH2 SONa 3-gO2-CH2-CH2-CH2-CO-N-CH2-COONa SO2C2CH2CHzSO2NHCEl2CHCIiSO3Li 1 Cu-SOtCH2CHzCHsSOLi 3 1 162 Cu-SO=CH2CH2CH2SO, Li 2-SO2CHtCHOCHiCHtOCHzCHtOH 2 CH3 163 Ou-SO2CH2CH2CH2SO3K 3-I I 164 Cu SO2CH2CH2CH2SO3Li 2 SO2GHtCH2CH2SO2NtCH2CH20H) 2 Z 165 Cu-CO-NH-CH=-CH-SO, K 3-CO-NH-CH2-CHz-0-CH2-CH !-OH 1 OH 166 Cu-CO-NH-CH2-CH2-SO NH-CHi-CH2-COONa 3 1 1 1 .. _ OU 167 Cu-1 15-CO-NH-CH2-CHa-OF-00-N-+CHI-C'41-OH) 2 S02 (CH2) 3SO2NHCH2-CH-CFi2CO2U 168 Cu-1 2-CO-CFh-C%-CF-CO-N-+CF-CFk-OH) 2 2 OH OH - C02-CI-4-C-C-SO-NH-CH2-CH-CI-b . 170 Cu-C02-CHi-CHz-CH=COOK Z-Cp2-Cli-CI-1-C1-4-SOZ-NH-CHz-CH-Ct-4-COOK M-pro (jazz (XP2). In the table, substituents (Xpl) and (42) are random in the order of introducing positions in, 8-position substituent. Compd No. M Xp1 m Xp2 n OH 171 Cu-CO,-CH,-CHrO-CHrCH,-0-CH,-C-SO, Ma 3-cOz-CHa./-sOzNH-CHz-CH-cHa-OH 1 ' !/ OH 172 Cu-SOpCH=CHEOCH2CN=O-CHzCHzSOK 2 2 - I-CO2-CH2-CK2-CH2-C%-CH2-CH2-CH-CR2-COOK- -SO2 G"S2C sSO2NHCH2CHCl-taH OH um C02-CH2-CH-CH2-SO3U _ SO2 (C~3SO2NHCH2CHC*903K _ OH QH 3-COZ-CI-4-CI-t-CH2-SOZ-NH-GHZ-CH-CHa- CH2-CH2-COOU 175 CU SO2 (CH2), SO2NH (CHZ), N (CH2CH20H) I 2 CO2-CH2CH2CH2CONCH2COOU 2 OH ~ CH2CH3 176 Cu CF6-CK2-CH2-SO2-NH I F6 3-802-CF6-CF6-CH2-SO2-NH-CH I N I OH 177 Cu-SOz-CH-CH1-4-CH-CH=-0-CH 2 _gp2_CI-t-CI-4-CI-4-S02-NH-CH2-CH-CH3 CH2CIi 178 Cu SOz-CH=-CHi-0-CH=-CH=-0-CH=-CHi OH 3 C 1 179 CU CH2CH3 2 O_ 2 50O-CHa __ 179 Cu-so-cHz-CH-CHzCHz-CHzCHa-SOz-CHz-CHz-CHz-SOz-NH-CHz-CH-CHa CH3 80-C6-OH-CF6CH2-CF6CF6 802-06-CK2-CF6-SO2-NH-CH2-CH-OF' OH CHa '" -CH.-CH,-CH,-CO,-NH-CH-C-C 3-SQ,-CH,-CH,-CH,-S (%-NH-CH-C), J a'I CH A9 <n) 9 i 5 S02-CF6-CF6-CF-CO2-NH-un-uM-CF4 M"Pc () n, () n ! n the tab ! e, substituents (Xpt) and (raz) are random in the order of introducing positions in ; 8-position substituent. Compd. No. M Xp1 m Xp2 n - __ __ _ C _ _- 183 Cu 2-SO2-CH2-CH2-CH-SO2-NHtCH2) 3-CH24-CH2CH2KH 2 OH 184 Cu I. 3-SO2-CHI-Cfi2-0-CH2-CH2-0-CHs I OH 185 Cu I. 3 SO2CH2CH20CHzCH2OCH2CH2OCH3 CN 186 Cu SQ2CH2CH2CH2C02NHCHCitl2Cki 3 SO2CH2CH2OCH2CH2OCH1CH2OH 1 ,, CHzCHa 187 Cu i 4) z 3 . CO2C8HCH2CH2CH2CH3 1 CHa 188 Cu-CO_CHz-CH-CH2-C02-NH-CH-CH2-Ct-3-CO2-CH=-Cti2-O-CHZ-CIi2- 0-CH3 1 CHzCHa 189 Cu-CO-NH-CH-CH2-S02-NH-CH-E-CI-) 2 3 3-gp2_NH-CFi2-CH-CH2-CI-I-CI-4-CI-b CH : Ch3 190 Ou íCH2CH3 3 CONHCH2CHzOCH2CHzOCH3 The structure of the phthalocyanine compound represented by M-Pc (Xpl) m (Xp2) n in Compound Nos.

146 to 190 is as follows. mg . 0 y ace Y9ty « t N yq N N Yt each independently \ or s/ Xpt The phthalocyanine dye represented by the general formula (1-2) can be synthesized according to the patent cited above. The phthalocyanine dye represented by the general formula (1-5) can be synthesized by the aforementioned method as well as the method disclosed in JP-A-2001-226275, JP-A-2001-96610, JP-A-2001- 47013 and JP-A-2001-193638. The starting material, intermediate dye and synthesis route are not limited to those according to these methods.

The content of the phthalocyanine dye represented by the general formula (1-2) in the ink is preferably from 0.2 to 20% by weight, more preferably from 0.5 to 15% by weight.

[Magenta dye] The azo dye to be used in the invention is preferably a dye having a maximal absorption at a wavelength of from 500 nm to 580 nm in an aqueous medium and an oxidation potential of more positive than 1. 0 V (vs SCE).

The first structural characteristic of preferred dye of this azo dye which is a magenta dye is that it is a dye having a chromophore represented by the general formula (heterocyclic ring A)-N=N- (heterocyclic ring B).

In this case, the heterocyclic ring A and the heterocyclic ring B in the aforementioned general formula may have the same structure. The heterocyclic ring A and heterocyclic ring B each are in detail a 5-or 6-membered heterocyclic ring which is selected from pyrazole, imidazole, triazole, oxazole, thiazole, selenazole, pyridone, pyrazine, pyrimidine and pyridine. In some detail, they are described in JP-A-2001-279145, JP-A-2001-15614, JP-A-2002-309116, JP-A-2003-12650, etc.

Further, the second preferred structural characteristic of the aforesaid azo dye is that the azo group is an azo dye having an aromatic nitrogen-containing 6-membered heterocyclic ring directly connected to at least one end thereof as a coupling component, and specific examples of such an azo dye are described in JP-A-2002- 371214.

The third preferred structural characteristic is that the chromophore has an aromatic cyclic amino group or heterocyclic amino group structure, and specific examples of the chromophore include anilino group, and heterylamino group.

The fourth preferred structural characteristic is that the azo dye has a stereostructure. This is described in detail in Japanese Patent Application 2002-12015.

By providing an azo dye with the aforesaid structural characteristics, the oxidation potential of the dye can be raised, making it possible to enhance the ozone fastness thereof. As a means of raising the oxidation potential there may be used a method involving the removal of a-hydrogen from the azo dye. Further, from the standpoint of rise of oxidation potential, an azo dye of the general formula (1-3) is particularly preferred. The means of raising the oxidation potential of an azo dye is described in detail in Japanese Patent Application 2001-254878.

The magenta ink of the present invention comprising an azo dye having the aforesaid characteristics preferably has Smax (maximal absorption wavelength) of from 500 to 580 nm from the standpoint of hue and has a small half-width on both the long and short wavelengths, i. e. , sharp absorption spectrum.

This is described in detail in JP-A-2002-309133. Further, if an azo dye of the general formula (1-3) is used, by introducing methyl group at a-position, the sharpening of absorption can be realized.

The forced fading rate constant of the magenta ink comprising the azo dye with respect to ozone gas is preferably not greater than 5.0 x 10-2 [h-l], more preferably not greater than 3.0 x 10-2 [h-l], particularly not greater than 1.5 x 10-2 [1ll.

For the measurement of the forced fading rate constant with respect to ozone gas, only the magenta ink is printed on a reflective image medium to obtain an image. The color of the main spectral absorption range of the ink constituting the image is measured for reflection density through a Status A filter. The colored area at which the reflection density thus measured ranges from 0.90 to 1.10 is predetermined to be initial density point.

The initial density is defined to be starting density (= 100%). Using an ozone fading machine in which an ozone concentration of 5 mg/L is always kept, the image is then allowed to fading. The time required until the reflection density of the initial density point reaches 80% of the initial value is then measured. The reciprocal of this value [Wl I is the determined. On the supposition that the relationship between the density of faded image and the time follows a first-order reaction rate equation, this reciprocal is determined as fading reaction rate constant.

Examples of the print patch for test employable herein include patch having solid rectangular symbols printed thereon according to JIS code 2223, stepwise color patch of Macbeth chart, and other arbitrary stepwise density patches allowing the measurement of area.

The reflection density of reflected image (stepwise color patch) printed for measurement is determined by measuring light ray passing through a Status A filter by a densitometer satisfying ISO5-4.

The testing chamber for measuring the forced fading rate constant with respect to ozone gas is equipped with an ozone generator (e. g. , of high voltage discharge type which applies ac voltage to dried air) capable of keeping the ozone gas concentration in the testing chamber at 5 mg/L. The aeration temperature is adjusted to 25°C.

The forced fading rate constant is a measure of oxidizability by ambient oixidizing atmosphere such as photochemical smog, automobile emission, organic vapor from coated surface of furniture or carpet and gas generated inside frame in daylight. Ozone gas represents these oxidizing atmospheres.

The compound having the aforementioned characteristics represented by the general formula (1-3) as an azo dye which is preferably used in the present invention will be described hereinafter. general formula (1-3): In the general formula (1-3), Asi represents a 5-membered heterocyclic ring.

Bsj and B32 each represent =CR3i-or-CR32= or one of B3l and B32 represents a nitrogen atom while the other represents = C R31-or-CR32=.

R35 and R36 each independently represent a hydrogen atom or a substituent which represents an aliphatic group, aromatic group, heterocyclic ring, acyl group, alkoxycarbonyl group, aryloxycarbonyl group, carbamoyl group, alkylsulfonyl group, arylsulfonyl group or sulfamoyl group the hydrogen atom of which may be substituted.

G3, R31 and R32 each independently represent a hydrogen atom or a substituent which represents a halogen atom, aliphatic group, aromatic group, heterocyclic ring, cyano group, carboxyl group, carbamoyl group, alkoxycarbonyl group, aryloxycarbonyl group, heterocyclic oxycarbonyl group, acyl group, hydroxy group, alkoxy group, aryloxy group, heterocyclic oxy group, silyloxy group, acyloxy group, carbamoyloxy group, alkoxycarbonyloxy group, aryloxycarbonyloxy group, amino group, acylamino group, ureido group, sulfamoylamino group, alkoxycarbonylamino group, aryloxycarbonylamino group, aLkylsulfonylamino group, arylsulfonylamino group, heterocyclic sulfonylamino group, nitro group, alkylthio group, arylthio group, heterocyclic thio group, alkylsulfonyl group, arylsulfonyl group, heterocyclic sulfonyl group, alkylsulfinyl group, arylsulfinyl group, heterocyclic sulfinyl group, sulfamoyl group or sulfo group the hydrogen atom of which may be substituted.

R31 and R3s or R35 and R36 may be connected to each other top form a 5-or 6-membered ring.

In the general formula (1-3), A3, represents a 5-membered heterocyclic ring and examples of hetero atoms in the heterocyclic ring include N, O and S. The 5-membered heterocyclic ring is preferably a nitrogen- containing 5-membered heterocyclic ring which may be condensed with aliphatic rings, aromatic rings or other heterocyclic rings.

Preferred examples of A31 may include pyrazole ring, imidazole ring, thiazole ring, isothiazole ring, thiadiazole ring, benzothiazole ring, benzooxazole ring, and benzoisothiazole ring. The various heterocyclic groups may further have substituents. Preferred among these heterocyclic rings are pyrazole ring, imidazole ring, isothiazole ring, thiadiazole ring and benzothiazole ring represented by the following general formulae (a) to (f) : In the aforesaid general formulae (a) to (f), R307 to R320 represent the same substituents as G3, R31 and R32 in the general formula (1-3).

Preferred among the compounds of the general formulae (a) to (f) are pyrazole ring represented by the general formula (a) and isothiazole ring represented by the general formula (b), most preferably pyrazole ring represented by the general formula (a).

In the general formula (1-3), Bsi and B32 each represent =CR31-or-CR32= or one of B3l and B32 represents a nitrogen atom while the other represents =CR31-or-CR32=, but B3, and B32 preferably each represent=CR3l-or-CR32=.

Preferred examples of R35 and R36 may include hydrogen atom, aliphatic group, aromatic group, heterocyclic group, acyl group, alkylsulfonyl group or arylsulfonyl group. More preferably, R35 and R36 each are a hydrogen atom, aromatic group, heterocyclic group, acyl group, alkylsulfonyl group or arylsulfonyl group.

Most preferably, R35 and R36 each are a hydrogen atom, aryl group or heterocyclic group. The hydrogen atom of the aforementioned various substituents may be substituted. However, R35 and R36 are not a hydrogen atom at the same time.

G3 is preferably a hydrogen atom, halogen atom, aliphatic group, aromatic group, hydroxy group, alkoxy group, aryloxy group, acyloxy group, heterocyclic oxy group, amino group, acylamino group, ureido group, sulfamoylamino group, alkoxycarbonylamino group, aryloxycarbonylamino group, alkylthio group, arylthio group or heterocyclic thio group, more preferably a hydrogen atom, halogen atom, alkyl group, hydroxy group, alkoxy group, aryloxy group, acyloxy group, amino group or acylamino group, most preferably a hydrogen atom, amino group (preferably anilino group) or acylamino group. The hydrogen atom of the aforesaid substituents may be substituted.

Preferred examples of R31 and R32 include hydrogen atom, alkyl group, halogen atom, alkoxycarbonyl group, carboxyl group, carbamoyl group, hydroxy group, alkoxy group, and cyano group. The hydrogen atom of the aforesaid substituents may be substituted.

Ruz and R35 or R35 and R36 may be connected to each other to form a 5-or 6-membered ring.

Examples of the substituents which may substitute on A3, or which may substitute on the substituents of R31, R32, R3s or G3 include those listed above with reference to G3, Rsi and R32.

In the case where the azo dye represented by the general formula (1-3) is a water-soluble dye, an ionic hydrophilic group is further provided on any position on A3,, R3,, R32, Rus, R36 and G3 as a substituent.

Examples of the ionic hydrophilic group as a substituent include sulfo group, carboxyl group, phosphono group, quaternary ammonium group, etc. The aforesaid ionic hydrophilic group is preferably a carboxyl group, phosphono group or sulfo group, particularly carboxyl group or sulfo group. The carboxyl group, phosphono group and sulfo group may be in the form of salt, and examples of counter ions constituting the salt include ammonium ion, alkaline metal ion (e. g. , lithium ion, sodium ion, potassium ion), and organic cation (e. g., tetramethylammonium ion, tetramethylguanidium ion, tetramethyl phosphonium).

The terms (substituent) as used in the description of the general formula (1-3) will be described. These terms are common even to the general formula (1-3) and the general formula (3-A) described later.

Examples of the halogen atom include fluorine atom, chlorine atom, and bromine atom.

The aliphatic group means alkyl group, substituted alkyl group, alkenyl group, substituted alkenyl group, alkinyl group, substituted alkinyl group, aralkyl group and substituted aralkyl group. In the present specification, the term"substituted"as used in"substituted alkyl group", etc. means that the hydrogen atom in "aLkyl group", etc. is substituted by substituents listed above with reference to G3, R31 and R32, etc.

The aliphatic group may have branches or may form a ring. The number of carbon atoms in the aliphatic group is preferably from 1 to 20, more preferably from 1 to 16. The aryl moiety of the aralkyl group or substituted aralkyl group is preferably a phenyl group or naphthyl group, particularly phenyl group. Examples of the aliphatic group include methyl group, ethyl group, butyl group, isopropyl group, t-butyl group, hydroxyethyl group, methoxyethyl group, cyanoethyl group, trifluoromethyl group, 3-sulfopropyl group, 4- sulfobutyl group, cyclohexyl group, benzyl group, 2-phenethyl group, vinyl group, and allyl group.

The aromatic group means an aryl group or substituted aryl group. The aryl group is preferably a phenyl group or naphthyl group, particularly phenyl group. The number of carbon atoms in the aromatic group is preferably from 6 to 20, more preferably from 6 to 16.

Examples of the aromatic group include phenyl group, p-tollyl group, p-methoxyphenyl group, o- chlorophenyl group, and m- (3-sulfopropylamino) phenyl group.

Examples of the heterocyclic group include substituted heterocyclic groups. The heterocyclic group may have its heterocyclic ring condensed with aliphatic rings, aromatic rings or other heterocyclic rings. The aforesaid heterocyclic group is preferably a 5-or 6-membered heterocyclic ring. Examples of the aforesaid substituents include aliphatic group, halogen atom, alkylsulfonyl group, arylsulfonyl group, acyl group, acylamino group, sulfamoyl group, carbamoyl group, ionic hydrophilic group, etc. Examples of the aforesaid heterocyclic group include 2-pyridyl group, 2-thienyl group, 2-thiazolyl group, 2-benzothiazolyl group, 2- benzooxazolyl group, and 2-furyl group.

Examples of the carbamoyl group include substituted carbamoyl groups. Examples of the aforesaid substituents include alkyl group. Examples of the aforesaid carbamoyl group include methylcarbamoyl group, and dimethylcarbamoyl group.

Examples of the alkoxycarbonyl group include substituted alkoxycarbonyl groups. The aforesaid alkoxycarbonyl group is preferably an alkoxycarbonyl group having from 2 to 20 carbon atoms. Examples of the aforesaid substituents include ionic hydrophilic groups. Examples of the aforesaid alkoxycarbonyl group include methoxycarbonyl group, and ethoxycarbonyl group.

Examples of the aryloxycarbonyl group include substituted aryloxycarbonyl groups. The aforesaid aryloxycarbonyl group is preferably an aryloxycarbonyl group having from 7 to 20 carbon atoms. Examples of the aforesaid substituents include ionic hydrophilic groups. Examples of the aforesaid aryloxycarbonyl group include phenoxycarbonyl group.

Examples of the heterocyclic oxycarbonyl group include substituted heterocyclic oxycarbonyl groups.

Examples of the heterocyclic ring include those listed above with reference to the heterocyclic group. The aforesaid heterocyclic oxycarbonyl group is preferably a heterocyclic oxycarbonyl group having from 2 to 20 carbon atoms. Examples of the aforesaid substituents include ionic hydrophilic groups. Examples of the aforesaid heterocyclic oxycarbonyl group include 2-pyridyloxycarbonyl group.

Examples of the acyl group include substituted acyl groups. The aforesaid acyl group is preferably an acyl group having from 1 to 20 carbon atoms. Examples of the aforesaid substituents include ionic hydrophilic groups. Examples of the aforesaid acyl group include acetyl group and benzoyl group.

Examples of the alkoxy group include substituted alkoxy groups. Examples of the aforesaid alkoxy group is preferably an alkoxy group having from 1 to 20 carbon atoms. Examples of the aforesaid substituents include alkoxy groups, hydroxyl groups, and ionic hydrophilic groups. Examples of the aforesaid alkoxy group include methoxy group, ethoxy group, isopropoxy group, methoxyethoxy group, hydroxyethoxy group, and 3- carboxypropoxy group.

Examples of the aryloxy group include substituted aryloxy groups. The aforesaid aryloxy group is preferably an aryloxy group having from 6 to 20 carbon atoms. Examples of the aforesaid substituents include alkoxy groups, and ionic hydrophilic groups. Examples of the aforesaid aryloxy group include phenoxy group, p-methoxyphenoxy group, and o-methoxyphenoxy group.

Examples of the heterocyclic oxy group include substituted heterocyclic oxy groups. Examples of the heterocyclic ring include those listed above with reference to the heterocyclic group. The aforesaid heterocyclic oxy group is preferably a heterocyclic oxy group having from 2 to 20 carbon atoms. Examples of the aforesaid substituents include alkyl groups, alkoxy group, and ionic hydrophilic groups. Examples of the aforesaid heterocyclic oxy group include 3-pyridyloxy group, and 3-thienyloxy group.

The silyloxy group is preferably a silyloxy group substituted by an aliphatic or aromatic group having from 1 to 20 carbon atoms. Examples of the aforesaid silyloxy group include trimethylsilyloxy, and diphenylmethyl silyloxy.

Examples of the acyloxy group include substituted acyloxy groups. The aforesaid acyloxy group is preferably an acyloxy group having from 1 to 20 carbon atoms. Examples of the aforesaid substituents include ionic hydrophilic groups. Examples of the aforesaid acyloxy group include acetoxy group, and benzoyloxy group.

Examples of the carbamoyloxy group include substituted carbamoyloxy groups. Examples of the aforesaid substituents include alkyl groups. Examples of the aforesaid carbamoyloxy group include N- methylcarbamoyloxy group.

Examples of the alkoxycarbonyloxy group include substituted alkoxycarbonyloxy groups. The aforesaid alkoxycarbonyloxy group is preferably an alkoxycarbonyloxy group having from 2 to 20 carbon atoms. Examples of the aforesaid alkoxycarbonyloxy group include methoxycarbonyloxy group, and isopropoxycarbonyloxy group.

Examples of the aryloxycarbonyloxy group include substituted aryloxycarbonyloxy groups. The aforesaid aryloxycarbonyloxy group is preferably an aryloxycarbonyloxy group having from 7 to 20 carbon atoms. Examples of the aforesaid aryloxycarbonyloxy group include-phenoxycarbonyloxy group.

Examples of the amino group include substituted amino groups. Examples of the aforesaid substituents include alkyl groups, aryl groups, and heterocylic groups, and the alkyl groups, aryl groups and heterocyclic groups may further have substituents. Examples of the alkylamino group include substituted alkylamino groups.

The alkylamino group is preferably an alkylamino group having from 1 to 20 carbon atoms. Examples of the aforesaid substituents include ionic hydrophilic groups. Examples of the aforesaid alkylamino group include methylamino group, and diethylamino group.

Examples of the arylamino group include substituted arylamino groups. The aforesaid arylamino group is preferably an arylamino group having from 6 to 20 carbon atoms. Examples of the aforesaid substituents include halogen atoms, and ionic hydrophilic groups. Examples of the aforesaid arylamino group include phenylamino group, and 2-chlorophenylamino group.

Examples of the heterocyclic amino group include substituted heterocyclic amino groups. Examples of the heterocyclic ring include those listed above with reference to the heterocyclic group. The aforesaid heterocyclic amino group is preferably a heterocyclic amino group having from 2 to 20 carbon atoms.

Examples of the aforesaid substituents include alkyl groups, halogen atoms, and ionic hydrophilic groups.

Examples of the acylamino group include substituted acrylamino groups. The aforesaid acylamino group is preferably an acylamino group having from 2 to 20 carbon atoms. Examples of the aforesaid substituents include ionic hydrophilic groups. Examples of the aforesaid acylamino group include acetylamino group, propionylamino group, benzoylamino group, N-phenylacetylamino group, and 3, 5-disulfobenzoylamino group.

Examples of the ureido group include substituted ureido groups. The aforesaid ureido group is. preferably an ureido group having from 1 to 20 carbon atoms. Examples of the aforesaid substituents include alkyl groups, and aryl groups. Examples of the aforesaid ureido group include 3-methylureido group, 3,3- dimethylureido group, and 3-phenylureido group.

Examples of the sulfamoylamino group include substituted sulfamoylamino groups. Examples of the aforesaid substituents include alkyl groups. Examples of the aforesaid sulfamoylamino group include N, N- dipropylsulfamoylamino group.

Examples of the alkoxycarbonylamino group include substituted alkoxycarbonylamino groups. The aforesaid alkoxycarbonylamino group is preferably an alkoxycarbonylamino group having from 2 to 20 carbon atoms. Examples of the aforesaid substituents include ionic hydrophilic groups. Examples of the aforesaid alkoxycarbonylamino group include ethoxycarbonylamino groups : Examples of the aryloxycarbonylamino group include substituted aryloxycarbonylamino groups. The aforesaid aryloxycarbonylamino group is preferably an aryloxycarbonylamino group having from 7 to 20 carbon atoms. Examples of the aforesaid substituents include ionic hydrophilic groups. Examples of the aforesaid aryloxycarbonylamino group include phenoxycarbonylamino groups.

Examples of the aLkylsulfonylamino group and arylsulfonylamino group include substituted alkylsulfonylamino groups and substituted arylsulfonylamino groups. The aforesaid alkylsulfonylamino group and arylsulfonylamino group are preferably an alkylsulfonylamino group and arylsulfonylamino group each having from 1 to 20 carbon atoms. Examples of the substituents include ionic hydrophilic groups. Examples of the aforesaid alkylsulfonylamino group and arylsulfonylamino group include methylsulfonylamino group, N- phenyl-methyl sulfonylamino group, phenylsulfonyl amino group, and 3-carboxyphenylsulfonyl amino group.

Examples of the heterocyclic sulfonylamino group include substituted sulfonylamino groups.

Examples of the heterocyclic ring include those listed above with reference to the heterocyclic group. The aforesaid heterocyclic sulfonylamino group is preferably a heterocyclic sulfonylamino group having from 1 to 12 carbon atoms. Examples of the aforesaid substituents include ionic hydrophilic groups. Examples of the aforesaid heterocyclic sulfonylamino group include 2-thienylsulfonylamino group, and 3-pyridylsulfonyl amino group.

Examples of the alkylthio group, arylthio group and heterocyclic thio group include substituted alkylthio group, substituted arylthio group, and substituted heterocyclic thio group. Examples of the heterocyclic ring include those listed above with reference to the heterocyclic group. The aforesaid alkylthio group, arylthio group and heterocyclic thio group each preferably have from 1 to 20 carbon atoms. Examples of the aforesaid substituents include ionic hydrophilic groups. Examples of the aforesaid alkylthio group, arylthio group and heterocyclic thio group include methylthio group, phenylthio group, and 2-pyridylthio group.

Examples of the alkylsulfonyl group and arylsulfonyl group include substituted alkylsulfonyl groups and substituted arylsulfonyl groups. Examples of the alkylsulfonyl group and arylsulfonyl group include methylsulfonyl group and phenylsulfonyl group, respectively.

Examples of the heterocyclic sulfonyl group include substituted heterocyclic sulfonyl groups.

Examples of the heterocyclic ring include those listed above with reference to the heterocyclic group. The aforesaid heterocyclic sulfonyl group is preferably a heterocyclic sulfonyl group having from 1 to 20 carbon atoms. Examples of the aforesaid substituents include ionic hydrophilic groups. Examples of the aforesaid heterocyclic sulfonyl group include 2-thienylsulfonyl group and 3-pyridylsulfonyl group.

Examples of the alkylsulfinyl group and arylsulfinyl group include substituted alkylsulfinyl groups and substituted arylsulfinyl groups. Examples of the alkylsulfinyl group and arylsulfinyl group include methylsulfinyl group and phenylsulfinyl group, respectively.

Examples of the heterocyclic sulfinyl group include substituted heterocyclic sulfinyl groups. Examples of the heterocyclic ring include those listed above with reference to the heterocyclic group. The aforesaid heterocyclic sulfinyl group is preferably a heterocyclic sulfinyl group having from 1 to 20 carbon atoms.

Examples of the aforesaid substituents include ionic hydrophilic groups. Examples of the heterocyclic sulfinyl group include 4-pyridylsulfinyl group.

Examples of the sulfamoyl group include substituted sulfamoyl groups. Examples of the aforesaid substituents include alkyl groups. Examples of the aforesaid sulfamoyl group include dimethylsulfamoyl group, and di- (2-hydroxyethyl) sulfamoyl group.

Particularly preferred among the structures of the general formula (1-3) is one represented by the following general formula (3-A). general formula (3-A) wherein R3"R32, R3s and R36 are as defined in the general formula (1-3).

R33 and R34 each independently represent a hydrogen atom or a substituent which represents an aliphatic group, aromatic group, heterocyclic group, acyl group, alkoxycarbonyl group, aryloxycarbonyl group, carbamoyl group, alkylsulfonyl group, arylsulfonyl group or sulfamoyl group. Preferred among these substituents is hydrogen atom, aromatic group, heterocyclic group, acyl group, alkylsulfonyl group or arylsulfonyl group, particularly hydrogen atom, aromatic group and heterocyclic group.

Z3, represents an electron-withdrawing group having a Hammett's substituent constant op of 0.20 or more. Z31 is preferably an electron-withdrawing group having a Hammett's substituent constant op of 0.30 or more, more preferably 0.45 or more, particularly 0.60 or more, but the Hammett's substituent constant csp of the electron-withdrawing group is preferably not greater than 1.0.

Specific examples of the electron-withdrawing group having a Hammett's substituent constant op of 0.60 or more include cyano group, nitro group, aLkylsulfonyl group (e. g., methylsulfonyl group), and arylsulfonyl group (e. g., phenylsulfonyl group).

Examples of the electron-withdrawing group having a Hammett's substituent constant op of 0.45 or more include acyl group (e. g. , acetyl group), alkoxycarbonyl group (e. g. , dodecyloxycarbonyl group), aryloxycarbonyl group (e. g., m-chlorophenoxycarbonyl), alkylsulfinyl group (e. g. , n-propylsulfinyl), arylsulfinyl group (e. g., phenylsulfinyl), sulfamoyl group (e. g., N-ethylsulfamoyl, N, N-dimethylsulfamoyl), and halogenated alkyl group (e. g. , trifluoromethyl) besides the aforesaid groups.

Examples of the electron-withdrawing group having a Hammett's substituent constant op of 0.30 or more include acyloxy group (e. g., acetoxy group), carbamoyl group (e. g. , N-ethylcarbamoyl, N, N- dibutylcarbamoyl), halogenated alkoxy group (e. g., trifluoromethyloxy), halogenated aryloxy group (e. g., pentafluorophenyloxy), sulfonyloxy group (e. g., metliylsulfonyloxy), halogenated alkylthio group (e. g., difluoromethylthio), aryl group substituted by two or more electron-withdrawing groups having ap of 0.15 or more (e. g. , 2,4-dinitrophenyl, pentachlorophenyl), and heterocyclic group (e. g. , 2-benzooxazolyl, 2- benzothiazolyl, l-phenyl-2-benzoimidazolyl) besides the aforesaid groups.

Specific examples of the electron-withdrawing group having op of 0.20 or more include halogen atoms besides the aforesaid groups.

Preferred among these groups are C2-C20 acyl group, C2-C20 alkyloxycarbonyl group, nitro group, cyano group, Cl-C20 alkylsulfonyl group, C6-C20 arylsulfonyl group, C,-C2o carbamoyl group, and Cl-C20 halogenated alkyl group. Particularly preferred among these groups are cyano group, Cl-C20 alkylsulfonyl group and C6-C20 arylsulfonyl group, most preferably cyano group.

Z32 represents a hydrogen atom or a substituent and the substituent represents an aliphatic group, aromatic group or heterocyclic group. Z32 is preferably an aliphatic group, more preferably a Cl-C6 alkyl group.

Q represents a hydrogen atom or a substituent and the substituent represents an aliphatic group, aromatic group or heterocyclic group. In particular, Q is preferably a group formed by a group of non-metallic atoms required to form a 5-to 8-membered ring. The aforementioned 5-to 8-membered ring may be substituted, may be a saturated ring or may have an unsaturated bond. Particularly preferred among these 5-to 8-membered rings are aromatic group and heterocyclic group. Preferred examples of the non-metallic atom include nitrogen atom, oxygen atom, sulfur atom, and carbon atom. Specific examples of these cyclic structures include benzene ring, cyclopentane ring, cyclohexane ring, cycloheptane ring, cyclooctane ring, cyclohexene ring, pyridine ring, pyrimidine ring, pyrazine ring, pyridazine ring, triazine ring, imidazole ring, benzoimidazole ring, oxazole ring, benzoxazole ring, thiazole ring, benzothiazole ring, oxane ring, sulfolan ring, and thiane ring.

The hydrogen atoms in the substituents described with reference to the general formula (3-A) may be substituted. Examples of the substituents on these substituents include substituents listed with reference to the general formula (1-3), and groups and ionic hydrophilic groups exemplified with reference to G3, R3, and Razz Referring to a particularly preferred combination of azo dyes represented by the general formula (1-3), Pas and R36 each are preferably a hydrogen atom, allyl group, aryl group, heterocyclic group, sulfonyl group or acyl group, more preferably hydrogen atom, aryl group, heterocyclic group or sulfonyl group, most preferably hydrogen atom, aryl group or heterocyclic group. However, R35 and R36 are not a hydrogen atom at the same time.

G3 is preferably a hydrogen atom, halogen atom, allyl group, hydroxyl group, amino group or acylamino group, more preferably hydrogen atom, halogen atom, amino group or acylamino group, most preferably hydrogen atom, amino group or acylamino group.

A31 is preferably a pyrazole ring, imidazole ring, isothiazole ring, thiadiazole ring or benzothiazole ring, more preferably pyrazole ring or isothiazole ring, most preferably pyrazole ring.

B31 and B32 are =CR3,-and-CR32=, respectively, in which R31 and R32 each are preferably a hydrogen atom, allyl group, halogen atom, cyano group, carbamoyl group, carboxyl group, hydroxyl group, alkoxy group or alkoxycarbonyl group, more preferably hydrogen atom, allyl group, carboxyl group, cyano group or carbamoyl group.

Referring to a preferred combination of substituents on the compound represented by the general formula (1-3), at least one of the various substituents is preferably a compound which is a preferred group as mentioned above, and more preferably, more of the various substituents are compounds which are preferred groups as mentioned above, and most preferably, all the various substituents are compounds which are preferred groups as mentioned above.

Specific examples of the azo dye represented by the general formula (1-3) will be given below, but the azo dye to be used in the present invention is not limited to the following examples. X H3C CN ) =N Rg ion R3 R2 \ R2 Dye Ri R2 R3 N- \=/\==/ N H3C \ eC8H17 ßCH3 Cl H3C H3C HIC \ CsH7 H3C HgC Na hic 8ho7 /H3C H3C nua 3 3 N H3C CN Nul I-N R3 KI H-N Rus R2 Dye R, R2 R3 gui S02NH--CHZO cH/ zon HIC a-7 2 3 C6H, 3 CH3--O-CH3 H3C N'v H3C NHCC3CH-O j , \ c$H7 f CaHz Et N (n) csH17o H3C a-9 S NHSO2< vCH3 C8H17 (t) SNHCOCH-<'J- \==/"\==/'" 'JL i Et" (n) CsHO HgQ N ( aHy (t) S m, oc12H25 o8H25 C12N25 C12H25 N ci-6 CIE R, CN H3C CN /H N N-N --N N R4 R2 H-N \ R3 Dye R, R2 R3 R4 s Na a-11 + J VYcH. VYsONa Z-1 N] a COOH OOH a-12 N COOL coos a-13 \ 53 SO K (4, 5-mix) S03Na H3C S03Na H3C S03Na a// N : a H3C H3C HsC SCgK HgC SCgK H3C H3C a-15 N H3C H3C a-15 + 5XS03K vCH3 X CH3 N" Lj/ N (CH2C02H) 2.,,./ N (CH2C02H) 2 H3C H3C s ci a-16 N H3C N (CH2CO2H) 2 H3C N (CH2CO2H) 2 g S03Na H3C H3C / a-17 + 5XSO3Na HX SO3Na 3 SO3Na N H3C H3C N H3C R >i XCN H C I-N R3 N R3 R1 HN\ R4 Dye R1 R2 R3 R4 H3C H3C a-18-- N N HaC HsC H3C H3C a-18 <\ 43 SX 3CH3 vCH3 H3C H3C a-19 : a,-S02CH3 CH3 CH3 Gui H3C S a-20 \ > COCH3 C8H17 (t) C8H17 (0 N C a-21-S02CH3 CH3 C8Hl7 (t) N H3C H3C S a-22-H CH3 CH3 N H3C H3C H3C H3C a-23--- Nib H3C H3C a-24-H N H3C H3C H3C H3C a-25 <\ 43 <° 43 vCH3 vCH3 H3C H3C N nay HIC CN R2 N N-N rN N R3 H-N \ R4 Dye R1 R2 R3 R4 H3C H3C S, g/SOzNH-CH2 0 a-26 H3C H3C HIC HIC 3 ) NH+CH2) 70 S02NH+CH2-3-CH3 CH3 a-27 H3C H3C a-27 <<3zSOzNH+CHzk0vX <v502 : H+CHz7 0 9 H3C H3C CH3 s Et H3C H3C a NCCH 0 CH3 CH3 CI-C O N OC2HZg OCZH2g non (n) c8H17o a-30 NHS02-02-C8Hl7 C8H17 (t) Nos N °C8H17 (t) oc2Hs sc2Hs H3C H3C a-31 SOZNHCH2CHC2H5 p S02NHCHZCHCZH5 H3C HgC N N : a W CN Ni CN H C , I-N R3 R1 H-N R4 R4 D R Dye R, R, R, R, H3C H3C SSvSO3K ASS03K H3C CH3 33CH3 HIC HIC H3C H3C COOH COOL a-33 s S02NH S : CCS02NH CH3 CH3 N COOH N COOH H3C H3C COOK COOK s/s H a-34 S02NH-, L,'--So2N CH3 CH3 (5, 6-mix) COOK (5, 6-mix) COOK H3C H3C COOH HsC COOH s f-I a-35 \N S3Na S \ gOZNH N (5, 6-mix) (5, 6-mix) OOH CN CN H3C N/\ Rz v I R3 N R3 Rl H-N R4 Dye R, R2 R3 R4 H3C S03Na H3C S03Na g S03Na g S03Na a-36--<N a N \ I CH3 H3C H3C COOK H3C S03K HIC SOUK a-37 S vSO2NHX N43 vCH3 vCH3 2-ji COOK H3C HgC HsC HsC g S03Li g S03Li a-38 s S03Li s S03Li S03Li S03Li H3C H3C H3C HsC g/S03Na g, S03Na a-39 N N/ CH2 N (CH2COOH) 2 H3 N (CH2COOH) 2 H3C H3C H3C H3C S g 50gK a-40 CH3 CH3 N HsC S03K H3C S03K Riv RZ R4 R5 N/\ Rs , N R7 R3 H-N R8 Dye R1 R2 Rs R4 R5 R6 R7 HIC OCgHlY HsC a-41 CN-D H CONH2 S02CH3 a-42 + Br HN3 COOEt AS CgH17 (t) COCH3 + N_ N NHCH3 N--C S Cl a-43-'\ SOzCHs- N CONHz H 'rtf"--CHs CO-Jr- zu CON S HIC a-44-]-CN- -CN H H'J !)// SOzCHg nu NC Cul CN a-45 Br N02 H CONH2 0 y CH3 eCaH17 Ct 0 a-46 + CN 4\ 43 CH3 AS <-CH3 vCH3 C2H5 C2H5 CH3 H--N \ / a-46 CN C2H5 C2H5 Ru'con / R4 N=N--N _N R5 H-N R6 Dye R, R, R, R4 R, R, b-1 CH3 CH3 CN H =9 C8H17 eC8H17 H3C H3C b-2 CH3 CH3 CN H CH3 CH3 HsC H3C H3C b-3 CH3 CH3 CONH2 H eC8H17 vCH3 H3C HsC H3C b-4 CH3 CH3 H H CH3 CH3 H3C S03Li H3C SO3Li b-5 CH3 H CN H eSO3Na t SO3Na Ruz CN v R2 Rs l Ra N PN R R N R5 H-N \ H-N R6 Dye R, R2 Rs R4 R5 R6 H3C H3C S b-6 CH3 CH3 AS CH3 CH3 N H3C CH2N (CH2C02K) 2 H3C CH2N (CH2C02K) 2 HsC b-7 CH3 CH3 H--<\ I CH3 CBH17 H3C H3C b-8 CH3 H H SO2CH3 X SO3Na X SO3Na Ri 4 Nv - N Rg H-N HN H-N R6 Dye R, R, R, R4 R, R, c-1-SCH3 CH3 CN H C8H17 (t) ec8H17 c-2 3 H CONH2 H S03K S03K s SO K c-3 S~S03K CH3 SeSO3K eSO3K 3so3K g S02NH (i H2) s (Cl H2) 3 c-4-CH3 CH3 H CH3--o-C8HI7 hic w/HgC- S-NHSOz OCaHi7 (n) H3C c-5 H H N : la CH3 C8H17 (t) C8H17 (t) HsC N-N R2 R3 //\ R4 Rl-\g-N=N- y-N N R5 H-N Re R6 Dye Ri d-1 Me CH3 CN H <3So3K 3So3K C2H5 C2H5 d-2 Me CH3 CN H vCH3 X CH3 C2H5 C2H5 H3C SO3K H3C SO3K S d-3 Me H H CH3 HIC HIC HIC HIC d-4 Ph CH3 CONH2 H eC8H17 X C8H17 s 50zNH -'' O d-5 Ph CH3 H 4 30c4Hg (n) vCH3 X C2H5 7 R2 R3 ion \ nu sN-N Rg H-N R6 Dye Rr R2 Rs R4 R5 R6 e-1 5Cl CH3 CONH2 H CeHi7 (t) CeHi7 (t) e-2 5, 6-diCl H H ( : : -C8Hl7--C8H17 H3C HsC e-3 5, 6diCI CH3 HS43 X CH3 COCH3 zizi H3C e-4 5-CH3 H CN H J S03K j S03K HsC HsC \ e-5 5-N02 CH3 H S02CH3 7v CH3 H3C f-1 H3C CN H3C f 2 NC 3 \>-N=N NH CH3 NC N CH3 I Nc-N \>-N=N N HN\ CH3 H3C NN-N w CHZCN NH H C I CH 3 3 H3C CH3 S03Na Na - (CCHg g CHs t ! [ CH3 CH3 The content of the azo dye represented by the general formula (1-3) in the ink is preferably from 0. 2% to 20% by weight, more preferably from 0. 5% to 15% by weight. The solubility (or dispersibility in stabilized state) of the azo dye represented by the general formula (1-3) in water at 20°C is preferably 5% by weight or more, more preferably 10% by weight or more.

[Black dye] As the black ink to be used in the invention there is used a dye (L) having a wavelength Smax of from 500 nm to 700 nm and a half width (W ?, 1/2) of 100 nm or more (preferably from not lower than 120 mu to not higher than 500 nm, preferably from not lower than 120 nm to not higher than 350 nm) in absorption spectrum of a diluted solution normalized to absorbance of 1.0.

In the case where" (sharp) black"having a high image quality, i. e. , black which can be difficultly emphasized in any of B, G and R without using an observation light source can be realized with this dye (L) alone, this dye (L) alone can be used as a dye for black ink. In general, however, this dye (L) is used in combination with dyes which compensate the dye (L) in the wavelength range where the dye (L) has a low absorption. It is normally preferred that the dye (L) be used in combination with a dye (S) having main absorption in yellow range (Rmax of from 350 to 500 nm). The dye (L) may also be used in combination with other dyes to prepare a black ink.

In the invention, these dyes are dissolved or dispersed in an aqueous medium singly or in admixture to prepare a black ink. In order that the black ink for ink jet recording satisfies desired requirements, i. e. , (1) excellent weather resistance and/or (2) maintenance of black balance even after fading, it is preferred that an ink satisfying the following requirements be prepared.

Using the black ink, solid rectangle number of JIS code 2223 is printed at 48 points. The print thus formed is then measured for reflection density (Dvis) through a Status A filter (visual filter). The reflection density thus measured is defined as initial density. As a reflection densitometer having a Status A filter mounted thereon there may be used, X-rite densitometer. In order to measure the density of"black", the value obtained with Dvis as standard observed reflection density is used. This printed matter is then forcedly faded using an ozone fading tester capable of always generating 5 ppm of ozone. The forced fading rate constant (kvis) is then determined from the time (t) required until the reflection density (Dvis) reaches 80% of the initial value using the equation (0.8 = exp (-kvis-t)).

The black ink preferably exhibits a forced fading rate constant (kvis) of not higher than 5.0 x 10-2 [h-l], more preferably not higher than 3.0 x 10-2 [h-'], particularly not higher than 1. 0 x10-2 [if'] (Condition 1).

Using the black ink, solid rectangle number of JIS code 2223 is printed at 48 points. The print thus formed is then measured for three color (C (cyan), M (magenta), Y (yellow) ) reflection densities (DR, DG, DB), which are not Dvis, through a Status A filter. The reflection densities thus measured each are defined as initial densities. DR, DG, DB indicate C reflection density through a red filter, M reflection density through a green filter and Y reflection density through a blue filter, respectively. This printed matter is then forcedly faded using an ozone fading tester capable of always generating 5 ppm of ozone in the aforementioned manner. The forced fading rate constants (kR, kG, kB) are then similarly determined from the time required until the reflection densities (DR, DG, DB) reach 80% of the initial value. The ratio (R) of the maximum value to the minimum value of the three rate constants thus determined (R = kR/kG if kR is maximum and kG is minimum) is preferably not greater than 1.2, more preferably not greater than 1.1, particularly not greater than 1.05 (Condition 2).

The"printed matter obtained by printing a solid rectangle of JIS code 2223 at 48 points"as used hereinabove has a size large enough to cover the aperture of the measuring instrument so that a sufficiently large area can be used for density measurement.

At least one dye to be used in the black ink has an oxidation potential of more positive than 1.0 V (vs SCE), preferably more positive than 1.1 V (vs SCE), more preferably more positive than 1.2 V (vs SCE) and most preferably more than 1.25 V (vs SCE), and at least one of the dyes has , max of 500 nm or more (Condition 3).

Further, the black ink is prepared using the azo dye represented by the general formula (1-4).

Examples of the azo dye represented by the general formula (1-4) include those corresponding to the dye (L) having Smax of 500 nm to 700 nm and a half width of 100 nm or more in absorption spectrum of a diluted solution normalized to absorbance of 1.0. In addition, the dye (S) having Smax of 350 nm to 500 nm is similarly included as one corresponding to the dye of the general formula (1-4). Preferably, at least one of the dye (L) is the dye of the general formula (1-4), and particularly preferably, at least one of both the dye (L) and the dye (S) are the dyes of the general formula (1-4), and among them, it is preferred that the dye of the general formula (1-4) amounts 90% by mass of the total dyes in the ink (Condition 4).

The black ink according to the invention is a black ink that satisfies at least one of the conditions 1 to 4.

The dye represented by the general formula (1-4) will be described hereinafter.

In the general formula (1-4), A41, B41 and C4l each independently represent an aromatic or heterocyclic group which may be substituted (A4l and 41 each are a monovalent group and B41 is a divalent group). The substituent on A4,, B41 and C41 may be an aromatic azo group or heterocyclic azo group.

The azo dye represented by the general formula (1-4) is particularly preferably a dye represented by the following general formula (4-A). general formula (4-A): In the general formula (4-A), A4, and B41 are as defined in the general formula (1-4). B42 and B43 each represent =CR4,-or-CR42= or one of B42 and B43 represents a nitrogen atom and the other represents =CR41-or - CR42=.

G4, IL) and R42 each independently represent a hydrogen atom, a halogen atom or an aliphatic group, aromatic group, heterocyclic group, cyano group, carboxyl group, carbamoyl group, alkoxycarbonyl group, aryloxycarbonyl group, heterocyclic oxycarbonyl group, acyl group, hydroxyl group, alkoxy group, aryloxy group, heterocyclic oxy group, silyloxy group, acyloxy group, carbamoyloxy group, alkoxycarbonyloxy group, aryloxy carbonyloxy group, amino group (including arylamino group and heterocyclic amino group), acylamino group, ureido group, sulfamonylamino group, alkoxycarbonyl amino group, aryloxycarbonylamino group, alkyl sulfonylamino group, arylsulfonylamino group, heterocyclic sulfonylamino group, nitro group, alkylthio group, arylthio group, heterocyclic thio group, alkylsulfonyl group, arylsulfonyl group, heterocyclic sulfonyl group, alkylsulfinyl group, arylsulfinyl group, heterocyclic sulfinyl group, sulfamoyl group or sulfo group which may be further substituted.

R4s and R46 each independently represent a hydrogen atom, or an aliphatic group, aromatic group, heterocyclic group, acyl group, alkoxycarbonyl group, aryloxy carbonyloxy group, carbamolyl group, alkylsulfonyl group, arylsulfonyl group or sulfamoyl group which may be further substituted, with the proviso that R45 and R46 are not a hydrogen atom at the same time.

R41 and R45 or R45 and R46 may be connected to each other to form a 5-or 6-membered ring.

The azo dye represented by the general formula (4-A) is preferably a dye represented by the following general formula (4-B). general formula (4-B): In the aforementioned general formula (4-B), R47 and R48 have the same meaning as lt4l in the general formula (4-A).

The terms (substituent) used with reference to the general formulae (1-4), (4-A) and (4-B) will be described hereinafter. These terms apply also to the general formulae (4-C) and (4-D).

Examples of the halogen atom include fluorine atom, chlorine atom, and bromine atom.

The aliphatic group means alkyl group, substituted alkyl group, alkenyl group, substituted alkenyl group, alkinyl group, substituted alkinyl group, aralkyl group and substituted araLkyl group. The aliphatic group may have branches or may form a ring. The number of carbon atoms in the aliphatic group is preferably from 1 to 20, more preferably from 1 to 16. The aryl moiety of the aralkyl group or substituted aralkyl group is preferably a phenyl group or naphthyl group, particularly phenyl group. Examples of the aliphatic group include methyl group, ethyl group, butyl group, isopropyl group, t-butyl group, hydroxyethyl group, methoxyethyl group, cyanoethyl group, trifluoromethyl group, 3-sulfopropyl group, 4-sulfobutyl group, cyclohexyl group, benzyl group, 2-phenethyl group, vinyl group, and allyl group.

The monovalent aromatic group means an aryl group or substituted aryl group. The aryl group is preferably phenyl or naphthyl, particularly phenyl. The number of carbon atoms in the monovalent aromatic group is preferably from 6 to 20, more preferably from 6 to 16. Examples of the monovalent aromatic group include phenyl, p-tollyl, p-methoxyphenyl, o-chlorophenyl, and m- (3-sulfopropylamino) phenyl. The divalent aromatic group is obtained by making the monovalent aromatic group divalent. Examples of the divalent aromatic group include phenylen, p-tollylene, p-methoxyphenylene, o-chlorophenylene, m- (3- sulfopropylamino) phenylene, and naphthylene.

Examples of the heterocyclic group include substituted and unsubstituted heterocyclic groups. The heterocyclic group may have its heterocyclic ring condensed with aliphatic rings, aromatic rings or other heterocyclic rings. The aforesaid heterocyclic group is preferably a 5-or 6-membered heterocyclic ring.

Examples of the hetero atom in the heterocycle include nitrogen, oxygen and sulfur atoms. Examples of the aforesaid substituents include aliphatic group, halogen atom, alkylsulfonyl group, arylsulfonyl group, acyl group, acylamino group,. sulfamoyl group, carbamoyl group, ionic hydrophilic group, etc. Examples of the heterocycle in the monovalent and divalent heterocyclic groups include pyridine, thiophene, thiazole, benozothiazole, benzoxazole, and furane ring.

Examples of the carbamoyl group include substituted and unsubstituted carbamoyl groups. Examples of the substituents on the carbamoyl group include alkyl groups. Examples of the carbamoyl group include methylcarbamoyl group, and dimethylcarbamoyl group.

Examples of the alkoxycarbonylamino group include substituted and unsubstituted alkoxycarbonylamino groups. These alkoxycarbonylamino groups each preferably have from 2 to 20 carbon atoms. Examples of the substituents on the alkoxycarbonylamino group include ionic hydrophilic groups.

Examples of the alkoxycarbonylamino group include methoxycarbonylamino, and ethoxycarbonylamino.

Examples of the aryloxycarbonyl group include substituted aryloxycarbonyl group and unsubstituted aryloxycarbonyl group. The aforesaid aryloxycarbonyl group is preferably an aryloxycarbonyl group having from 7 to 20 carbon atoms. Examples of the aforesaid substituents on aryloxycarbonyl group include ionic hydrophilic groups. Examples of the aforesaid aryloxycarbonyl group include phenoxycarbonyl group.

Examples of the heterocyclic oxycarbonyl group include substituted heterocyclic oxycarbonyl group and unsubstituted heterocyclic oxycarbonyl group. The aforesaid heterocyclic oxycarbonyl group is preferably a heterocyclic oxycarbonyl group having from 2 to 20 carbon atoms. Examples of the aforesaid substituents include ionic hydrophilic groups. Examples of the aforesaid heterocyclic oxycarbonyl group include 2- pyridyloxycarbonyl group.

Examples of the acyl group include substituted acyl group and unsubstituted acyl group. The aforesaid acyl group is preferably an acyl group having from 1 to 20 carbon atoms. Examples of the aforesaid substituents include ionic hydrophilic groups. Examples of the aforesaid acyl group include acetyl group and benzoyl group.

Examples of the alkoxy group include substituted alkoxy group and unsubstituted alkoxy group.

Examples of the aforesaid alkoxy group is preferably an alkoxy group having from 1 to 20 carbon atoms.

Examples of the aforesaid substituents include alkoxy groups, hydroxyl groups, and ionic hydrophilic groups.

Examples of the aforesaid alkoxy group include methoxy group, ethoxy group, isopropoxy group, methoxyethoxy group, hydroxyethoxy group, and 3-carboxypropoxy group.

Examples of the aryloxy group include substituted aryloxy group and unsubstituted aryloxy group. The aforesaid aryloxy group is preferably an aryloxy group having from 6 to 20 carbon atoms. Examples of the aforesaid substituents include alkoxy groups, and ionic hydrophilic groups. Examples of the aforesaid aryloxy group include phenoxy group, p-methoxyphenoxy group, and o-methoxyphenoxy group.

Examples of the heterocyclic oxy group include substituted heterocyclic oxy group and unsubstituted heterocyclic oxy group. The aforesaid heterocyclic oxy group is preferably a heterocyclic oxy group having from 2 to 20 carbon atoms. Examples of the aforesaid substituents include alkyl group, alkoxy group, and ionic hydrophilic groups. Examples of the aforesaid heterocyclic oxy group include 3-pyridyloxy group, and 3- thienyloxy group.

The silyloxy group is preferably a silyloxy group substituted by an aliphatic or aromatic group having from 1 to 20 carbon atoms. Examples of the aforesaid silyloxy group include trimethylsilyloxy, and diphenylmethyl silyloxy.

Examples of the acyloxy group include substituted acyloxy group and unsubstituted acyloxy group.

The aforesaid acyloxy group is preferably an acyloxy group having from 1 to 20 carbon atoms. Examples of the aforesaid substituents include ionic hydrophilic groups. Examples of the aforesaid acyloxy group include acetoxy group, and benzoyloxy group.

Examples of the carbamoyloxy group include substituted carbamoyloxy groups. Examples of the aforesaid substituents include alkyl groups. Examples of the aforesaid carbamoyloxy group include N- methylcarbamoyloxy group.

Examples of the alkoxycarbonyloxy group include substituted alkoxycarbonyloxy group and unsubstituted alkoxycarbonyloxy group. The aforesaid alkoxy carbonyloxy group is preferably an alkoxycarbonyloxy group having from 2 to 20 carbon atoms. Examples of the aforesaid alkoxycarbonyloxy group include methoxycarbonyloxy group, and isopropoxycarbonyloxy group.

Examples of the aryloxycarbonyloxy group include substituted aryloxycarbonyloxy group and unsubstituted aryloxycarbonyloxy group. The aforesaid aryloxy carbonyloxy group is preferably an aryloxycarbonyloxy group having from 7 to 20 carbon atoms. Examples of the aforesaid aryloxycarbonyloxy group include phenoxycarbonyloxy group.

Examples of the amino group include substituted amino group and unsubstituted amino group.

Examples of the aforesaid substituents include aLkyl groups, aryl groups, and heterocylic groups, and the alkyl groups, aryl groups and heterocyclic groups may further have substituents. The alkylamino group is preferably an alkylamino group having from 1 to 20 carbon atoms. Examples of the aforesaid substituents include ionic hydrophilic groups. Examples of the aforesaid alkylamino group include methylamino group, and diethylamino group.

Examples of the arylamino group include substituted arylamino group and unsubstituted arylamino group. The aforesaid arylamino group is preferably an arylamino group having from 6 to 20 carbon atoms.

Examples of the aforesaid substituents include halogen atoms, and ionic hydrophilic groups. Examples of the aforesaid arylamino group include anilino group, and 2-chlorophenylamino group.

Examples of the heterocyclic amino group include substituted heterocyclic amino group and unsubstituted heterocyclic amino group. The aforesaid heterocyclic amino group is preferably a heterocyclic amino group having from 2 to 20 carbon atoms. Examples of the aforesaid substituents include alkyl groups, halogen atoms, and ionic hydrophilic groups.

Examples of the acylamino group include substituted acylamino group and unsubstituted acylamino group. The aforesaid acylamino group is preferably an acylamino group having from 2 to 20 carbon atoms.

Examples of the aforesaid substituents include ionic hydrophilic groups. Examples of the aforesaid acylamino group include acetylamino group, propionylamino group, benzoylamino group, N-phenylacetylamino group, and 3, 5-disulfobenzoylamino group.

Examples of the ureido group include substituted and unsubstituted ureido groups. These ureido groups each preferably have from 1 to 20 carbon atoms. Examples of the substituents on the ureido group include alkyl groups, and aryl groups. Examples of the ureido group include 3-methylureide group, 3,3-dimethylureido group, and 3-phenylureido group.

Examples of the sulfamoylamino group include substituted sulfamoylamino group and unsubstituted sulfamoylamino group. Examples of the aforesaid substituents include alkyl groups. Examples of the aforesaid sulfamoylamino group include N, N-dipropylsulfamoylamino group.

Examples of the alkoxycarbonylamino group include substituted alkoxycarbonylamino group and unsubstituted alkoxycarbonylamino group. The aforesaid alkoxy carbonylamino group is preferably an alkoxycarbonylamino group having from 2 to 20 carbon atoms. Examples of the aforesaid substituents include ionic hydrophilic groups. Examples of the aforesaid alkoxycarbonylamino group include ethoxycarbonylamino groups.

Examples of the aryloxycarbonylamino group include substituted aryloxycarbonylamino group and unsubstituted aryloxycarbonylamino group. The aforesaid aryloxycarbonylamino group is preferably an aryloxycarbonylamino group having from 7 to 20 carbon atoms. Examples of the aforesaid substituents include ionic hydrophilic groups. Examples of the aforesaid aryloxycarbonylamino group include phenoxycarbonyl amino groups.

Examples of the alkylsulfonylamino group and arylsulfonylamino group include substituted alkylsulfonylamino groups and substituted arylsulfonylamino groups. The aforesaid sulfonyl amino group is preferably a sulfonylamino group having from 1 to 20 carbon atoms. Examples of the substituents include ionic hydrophilic groups. Examples of the aforesaid sulfonyl groups include methylsulfonylamino group, N-phenyl- methyl sulfonylamino group, phenyl sulfonyl amino group, and 3-carboxyphenylsulfonyl amino group.

Examples of the heterocyclic sulfonyl group include substituted sulfonylamino group and unsubstituted sulfonylamino group. The aforesaid heterocyclic sulfonyl group is preferably a heterocyclic sulfonylamino group having from 1 to 12 carbon atoms. Examples of the aforesaid substituents include ionic hydrophilic groups. Examples of the aforesaid heterocyclic sulfonyl group include 2-thiophenesulfonyl group, and 3- pyridylsulfonyl group.

Examples of the heterocyclic sulfonyl group include substituted heterocyclic sulfonyl group and unsubstituted heterocyclic sulfonyl group. The aforesaid heterocyclic sulfonyl group is preferably a heterocyclic sulfonyl group having from 1 to 20 carbon atoms. Examples of the aforesaid substituents include ionic hydrophilic groups. Examples of the heterocyclic sulfonyl group include 2-thiophene sulfonyl group and 3-pyridylsulfonyl group.

Examples of the heterocyclic sulfinyl group include substituted heterocyclic sulfinyl group and unsubstituted heterocyclic sulfinyl group. The aforesaid heterocyclic sulfinyl group is preferably a heterocyclic sulfinyl group having from 1 to 20 carbon atoms. Examples of the aforesaid substituents include ionic hydrophilic groups. Examples of the heterocyclic sulfinyl group include 4-pyridylsulfinyl group.

Examples of the alkyl group, aryl group and heterocyclic thio group include substituted alkyl, aryl and heterocyclic thio groups and unsubstituted alkyl, aryl and heterocyclic thio groups. The alkyl, aryl and heterocyclic thio groups each preferably have from 1 to 20 carbon atoms. Examples of the substituents on the alkyl, aryl and heterocyclic thio groups include ionic hydrophilic groups. Examples of the alkyl, aryl and heterocyclic thio groups include methylthio group, phenylthio group, and 2-pyridylthio group.

Examples of the alkylsulfonyl and arylsulfonyl groups include substituted alkylsulfonyl and arylsulfonyl groups and unsubstituted alkylsulfonyl and arylsulfonyl groups. Examples of the alkylsulfonyl and arylsulfonyl groups include methylsulfonyl group and phenylsulfonyl group.

Examples of the alkylsulfinyl and arylsulfinyl groups include substituted alkylsulfinyl and arylsulfinyl groups and unsubstituted alkylsulfinyl and arylsulfinyl groups. Examples of the alkylsulfinyl and arylsulfinyl groups include methylsulfinyl group and phenylsulfinyl group.

Examples of the sulfamoyl group include substituted and unsubstituted sulfamoyl groups. Examples of the substituents on the sulfamoyl group include alkyl groups. Examples of the sulfamoyl group include dimethylsulfamoyl group, and di- (2-hydroxyethyl) sulfamoyl group.

The general formulae (1-4), (4-A) and (4-B) will be further described hereinafter.

Those described with reference to groups and substituents apply to the following description.

In the general formula (1-4), A4l, B41 and 41 each independently represent an aromatic group (A41 and C4, each are a monovalent aromatic group such as aryl group; B41 is a divalent aromatic group such as arylene group) which may be substituted or a heterocyclic group (A4l and C4, each are a monovalent heterocyclic group; B41 is a divalent heterocyclic group) which may be substituted. Examples of the aromatic ring include benzene ring, and naphthalene ring. Examples of the hetero atoms in the heterocycle include nitrogen atom, oxygen atom, and sulfur atom. The heterocyclic group may have aliphatic rings, aromatic rings or other heterocycles condensed thereto.

The substituents may be arylazo groups or heterocyclic azo groups.

Preferably, at least one of A4l, B4l and C41 is a heterocyclic group. More preferably, at least two of A41, Bai and C41 are heterocyclic groups. All of A41, B4l and 41 may be heterocyclic groups.

A preferred example of the heterocyclic group represented by C41 is an aromatic group-containing 6- membered heterocyclic group represented by the following general formula (4-C). In the case where C4, is an aromatic group-containing 6-membered heterocyclic group represented by the following general formula (4-C), the general formula (1-4) corresponds to the general formula (4-A). general formula (4-C): In the general formula (4-C), B42 and B43 each represent =CR4,-or-CR42= or one of B42 and B43 represents a nitrogen atom and the other represents =CR41-or-CR4z=. Preferably, B42 and B43 each represent =CR41-or-CR42=.

R45 and R46 each independently represent a hydrogen atom or an aliphatic group, aromatic group, heterocyclic group, acyl group, alkoxycarbonyl group, aryloxycarbonyl group, carbamoyl group, alkylsulfonyl group, arylsulfonyl group or sulfamoyl group which may further have substituents. Preferred examples of the substituents represented by R45 and R46 include hydrogen atom, aliphatic group, aromatic group, heterocyclic group, acyl group, allylsulfonyl group, and arylsulfonyl group. More desirable among these substituents are hydrogen atom, aromatic group, heterocyclic group, acyl group, alkylsulfonyl group, and arylsulfonyl group.

Most desirable among these substituents are hydrogen atom, aryl group, and heterocyclic group. These substituents may further have substituents. However, R45 and R46 are not a hydrogen atom at the same time.

G4, R4, and R42 each independently represent a hydrogen atom, a halogen atom or an aliphatic group, aromatic group, heterocyclic group, cyano group, carboxyl group, carbamoyl group, alkoxycarbonyl group, aryloxycarbonyl group, heterocyclic oxycarbonyl group, acyl group, hydroxyl group, alkoxy group, aryloxy group, heterocyclic oxy group, silyloxy group, acyloxy group, carbamoyloxy group, alkoxycarbonyloxy group, aryloxycarbonyloxy group, amino group (including alkylamino group, arylamino group and heterocyclic amino group), acylamino group, ureido group, sulfamonylamino group, alkoxycarbonylamino group, aryloxycarbonylamino group, aLkylsulfonylamino group, arylsulfonylamino group, heterocyclic sulfonylamino group, nitro group, alkylthio group, arylthio group, heterocyclic thio group, aLkylsulfonyl group, arylsulfonyl group, heterocyclic sulfonyl group, alkylsulfinyl group, arylsulfinyl group, heterocyclic sulfinyl group, sulfamoyl group, and sulfo group which may be further substituted.

Preferred among the substituents represented by G4 are hydrogen atom, halogen atom, aliphatic group, aromatic group, hydroxyl group, alkoxy group, aryloxy group, heterocyclic oxy group, amino group (including alkylamino group, arylamino group and heterocyclic amino group), acylamino group, ureido group, sulfamonylamino group, alkoxycarbonylamino group, aryloxycarbonylamino group, alkylthio group, arylthio group, and heterocyclic thio group. More desirable among these substituents are hydrogen atom, halogen atom, alkyl group, hydroxyl group, alkoxy group, aryloxy group, acyloxy group, amino group (including alkylamino group, arylamino group and heterocyclic amino group) and acylamino group. Most desirable among these substituents are hydrogen atom, aniline group, and acylamino group. These groups may further have substituents.

Preferred examples of the substituents represented by R41 and R42 include hydrogen atom, alkyl group, halogen atom, alkoxycarbonyl group, carboxyl group, carbamoyl group, hydroxyl group, alkoxy group, and cyano group. These groups may further have substituents.

R4, and R42 or R45 and R46 may be connected to each other to form a 5-or 6-membered ring.

Examples of the substituents on the substituents represented by A4l, Rai, R42, R4s, R46 and G4 include those listed with reference to G4, R4l, and R42. A4l, R41, R42, R4 R46 and G4 preferably further have an ionic hydrophilic group in any position as substituent.

Examples of the ionic hydrophilic group include sulfo group, carboxyl group, phosphono group, and quaternary ammonium group. Preferred among these ionic hydrophilic groups are carboxyl group, phosphono group, and sulfo group, and particularly preferred among these ionic hydrophilic groups are carboxyl group and sulfo group. The carboxyl group, phosphono group and sulfo group may be used in the form of salt. Examples of the counter ion forming the salt include ammonium ion, alkaline metal ion (e. g. , lithium ion, sodium ion, potassium ion), and organic cation (e. g., tetramethyl ammonium ion, tetramethylguanidium ion, tetramethyl phosphonium ion). Preferred among these counter ions is lithium ion.

Preferred examples of the heterocyclic structure represented by B41 include thiophene ring, thiazole ring, imidazole ring, benzothiazole ring, and thienothiazole ring. These heterocyclic groups may further have substituents. Preferred among these heterocyclic groups are thiophene ring, thiazole ring, imidazole ring, benzothiazole ring, and thienothiazole ring represented by the following general formulae (h) to (1). In the case where B41 is a thiophene ring represented by the general formula (h) and C4l has a structure represented by the general formula (4-C), the general formula (1-4) corresponds to the general formula (4-B).

In the general formulae (h) to (1), R4o9 to R4, 7 have the same meaning as the substituents G4, R4, and R42 in the general formula (4-A).

Particularly preferred among the dye structures represented by the general formula (4-B) is one represented by the following general formula (4-D). general formula (4-D): wherein Z4 represents an electron-withdrawing group having a Hammett's substituent constant ap of 0.20 or more. Z4 is preferably an electron-withdrawing group having a Hammett's substituent constant ap of 0.30 or more, more preferably 0.45 or more, particularly 0.60 or more, but the Hammett's substituent constant op of the electron-withdrawing group is preferably not greater than 1.0.

Specific examples of the electron-withdrawing group having a Hammett's substituent constant up of 0.60 or more include cyano group, nitro group, alkylsulfonyl group (e. g., methylsulfonyl group), and arylsulfonyl group (e. g., plienylsulfonyl group).

Examples of the electron-withdrawing group having a Hammett's substituent constant op of 0.45 or more include acyl group (e. g. , acetyl group), alkoxycarbonyl group (e. g. , dodecyloxycarbonyl group), aryloxycarbonyl group (e. g., m-chlorophenoxycarbonyl), alkylsulfinyl group (e. g. , n-propylsulfinyl), arylsulfinyl group (e. g. , phenylsulfinyl), sulfamoyl group (e. g., N-ethylsulfamoyl, N, N-dimethylsulfamoyl), and halogenated alkyl group (e. g., trifluoromethyl) besides the aforesaid groups.

Examples of the electron-withdrawing group having a Hammett's substituent constant op of 0.30 or more include acyloxy group (e. g. , acetoxy group), carbamoyl group (e. g. , N-ethylcarbamoyl, N, N- dibutylcarbamoyl), halogenated alkoxy group (e. g. , trifluoromethyloxy), halogenated aryloxy group (e. g., pentafluorophenyloxy), sulfonyloxy group (e. g., methylsulfonyloxy), halogenated alkylthio group (e. g., difluoromethylthio), aryl group substituted by two or more electron-withdrawing groups having op of 0.15 or more (e. g. , 2,4-dinitrophenyl, pentachlorophenyl), and heterocyclic group' (e. g. , 2-benzooxazolyl, 2- benzothiazolyl, l-phenyl-2-benzoimidazolyl) besides the aforesaid groups.

Specific examples of the electron-withdrawing group having up of 0.20 or more include halogen atoms besides the aforesaid groups.

Preferred among these groups are C2-C2o acyl group, C2-C20 alkyloxycarbonyl group, nitro group, cyano group, Cl-C20 aLkylsulfonyl group, C6-C20 arylsulfonyl group, Cl-C20 carbamoyl group, and Cl-C20 halogenated alkyl group as Z4. Particularly preferred among these groups are cyano group, Cl-C20 alkylsulfonyl group and C6-C20 arylsulfonyl group, most preferably cyano group.

Rai , R42, R4s and R46 in the general formula (4-D) are as defined in the general formula (4-A). R43 and R44 each independently represent a hydrogen atom, aliphatic group, aromatic group, heterocyclic group, acyl group, alkoxycarbonyl group, aryloxycarbonyl group, carbamoyl group, alkylsulfonyl group, arylsulfonyl group or sulfamoyl group. Preferred among these groups are hydrogen atom, aromatic group, heterocyclic group, acyl group, alkylsulfonyl group, and arylsulfonyl group. Particularly preferred among these groups are hydrogen atom, aromatic group, and heterocyclic group.

The groups described with reference to the general formula (4-D) may further have substituents. In the case where these groups further have substituents, examples of these substituents include the substituents described with reference to the general formula (4-A) and the groups and ionic hydrophilic groups exemplified with reference to G4, R4, and R42.

Referring to a particularly preferred combination of azo dyes represented by the general formula (4-B), R45 and R46 each are preferably a hydrogen atom, alkyl group, aryl group, heterocyclic group, sulfonyl group or acyl group, more preferably hydrogen atom, aryl group, heterocyclic group or sulfonyl group, most preferably hydrogen atom, aryl group or heterocyclic group. However, R45 and R46 are not a hydrogen atom at the same time.

G4 is preferably a hydrogen atom, halogen atom, alkyl group, hydroxyl group, amino group or acylamino group, more preferably hydrogen atom, halogen atom, amino group or acylamino group, most preferably hydrogen atom, amino group or acylamino group.

A4l is preferably a pyrazole ring, imidazole ring, isothiazole ring, thiadiazole ring or benzothiazole ring, more preferably pyrazole ring or isothiazole ring, most preferably pyrazole ring.

B42 and B43 are =CR41-and-CR42=, respectively, in which R41 and R42 each are preferably a hydrogen atom, alkyl group, halogen atom, cyano group, carbamoyl group, carboxyl group, hydroxyl group, alkoxy group or alkoxycarbonyl group, more preferably hydrogen atom, alkyl group, carboxyl group, cyano group or carbamoyl group.

Referring to a preferred combination of substituents on the aforementioned azo dye, at least one of the various substituents is preferably a compound which is a preferred group as mentioned above, and more preferably, more of the various substituents are compounds which are preferred groups as mentioned above, and most preferably, all the various substituents are compounds which are preferred groups as mentioned above.

Specific examples of the azo dye represented by the general formula (1-4) will be given below, but the azo dye to be used in the present invention is not limited to the following examples. In the following specific examples, the carboxyl group, phosphono group and sulfo group may be used in the form of salt. Examples of the counter ion forming the salt include ammonium ion, alkaline metal ion (e. g., lithium ion, sodium ion, potassium ion), and organic cation (e. g., tetramethylanunonium ion, tetramethylguanidium ion, tetramethylphosphonium ion). Preferred among these counter ions is lithium ion.

The azo dyes represented by the aforementioned general formulae (1-4), (4-A), (4-B) and (4-D) can be synthesized by the coupling reaction of diazo component with coupler. As a main synthesis method there may be used one disclosed in Japanese Patent Application No. 2002-113460.

As a dyes (S) having % mat of from 350 mm to 500 nm there is preferably used a yellow dye or yellow pigment described below.

The content of the azo dye represented by the general formula (1-4) in the ink is preferably from 0.2% to 20% by weight, more preferably from 0. 5% to 15% by weight.

In order to obtain a full-color image or adjust the color tone of the image, the ink of the invention may comprise other dyes in combination with the dyes of the present invention. Examples of these dyes which can be used in combination with the dyes of the present invention include the following dyes.

Examples of yellow dyes include aryl or heterylazo dyes having phenols, naphthols, anilines, pyrazolones, pyridones or closed-chain type active methylene compounds as coupling components, azomethine dyes having closed-chain type active methylene compounds as coupling components, methine dyes such as benzylidene dyes and monomethine oxonol dyes, and quinone-based dyes such as naphthoquinone dye and anthraquinone dye. Other examples of yellow dyes include quinophthalone dye, nitro-nitroso dye, acridine dye, and acridinone dye. These dyes may assumes yellow only when chromophore is partly dissociated, and, in this case, the counter cation may be an inorganic cation such as alkaline metal ion and ammonium ion or an organic cation such as pyridinium ion and quaternary ammonium salt ion or may be contained in a polymer cation as a partial structure.

Examples of magenta dyes include aryl or heterylazo dyes having phenols, naphthols or anilines as coupling components, azomethine dyes having pyrazolones or pyrazolotriazoles as coupling components, methine dyestuffs such as arylidene dye, styryl dye, melocyanine dye and oxonol dye, carbonium dye such as diphenylmethane dye, triphenylmethane dye and xanthene dye, quinone-based dye such as naphthoquinone, anthraquinone and anthrapyridone, and condensed polycyclic dye such as dioxazine dye. These dyes may assume magenta only when chromophore is partly dissociated, and, in this case, the counter cation may be an inorganic cation such as alkaline metal ion and ammonium ion or an organic cation such as pyridinium ion and quaternary ammonium salt ion or may be contained in a polymer cation as a partial structure.

Examples of cyan dyes include azomethine dyes such as indoaniline dye and indophenol dye, polymethine dyes such as cyanine dye, oxonol dye and melocyanine dye, carbonium dyes such as diphenylmethane dye, triphenylmethane dye and xanthene dye, phthalocyanine dyes, anthraquinone dyes, aryl or heterylazo dyes having phenols, naphthols or anilines as coupling components, and indigo-thioindigo dyes.

These dyes may assume cyan only when chromophore is partly dissociated, and, in this case, the counter cation may be an inorganic cation such as alkaline metal ion and ammonium ion or an organic cation such as pyridinium ion and quaternary ammonium salt ion or may be contained in a polymer cation as a partial structure.

Alternatively, a black dyestuff such as polyazo dye may be used : Other examples of dyes employable herein include water-soluble dyes such as direct dye, acidic dye, food dye, basic dye and reactive dye. Preferred examples of these water-soluble dyes include: C. I. Direct Red 2, 4,9, 23,26, 31, 39, 62,63, 72,75, 76,79, 80,81, 83,84, 89, 92,95, 111,173, 184,207, 211, 212,214, 218,21, 223,224, 225,226, 227, 232, 233,240, 241,242, 243,247 ; C. I. Direct Violet 7,9, 47,48, 51,66, 90,93, 94,95, 98,100, 101 ; C. I. Direct Yellow 8, 9,11, 12,27, 28, 29,33, 35,39, 41,44, 50,53, 58,59, 68, 86, 87, 93,96, 98,100, 106, 108, 109,110, 130,132, 142,144, 161, 163 ; C. I. Direct Blue 1,10, 15,22, 25,55, 67,68, 71,76, 77, 78, 80,84, 86,87, 90,98, 106,108, 109,151, 156,158, 159,160, 168, 189,192, 193,194, 199,200, 201,202, 203,207, 211,213, 214,218, 225,229, 236,237, 244, 248,249, 251,252, 264,270, 280,288, 289, 291 ; C. I. Direct Black 9,17, 19, 22,32, 51, 56,62, 69,77, 80,91, 94,97, 108, 112, 113,114, 117,118, 121,122, 125,132, 146,154, 166,168, 173, 199 ; C. I. Acid Red 35,42, 52,57, 62,80, 82, 111,114, 118, 119,127, 128, 131,143, 151,154, 158, 249,254, 257, 261,263, 266,289, 299,301, 305,336, 337,361, 396,397 ; C. I. Acid Violet 5,34, 43,47, 48,90, 103,126 ; C. I. Acid yellow 17,19, 23,25, 39,40, 42,44, 49,50, 61,64, 76,79, 110,127, 135, 143,151, 159, 169, 174, 190,195, 196,197, 199,218, 219,222, 227; C. I. Acid Blue 9,25, 40,41, 62,72, 76,78, 80,82, 92,106, 112,113, 120,127 : 1,129, 138, 143,175, 181, 205, 207, 220, 221, 230,232, 247,258, 260,264, 271,277, 278,279, 280, 288,290, 326; C. I. Acid Black 7,24, 48,52 : 1, 172; C. I. Reactive Red 3, 13,17, 19,21, 22,23, 24,29, 35,37, 40,41, 43,45, 49,55 ; C. I. Reactive Violet 1, 3,4, 5,6, 7, 8, 9, 16, 17, 22, 23,24, 26,27, 33,34 ; C. I. Reactive Yellow 2,3, 13,14, 15,17, 18,23, 24,25, 26,27, 29,35, 37,41, 42; C. I. Reactive Blue 2,3, 5,8, 10,13, 14, 15, 17, 18, 19,21, 25,26, 27,28, 29,38 ; C. I. Reactive Black 4,5, 8, 14,21, 23,26, 31,32, 34; C. I. Basic Red 12,13, 14,15, 18,22, 23,24, 25,27, 29,35, 36,38, 39,45, 46; C. I. Basic Violet 1, 2,3, 7,10, 15,16, 20,21, 25,27, 28,35, 37,39, 4p, 48; C. I. Basic Yellow 1, 2,4, 11, 13,14, 15, 19, 21, 23,24, 25,28, 29,32, 36,39, 40; C. I. Basic Blue 1, 3,5, 7,9, 22,26, 41,45, 46,47, 54,57, 60,62, 65,66, 69,71 ; C. I. Basic Black 8, etc.

Further, the ink composition of the invention may comprise pigments incorporated therein as well.

As the pigments to be used in the present invention there may be used commercially available products as well as known compounds listed in various literatures. Examples of these literatures include Color Index (compiled by The Society of Dyers and Colourists),"Kaitei Shinban Ganryo Binran (Revised Edition of Handbook of Pigments)", compiled by Japan Association of Pigment Technology, 1989, "Saishin Ganryo Ouyou Gijutsu (Modern Applied Technology of Pigments) ", CMC, 1986,"Insatsu Inki Gijutsu (Printing Ink Technology) ", CMC, 1984, and W. Herbst, K. Hunger, "Industrial Organic Pigments", VCH Verlagsgesellschaft, 1993. Specific examples of these pigments include organic pigments such as azo pigment (e. g., azo lake pigment, insoluble azo pigment, condensed azo pigment, chelate azo pigment), polycyclic pigment (e. g. , phthalocyanine pigment, anthraquinone-based pigment, perylene-based pigment, perynone-based pigment, indigo-based pigment, quinacridone-based pigment, dioxazine-based pigment, isoindolinone-based pigment, quinophthalone-based pigment, diketopypyrrolopyrrole-based pigment), dyed lake pigment (e. g., acidic or basic dye lake pigment) and azine pigment, and inorganic pigments such as yellow pigment (e. g. , C. I.

Pigment Yellow 34,37, 42,53), red pigment (e. g. , C. I. Pigment Red 101, 108), blue pigment (e. g. , C. I. Pigment blue 27,29, 17: 1), black pigment (e. g. , C. I. Pigment Black 7, magnetite) and white pigment (e. g. , C. I. Pigment White 4,6, 18, 21).

As a pigment having a color tone suitable for image formation there is preferably used a blue or cyan pigment such as phthalocyanine pigment, anthraquinone-based indanthrone pigment (e. g. , C. I. Pigment Blue 60) and dyed lake pigment-based triarylcarbonium pigment, particularly phthalocyanine pigment (Preferred examples of the phthalocyanine pigment include copper phthalocyanine such as C. I. Pigment Blue 15: 1,15 : 2, 15: 3,15 : 4 and 15: 6, monochlorophthalocyanine, low chlorination copper phthalocyanine, aluminum phthalocyanine such as pigment listed in European Patent 860475, metal-free phthalocyanine such as C. I.

Pigment Blue 16, and phthalocyanine having Zn, Ni or Ti as a central metal. Particularly preferred among these phthalocyanine dyes are C. I. Pigment Blue 15: 3,15 : 4, and aluminum phthalocyanine).

Preferred examples of red or purple pigments include azo pigments (Preferred examples of these dyes include C. I. Pigment Red 3,5, 11,22, 38,48 : 1,48 : 2,48 : 3,48 : 4,49 : 1,52 : 1,53 : 1,57 : 1,63 : 2,144, 146,184.

Particularly preferred among these dyes are C. I. Pigment Red 57: 1,146, 184), quinacridone-based pigments (Preferred examples of these dyes include C. I. Pigment Red 122,192, 202,207, 209, and C. I. Pigment Violet 19,42. Particularly preferred among these dyes is C. I. Pigment Red 122), dyed lake-based triarylcarbonium pigments (Preferred examples of these dyes include xanthene-based C. I. Pigment Red 81: 1, C. I. Pigment Violet 1,2, 3,27, 39), dioxazine-based pigments (e. g. , C. I. Pigment Violet 23,37), diketopyrrolopyrrole-based pigments (e. g. , C. I. Pigment Red 254), perylene pigments (e. g. , C. I. Pigment Violet 29), anthraquinone-based pigments (e. g. , C. I. Pigment Violet 5: 1,31, 33), and thioindigo-based pigments (e. g. , C. I. Pigment Red 38,88).

Preferred examples of yellow pigments include azo pigments (Preferred examples of these dyes include monoazo pigment-based dyes such as C. I. Pigment Yellow 1,3, 74,98, disazo pigment-based dyes such as C. I.

Pigment Yellow 12,13, 14,16, 17,83, general azo-based dyes such as C. I. Pigment Yellow 93,94, 95,128, 155 and benzimidazolone-based dyes such as C. I. Pigment Yellow 120,151, 154,156, 180. Particularly preferred among these dyes are those prepared from materials other than benzidine-based compounds), isoindoline- isoindolinone-based pigments (Preferred examples of these dyes include C. I. Pigment Yellow 109,110, 137, 139), quinophthalone pigments (Preferred examples of these dyes include C. I. Pigment Yellow 138), and flavanthrone pigment (e. g. , C. I. Pigment Yellow 24).

Preferred examples of black pigments include inorganic pigments (Preferred examples of these pigments include carbon black, and magnetite), and aniline black.

Besides these pigments, orange pigments (C. I. Pigment Orange 13,16), and green pigments (C. I.

Pigment Green 7) may be used.

The pigments which may be used in the present technique may be untreated pigments as mentioned above or may be surface-treated pigments. As surface treatment methods there may be proposed a method involving surface coat with a resin or wax, a method involving the attachment of a surface activator, a method involving the bonding of a reactive material (e. g. , silane coupling agent, radical produced from an epoxy compound, polyisocyanate or diazonium salt) to the surface of pigment, etc. , and these methods are described in the following literatures and patents.

(1) Kinzoku Sekken no Seishitsu to Ouyou (Properties and Application of Metal Soap) (Saiwai Shobo) (2) Insatsu Inki Insatsu (Printing with Printing Ink) (CMC Shuppan, 1984) (3) Saishin Gamyo Ouyou Gijutsu (Modern Applied Technology of Pigments (CMC, 1986) (4) US Patents 5,554, 739,5, 571,311 (5) JP-A-9-151342, JP-A-10-140065, JP-A-10-292143, JP-A-11-166145 In particular, self-dispersible pigments prepared by reacting the diazonium salt disclosed in the US patents (4) with carbon black and capsulized pigments prepared according to the method disclosed in the Japanese patents (5) are useful to obtain dispersion stability without using extra dispersant in the ink.

In the ink of the invention, the pigment may be further dispersed with a dispersant. As such a dispersant there may be used any of known compounds depending on the pigment used, e. g., surface active agent type low molecular dispersant or polymer type dispersant. Examples of these dispersants include those disclosed in JP-A-3-69949 and European Patent 549,486. In order to accelerate the adsorption of the pigment to the dispersant used, a pigment derivative called synergist may be added.

The particle diameter of the pigment which may be used in the present invention is preferably from 0.01 llm to 10 llm, more preferably from 0.05 Fm to 1 llm.

As a method for dispersing the pigment there may be used a known dispersion technique for use in the production of ink or toner. Examples of the dispersing machine include vertical or horizontal agitator mill, attritor, colloid mill, ball mill, three-roll mill, pearl mill, super mill, impeller, disperser, KD mill, dynatron, and pressure kneader. The details of these dispersing machines are described in"Saishin Ganryo Ouyou Gijutsu (Modern Applied Technology of Pigments) ", CMC, 1986.

The surface active agent to be incorporated in a recording ink (preferably, an ink for inkjet recording) composition of the present invention will be described hereinafter. By adding the surface active agent to the recording ink (preferably, an ink for inkjet recording) composition and adjusting the physical properties such as surface tension of the ink, the ejection stability of the ink can be enhanced, exerting an excellent effect of enhancing the water resistance of image and preventing bleeding of ink printed.

Examples of the aforementioned surface active agents include anionic surface active agents such as sodium dodecylsulfate, sodium dodecyloxysulfonate and sodium alkylbenzenesulfonate, cationic surface active agents such as cetyl pyridinium chloride, trimethylcetyl ammonium chloride and tetrabutylammonium chloride, and nonionic surface active agents such as polyoxyethylenenonly phenyl ether, polyoxyethylene naphthyl ether and polyoxyethyleneoctylphenyl ether. Preferred among these surface active agents are nonionic surface active agents.

The content of the surface active agent is from 0. 001 to 20% by weight, preferably from 0.005 to 10% by weight, more preferably from 0. 01 to 5% by weight based on the weight of the ink.

[Second Embodiment], The second embodiment of the invention will be further described hereinafter.

According to the second embodiment of the invention, there is provided a recording method comprising ejecting ink drops by using at least two color inks of yellow and magenta each comprising a dye onto a recording material, the recording material comprising a support and an ink-receptive layer provided on the support, according to a recording signal, so as to record an image on the recording material, wherein the percent bleeding of the recorded image is 30% or less.

The yellow dye will be first described.

[Yellow dye] The yellow dye to be used in the invention preferably has an oxidation potential of more positive than 1.0 V (vs SCE), more preferably more positive than 1.1 V (vs SCE), particularly more positive than 1. 15 V (vs SCE) from the standpoint of fastness, particularly to ozone gas. As such a yellow dye, an azo dye satisfying the aforementioned requirements is particularly preferred.

The oxidation potential (Eox) can be easily measured by those skilled in the art. For the details of the method for measuring the oxidation potential, reference can be made to P. Delahay,"New Instrumental Methods in Electrochemistry", 1954, Interscience Publishers, A. J. Bard et al, "Electrochemical Methods", 1980, John Wiley & Sons, and Akiya Fujishima,"Denki Kagaku Sokuteiho (Electrochemical Measuring Methods) ", 1984, Gihodo Shuppansha.

In some detail, the measurement of oxidation potential is carried out by dissolving the test specimen in a solvent such as dimethylformamide and acetonitrile containing a supporting electrolyte such as sodium perchlorate and tetrapropylammonium perchlorate in a concentration of from l x 10-4 to 1 x 10-6 mol/1, and then measuring the test solution for oxidation potential with respect to SCE (saturated calomel electrode) using cyclic voltammetry or DC polarography. This value may deviate by scores of millivolts due to the effect of difference in potential between solutions or resistivity of test solution. However, the incorporation of a standard specimen (e. g., hydroquinone) makes it possible to assure the reproducibility of potential.

In order to unequivocally define potential, the potential (vs SCE) measured in dimethylformamide containing 0.1 mol dre of tetrapropylammonium perchlorate as a supporting electrolyte (concentration of dye: 0.001 mol dite) using DC polarography is defined as oxidation potential of dye.

The value of oxidation potential Eox indicates the transferability of electrons from the specimen to the electrode. The greater this value is (the more positive the oxidation potential is), the more difficultly can be transferred electrons from the specimen to the electrode, i. e. , the more difficultly can be oxidized the specimen.

With regard to the structure of the compound, the incorporation of electron-withdrawing group causes the oxidation potential to be more positive while the incorporation of electron-donative group causes the oxidation potential to be more negative. In the invention, in order to reduce the reactivity with ozone, which is an electrophilic agent, it is preferred that an electron-withdrawing group be introduced into the skeleton of yellow dye to make the oxidation potential thereof more positive.

The dye to be used in the invention preferably exhibits a good fastness as well as a good hue. It is particularly preferred that the dye of the invention show a sharp absorption spectrum on the longer wavelength side thereof. Therefore, the yellow dye to be used in the invention preferably exhibits % maux of from 390 nm to 470 nm and I (9, maux + 70 nm) (may) ratio (ratio of absorbance at Xmax + 70 nm (I (max + 70 nm)) to absorbance at max (I (max)) of 0.20 or less, more preferably 0.15 or less, even more preferably 0.10 or less.

The absorption wavelength and absorbance defined herein indicate value measured in a solvent (water or ethyl acetate).

As a dye satisfying these oxidation potential and absorption characteristics there is preferably used one represented by the following general formula (2-2).

(Asl-N=N-Bll) n-L... (2-2) wherein Al l and Bl l each independently represent a heterocyclic group which may be substituted ; n represents an integer 1 or 2 ; and L represents a hydrogen atom, mere bond or divalent connecting group, with the proviso that when n is 1, L represents a hydrogen atom and both Al and Bl, are a monovalent heterocyclic group and when n is 2, L represents a mere bond or divalent connecting group, one of Am and Bll is a monovalent heterocyclic group and the other is a divalent connecting group, and two All's and B, l's each may be the same or different.

The heterocyclic group is preferably a heterocyclic group formed by a 5-membered or 6-membered ring. The heterocyclic group may have a monocyclic structure or a polycyclic structure formed by the condensation of two or more rings or may be an aromatic heterocyclic group or non-aromatic heterocyclic group. As hetero atoms constituting the aforementioned heterocyclic group there are preferably used nitrogen, oxygen and sulfur atoms. The suffix n is more preferably 2.

When L is a hydrogen atom, L can be connected to All or Bll at arbitrary position. When L is a mere bond or divalent connecting group, L may be connected to Al l or Bl] at arbitrary position but is preferably connected to the carbon atom or hetero atoms (preferably nitrogen atom) constituting the ring of the heterocyclic groups All and Bll.

Specific examples of All, Bll and L, the preferred embodiments and examples of the general formula (2-2) are same as those explained in the general formula (1-1) in the first embodiment.

Specific examples of the yellow dye to be used in the invention will be given below.

The magenta ink to be incorporated in the recording ink of the invention (preferably ink for ink jet recording) comprises a magenta dye selected from azo dyes dissolved or dispersed in an aqueous medium. The magenta dye to be used herein is basically characterized in that it is a dye having a maximal absorption at a wavelength of from 500 nm to 580 nm in the aqueous medium and an oxidation potential of more positive than 1. 0 V (vs SCE).

The first structural characteristic of preferred dye of this azo dye is that it is a dye having a chromophore represented by the general formula (heterocyclic ring A)-N=N- (heterocyclic ring B). In this case, the heterocyclic ring A and the heterocyclic ring B in the aforementioned general formula may have the same structure. The heterocyclic ring A and heterocyclic ring B each are in detail a 5-or 6-membered heterocyclic ring which is selected from pyrazole, imidazole, triazole, oxazole, thiazole, selenazole, pyridone, pyrazine, pyrimidine and pyridine. In some detail, they are described in JP-A-2001-279145, JP-A-2002-309116, JP-A- 2003-12650, etc.

Further, the second preferred structural characteristic of the aforesaid azo dye is that the azo group is an azo dye having an aromatic nitrogen-containing 6-membered heterocyclic ring directly connected to at least one end thereof as a coupling component, and specific examples of such an azo dye are described in JP-A-2002- 371214.

The third preferred structural characteristic is that the chromophore has an aromatic cyclic amino group or heterocyclic amino group structure, and specific examples of the chromophore include aniline group, and heterylamino group.

The fourth preferred structural characteristic is that the azo dye has a stereostructure. This is described in detail in JP-A-2002-371214.

Among the aforementioned preferred structural characteristics of azo dye, the dye represented by the aforementioned general formula (MI) is most desirable for the purpose of accomplishing the aim of the invention.

The dye of the general formula (MI) will be further described hereinafter.

In the general formula (MI, A31 represents a 5-membered heterocyclic ring. Examples of hetero atoms in the heterocyclic ring include N, O and S. The 5-membered heterocyclic ring is preferably a nitrogen- containing 5-membered heterocyclic ring which may be condensed with aliphatic rings, aromatic rings or other heterocyclic rings. Preferred examples of the heterocyclic group include pyrazole ring, imidazole ring, thiazole ring, isothiazole ring, thiadiazole ring, benzothiazole ring, benzooxazole ring, and benzoisothiazole ring. The various heterocyclic groups may further have substituents. Preferred among these heterocyclic rings are pyrazole ring, imidazole ring, isothiazole ring, thiadiazole ring and benzothiazole ring represented by the following general formulae (a) to (f) : In the aforesaid general formulae (a) to (g), R7 to R22 represent the same substituents as G, Rl and R2 in the general formula (MI).

Preferred among the compounds of the general formulae (a) to (g) are pyrazole ring represented by the general formula (a) and isothiazole ring represented by the general formula (b), most preferably pyrazole ring represented by the general formula (a).

In the general formula (MI), B31 and B32 each represent =CR1- or -CR2= or one of B31 and B32 represents a nitrogen atom while the other represents =CRi-or-CR2=, but B31 and B32 preferably each represent =CR1- or -CR2= Rs and R6 each independently represent a hydrogen atom or substituent. The substituent represents an aliphatic group, aromatic group, heterocyclic group, acyl group, alkoxycarbonyl group, aryloxycarbonyl group, carbamoyl group, alkylsulfonyl group, arylsulfonyl group or sulfamoyl group. The hydrogen atom of these substituents may be substituted.

Preferred examples of R5 and R6 may include hydrogen atom, aliphatic group, aromatic group, heterocyclic group, acyl group, alkylsulfonyl group, and arylsulfonyl group. More preferably, Rs and R6 each are a hydrogen atom, aromatic group, heterocyclic group, acyl group, alkylsulfonyl group or arylsulfonyl group.

Most preferably, Rs and R6 each are a hydrogen atom, aryl group or heterocyclic group. The hydrogen atom of the aforementioned various substituents may be substituted. However, Rs and R6 are not a hydrogen atom at the same time.

G3', Rl and R2 each independently represent a hydrogen atom or substituent. The substituent represents a halogen atom or an aliphatic group, aromatic group, heterocyclic group, cyano group, carboxyl group, carbamoyl group, alkoxycarbonyl group, aryloxycarbonyl group, heterocyclic oxycarbonyl group, acyl group, hydroxyl group, alkoxy group, aryloxy group, heterocyclic oxy group, silyloxy group, acyloxy group, carbamoyloxy group, alkoxycarbonyloxy group, aryloxy carbonyloxy group, amino group (including alkylamino group, arylamino group and heterocyclic amino group), acylamino group, ureido group, sulfamonylamino group, alkoxycarbonyl amino group, aryloxycarbonylamino group, alkyl sulfonylamino group, arylsulfonylamino group, heterocyclic sulfonylamino group, nitro group, alkylthio group, arylthio group, heterocyclic thio group, alkylsulfonyl group, arylsulfonyl group, heterocyclic sulfonyl group, alkylsulfinyl group, arylsulfinyl group, heterocyclic sulfinyl group, sulfamoyl group or sulfo group. The hydrogen atom of these substituents may be further substituted. æl is preferably a hydrogen atom, halogen atom, aliphatic group, aromatic group, hydroxy group, alkoxy group, aryloxy group, acyloxy group, heterocyclic oxy group, amino group (including alkylamino group, arylamino group, and heterocyclic amino group), acylamino group, ureido group, sulfamoylamino group, alkoxycarbonylamino group, aryloxycarbonylamino group, alkylthio group, arylthio group or heterocyclic thio group, more preferably a hydrogen atom, halogen atom, alkyl group, hydroxy group, alkoxy group, aryloxy group, acyloxy group, amino group or acylamino group, most preferably a hydrogen atom, amino group (preferably aniline group) or acylamino group. The hydrogen atom of the aforesaid substituents may be substituted.

Preferred examples of Rl and R2 include hydrogen atom, alkyl group, halogen atom, alkoxycarbonyl group, carboxyl group, carbamoyl group, hydroxy group, alkoxy group, and cyano group. The hydrogen atom of the aforesaid substituents may be substituted.

W and W or Rs and R6 may be connected to each other to form a 5-or 6-membered ring.

Examples of the substituents which may substitute on A31 or which may substitute on the substituents of Rl, R2, Rs, R6 or G include those listed above with reference to G3', R'and R2.

In the case where the dye represented by the general formula (MI) is a water-soluble dye, an ionic hydrophilic group is further provided on any position on A3', R', R2, R5, R6 and G3'as a substituent. Examples of the ionic hydrophilic group as a substituent include sulfo group, carboxyl group, phosphono group, quaternary ammonium group, etc. The aforesaid ionic hydrophilic group is preferably a carboxyl group, phosphono group or sulfo group, particularly carboxyl group or sulfo group. The carboxyl group, phosphono group and sulfo group may be in the form of salt. Examples of counter ions constituting the salt include ammonium ion, alkaline metal ion (e. g., lithium ion, sodium ion, potassium ion), and organic cation (e. g., tetramethylammonium ion, tetramethylguanidium ion, tetramethyl phosphonium).

The terms (substituent) as used herein will be described. These terms are common to the general formula (MI) and the general formula Ma) described later even the signs are different.

Examples of the halogen atom include fluorine atom, chlorine atom, and bromine atom.

The aliphatic group means alkyl group, substituted alkyl group, alkenyl group, substituted alkenyl group, alkinyl group, substituted alkinyl group, aralkyl group and substituted aralkyl group. In the present specification, the term"substituted"as used in"substituted alkyl group", etc. means that the hydrogen atom in "alkyl group", etc. is substituted by substituents listed above with reference to Gl, Rl and R2, etc.

The aliphatic group may have branches or may form a ring. The number of carbon atoms in the aliphatic group is preferably from 1 to 20, more preferably from 1 to 16. The aryl moiety of the aralkyl group or substituted aralkyl group is preferably a phenyl group or naphthyl group, particularly phenyl group. Examples of the aliphatic group include methyl group, ethyl group, butyl group, isopropyl group, t-butyl group, hydroxyethyl group, methoxyethyl group, cyanoethyl group, trifluoromethyl group, 3-sulfopropyl group, 4- sulfobutyl group, cyclohexyl group, benzyl group, 2-phenethyl group, vinyl group, and allyl group.

The aromatic group means an aryl group or substituted aryl group. The aryl group is preferably a phenyl group or naphthyl group, particularly phenyl group. The number of carbon atoms in the aromatic group is preferably from 6 to 20, more preferably from 6 to 16.

Examples of the aromatic group include phenyl group, p-tollyl group, p-methoxyphenyl group, o- chlorophenyl group, and m- (3-sulfopropylamino) phenyl group.

Examples of the heterocyclic group include substituted heterocyclic groups. The heterocyclic group may have its heterocyclic ring condensed with aliphatic rings, aromatic rings or other heterocyclic rings. The aforesaid heterocyclic group is preferably a 5-or 6-membered heterocyclic ring. Examples of the aforesaid substituents include aliphatic group, halogen atom, alkylsulfonyl group, arylsulfonyl group, acyl group, acylamino group, sulfamoyl group, carbamoyl group, ionic hydrophilic group, etc. Examples of the aforesaid heterocyclic group include 2-pyridyl group, 2-thienyl group, 2-thiazolyl group, 2-benzothiazolyl group, 2- benzooxazolyl group, and 2-furyl group.

Examples of the carbamoyl group include substituted carbamoyl groups. Examples of the aforesaid substituents include alkyl group. Examples of the aforesaid carbamoyl group include methylcarbamoyl group, and dimethylcarbamoyl group.

Examples of the alkoxycarbonyl group include substituted alkoxycarbonyl groups. The aforesaid alkoxycarbonyl group is preferably an alkoxycarbonyl group having from 2 to 20 carbon atoms. Examples of the aforesaid substituents include ionic hydrophilic groups. Examples of the aforesaid alkoxycarbonyl group include methoxycarbonyl group, and ethoxycarbonyl group.

Examples of the aryloxycarbonyl group include substituted aryloxycarbonyl groups. The aforesaid aryloxycarbonyl group is preferably an aryloxycarbonyl group having from 7 to 20 carbon atoms. Examples of the aforesaid substituents include ionic hydrophilic groups. Examples of the aforesaid aryloxycarbonyl group include phenoxycarbonyl group.

Examples of the heterocyclic oxycarbonyl group include substituted heterocyclic oxycarbonyl groups.

Examples of the heterocyclic ring include those listed above with reference to the heterocyclic group. The aforesaid heterocyclic oxycarbonyl group is preferably a heterocyclic oxycarbonyl group having from 2 to 20 carbon atoms. Examples of the aforesaid substituents include ionic hydrophilic groups. Examples of the aforesaid heterocyclic oxycarbonyl group include 2-pyridyloxycarbonyl group.

Examples of the acyl group include substituted acyl groups. The aforesaid acyl group is preferably an acyl group having from 1 to 20 carbon atoms. Examples of the aforesaid substituents include ionic hydrophilic groups. Examples of the aforesaid acyl group include acetyl group and benzoyl group.

Examples of the alkoxy group include substituted alkoxy groups. Examples of the aforesaid alkoxy group is preferably an alkoxy group having from 1 to 20 carbon atoms. Examples of the aforesaid substituents include alkoxy groups, hydroxyl groups, and ionic hydrophilic groups. Examples of the aforesaid alkoxy group include methoxy group, ethoxy group, isopropoxy group, methoxyethoxy group, hydroxyethoxy group, and 3- carboxypropoxy group.

Examples of the aryloxy group include substituted aryloxy groups. The aforesaid aryloxy group is preferably an aryloxy group having from 6 to 20 carbon atoms. Examples of the aforesaid substituents include alkoxy groups, and ionic hydrophilic groups. Examples of the aforesaid aryloxy group include phenoxy group, p-methoxyphenoxy group, and o-methoxyphenoxy group.

Examples of the heterocyclic oxy group include substituted heterocyclic oxy groups. Examples of the heterocyclic ring include those listed above with reference to the heterocyclic group. The aforesaid heterocyclic oxy group is preferably a heterocyclic oxy group having from 2 to 20 carbon atoms. Examples of the aforesaid substituents include alkyl groups, alkoxy group, and ionic hydrophilic groups. Examples of the aforesaid heterocyclic oxy group include 3-pyridyloxy group, and 3-thienyloxy group.

The silyloxy group is preferably a silyloxy group substituted by an aliphatic or aromatic group having from 1 to 20 carbon atoms. Examples of the aforesaid silyloxy group include trimethylsilyloxy, and diphenylmethyl silyloxy.

Examples of the acyloxy group include substituted acyloxy groups. The aforesaid acyloxy group is preferably an acyloxy group having from 1 to 20 carbon atoms. Examples of the aforesaid substituents include ionic hydrophilic groups. Examples of the aforesaid acyloxy group include acetoxy group, and benzoyloxy group.

Examples of the carbamoyloxy group include substituted carbamoyloxy groups. Examples of the aforesaid substituents include alkyl groups. Examples of the aforesaid carbamoyloxy group include N- methylcarbamoyloxy group.

Examples of the alkoxycarbonyloxy group include substituted alkoxycarbonyloxy groups. The aforesaid alkoxycarbonyloxy group is preferably an alkoxycarbonyl oxy group having from 2 to 20 carbon atoms. Examples of the aforesaid alkoxycarbonyloxy group include methoxy carbonyloxy group, and isopropoxycarbonyloxy group.

Examples of the aryloxycarbonyloxy group include substituted aryloxycarbonyloxy groups. The aforesaid aryloxycarbonyloxy group is preferably an acyloxy carbonyloxy group having from 7 to 20 carbon atoms. Examples of the aforesaid aryloxycarbonyloxy group include phenoxycarbonyloxy group.

Examples of the amino group include substituted amino groups. Examples of the aforesaid substituents include alkyl groups, aryl groups, and heterocylic groups, and the aLkyl groups, aryl groups and heterocyclic groups may further have substituents. Examples of the alkylamino group include substituted alkylamino groups.

The alkylamino group is preferably an alkylamino group having from 1 to 20 carbon atoms. Examples of the aforesaid substituents include ionic hydrophilic groups. Examples of the aforesaid alkylamino group include methylamino group, and diethylamino group.

Examples of the arylamino group include substituted arylamino groups. The aforesaid arylamino group is preferably an arylamino group having from 6 to 20 carbon atoms. Examples of the aforesaid substituents include halogen atoms, and ionic hydrophilic groups. Examples of the aforesaid arylamino group include phenylamino group, and 2-chlorophenylamino group.

Examples of the heterocyclic amino group include substituted heterocyclic amino groups. Examples of the heterocyclic ring include those listed above with reference to the heterocyclic group. The aforesaid heterocyclic amino group is preferably a heterocyclic amino group having from 2 to 20 carbon atoms.

Examples of the aforesaid substituents include alkyl groups, halogen atoms, and ionic hydrophilic groups.

Examples of the acylamino group include substituted acrylamino groups. The aforesaid acylamino group is preferably an acylamino group having from 2 to 20 carbon atoms. Examples of the aforesaid substituents include ionic hydrophilic groups. Examples of the aforesaid acylamino group include acetylamino group, propionylamino group, benzoylamino group, N-phenyl acetylamino group, and 3, 5-disulfobenzoylamino group.

Examples of the ureido group include substituted ureido groups. The aforesaid ureido group is preferably an ureido group having from 1 to 20 carbon atoms. Examples of the aforesaid substituents include alkyl groups, and aryl groups. Examples of the aforesaid ureido group include 3-methylureido group, 3,3- dimethyl ureido group, and 3-phenylureido group.

Examples of the sulfamoylamino group include substituted sulfamoylamino groups. Examples of the aforesaid substituents include alkyl groups. Examples of the aforesaid sulfamoylamino group include N, N- dipropylsulfamoylamino group.

Examples of the alkoxycarbonylamino group include substituted alkoxycarbonylamino groups. The aforesaid alkoxycarbonylamino group is preferably an alkoxy carbonylamino group having from 2 to 20 carbon atoms. Examples of the aforesaid substituents include ionic hydrophilic groups. Examples of the aforesaid alkoxycarbonylamino group include ethoxycarbonylamino groups.

Examples of the aryloxycarbonylamino group include substituted aryloxycarbonylamino groups. The aforesaid aryloxycarbonylamino group is preferably an aryloxycarbonylamino group having from 7 to 20 carbon atoms. Examples of the aforesaid substituents include ionic hydrophilic groups. Examples of the aforesaid aryloxycarbonylamino group include phenoxycarbonyl amino groups.

Examples of the alkylsulfonylamino group and arylsulfonylamino group include substituted alkyl sulfonylamino groups and substituted arylsulfonylamino groups. The aforesaid alkylsulfonylamino group and arylsulfonylamino group are preferably an alkylsulfonyl amino group having from 1 to 20 atoms and arylsulfonylamino group having from 7 to 20 carbon atoms. Examples of the substituents include ionic hydrophilic groups. Examples of the aforesaid alkylsulfonylamino group and arylsulfonyl amino group include methylsulfonylamino group, N-phenyl-methyl sulfonylamino group, phenylsulfonyl amino group, and 3- carboxyphenylsulfonyl amino group.

Examples of the heterocyclic sulfonylamino group include substituted sulfonylamino groups.

Examples of the heterocyclic ring include those listed above with reference to the heterocyclic group. The aforesaid heterocyclic sulfonylamino group is preferably a heterocyclic sulfonylamino group having from 1 to 12 carbon atoms. Examples of the aforesaid substituents include ionic hydrophilic groups. Examples of the aforesaid heterocyclic sulfonylamino group include 2-thienylsulfonylamino group, and 3-pyridylsulfonyl amino group.

Examples of the alkylthio group, arylthio group and heterocyclic thio group include substituted alkylthio group, substituted arylthio group, and substituted heterocyclic thio group. Examples of the heterocyclic ring include those listed above with reference to the heterocyclic group. The aforesaid alkylthio group, arylthio group and heterocyclic thio group each preferably have from 1 to 20 carbon atoms. Examples of the aforesaid substituents include ionic hydrophilic groups. Examples of the aforesaid alkylthio group, arylthio group and heterocyclic thio group include methylthio group, phenylthio group, and 2-pyridylthio group.

Examples of the alkylsulfonyl group and aryl sulfonyl group include substituted alkylsulfonyl groups and substituted arylsulfonyl groups. Examples of the alkylsulfonyl group and arylsulfonyl group include methylsulfonyl group and phenylsulfonyl group, respectively.

Examples of the heterocyclic sulfonyl group include substituted heterocyclic sulfonyl groups.

Examples of the heterocyclic ring include those listed above with reference to the heterocyclic group. The aforesaid heterocyclic sulfonyl group is preferably a heterocyclic sulfonyl group having from 1 to 20 carbon atoms. Examples of the aforesaid substituents include ionic hydrophilic groups. Examples of the aforesaid heterocyclic sulfonyl group include 2-thienylsulfonyl group and 3-pyridylsulfonyl group.

Examples of the alkylsulfinyl group and arylsulfinyl group include substituted alkylsulfinyl groups and substituted arylsulfinyl groups. Examples of the alkylsulfinyl group and arylsulfinyl group include methylsulfinyl group and phenylsulfinyl group, respectively.

Examples of the heterocyclic sulfinyl group include substituted heterocyclic sulfinyl groups. Examples of the heterocyclic ring include those listed above with reference to the heterocyclic group. The aforesaid heterocyclic sulfonyl group is preferably a heterocyclic sulfinyl group having from 1 to 20 carbon atoms.

Examples of the aforesaid substituents include ionic hydrophilic groups. Examples of the heterocyclic sulfinyl group include 4-pyridylsulfinyl group.

Examples of the sulfamoyl group include substituted sulfamoyl groups. Examples of the aforesaid substituents include alkyl groups. Examples of the aforesaid sulfamoyl group include dimethylsulfamoyl group, and di- (2-hydroxyethyl) sulfamoyl group.

Particularly preferred among the structures of the general formula) is one represented by the following general formula (mixa). general formula (MIa) : wherein R', R, R5 and R6 are as defined in the general formula (AG).

R3 and each independently represent a hydrogen atom or a substituent which represents an aliphatic group, aromatic group, heterocyclic group, acyl group, alkoxycarbonyl group, aryloxycarbonyl group, carbamoyl group, alkylsulfonyl group, arylsulfonyl group or sulfamoyl group. Preferred among these substituents is hydrogen atom, aromatic group, heterocyclic group, acyl group, alkylsulfonyl group or arylsulfonyl group, particularly hydrogen atom, aromatic group and heterocyclic group- zl represents an electron-withdrawing group having a Hammett's substituent constant ap of 0.20 or more. Z'is preferably an electron-withdrawing group having a Hammett's substituent constant ap of 0.30 or more, more preferably 0.45 or more, particularly 0.60 or more, but the Hammett's substituent constant op of the electron-withdrawing group is preferably not greater than 1.0. Specific preferred examples of the substituents include electron-withdrawing substituents described later. Preferred among these electron-withdrawing substituents are C2-C20 acyl group, Cz-C2o alkyloxycarbonyl group, nitro group, cyano group, Cl-C20 alkylsulfonyl group, C6-C20 arylsulfonyl group, Cl-C20 carbamoyl group, and Cl-C20 halogenated alkyl group.

Particularly preferred among these electron-withdrawing substituents are cyano group, Cl-C20 aLkylsulfonyl group, and C6-C20 arylsulfonyl group. Most desirable among these electron-withdrawing substituents is cyano group.

2 represents a hydrogen atom or a substituent and the substituent represents an aliphatic group, aromatic group or heterocyclic group. Z2 is preferably an aliphatic group, more preferably a Cl-C6 alkyl group.

Q represents a hydrogen atom or a substituent and the substituent represents an aliphatic group, aromatic group or heterocyclic group. In particular, Q is preferably a group formed by a group of non-metallic atoms required to form a 5-to 8-membered ring. The aforementioned 5-to 8-membered ring may be substituted, may be a saturated ring or may have an unsaturated bond. Particularly preferred among these 5-to 8-membered rings are aromatic group and heterocyclic group. Preferred examples of the non-metallic atom include nitrogen atom, oxygen atom, sulfur atom, and carbon atom. Specific examples of these cyclic structures include benzene ring, cyclopentane ring, cyclohexane ring, cycloheptane ring, cyclooctane ring, cyclohexene ring, pyridine ring, pyrimidine ring, pyrazine ring, pyridazine ring, triazine ring, imidazole ring, benzoimidazole ring, oxazole ring, benzoxazole ring, thiazole ring, benzothiazole ring, oxane ring, sulfolan ring, and thiane ring.

The hydrogen atoms in the substituents described with reference to the general formula (lia) may be substituted. Examples of the substituents on these substituents include substituents listed with reference to the general formula (MI), and groups and ionic hydrophilic groups exemplified with reference to G3l, Rl and R2.

The Hammett's substituent constant crp will be described hereinafter. Hammett's rule is an empirical rule which L. P. Hammett proposed in 1935 to quantitatively discuss the effect of substituents on the reaction or equilibrium of benzene derivatives, and the validity of this empirical rule has been widely accepted today.

Substituent constants required in Hammett's rule are op value and am value, and these values are found in many general literatures, and for the details of these values, reference can be made to J. A. Dean,"Lange's Handbook of Chemistry", 12th ed. , 1979 (Mc Graw-Hill), and"Kagaku no Ryoiki (Region of Chemistry)", extra edition, No. 122, pp. 96-103,1979 (Nankodo). In the present invention, these substituents are defined or described by Hammett's substituent constant ap, but this does not mean that the known values found in the aforementioned literatures are not limited to certain substituents and it goes without saying that even if the values are unknown in literatures, they contain substituents which may fall within the defined range when measured according to Hammett's rule. Further, the compounds of the present invention contain those of the general formula (la) which are not benzene derivatives, and as a measure for indicating the electron effect of substituents there is used op value regardless of substitution position. In the present invention, sp value is used in this sense.

Specific examples of the electron-withdrawing group having a Hammett's substituent constant op of 0.60 or more include cyano group, nitro group, alkylsulfonyl group (e. g., methylsulfonyl group), and arylsulfonyl group (e. g., phenylsulfonyl group).

Examples of the electron-withdrawing group having a Hammett's substituent constant ap of 0.45 or more include acyl group (e. g. , acetyl group), alkoxycarbonyl group (e. g., dodecyloxycarbonyl group), aryloxycarbonyl group (e. g. , m-chlorophenoxycarbonyl), alkylsulfinyl group (e. g., n-propylsulfinyl), arylsulfinyl group (e. g., phenylsulfinyl), sulfamoyl group (e. g. , N-ethyl sulfamoyl, N, N-dimethylsulfamoyl), and halogenated alkyl group (e. g., trifluoromethyl) besides the aforesaid groups.

Examples of the electron-withdrawing group having a Hammett's substituent constant op of 0.30 or more include acyloxy group (e. g. , acetoxy group), carbamoyl group (e. g. , N-ethylcarbamoyl, N, N- dibutylcarbamoyl), halogenated alkoxy group (e. g. , trifluoromethyloxy), halogenated aryloxy group (e. g., pentafluorophenyloxy), sulfonyloxy group (e. g., methylsulfonyloxy), halogenated alkylthio group (e. g., difluoromethylthio), aryl group substituted by two or more electron-withdrawing groups having op of 0.15 or more (e. g. , 2, 4-dinitrophenyl, pentachlorophenyl), and heterocyclic group (e. g. , 2-benzooxazolyl, 2- benzothiazolyl, l-phenyl-2-benzoimidazolyl) besides the aforesaid groups.

Specific examples of the electron-withdrawing group having op of 0.20 or more include halogen atoms besides the aforesaid groups.

Referring to a particularly preferred combination of azo dyes represented by the general formula (MI), Rs and R6 each are preferably a hydrogen atom, alkyl group, aryl group, heterocyclic group, sulfonyl group or acyl group, more preferably hydrogen atom, aryl group, heterocyclic group or sulfonyl group, most preferably hydrogen atom, aryl group or heterocyclic group. However, RS and R6 are not a hydrogen atom at the same time. G is preferably a hydrogen atom, halogen atom, alkyl group, hydroxyl group, amino group or acylamino group, more preferably hydrogen atom, halogen atom, amino group or acylamino group, most preferably hydrogen atom, amino group or acylamino group.

A31 is preferably a pyrazole ring, imidazole ring, isothiazole ring, thiadiazole ring or benzothiazole ring, more preferably pyrazole ring or isothiazole ring, most preferably pyrazole ring.

B"and B 32 are =CRl-and-CR2=, respectively, in which Rl and R2 each are preferably a hydrogen atom, alkyl group, halogen atom, cyano group, carbamoyl group, carboxyl group, hydroxyl group, alkoxy group or alkoxycarbonyl group, more preferably hydrogen atom, alkyl group, carboxyl group, cyano group or carbamoyl group.

Referring to a preferred combination of substituents on the compound represented by the general formula (MI), at least one of the various substituents is preferably a compound which is a preferred group as mentioned above, and more preferably, more of the various substituents are compounds which are preferred groups as mentioned above, and most preferably, all the various substituents are compounds which are preferred groups as mentioned above.

Specific examples of the compound (azo dye) represented by the general formula (Ml) are same as those explained in the general formula (1-3) in the first embodiment.

The recording ink (preferably ink for ink jet recording) composition of the invention (herein simply referred to as"ink"also) can be prepared by dissolving and/or dispersing at least one of the aforementioned azo magenta dyes in an aqueous medium. The recording ink of the invention preferably contains an azo dye in an amount of from 0.2 to 20% by weight, more preferably from 0. 5 to 15% by weight The aforementioned azo magenta dye to be used is substantially water-soluble. The term"substantially water-soluble"as used herein is meant to indicate that the azo magenta dye is dissolved in 20°C water in an amount of 2% by weight or more.

The ink composition for ink jet recording of the invention may comprise other magenta dyes incorporated therein in combination with the aforementioned azo magenta dye.

Examples of the magenta dyes which can be used in combination with the azo magenta dye include aryl or heterylazo dyes having phenols, naphthols or anilines as coupling components, azomethine dyes having pyrazolones or pyrazolotriazoles as coupling components, methine dyestuffs such as arylidene dye, styryl dye, melocyanine dye and oxonol dye, carbonium dye such as diphenylmethane dye, triphenylmethane dye and xanthene dye, quinone-based dye such as naphthoquinone, anthraquinone and anthrapyridone, and condensed polycyclic dye such as dioxazine dye. These dyes may assume magenta only when chromophore is partly dissociated. In this case, the counter cation may be an inorganic cation such as alkaline metal ion and ammonium ion or an organic cation such as pyridinium ion and quaternary ammonium salt ion or may be contained in a polymer cation as a partial structure. The ink composition containing a compound of the general formula (MI) of the invention further comprises other dyes incorporated therein so far as it can satisfy the ink precipitation test as defined herein.

The ink composition of the invention is a recording ink (preferably, an ink for inkjet recording) containing, preferably, a water-miscible organic solvent on a betaine-based surface active agent other than dyes.

The betaine-based surface active agent to be used in the invention has both cationic and anionic moieties in its molecule and is defined as a compound having surface activity. Examples of the cationic moiety include aminic nitrogen atom, nitrogen atom in heteroaromatic ring, and boron atom having four bonds to carbon. Preferred among these cationic moieties are aminic nitrogen atom and nitrogen atom in heteroaromatic ring. Particularly preferred among these cationic moieties is quaternary nitrogen atom. Examples of the anionic moiety include hydroxyl group, thio group, sulfonamide group, sulfo group, carboxyl group, imido group, phosphoric acid group, and phosphonic acid group. Particularly preferred among these anionic moieties are carboxyl group and sulfo group. The charge of the entire surface active agent molecule may be cationic, anionic or neutral but is preferably neutral.

It is particularly preferred that the betaine-based surface active agent to be used in the invention be a compound represented by the general formula (2-1).

In the general formula (2-1), R represents a hydrogen atom, alkyl group, aryl group or heterocyclic group. L represents a divalent connecting group. M represents a hydrogen atom, alkaline metal atom, ammonium group, protonated organic amine, protonated nitrogen-containing heterocyclic group or quaternary ammonium ion, with the proviso that if it is a counter ion of ammonium ion formed by nitrogen atoms in the molecule represented by the general formula (2-1), it represents a group which does not exist as a cation. The suffix q represents an integer of 1 or more. The suffix r represents an integer of 4 or less. The suffix p represents an integer of from 0 to 4. The sum of p and r is 3 or 4. When the sum of p and r is 4, the nitrogen atom is a protonated ammonium atom (=nif=). When m is 2 or more, the plurality of L's may be the same or different. When q is 2 or more, the plurality of COOM groups may be the same or different. When r is 2 or more, the plurality of-(COOM) q] groups may be the same or different. When p is 2 or more, the plurality of R's may be the same or different.

As the betaine-based surface active agent to be used in the invention there is preferably used a compound represented by the following general formula (2-6) or (2-7) among those represented by the general formula (2-1). general formula (2-6): In the general formula (2-6), RIB to R3B each represent an alkyl group which may be substituted and preferably has from 1 to 20 carbon atoms (e. g. , methyl group, ethyl group, propyl group, butyl group, hexyl group, octyl group, dodecyl group, cetyl group, stearyl group, oleyl group), aryl group which may be substituted and preferably has from 6 to 20 carbon atoms (e. g. , phenyl group, tollyl group, xylyl group, naphthyl group, cumyl group, dodecylphenyl group) or heterocyclic group which may be substituted and preferably has from 2 to 20 carbon atoms (e. g. , pyridyl group, quinolyl group). Ris to R3B may be connected to each other to form a cyclic structure. Particularly preferred among these groups is alkyl group. L represents a divalent connecting group. Preferred examples of the divalent connecting group include divalent connecting groups containing alkylene group or arylene group as a basic constituent. The connecting main chain may contain hetero atoms such as oxygen atom, sulfur atom and nitrogen atom. RIB to R3B or L may be substituted by various substituents. Examples of these substituents include alkyl groups preferably having from 1 to 20 carbon atoms, more preferably from 1 to 12 carbon atoms, particularly from 1 to 8 carbon atoms (e. g. , methyl, ethyl, iso- propyl, tert-butyl, n-octyl, n-decyl, n-hexadecyl, cyclopropyl, cyclopentyl, cyclohexyl), alkenyl groups preferably having from 2 to 20 carbon atoms, more preferably from 2 to 12 carbon atoms, particularly from 2 to 8 carbon atoms (e. g. , vinyl, allyl, 2-butenyl, 3-pentenyl), alkinyl groups preferably having from 2 to 20 carbon atoms, more preferably from 2 to 12 carbon atoms, particularly from 2 to 8 carbon atoms (e. g. , propargyl, 3- pentinyl), aryl groups preferably having from 6 to 30 carbon atoms, more preferably from 6 to 20 carbon atoms, particularly from 6 to 12 carbon atoms (e. g. , phenyl, p-methylphenyl, naphthyl), amino groups preferably having from 0 to 20 carbon atoms, more preferably from 0 to 12 carbon atoms, particularly from 0 to 6 carbon atoms (e. g. , amino, methylamino, dimethylamino, diethylamino, diphenylamino, dibenzylamino), alkoxy groups preferably having from 1 to 20 carbon atoms, more preferably from 1 to 12 carbon atoms, particularly from 1 to 8 carbon atoms (e. g. , methoxy, ethoxy, butoxy), aryloxy groups preferably having from 6 to 20 carbon atoms, more preferably from 6 to 16 carbon atoms, particularly from 6 to 12 carbon atoms (e. g., phenyloxy, 2-naphthyl oxy), acyl groups preferably having from 1 to 20 carbon atoms, more preferably from 1 to 16 carbon atoms, particularly from 1 to 12 carbon atoms (e. g. , acetyl, benzoyl, formyl, pivaloyl), alkoxycarbonyl groups preferably having from 2 to 20 carbon atoms, more preferably from 2 to 16 carbon atoms, particularly from 2 to 12 carbon atoms (e. g., methoxycarbonyl, ethoxycarbonyl), aryloxycarbonyl groups preferably having from 7 to 20 carbon atoms, more preferably from 7 to 16 carbon atoms, particularly from 7 to 10 carbon atoms (e. g., phenyloxycarbonyl), acyloxy groups preferably having from 2 to 20 carbon atoms, more preferably from 2 to 16 carbon atoms, particularly from 2 to 10 carbon atoms (e. g., acetoxy, benzoyloxy), acylamino groups preferably having from 2 to 20 carbon atoms, more preferably from 2 to 16 carbon atoms, particularly from 2 to 10 carbon atoms (e. g. , acetylamino, benzoylamino), alkoxycarbonylamino groups preferably having from 2 to 20 carbon atoms, more preferably from 2 to 16 carbon atoms, particularly from 2 to 12 carbon atoms (e. g., methoxycarbonylamino), aryloxycarbonyl amino groups preferably having from 7 to 20 carbon atoms, more preferably from 7 to 16 carbon atoms, particularly from 7 to 12 carbon atoms (e. g. , phenyloxycarbonyl amino), sulfonylamino groups preferably having from 1 to 20 carbon atoms, more preferably from 1 to 16 carbon atoms, particularly from 1 to 12 carbon atoms (e. g. , methyl sulfonylamino, phenylsulfonylamino), sulfamoyl groups preferably having from 0 to 20 carbon atoms, more preferably from 0 to 16 carbon atoms, particularly from 0 to 12 carbon atoms (e. g., sulfamoyl, methylsulfamoyl, dimethylsulfamoyl, phenylsulfamoyl), carbamoyl groups preferably having from 1 to 20 carbon atoms, more preferably from 1 to 16 carbon atoms, particularly from 1 to 12 carbon atoms (e. g., carbamoyl, methylcarbamoyl, diethylcarbamoyl, phenylcarbamoyl), alkylthio groups preferably having from 1 to 20 carbon atoms, more preferably from 1 to 16 carbon atoms, particularly from 1 to 12 carbon atoms (e. g. , methylthio, ethylthio), arylthio groups preferably having from 6 to 20 carbon atoms, more preferably from 6 to 16 carbon atoms, particularly from 6 to 12 carbon atoms (e. g., phenylthio), sulfonyl groups preferably having from 1 to 20 carbon atoms, more preferably from 1 to 16 carbon atoms, particularly from 1 to 12 carbon atoms (e. g., mesyl, tosyl), sulfinyl groups preferably having from 1 to 20 carbon atoms, more preferably from 1 to 16 carbon atoms, particularly from 1 to 12 carbon atoms (e. g. , methyl sulfinyl, phenylsulfinyl), ureido groups preferably having from 1 to 20 carbon atoms, more preferably from 1 to 16 carbon atoms, particularly from 1 to 12 carbon atoms (e. g., ureido, methylureido, phenylureido), phosphoric acid amide groups preferably having from 1 to 20 carbon atoms, more preferably from 1 to 16 carbon atoms, particularly from 1 to 12 carbon atoms (e. g. , diethylphosphoric acid amide, phenylphosphoric acid amide), hydroxyl groups, mercapto groups, halogen atoms (e. g. , fluorine atom, chlorine atom, bromine atom, iodine atom), cyano groups, sulfo groups, carboxyl groups, nitro groups, hydroxamic acid groups, sulfino groups, hydrazino groups, imino groups, heterocyclic groups preferably having from 1 to 30 carbon atoms, more preferably from 1 to 12 carbon atoms and containing nitrogen atom, oxygen atom and sulfur atom as hetero atoms (e. g. , imidazolyl, benzoimidazolyl, benzothiazolyl, carbazolyl, azepinyl), and silyl groups preferably having from 3 to 40 carbon atoms, more preferably from 3 to 30 carbon atoms, particularly from 3 to 24 carbon atoms (e. g., trimethylsilyl, triphenylsilyl). These substituents may be further substituted. When there are two or more of these substituents, they may be the same or different. If possible, these substituents may be connected to each other to form a ring. A plurality of betaine structures may be contained via Ri to R3 or L.

In the betaine-based surface active agent to be used in the invention, at least one of RIB to R3B and L contains a group having 8 or more carbon atoms. It is particularly preferred that RIB to R3B contain a long-chain alkyl group. general formula (2-7): (R) -N- [L- (COOM') q] ri wherein R, L and q are as defined in the general formula (1) ; pl represents an integer of from 0 to 3; rl represents an integer of from 1 to 3; and M'represents an alkaline metal cation or hydrogen atom, with the proviso that the sum of pl and rl is 3, when pl is 2 or more, the plurality of R's may be the same or different, and when rl is 2 or more, the plurality of [L- (COOM') q,] groups may be the same or different.

The general formulae (2-1) and (2-7) will be further described hereinafter.

In these general formulae, R represents a hydrogen atom or an alkyl group which may be substituted and preferably has from 1 to 20 carbon atoms (e. g. , methyl group, ethyl group, propyl group, butyl group, hexyl group, octyl group, dodecyl group, cetyl group, stearyl group, oleyl group), aryl group which may be substituted and preferably has from 6 to 20 carbon atoms (e. g. , phenyl group, tollyl group, xylyl group, naphthyl group, cumyl group, dodecylphenyl group) or heterocyclic group which may be substituted and preferably has from 2 to 20 carbon atoms (e. g. , pyridyl group, quinolyl group). These groups may be connected to each other to form a cyclic structure. Particularly preferred among these groups is alkyl group.

L represents a divalent connecting group. Preferred examples of the divalent connecting group include divalent connecting groups containing alkylen group or arylene group as a basic constituent. The connecting main chain may contain hetero atoms such as oxygen atom, sulfur atom and nitrogen atom.

R or L may be substituted by various substituents. Examples of these substituents include alkyl groups preferably having from 1 to 20 carbon atoms, more preferably from 1 to 12 carbon atoms, particularly from 1 to 8 carbon atoms (e. g. , methyl, ethyl, iso-propyl, tert-butyl, n-octyl, n-decyl, n-hexadecyl, cyclopropyl, cyclopentyl, cyclohexyl), alkenyl groups preferably having from 2 to 20 carbon atoms, more preferably from 2 to 12 carbon atoms, particularly from 2 to 8 carbon atoms (e. g. , vinyl, allyl, 2-butenyl, 3-pentenyl), alkinyl groups preferably having from 2 to 20 carbon atoms, more preferably from 2 to 12 carbon atoms, particularly from 2 to 8 carbon atoms (e. g. , propargyl, 3-pentinyl), aryl groups preferably having from 6 to 30 carbon atoms, more preferably from 6 to 20 carbon atoms, particularly from 6 to 12 carbon atoms (e. g. , phenyl, p- methylphenyl, naphthyl), amino groups preferably having from 0 to 20 carbon atoms, more preferably from 0 to 12 carbon atoms, particularly from 0 to 6 carbon atoms (e. g., amino, methylamino, dimethylamino, diethylamino, diphenylamino, dibenzylamino), alkoxy groups preferably having from 1 to 20 carbon atoms, more preferably from 1 to 12 carbon atoms, particularly from 1 to 8 carbon atoms (e. g. , methoxy, ethoxy, butoxy), aryloxy groups preferably having from 6 to 20 carbon atoms, more preferably from 6 to 16 carbon atoms, particularly from 6 to 12 carbon atoms (e. g., phenyloxy, 2-naphthyl oxy), acyl groups preferably having from 1 to 20 carbon atoms, more preferably from 1 to 16 carbon atoms, particularly from 1 to 12 carbon atoms (e. g., acetyl, benzoyl, formyl, pivaloyl), alkoxycarbonyl groups preferably having from 2 to 20 carbon atoms, more preferably from 2 to 16 carbon atoms, particularly from 2 to 12 carbon atoms (e. g. , methoxycarbonyl, ethoxycarbonyl), aryloxycarbonyl groups preferably having from 7 to 20 carbon atoms, more preferably from 7 to 16 carbon atoms, particularly from 7 to 10 carbon atoms (e. g. , phenyloxycarbonyl), acyloxy groups preferably having from 2 to 20 carbon atoms, more preferably from 2 to 16 carbon atoms, particularly from 2 to 10 carbon atoms (e. g., acetoxy, benzoyloxy), acylamino groups preferably having from 2 to 20 carbon atoms, more preferably from 2 to 16 carbon atoms, particularly from 2 to 10 carbon atoms (e. g., acetylamino, benzoylamino), alkoxycarbonylamino groups preferably having from 2 to 20 carbon atoms, more preferably from 2 to 16 carbon atoms, particularly from 2 to 12 carbon atoms (e. g., methoxycarbonylamino), aryloxycarbonyl amino groups preferably having from 7 to 20 carbon atoms, more preferably from 7 to 16 carbon atoms, particularly from 7 to 12 carbon atoms (e. g. , phenyloxycarbonyl amino), sulfonylamino groups preferably having from 1 to 20 carbon atoms, more preferably from 1 to 16 carbon atoms, particularly from 1 to 12 carbon atoms (e. g. , methyl sulfonylamino, phenylsulfonylamino), sulfamoyl groups preferably having from 0 to 20 carbon atoms, more preferably from 0 to 16 carbon atoms, particularly from 0 to 12 carbon atoms (e. g., sulfamoyl, methylsulfamoyl, dimethylsulfamoyl, phenylsulfamoyl), carbamoyl groups preferably having from 1 to 20 carbon atoms, more preferably from 1 to 16 carbon atoms, particularly from 1 to 12 carbon atoms (e. g., carbamoyl, methylcarbamoyl, diethylcarbamoyl, phenylcarbamoyl), alkylthio groups preferably having from 1 to 20 carbon atoms, more preferably from 1 to 16 carbon atoms, particularly from 1 to 12 carbon atoms (e. g., methylthio, ethylthio), arylthio groups preferably having from 6 to 20 carbon atoms, more preferably from 6 to 16 carbon atoms, particularly from 6 to 12 carbon atoms (e. g., phenylthio), sulfonyl groups preferably having from 1 to 20 carbon atoms, more preferably from 1 to 16 carbon atoms, particularly from 1 to 12 carbon atoms (e. g., mesyl, tosyl), sulfinyl groups preferably having from 1 to 20 carbon atoms, more preferably from 1 to 16 carbon atoms, particularly from 1 to 12 carbon atoms (e. g. , methyl sulfinyl, phenylsulfinyl), ureido groups preferably having from 1 to 20 carbon atoms, more preferably from 1 to 16 carbon atoms, particularly from 1 to 12 carbon atoms (e. g. , ureido, methylureido, phenylureido), phosphoric acid amide groups preferably having from 1 to 20 carbon atoms, more preferably from 1 to 16 carbon atoms, particularly from I to 12 carbon atoms (e. g. , diethylphosphoric acid amide, phenylphosphoric acid amide), hydroxyl groups, mercapto groups, halogen atoms (e. g. , fluorine atom, chlorine atom, bromine atom, iodine atom), cyano groups, sulfo groups, carboxyl groups, nitro groups, hydroxamic acid groups, sulfino groups, hydrazino groups, imino groups, heterocyclic groups preferably having from 1 to 30 carbon atoms, more preferably from 1 to 12 carbon atoms and containing nitrogen atom, oxygen atom and sulfur atom as hetero atoms (e. g. , imidazolyl, benzoimidazolyl, benzothiazolyl, carbazolyl, azepinyl), and silyl groups preferably having from 3 to 40 carbon atoms, more preferably from 3 to 30 carbon atoms, particularly from 3 to 24 carbon atoms (e. g. , trimethylsilyl, triphenylsilyl). These substituents may be further substituted. When there are two or more of these substituents, they may be the same or different.

If possible, these substituents may be connected to each other to form a ring. A plurality of betaine structures may be contained via R or L.

M represents a hydrogen atom, alkaline metal cation (e. g. , sodium ion, potassium ion, lithium ion, cesium ion), ammonium ion or aminic organic cation (If it is a primary or tertiary amine, it represents a protonated cation such as protonated methylamine, dimethylamine, ethylamine, diethylamine, triethylamine, diazabicycloundecene, diazabicycloctane, piperidine, pyrrolidine, morpholine, N-methylpiperidine, N- methylmoropholine, pyridine, pyrazine, aniline and N, N-dimetliylaniline. If it is a quaternary ammonium salt, it represents, e. g., tetramethylammonium ion, tetraethylammonium ion, trimethylbenzylammonium ion, methylpyridinium ion, benzylpyridinium ion. ). Particularly preferred among these groups are alkaline metal cation and hydrogen atom.

The suffix q represents an integer of 1 or more (preferably 5 or less, more preferably 2 or less). The suffix r represents an integer of from 1 to 4 (preferably 1 or 2). The suffix p represents an integer of from 0 to 4 (preferably 1 or 2). The sum of p and r is 3 or 4. When the sum of p and 4 is 4, the nitrogen atom is a quaternary ammonium cation and one of the plurality of M's is a dissociated anion. When q is 2 or more, the plurality of (COOM) groups may be the same or different. When r is 2 or more, the plurality of [L- (COOM) q] groups may be the same or different. When p is 2 or more, the plurality of R's may be the same or different.

The suffix pl represents an integer of from 0 to 3 (preferably 2 or less). The suffix rl represents an integer of from 1 to 3 (preferably 2 or less). M'represents an alkaline metal cation or hydrogen atom. The sum of pl and rl is 3. When pl is 2 or more, the plurality of R's may be the same or different. When rl is 2 or more, the plurality of [L-(COOM) q] groups may be the same or different.

R or L preferably contains a hydrocarbon group having 8 or more carbon atoms. Most desirable among the compounds represented by the general formula (2-7) is one represented by the following general formula (2- 8). general formula (2-8): R-N- (L-COOM') a R, L and Ml are as defined in the general formula (2-7). Two (L-COOMl) groups may be the same or different (The two L's and Ml's each may be the same or different). A particularly preferred example of R is alkyl group. L is preferably an alkylene group.

Preferred examples of the betaine-based surface active agent will be given below, but it goes without saying that the invention is not limited thereto.

The preferred added amount of the betaine-based surface active agent may be arbitrary so far as the effect of the invention can be exerted but is preferably from 0.001 to 50% by weight, more preferably from 0.01 to 20% by weight based on the weight of the ink composition. In the ink set comprising at least two inks having the same hue and different densities, it is preferred that the concentration of the betaine-based surface active agent in the ink having the highest dye concentration be higher than that of the ink having the lowest dye concentration. It is particularly preferred that as the concentration of dye in the ink increases, the content of betaine-based surface active agent increases.

Supposing that the concentration of dye in two inks A and B are Da and Db (Da > Db) and the concentration of betaine-based surface active agent in the two inks A and B are Va and Vb (Va > Vb), k represented by Da/Db (Va/Vb) is preferably from 0.1 to 10.

The ink to be used in the invention is of a type obtained by dissolving and/or dispersing a dye in water or a water-miscible organic solvent. In particular, the ink of the invention is preferably a water-soluble type of ink comprising a water-soluble dye incorporated therein. In the ink set, the ink comprising a betaine-based surface active agent may have any color but preferably comprises a betaine-based surface active agent incorporated in a yellow ink and/or magenta ink.

In order to adjust the color tone for full-color image, the ink of the invention may comprise other dyes in combination with the dyes of the present invention. Examples of these dyes which can be used in combination with the dyes of the invention include cyan dyes and black dyes.

The physical characteristics of the dyes which can be used as the cyan dye and black dye is that they have a high oxidation potential. the oxidation potential of the dyes is preferably more positive than 1.00 V, more preferably more positive than 1.1 V, most preferably more positive than 1.15 V.

As the cyan dyes there are preferably used those described as water-soluble phthalocyanine dye in JP- A-2003-12952 and JP-A-2003-12956. Specific preferred examples of the phthalocyanine dye are Exemplary Compounds I-1 to I-12 and 101 to 190 given in the first embodiment.

Preferred embodiments and specific examples of the black dye are same as those given in the general formula (1-4) in the first embodiment.

Incidentally, these dyes may be singly used as a black ink dye but normally is used in combination with dyes which compensate for these dyes in the range where these dyes have a low absorption. In general, the aforementioned dyes are used in combination with dyes or pigments having main absorption in the yellow range to realize desirable black. As yellow dyes there may be used direct dyes or acidic dyes represented by azo dye or azo methine dye which are commonly used. As the dyes to be used for the adjustment of color tone for full- color image there may be used various dyes disclosed in JP-A-2003-306623, paragraph [0090]- [0092]. As a black coloring material there may be used a dispersion of carbon black.

Examples of the water-miscible organic solvent (including water-soluble organic solvent) employable herein include alcohols (e. g. , methanol, ethanol, propanol, isopropanol, butanol, isobutanol, sec-butanol, t- butanol, pentanol, hexanol, cyclohexanol, benzylalcohol), polyvalent alcohols (e. g. , ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, butylene glycol, hexanediol, pentanediol, glycerin, hexatriol, thiodiglycol), glycol derivatives (e. g. , ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, triethylene glycol monomethyl ether, tripropylene glycol monomethyl ether, triethylene glycol monobutyl ether, ethylene glycol diacetate, ethylene glycol monomethyl ether acetate, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, ethylene glycol monophenyl ether), amines (e. g., ethanolamine, diethanolamine, triethanolamine, N-methyldiethanol amine, N-ethyldiethanolamine, morpholine, N-ethyl morpholine, ethylenediamine, diethylenetriamine, triethylenetetramine, polyethyleneimine, tetramethyl propylenediamine), and other polar solvents (e. g., formamide, N, N-dimethylformamide, N, N-dimethyl acetamid, dimethylsulfoxide, sulfolan, 2-pyrrolidone, N- methyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, 2-oxazolidone, 1, 3-dimethyl-2-imidazolidinone, acetonitrile, acetone). Two or more of these water-miscible organic solvents may be used in combination. In the invention, a water-miscible organic solvent (preferably water-soluble organic solvent) having a boiling point of 150°C or more (preferably 200°C or more) is preferably used.

In the invention, preferred among the aforementioned water-miscible organic solvents is one (preferably water-soluble organic solvent) having a boiling point of 150°C or more (preferably 170°C or more).

The water-miscible organic solvents belonging to the aforementioned glycol derivatives are preferred.

Particularly preferred among these glycol derivatives are triethylene glycol monobutyl ether, diethylene glycol monobutyl ether, tripropylene glycol monomethyl ether, and dipropylene glycol monomethyl ether.

The water-miscible organic solvent may be used in an amount of from 0.01 to 0.95 times, preferably from 0.01 to 0.7 times the weight of the ink composition.

These water-miscible organic solvents may be used singly or in admixture.

The recording ink (preferably ink for ink jet recording) (composition) may comprise a surface active agent incorporated therein. In this arrangement, the liquid physical properties of the ink composition can be properly adjusted to enhance the ejection stability of the ink composition, making it possible to exert an excellent effect of enhancing the waterproofness of the image or preventing the bleeding of ink composition.

Examples of the aforementioned surface active agents include anionic surface active agents such as sodium dodecylsulfate, sodium dodecyloxysulfonate and sodium alkylbenzenesulfonate, cationic surface active agents such as cetyl pyridinium chloride, trimethylcetyl ammonium chloride and tetrabutylammonium chloride, and nonionic surface active agents such as polyoxyethylenenonly phenyl ether, polyoxyethylene naphthyl ether and polyoxyethyleneoctylphenyl ether. Preferred among these surface active agents are nonionic surface active agents.

The content of the surface active agent is from 0.001 to 15% by weight, preferably from 0.005 to 10% by weight, more preferably from 0.01 to 5% by weight based on the weight of the ink composition.

In the invention, in addition to the betaine-based surface active agent, there may be used nonionic, cationic or anionic surface active agents as surface tension adjustor. Examples of the anionic surface active agent include aliphatic acid salts, alkylsulfuric acid esters, alkylbenzenesulfonates, alkylnapthalene sulfonates, dialkylsulfosuccinates, alkylphosphoric acid esters, naphthalenesulfonic acid-formalin condensates, and polyoxyethylenealkylsulfuric acid esters. Examples of the nonionic surface active agent include polyoxyethylenealkyl ethers, polyoxyethylene allyl allyl ethers, polyoxyethylenealiphatic acid esters, sorbitanaliphatic acid esters, polyoxyethylene sorbitanaliphatic acid esters, polyoxyethylene alkylamines, glycerinaliphatic acid esters, and oxyethyleneoxypropylene block copolymers. SURFYNOLS (produced by Air Products & Chemicals Inc.), which are acetylene-based polyoxyethylene oxide surface active agents, are preferably used as well.

In the first and second embodiments of the invention, the ink for ink jet recording of the invention can be prepared by dissolving or dispersing the aforementioned dyes and preferably a surface active agent in an aqueous medium. The term"aqueous medium"as used in the invention is meant to indicate water or a mixture of water and a small amount of a water-miscible organic solvent optionally comprising additives such as wetting agent, stabilizer and preservative incorporated therein.

In order to prepare the ink solution of the invention, which is a water-soluble ink, the dyes are preferably dissolved in water. Thereafter, various solvents and additives are added to and dissolved in the solution which is then stirred to obtain a uniform ink solution.

Examples of the dissolution method employable herein include dissolution by agitation, dissolution by irradiation with ultrasonic wave, and dissolution by shaking. Particularly preferred among these methods is agitation method. In order to effect stirring, various methods such as fluid agitation known in the art and agitation utilizing shearing force developed by reverse agitator or dissolver may be used. On the other hand, an agitation method utilizing shearing force with respect to the bottom of vessel may be used to advantage.

Examples of the water-miscible organic solvent employable in the present invention include alcohols (e. g. , methanol, ethanol, propanol, isopropanol, butanol, isobutanol, sec-butanol, t-butanol, pentanol, hexanol, cyclohexanol, benzyl alcohol), polyvalent alcohols (e. g. , ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, butylene glycol, hexanediol, pentanediol, glycerin, hexanetriol, thiodiglycol), glycol derivatives (e. g., ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, triethylene glycol monomethyl ether, ethylene glycol diacetate, ethylene glycol monomethyl ether acetate, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, ethylene glycol monophenyl ether), amines (e. g., ethanolamine, diethanolamine, triethanolamine, N- methyldiethanolamine, N-ethyldiethanolamine, morpholine, N-ethylmorpholine, ethylene diamine, diethylene triamine, triethylene tetramine, polyethyleneimine, tetramethylpropylenediamine), and other polar solvents (e. g., formamide, N, N-dimethylformamide, N, N-dimetliylacetamide, dimethylsulfoxide, sulfolane, 2-pyrrolidone, N- methyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, 2-oxazolidone, 1, 3-dimethyl-2-imidazolidinone, acetonitrile, acetone). Two or more of the aforementioned water-miscible organic solvents may be used in combination.

In the case where the dye of the present invention is oil-soluble, the ink can be prepared by emulsion- dispersing the oil-soluble dye in an aqueous medium in the form of solution in a high boiling organic solvent.

The boiling point of the aforesaid high boiling organic solvent is 150°C or more, preferably 170°C or more.

Examples of the high boiling organic solvent employable herein include phthalic acid esters (e. g., dibutyl phthalate, dioctyl phthalate, dicyclohexyl phthalate, di-2-ethylhexyl phthalate, decyl phthalate, bis (2,4- di-tert-amylphenyl) isophthalate, bis (l, l-diethylpropyl) phthalate), phosphoric or phosphonic acid esters (e. g., diphenyl phosphate, triphenyl phosphate, tricresyl phosphate, 2-ethylhexyl diphenyl phosphate, dioctyl butyl phosphate, tricyclohexyl phosphate, tri-2-ethylhexyl phosphate, tridodecyl phosphate, di-2-ethylhexyl phenyl phosphate), benzoic acid esters (e. g., 2-ethylhexyl benzoate, 2,4-dichlorobenzoate, dodecyl benzoate, 2- ethylhexyl-p-hydroxybenzoate), amides (e. g., N, N-diethyl dodecaneamide, N, N-diethyllaurylamide), alcohols or phenols (e. g. , isostearyl alcohol, 2,4-di-tert-amylphenol), aliphatic esters (e. g. , dibutoxyethyl succinate, di-2- ethylhexyl succinate, 2-hexyldecyl tetradecanoate, tributyl citrate, diethyl azelate, isostearyl lactate, trioctyl citrate), aniline derivatives (e. g. , N, N-dibutyl-2-butoxy-5-tert-octylaniline), chlorinated paraffins (e. g., parafflns having a chlorine content of from 10% to 80%), trimesic acid esters (e. g. , tributyl trimesate), dodecyl benzene, diisopropylene naphthalene, phenols (e. g. , 2,4-di-tert-amylphenol, 4-dodecyloxyphenol, 4- dodecyloxycarbonylphenol, 4- (4-dodecyloxy phenylsulfonyl) phenol), carboxylic acids (e. g., 2- (2, 4-di-tert- amylphenoxybutyric acid, 2-ethoxy octanedecanoic acid), and alkylphosphoric acids (e. g. , di- 2 (ethylhexyl) phosphoric acid, dipheylphosphoric acid). The high boiling organic solvent may be used in an amount of from 0.01 to 3 times, preferably from 0.01 to 1.0 times that of the oil-soluble dye.

These high boiling organic solvents may be used singly or in admixture of two or more thereof (e. g., tricresyl phosphate and dibutyl phthalate, trioctyl phosphate and di (2-ethylhexyl) sebacate, dibutyl phthalate and poly (N-t-butylacrylamide)).

For examples of compounds other than the aforementioned high boiling organic solvents to be used in the invention and/or methods for the synthesis of these high boiling organic solvents, reference can be made to US Patents 2,322, 027,2, 533,514, 2,772, 163,2, 835,579, 3,594, 171,3, 676,137, 3,689, 271,3, 700,454, 3,748, 141,3, 764,336, 3,765, 897,3, 912,515, 3,936, 303,4, 004,928, 4,080, 209,4, 127,413, 4, 193, 802, 4,207, 393, 4,220, 711,4, 239,851, 4,278, 757,4, 353,979, 4,363, 873,4, 430,421, 4,430, 422,4, 464,464, 4,483, 918,4, 540,657, 4,684, 606,4, 728,599, 4,745, 049,4, 935, 321, 5,013, 639, European Patents 276, 319A, 286, 253A, 289, 820A, 309, 158A, 309, 159A, 309,160A, 509, 311A, 510, 576A, East German Patents 147,009, 157,147, 159,573, 225, 240A, British Patent 2,091, 124A, JP-A-48-47335, JP-A-50-26530, JP-A-51-25133, JP-A-51-26036, JP-A- 51-27921, JP-A-51-27922, JP-A-51-149028, JP-A-52-46816, JP-A-53-1520, JP-A-53-1521, JP-A-53-15127, JP- A-53-146622, JP-A-54-91325, JP-A-54-106228, JP-A-54-118246, JP-A-55-59464, JP-A-56-64333, JP-A-56- 81836, JP-A-59-204041, JP-A-61-84641, JP-A-62-118345, JP-A-62-247364, JP-A-63-167357, JP-A-63-214744, JP-A-63-301941, JP-A-64-9452, JP-A-64-9454, JP-A-64-68745, JP-A-1-101543, JP-A-1-102454, JP-A-2-792, JP-A-2-4239, JP-A-2-43541, JP-A-4-29237, JP-A-4-30165, JP-A-4-232946, and JP-A-4-346338.

The aforementioned high boiling organic solvents are used in an amount of preferably from 0. 01 to 3.0 times, pre preferably from 0.01 to 1.0 times that of the oil-soluble dye by weight.

In the invention, the oil-soluble dye and the high boiling organic solvent are used in the form of emulsion dispersion in an aqueous medium. During emulsion dispersion, a low boiling organic solvent may be used in some cases from the standpoint of emulsifiability. As such a low boiling organic solvent there may be used an organic solvent having a boiling point of from about 30°C to 150°C at atmospheric pressure. Preferred examples of the organic solvent employable herein include esters (e. g. , ethyl acetate, butyl acetate, ethyl propionate, p-ethoxyethyl acetate, methyl cellosolve acetate), alcohols (e. g., isopropyl alcohol, n-butyl alcohol, secondary butyl alcohol), ketones (e. g. , methyl isobutyl ketone, methyl ethyl ketone, cyclohexanone), amides (e. g., dimethylformamide, N-methylpyrrolidone), and ethers (e. g., tetrahydrofurane, dioxane). However, the present invention is not limited to these organic solvents.

The emulsion dispersion is effected to disperse an oil phase having a dye dissolved in a high boiling organic solvent optionally mixed with a low boiling organic solvent in an aqueous phase mainly composed of water to make minute oil droplets of oil phase. During this procedure, additives such as surface active agent, wetting agent, dye stabilizer, emulsion stabilizer, preservative and antifungal agent described later may be added to either or both of the aqueous phase and the oil phase as necessary.

The emulsification is normally accomplished by adding the oil phase to the aqueous phase, but a so- called phase inversion emulsification method involving the dropwise addition of an aqueous phase to an oil phase is preferably used. The aforementioned emulsification method may be used also in the case where the dye to be used in the invention is water-soluble and the additives are oil-soluble.

The emulsion dispersion may be effected with the aforesaid surface active agents. Preferred examples of the surface active agents employable herein include anionic surface active agents such as aliphatic acid salt, alkylsulfuric acid ester, alkylbenzenesulfonate, alkylnaphthalenesulfonate, dialkylsulfosuccinate, alkylphosphoric acid esters, naphthalenesulfonic acid-formalin condensate and polyoxyethylenealkylsulfuric acid ester, and nonionic surface active agents such as polyoxyethylenealkyl ether, polyoxyethylenealkylallyl ether, polyoxyethylene aliphatic acid ester, sorbitanaliphatic acid ester, polyoxyethylenesorbitanaliphatic acid ester, polyoxyethyleneallylamine, glycerinalipliatic acid ester and oxyethyleneoxypropylene block copolymer.

Alternatively, SURFYNOLS (produced by Air Products & Chemicals Inc. ), which are acetylene-based polyoxyethylene oxide surface active agents, are preferably used as well. Further, amine oxide-based amphoteric surface active agents such as N, N-dimethyl-N-alkylamine oxide may be used. Those listed as surface active agents in JP-A-59-157,636, pp. 37-38, and Research Disclosure No. 308119 (1989) may be used.

For the purpose of stabilizing the ink shortly after emulsification, the aforementioned surface active agents may be used in combination with a water-soluble polymer. As such a water-soluble polymer there may be preferably used a polyvinyl alcohol, polyvinyl pyrrolidone, polyethylene oxide, polyacrylic acid, polyacrylamide or copolymer thereof. Further, natural water-soluble polymers such as polysaccharides, casein and gelatin may be preferably used. For the purpose of stabilizing the dye dispersion, polyvinyl obtained by the polymerization of acrylic acid esters, methacrylic acid esters, vinyl esters, acrylamides, methacrylamides, olefins, styrenes, vinylethers or acrylonitriles, polyurethanes, polyesters, polyamides, polyureas, polycarbonates, etc. , which are substantially insoluble in an aqueous medium, may be used. These polymers preferably have- S03 or-COO-. In the case where these polymers substantially insoluble in an aqueous medium are used ; they are preferably used in an amount of not greater than 20% by weight, preferably not greater than 10% by weight based on the amount of the high boiling organic solvent.

In the case where emulsion dispersion is effected to disperse the oil-soluble dye or high boiling organic solvent to make an aqueous ink, a particularly important factor is control over the particle size of the aqueous ink. In order to enhance the color purity or density during the formation of an image by ink ejection, it is essential to reduce the average particle size. The volume-average particle diameter of the aqueous ink is preferably not greater than 1 pii, more preferably from 5 nm to 100 nm.

The measurement of the volume-average particle diameter and the particle size distribution of the dispersed particles can be easily accomplished by any known method such as static light scattering method, dynamic light scattering method, centrifugal sedimentation method and method as disclosed in"Jikken Kagaku Koza (Institute of Experimental Chemistry)", 4th ed. , pp. 417-418. For example, measurement can be easily carried out by diluting the ink with distilled water such that the particle concentration in the ink reaches 0.1% to 1% by weight, and then subjecting the solution to measurement using a commercially available volume-average particle diameter measuring instrument (e. g., Microtrack UPA (produced by NIKKISO CO. , LTD. ). Further, dynamic light scattering method utilizing laser doppler effect is particularly preferred because it is capable of measuring even small particle size.

The term"volume-average particle diameter"as used herein is meant to indicate average particle diameter weighted with particle volume, which is obtained by dividing the sum of the product of the diameter and the volume of individual particles in the aggregate of particles by the total volume of the particles. For the details of volume-average particle diameter, reference can be made to Souichi Muroi,"Koubunshi Ratekkusu no Kagaku (Chemistry of Polymer Latexes)", Koubunshi Kankokai, page 119.

It was also made obvious that the presence of coarse particles has an extremely great effect on the printing properties. In other words, coarse particles clog. the head nozzle. Even if coarse particles do not go so far as to clog the head nozzle, the ink cannot be ejected or can be deviated when ejected, giving a serious effect on the printing properties. In order to prevent this trouble, it is important to keep the number of particles having a diameter of not smaller than 5 am and not smaller than 1 pm in the resulting ink to 10 or less and 1,000 or less, respectively.

The removal of these coarse particles can be accomplished by any known method such as centrifugal separation method and precision filtration method. The separation step may be effected shortly after emulsion dispersion or shortly before the filling of the emulsion dispersion comprising various additives such as wetting agent and surface active agent in the ink cartridge.

As an effective unit for reducing the average particle diameter of particles and eliminating coarse particles there may be used a mechanical emulsifier.

As such an emulsifier there may be used any known device such as simple stirrer, impeller type agitator, in-line agitator, mill type agitator (e. g. , colloid mill) and ultrasonic agitator. The use of a high pressure homogenizer is particularly preferred.

For the details of the mechanism of high pressure homogenizer, reference can be made to US Patent 4,533, 254, JP-A-6-47264, etc. , and examples of commercially available high pressure homogenizers include Gaulin homogenizer (produced by A. P. V GAULLN INC. ), microfluidizer (produced by MICROFLUIDEX INC. ) and altimizer (produced by SUGINO MACHINE LIMITED).

In recent years, a high pressure homogenizer having a mechanism for atomizing a material in a ultrahigh pressure jet stream as disclosed in US Patent 5,720, 551 is particularly useful in the emulsion dispersion of the invention. An example of the emulsifier using a ultrahigh jet stream is De BEE2000 (produced by BEE INTERNATIONAL LTD.).

The pressure at which emulsion is carried out by a high pressure emulsion disperser is not lower than 50 MPa, preferably not lower than 60 MPa, more preferably not lower than 180 MPa.

For example, the combined use of two or more emulsifiers as in a method involving the emulsification by an agitated emulsifier followed by the passage through a high pressure homogenizer is particularly preferred.

Alternatively, a method is preferably used which comprises effecting the emulsion of the material using such an emulsifier, adding additives such as wetting agent and surface active agent, and then passing the ink composition again through the high pressure homogenizer before being filled in the cartridge.

In the case where the dye composition comprises a low boiling organic solvent incorporated therein in addition to the high boiling organic solvent, it is preferred to remove the low boiling organic solvent from the standpoint of emulsion stability and safety/hygiene. The removal of the low boiling solvent can be accomplished by any known method such as evaporation method, vacuum evaporation method and ultrafiltration method depending on the solvent to be removed. The step of removing the low boiling organic solvent is preferably effected as rapidly as possible shortly after emulsification.

For the details of the process for the preparation of ink for ink jet recording, reference can be made to JP-A-5-148436, JP-A-5-295312, JP-A-7-97541, JP-A-7-82515, and JP-A-7-118584. These preparation processes can be used also in the preparation of the ink for ink jet recording of the invention.

During the production of the ink for ink jet recording of the invention, ultrasonic vibration may be applied at the step of dissolving additives such as dye and like steps.

Referring further to ultrasonic vibration, an ultrasonic energy equal to or greater than the energy received by the recording head has been previously applied during the production of the ink to remove bubbles, preventing the generation of bubbles due to the pressure applied to the ink by the recording head.

The ultrasonic vibration is an ultrasonic wave having a frequency of normally 20 kHz or more, preferably 40 kHz or more, more preferably 50 kHz. The energy applied to the solution by the ultrasonic vibration is normally 2 x 107 J/m3 or more, preferably 5 x 107 J/m3 or more, more preferably 1 x 108 J/m3 or more. The time during which the ultrasonic vibration is applied is normally from about 10 minutes to 1 hour.

The step of applying ultrasonic vibration may be effected at any time after the incorporation of the dye in the medium to exert the effect. Even when the ultrasonic vibration is applied after the storage of the ink completed, the effect can be exerted. However, it is preferred that the ultrasonic vibration be applied during the dissolution and/or dispersion of the dye in the medium because the effect of removing bubbles can be more exerted and the dissolution and/or dispersion of the dyestuff in the medium can be accelerated by the ultrasonic vibration.

In other words, the aforementioned step of applying at least ultrasonic vibration may be effected either during or after the step of dissolving and/or dispersing the dye in the medium. In other words, the aforementioned step of applying at least ultrasonic vibration may be effect one or more times between after the preparation of the ink and the completion of the product.

In an embodiment of implementation of the invention of the invention, the step of dissolving and/or dispersing the dye in the medium preferably involves a step of dissolving the aforementioned dye in a part of the entire medium and a step of adding the rest of the medium, and it is preferred that ultrasonic vibration be applied at any of the aforementioned steps, more preferably at the step of dissolving the dye in a part of the entire medium.

The aforementioned step of adding the rest of the medium may consist of a single step or a plurality of steps.

Further, the process for the production of the ink according to the present invention is preferably accompanied by heat deaeration or deaeration under reduced pressure to enhance the effect of removing bubbles from the ink. Heat deaeration or vacuum deaeration is preferably effected at the same time with or after the step of adding the rest of the medium to the solution. adding the rest of the medium to the solution.

Examples of the unit for generating sound vibration at the step of giving sound vibration include known devices such as ultrasonic dispersing machine.

In the process for the preparation of the ink composition according to the invention, it is important to effect a step of removing dust as solid content by filtration after the preparation of the ink solution. For this job, a filter is used, and, as such a filter there is used a filter having an effective pore diameter of 1 tm or less, preferably from 0.05 Fm to 0. 3 im, particularly from 0.25 um to 0. 3, um. As the filter material there may be used any of various known materials, and, in the case where a water-soluble dye ink is used, a filter prepared for aqueous solvent is preferably used. In particular, a filter made of a polymer material which can difficultly give dust is preferably used. Filtration may be accomplished by pumping the solution through the jacket or may be effected under pressure or reduced pressure.

Filtration is often accompanied by the entrapment of air in the solution. Since bubbles due to air thus entrapped can often cause disturbance in image in the ink jet recording, the aforementioned deaeration step is preferably provided separately. As the deaeration method there may be used a method which comprises allowing the solution thus filtered to stand or various methods such as ultrasonic deaeration and vacuum deaeration using commercially available. apparatus. The ultrasonic deaeration process, if effected, preferably lasts for about 30 seconds to 2 hours, more preferably for about 5 minutes to 1 hour.

These jobs are preferably effected in a space such as clean room and clean bench to prevent the contamination by dust. In the present invention, these jobs are preferably effected in a space having a cleanness degree of 1,000 class or less. The term"cleanness"as used herein is meant to indicate the value counted by a dust counter.

The ink for ink jet recording of the invention may comprise properly selected additives incorporated therein in a proper amount such as drying inhibitor for preventing the clogging of the ejection nozzle with dried ink, penetration accelerator for helping the ink to penetrate in the page, ultraviolet absorber, oxidation inhibitor, viscosity adjustor, surface tension adjustor, dispersant, dispersion stabilizer, antifungal agent, rust preventive, pH adjustor, anti-foaming agent and chelating agent.

As the drying inhibitor there is preferably used a water-soluble organic solvent having a lower vapor pressure than water. Specific examples of the water-soluble organic solvent include polyvalent alcohols such as ethylene glycol, propylene glycol, diethylene glycol, polyethylene glycol, thiodiglycol, dithiodigycol, 2-methyl- 1,3-propanediol, 1,2, 6-hexanetriol, acetylene glycol derivative, glycerin and trimethylolpropane, lower alkylethers of polyvalent alcohol such as ethylene glycol monomethyl (or ethyl) ether, diethylene glycol monomethyl (or ethyl) ether and triethylene glycol monoethyl (or butyl) ether, heterocyclic compounds such as 2- pyrrolidone, N-methyl-2-pyrrolidone, 1, 3-dimethyl-2-imidazolidinone and N-ethylmorpholine, sulfur-containing compounds such as sulfolan, dimethylsulfoxide and 3-sulfolene, polyfunctional compounds such as diacetone alcohol and diethanolamine, and urea derivatives. Preferred among these water-soluble organic solvents are polyvalent alcohols such as glycerin and diethylene glycol. These drying inhibitors may be used singly or in combination of two or more thereof. These drying inhibitors are preferably incorporated in the ink in an amount of from 10% to 50% by weight.

Examples of the penetration accelerator employable in the present invention include alcohols such as ethanol, isopropanol, butanol, di (tri) ethylene glycol monobutyl ether and 1,2-hexanediol, sodium laurylsulfate, sodium oleate, and nonionic surface active agents. These penetration accelerators can exert a sufficient effect when incorporated in the ink in an amount of from 10% to 30% by weight. These penetration accelerators are preferably used in an amount such that no printing run or print through occurs.

Examples of the ultraviolet absorber to be used to enhance the preservability of the image in the present invention include benzotriazole-based compounds as disclosed in JP-A-58-185677, JP-A-61-190537, JP-A-2- 782, JP-A-5-197075 and JP-A-9-34057, benzophenone-based compounds as disclosed in JP-A-46-2784, JP-A-5- 194483 and US Patent 3,214, 463, cinnamic acid-based compounds as disclosed in JP-B-48-30492, JP-A-56- 21141 and JP-A-10-88106, triazine-based compounds as disclosed in JP-A-4-298503, JP-A-8-53427, JP-A-8- 239368, JP-A-10-182621 and JP-T-8-501291, compounds as disclosed in Research Disclosure No. 24239, and compounds which absorb ultraviolet rays to emit fluorescence, i. e. , so-called fluorescent brighteners, such as stilbene-based and benzoxazole-based compounds.

In the present invention, as the oxidation inhibitor to be used to enhance the image preservability there may be used any of various organic and metal complex-based discoloration inhibitors. Examples of the organic discoloration inhibitors include hydroquinones, alkoxyphenols, dialkoxyphenols, phenols, anilines, amines, indanes, chromans, alkoxyanilines, and heterocyclic compounds. Examples of the metal complex-based discoloration inhibitors include nickel complex, and zinc complex. Specific examples of these oxidation inhibitors include compounds listed in the patents cited in Research Disclosure No. 18716, Articles VI-I and J, Research Disclosure No. 15162, Research Disclosure No. 17643, left column, page 650, Research Disclosure No. 36544, page 527, Research Disclosure No. 307105, page 872, and Research Disclosure No. 15162, and compounds included in the general formula and examples of representative compounds listed in JP-A-62- 215272, pp. 127-137.

Examples of the antifungal agent to be incorporated in the present invention include sodium dehydroacetate, sodium benzoate, sodium pyridinethione-1-oxide, ethyl p-hydroxybenzoate, 1,2- benzoisothiazoline-3-one, and salts thereof. These antifungal agents are preferably incorporated in the ink in an amount of from 0.02% to 5.00% by weight.

For the details of these antifungal agents, reference can be made to"Bokin Bobizai Jiten (Dictionary of Anti-bacterial and Antifungal Agents) ", compiled by Dictionary Compilation Committee of The Society for Antibacterial and Antifungal Agents, Japan.

Examples of the rust preventive employable herein include acidic sulfites, sodium thiosulfate, ammonium thioglycolate, diisopropylammonium nitrite, pentaerthyritol tetranitrate, dicyclohexylammonium nitrite, and benzotriazole. These rust preventives are preferably incorporated in the ink in an amount of from 0.02% to 5.00% by weight.

The pH adjustor to be incorporated in the ink for ink set of the invention is preferably used for the purpose of adjusting the pH value of the ink, providing dispersion stability or like purposes. It is preferred that the pH value of the ink be adjusted to a range of from 8 to 11 at 25°C. When the pH value of the ink falls below 8, the resulting dye composition exhibits a deteriorated solubility, causing nozzle clogging. On the contrary, when the pH value of the ink exceeds 11, the resulting ink tends to exhibit a deteriorated water resistance.

Examples of the pH adjustor include basic pH adjustors such as organic base and inorganic alkali, and acidic pH adjustors such as organic acid and inorganic acid.

Examples of the basic compounds employable herein include inorganic compounds such as sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium hydrogencarbonate, potassium hydrogencarbonate, sodium acetate, potassium acetate, sodium phosphate and disodium hydrogenphosphate, and organic bass such as aqueous ammonia, methylamine, ethylamine, diethylamine, triethylamine, ethanolamine, diethanolamine, triethanolamine, ethylenediamine, piperidine, diazabicyclooctane, diazabicycloundecene, pyridine, quinoline, picoline, lutidine and collidine.

Examples of the acidic compounds employable herein include inorganic compounds such as hydrochloric acid, sulfuric acid, phosphoric acid, boric acid, sodium hydrogensulfate, potassium hydrogensulfate, potassium dihydrogenphosphate and sodium dihydrogenphosphate, and organic compounds such as acetic acid, tartaric acid, benzoic acid, trifluoroacetic acid, methanesulfonic acid, ethanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, saccharinic acid, phthalic acid, picolic acid and quinolinic acid.

The electrical conductance of the ink of the invention falls within a range of from 0.01 to 10 S/m. A particularly preferred range of electrical conductance is from 0.05 to 5 S/m.

The measurement of electric conductance can be accomplished by en electrode method using a commercially available saturated potassium chloride.

The electric conductance of the ink can be controlled mainly by the ionic concentration of the aqueous solution. In the case where the salt concentration is high, desalting may be effected using a ultrafiltration membrane or the like. Further, in the case where salts or the like are added to adjust electric conductance, various organic or inorganic salts may be added.

As the inorganic salts there may be used inorganic compounds such as potassium halide, sodium halide, sodium sulfate, potassium sulfate, sodium hydrogensulfate, potassium hydrogensulfate, sodium nitrate, potassium nitrate, sodium hydrogencarbonate, potassium hydrogencarbonate, sodium phosphate, disodium hydrogenphosphate, boric acid, potassium dihydrogenphosphate and sodium dihydrogenphosphate. Organic compounds such as sodium acetate, potassium acetate, potassium tartrate, sodium tartrate, sodium benzoate, potassium benzoate, sodium p-toluenesulfonate, potassium saccharinate, potassium phthalate and sodium picolate may be used.

Alternatively, the selection of other additive components makes it possible to adjust the electric conductance of the ink.

The ink of the invention exhibits a viscosity of from 1 to 20 mPa-s, more preferably from 2 to 15 mPa-s, particularly from 2 to 10 mPa-s at 25°C. When the viscosity of the ink exceeds 30 mPa-s, the resulting recorded image can be fixed only at a reduced rate. Further, the resulting ink exhibits a deteriorated ejectability. On the contrary, when the viscosity of the ink falls below 1 mPa-s, the resulting recorded image runs and thus exhibits a reduced quality.

The adjustment of viscosity can be arbitrarily carried out by controlling the added amount of the ink solvent. Examples of the ink solvent employable herein include glycerin, diethylene glycol, triethanolamine, 2- pyrrolidone, diethylene glycol monobutyl ether, and triethylene glycol monobutyl ether.

Further, a viscosity adjustor may be used. Examples of the viscosity adjustor employable herein include celluloses, water-soluble polymers such as polyvinyl alcohol, and nonionic surface active agents. For the details of these viscosity adjustors, reference can be made to"Nendo Chousei Gijutsu (Technology for Viscosity Adjustment)", Gijutsu Joho Kyoukai, Article 9,1999, and"Inku Jetto Purintayou Kemikaruzu (98 zouho) -Zairyou no Kaihatsu Doko/Tenbo Chousa (Chemicals for Ink Jet Printer (98 enlarged edition) - Research on Trend and View of Development of Materials) ", CMC, pp. 162-174,1997.

For the details of the method for the measurement of viscosity of liquid, reference can be made to JIS Z8803. In practice, however, the viscosity of liquid can be simply measured using a commercially available viscometer. Examples of the rotary viscometer include Type B viscometer and Type E viscometer produced by Tokyo Keiki Kogyo K. K. In the invention, a Type VM-IOOA-L vibration viscometer (produced by YAMAICHI ELECTRONICS CO. , LTD. ) was used to measure viscosity at 25°C. The unit of viscosity is Pa-s. In practice, however, mPa-s is used.

The surface tension, regardless of which it is static or dynamic, of the ink to be used in the invention is preferably from 20 to not greater than 50 mN/m, more preferably from 20 to not greater than 40 mN/m at 25°C.

When the surface tension of the ink exceeds 50 mN/m, the resulting ink exhibits a drastic deterioration in print quality such as ejection stability and resistance to running and whisker during color mixing. On the contrary, when the surface tension of the ink falls below 20 mN/m, the resulting ink can be attached to hard surface when ejected, causing defective printing.

The aforementioned various cationic, anionic and nonionic surface active agents may be added also for the purpose of adjusting surface tension. These surface active agents are preferably used in an amount of from 0. 01 to 20% by weight, more preferably from 0.1 to 10% by weight based on the weight of the ink for ink jet recording. Two or more of these surface active agents may be used in combination.

Known examples of the static surface tension measuring method include capillary rise method, dropping method, and ring method. In the invention, as the static surface tension measuring method there is used a perpendicular plate method.

When a thin glass or platinum plate is hanged partially dipped in a liquid, surface tension of the liquid acts downward along the length of the plate in contact with the liquid. The surface tension is measured by balancing this force by a upward force.

As dynamic surface tension measuring methods there are known vibration jet method, meniscus dropping method and maximum bubble pressure method as disclosed in"Shinjikken Kagaku Koza (New Institute of Experimental Chemistry), 18th ed. , Kaimen to Koroido (Interface and Colloid)", Maruzen, pp. 69- 90 (1977). Further, a liquid film destruction method is known as disclosed in JP-A-3-2064. In the invention, as the dynamic viscosity measuring method there is used a differential bubble pressure method. The principle and method of effecting this measuring method will be described hereinafter.

When bubbles are formed in a solution which has been stirred to uniformity, a new gas-liquid interface is produced. Surface active agent molecules in the solution then gather on the surface of water at a constant rate. The bubble rate (rate of formation of bubbles) is changed. As the formation rate decreases, more surface active agent components gather on the surface of bubbles, reducing the maximum bubble pressure shortly before the burst of bubbles. Thus, the maximum bubble pressure (surface tension) with respect to bubble rate can be detected. As a method for the measurement of dynamic surface tension there is preferably used a method which comprises forming bubbles in a solution using a large probe and a small probe, measuring the differential pressure of the two probes in the state of maximum bubble pressure, and then calculating the dynamic surface tension from the differential pressure.

The content of no-volatile components in the ink of the invention is preferably from 10% to 70% by weight based on the total amount of the ink from the standpoint of enhancement of ejection stability of ink, printed image quality and various fastnesses of image and elimination of running of printed image and stickiness of printed surface, more preferably from 20% to 60% by weight from the standpoint of enhancement of ejection stability of ink and elimination of running of printed image.

The term"non-volatile component"as used herein is meant to indicate a liquid, solid or polymer component having a boiling point of not lower than 150°C at 1 atm. Examples of the non-volatile components to be incorporated in the ink for ink jet recording include dyes, and high boiling solvents, and polymer latexes, surface active agents, dye stabilizers, antifungal agents and buffers which are optically added. Most of these non-volatile components but dye stabilizers deteriorate the dispersion stability of the ink. Further, these non- volatile components are still present on the ink jet image-receiving paper after printing, inhibiting the stabilization of dyes by association on the image-receiving paper and hence deteriorating various fastnesses of the image area and worsening the image running at high temperature and humidity.

In the invention, the ink may comprise a polymer compound incorporated therein. The term"polymer compound"as used herein is meant to indicate all polymer compounds having a number-average molecular weight of not smaller than 5,000 contained in the ink. Examples of these polymer compounds include water- soluble polymer compounds substantially soluble in an aqueous medium, water-dispersible polymer compounds such as polymer latex and polymer emulsion, and alcohol-soluble polymer compounds soluble in polyvalent alcohols used as auxiliary solvents. All polymer compounds are included in the polymer compounds of the invention so far as they can be substantially uniformly dissolved or dispersed in the ink solution.

Specific examples of the water-soluble polymer compounds employable herein include water-soluble polymers such as polyvinyl alcohol, silanol-modified polyvinyl alcohol, carboxymethyl cellulose, hydroxyethyl cellulose, polyvinyl pyrrolidone, polyalkylene oxide (e. g. , polyethylene oxide, polypropylene oxide) and polyalkylene oxide derivative, natural water-soluble polymers such as polysaccharide, starch, cationated starch, casein and gelatin, aqueous acrylic resins such as polyacrylic acid, polyacrylamide and copolymer thereof, aqueous alkyd resins, and water-soluble compounds which have-S03 or-COO-group and thus are substantially soluble in an aqueous medium.

Examples of the polymer latexes include styrene-butadiene latexes, styrene-acryl latexes, and polyurethane latexes. Examples of the polymer emulsions include acryl emulsions.

These water-soluble polymer compounds may be used singly or in combination of two or more thereof.

Such a water-soluble polymer compound is used as a viscosity adjustor to adjust the ink viscosity to a value falling within a range that provides the ink a good ejectability. When the added amount of the water- soluble polymer compound is too great, the resulting ink exhibits too high a viscosity that deteriorates the ejection stability of the ink solution. Thus, when time elapses, the ink undergoes precipitation, causing clogging of the nozzle.

The added amount of the polymer compound to be used as a viscosity adjustor depends on the molecular weight of the polymer compound added (The greater the molecular weight of the polymer compound to be added is, the smaller is the added amount thereof) but is normally from 0% to 5% by weight, preferably from 0% to 3% by weight, more preferably from 0% to 1% by weight based on the total amount of the ink composition.

In the invention, in addition to the surface active agent,. there may be used nonionic, cationic or anionic surface active agents as surface tension adjustor. Examples of the anionic surface active agent include aliphatic acid salts, alkylsulfuric acid esters, alkylbenzenesulfonates, alkylnapthalenesulfonates, dialkylsulfosuccinates, alkylphosphoric acid esters, naphthalenesulfonic acid-formalin condensates, and polyoxyethylenealkylsulfuric acid esters. Examples of the nonionic surface active agent include polyoxyethylenealkyl ethers, polyoxyethylenealkyl allyl ethers, polyoxyethylenealiphatic acid esters, sorbitanaliphatic acid esters, polyoxyethylene sorbitanaliphatic acid esters, polyoxyethylene alkylamines, glycerinaliphatic acid esters, and oxyethyleneoxypropylene block copolymers. SURFYNOLS (produced by Air Products & Chemicals Inc.), which are acetylene-based polyoxyethylene oxide surface active agents, are preferably used as well. Further, amine oxide-based amphoteric surface active agents such as N, N-dimethyl-N-alkylamine oxide are preferred.

Moreover, those listed as surface active agents in JP-A-59-157,636, pp. 37-38, and Research Disclosure No.

308119, 1989, maybe used.

In the invention, as the dispersant and dispersion stabilizer there may be used the aforementioned various cationic, anionic and nonionic surface active agents as necessary. As the anti-forming agent there may be used a fluorine-based or silicone-based compound or a chelating agent such as EDTA as necessary.

[Image-receiving material] As the image-receiving material there may be used a recording paper or recording film which is a reflection medium described hereinafter.

As the support in the recording paper or recording film there may be used one obtained by processing a chemical pulp such as LBKP and NBKP, a mechanical pulp such as GP, PGW, RMP, TMP, CTMP, CMP and CGP, used paper pulp such as DIP or the like, optionally mixed with known additives such as pigment, binder, sizing agent, fixing agent, cationic agent and paper strength improver, through various paper machines such as foundrinier paper machine and cylinder paper machine. As the support there may be used either a synthetic paper or plastic film sheet besides these support materials. The thickness of the support is preferably from 10 elm to 250 m. The basis weight of the support is preferably from 10 to 250 g/m2.

An ink-receiving layer and a back coat layer may be provided on the support directly or with a size press or anchor coat layer of starch, polyvinyl alcohol or the like interposed therebetween to prepare a material for receiving the ink of the invention. The support may be further subjected to leveling using a calendering machine such as machine calender, TG calender and soft calender.

As the support there is preferably used a paper or plastic film laminated with a polyolefin (e. g., polyethylene, polystyrene, polybutene, copolymer thereof) or polyethylene terephthalate on both sides thereof.

The polyolefin preferably comprises a white pigment (e. g. , titanium oxide, zinc oxide) or a tinting dye (e. g., cobalt blue, ultramarine, neodynium oxide) incorporated therein.

The ink-receiving layer to be provided on the support comprises a porous material or aqueous binder incorporated therein. The image receiving layer (ink-receiving layer) also preferably comprises a pigment incorporated therein. As such a pigment there is preferably used an inorganic white pigment (particles).

Examples of the inorganic white pigments include calcium carbonate, kaolin, talc, clay, diatomaceous earth, synthetic amorphous silica, aluminum silicate, magnesium silicate, calcium silicate, aluminum hydroxide, alumina, lithopone, zeolite, barium sulfate, calcium sulfate, titanium dioxide, zinc sulfate and zinc carbonate, and organic pigments such as styrene-based pigment, acrylic pigment, urea resin and melamine resin.

Particularly preferred among these pigments are porous inorganic white pigments. In particular, synthetic amorphous silica having a large pore area, etc. are preferred. As the synthetic amorphous silica there may be also used anhydrous silicate obtained by dry method or hydrous silicate obtained by wet method, but hydrous silicate is particularly preferred. These pigments may be used in combination of two or more thereof.

Specific examples of the recording paper comprising the aforementioned pigments incorporated in the image-receiving layer include those disclosed in JP-A-10-81064, JP-A-10-119423, JP-A-10-157277, JP-A-10- 217601, JP-A-11-348409, JP-A-2001-138621, JP-A-2000-43401, JP-A-2000-211235, JP-A-2000-309157, JP-A- 2001-96897, JP-A-2001-138627, JP-A-11-91242, JP-A-8-2087, JP-A-8-2090, JP-A-8-2091, JP-A-8-2093, JP-A- 174992, JP-A-11-192777, and JP-A-2001-301314.

Examples of the aqueous binder to be incorporated in the image-receiving layer include water-soluble polymers such as polyvinyl alcohol, silanol-modified polyvinyl alcohol, starch, cationated starch, casein, gelatin, carboxymethyl cellulose, hydroxyethyl cellulose, polyvinyl pyrrolidone, polyalkylene oxide and polyalkylene oxide derivative, and water-dispersible polymers such as styrene butadiene latex and acryl emulsion. These aqueous binders may be used singly or in combination of two or more thereof. In the invention, particularly preferred among these aqueous binders are polyvinyl alcohol and silanol-modified polyvinyl alcohol from the standpoint of adhesion to pigment and exfoliation resistance of ink-receiving layer.

The ink-receiving layer may comprise a mordant, a waterproofing agent, a light-resistance improver, a gas resistance improver, a surface active agent, a film hardener and other additives incorporated therein besides the pigments and aqueous binders.

The mordant to be incorporated in the image-receiving layer is preferably passivated. To this end, a polymer mordant is preferably used.

For the details of the polymer mordant, reference can be made to JP-A-48-28325, JP-A-54-74430, JP- A-54-124726, JP-A-55-22766, JP-A-55-142339, JP-A-60-23850, JP-A-60-23851, JP-A-60-23852, JP-A-60- 23853, JP-A-60-57836, JP-A-60-60643, JP-A-60-118834, JP-A-60-122940, JP-A-60-122941, JP-A-60-122942, JP-A-60-235134, JP-A-1-161236, US Patents 2,484, 430,2, 548, 564,3, 148,061, 3,309, 690,4, 115,124, 4,124, 386,4, 193,800, 4,273, 853,4, 282,305 and 4,450, 224. An image-receiving material containing a polymer mordant disclosed in JP-A-1-161236, pp. 212 to 215 is particularly preferred. The use of the polymer mordant disclosed in the above cited patent makes it possible to obtain an image having an excellent quality and hence improve the light-resistance of the image.

The waterproofing agent can be used to render the image waterproof. As such a waterproofing agent there is preferably used a cationic resin in particular. Examples of such a cationic resin include polyamide polyamine epichlorohydrin, polyethylenimine, polyamine sulfone, dimethyl diallyl ammonium chloride polymer, and cation polyacrylamide. Particularly preferred among these cationic resins is polyamine epichlorohydrin. The content of such a cationic resin is preferably from 1% to 15% by weight, particularly from 3% to 10% by weight based on the total solid content of the ink-receiving layer.

Examples of the light-resistance improver and gas resistance improver include phenol compounds, hindered phenol compounds, thioether compounds, thiourea compounds, thiocyanic acid compounds, amine compounds, hindered amine compounds, TEMPO compounds, hydrazine compounds, hydrazide compounds, amidine compounds, vinyl-containing compounds, ester compounds, amide compounds, ether compounds, alcohol compounds, sulfinic acid compounds, saccharides, water-soluble reducing compounds, organic acids, inorganic acids, hydroxyl-containing organic acids, benzotriazole compounds, benzophenone compounds, triazine compounds, heterocyclic compounds, water-soluble metal salts, organic metal compounds, and metal complexes.

Specific examples of these compounds include those disclosed in JP-A-10-182621, JP-A-2001-260519, JP-A-2000-260519, JP-B-4-34953, JP-B-4-34513, JP-B-4-34512, JP-A-11-170686, JP-A-60-67190, JP-A-7- 276808, JP-A-2000-94829, JP-T-8-512258, and JP-A-11-321090.

Examples of the light-resistance improver include zinc sulfate, zinc oxide, hindered amine-based oxidation inhibitor, and benzotriazole-based ultraviolet, absorber such as benzophenone. Particularly preferred among these light-resistance improvers is zinc sulfate.

The surface active agent acts as a coating aid, releasability improver, slipperiness improver or antistat.

For the details of the surface active agent, reference can be made to JP-A-62-173463 and JP-A-62-183457.

An organic fluoro-compounds may be used instead of the surface active agent. The organic fluoro- compound is preferably hydrophobic. Examples of the organic fluoro-compound include fluorine-based surface active agents, oil-based fluorine compounds (e. g., fluorine-based oil), and solid fluorine-based compound resins (e. g. , tetrafluoroethylene resin). For the details of the organic fluoro-compound, reference can be made to JP-B- 57-9053 (8th to 17th columns), JP-A-61-20994, and JP-A-62-135826.

As the film hardener there may be used any of materials disclosed in JP-A-1-161236, page 222, JP-A-9- 263036, JP-A-10-119423, and JP-A-2001-310547.

Other examples of additives to be incorporated in the image-receiving layer include pigment dispersants, thickening agents, antifoaming agents, dyes, fluorescent brighteners, preservatives, pH adjustors, matting agents, and film hardeners. There may be provided one or two ink-receiving layers.

The recording paper and recording film may comprise a back coat layer provided thereon. Examples of the components which can be incorporated in the back coat layer include white pigments, aqueous binders, and other components.

Examples of the white pigments to be incorporated in the back coat layer include inorganic white pigments such as light calcium carbonate, heavy calcium carbonate, kaolin, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, zinc sulfide, zinc carbonate, satin white, aluminum silicate, diatomaceous earth, calcium silicate, magnesium silicate, synthetic amorphous silica, colloidal silica, colloidal alumina, pseudo- boehmite, aluminum hydroxide, alumina, lithopone, hydrated halloysite, magnesium carbonate and magnesium hydroxide, and organic pigments such as styrene-based plastic pigment, acrylic plastic pigment, polyethylene, microcapsule, urea resin and melamine resin.

Examples of the aqueous binder to be incorporated in the back coat layer include water-soluble polymers such as styrene/maleate copolymer, styrene/acrylate copolymer, polyvinyl alcohol, silanol-modified polyvinyl alcohol, starch, cationated starch, casein, gelatin, carboxymethyl cellulose, hydroxyethyl cellulose and polyvinylpyrrolidone, and water-dispersible polymers such as styrenebutadiene latex and acryl emulsion.

Examples of other components to be incorporated in the back coat layer include antifoaming agents, foaming inhibitors, dyes, fluorescent brightening agents, preservatives, and waterproofing agents.

The layers (including back layer) constituting the ink jet recording paper and film may comprise a fine dispersion of polymer incorporated therein. The fine dispersion of polymer is used for the purpose of improving physical properties of film, e. g. , stabilizing dimension, inhibiting curling, adhesion and film cracking. For the details of the fine dispersion of polymer, reference can be made to JP-A-62-245258, JP-A-62-1316648, and JP- A-62-110066. The incorporation of a fine dispersion of polymer having a glass transition temperature as low as not higher than 40°C in a layer containing a mordant makes it possible to prevent the cracking or curling of the layer. The incorporation of a fine dispersion of polymer having a high glass transition temperature, too, in the back layer makes it possible to prevent the curling of the back layer.

[Ink jet recording] The volume of the droplet to be ejected onto the ink recording material of the invention is from not smaller than 0.1 pl to not greater than 100 pl, preferably from not smaller than 0.5 pi to not greater than 50 pl, particularly from not smaller than 2 pl to not greater than 50 pl.

In the present invention, the ink jet recording method is not limited. The ink of the present invention may be used in any known recording method such as electrostatic control method which utilizes electrostatic attraction to eject ink, drop-on-demand method (pressure pulse method) utilizing vibrational pressure of piezoelectric element, acoustic ink jet method which comprises converting electrical signal to acoustic beam with which the ink is irradiated to produce a radiation pressure that is utilized to eject the ink and thermal ink jet (bubble jet (registered trademark)) method which comprises heating the ink to form bubbles that raise the pressure to eject the ink.

Examples of the ink jet recording method include a method which comprises ejecting many portions of an ink having a low concentration called photoink in a small volume, a method which comprises using a plurality of inks having substantially the same hue but different densities to improve the image quality, and a method involving the use of a colorless transparent ink. The volume of the ink droplet to be ejected is controlled mainly by the print head.

For example, in the thermal ink jet recording system, the volume of the ink droplet to be ejected can be controlled by the structure of the print head. In some detail, the ink droplet can be ejected in a desired size by properly changing the size of the ink chamber, heating zone and nozzle. Even in the thermal ink jet recording system, the ink droplet can be ejected in a plurality of sizes by using a plurality of print heads comprising heating zones and nozzles having different sizes.

In the case of drop-on-demand system using a piezoelectric element, the volume of the ink droplet to be ejected can be varied due to the structure of the print head as in the thermal ink jet recording system. As described later, however, by controlling the waveform of the driving signal for driving the piezoelectric element, the ink droplet can be ejected in a plurality of sizes by the same structure of print head.

In the invention, the frequency at which the ink droplet is ejected onto the recording material is not lower than 1 kHz.

In order to record a high quality image as in photographic system, it is necessary that the ejection density be not smaller than 600 dpi (number of dots per inch) to reproduce an image having a high sharpness with small ink droplets.

In the system involving the ejection of the ink droplet through a head having a plurality of nozzles, on the other hand, the number of heads which can be driven at the same time in a type of recording system involving the cross movement of the recording paper and the head is from scores to about 200. Even in a type having heads called line heads fixed therein, the number of heads which can be driven at the same time is limited to hundreds. This is because the driving electric power is limited or the heat generated on the head gives an adverse effect on the image thus formed, making it impossible to drive a large number of head nozzles at the same time. Therefore, the recording rate tends to be prolonged to raise the ejection density. By raising the driving frequency, the recording rate can be raised.

The control over the ejection frequency in the case of thermal ink jet recording system can be accomplished by controlling the frequency of the head driving signal for heating the head.

In the piezoelectric system, the control over the ejection frequency can be accomplished by controlling the frequency of the signal for driving the piezoelectric element.

The driving of piezoelectric element will be described hereinafter. The image signal to be printed is made as follows. In some detail, the size of ink droplet to be ejected, the ejection rate and the ejection frequency are determined at the printer control. Thus, the signal for driving the print head is developed. The driving signal thus developed is then supplied into the print head. The size of ink droplet to be ejected, the ejection rate and the ejection frequency are controlled by the signal for driving the piezoelectric element. The size of ink droplet to be ejected and the ejection rate are determined by the shape and amplitude of the driving waveform and the ejection frequency is determined by the repetition frequency of the signal.

When the ejection frequency is predetermined to 10 kHz, the head is driven every 100 microseconds.

One line of recording is finished in 400 microseconds. By predetermining the moving rate of the recording paper such that it moves at a rate of 1/600 inch or about 42 micrometers per 400 microseconds, printing can be made at a rate of one sheet per 1. 2 seconds.

The configuration of the printing device using the ink for ink jet recording of the invention can be applied is preferably in an embodiment disclosed in JP-A-11-170527. The configuration of the ink cartridge to which the invention can be applied is preferably in an embodiment disclosed in JP-A-5-229133. The configuration of the suction system and the cap covering the print head 28 are preferably in an embodiment disclosed inJP-A-7-276671. It is preferred that a filter for evacuating bubbles as disclosed in JP-A-9-277552 be provided in the vicinity of the head.

The surface of the nozzle is preferably subjected to water repellent treatment as disclosed in Japanese Patent No. 2001-016738. The invention may be used with a printer connected to computer. The invention may be used with an apparatus dedicated for printing photograph.

The ink for ink jet recording of the invention is preferably ejected onto the recording material at an average rate of not smaller than 2 m/sec, preferably not smaller than 5 m/sec.

The control over the ejection rate is accomplished by controlling the form and amplitude of the signal for driving the head.

By using a plurality of driving waveforms properly, ink droplets having a plurality of sizes can be ejected by the same head.

[Purpose of ink for ink jet recording] The ink for ink jet recording medium of the present invention may be used purposes other than ink jet recording such as display image material, image-forming material for indoor decoration material, and image- forming material for outdoor decoration material.

Examples of the display image material include various materials such as poster, wall paper, small decoration articles (ornament, doll, etc.), commercial flyer, wrapping paper, wrapping material, paper bag, vinyl bag, packaging material, signboard, picture drawn or attached to the side of traffic facilities (automobile, bus, train, etc. ) and clothing with logogram. In the case where the dye of the invention is used as a material for forming a display image, the term"image"as used herein means an image in a narrow sense as well as all dye patterns perceivable by human being such as abstract design, letter and geometrical pattern.

The term"indoor decoration material"as used herein is meant to include various materials such as wall paper, small decoration articles (ornament, doll, etc. ), members of lighting fixture, members of furniture and design members of floor and ceiling. In the case where the dye of the invention is used as an image-forming material, the term"image"as used herein means an image in a narrow sense as well as all dye patterns perceivable by human being such as abstract design, letter and geometrical pattern.

The term"outdoor decoration material"as used herein is meant to include various materials such as wall material, roofing material, signboard, gardening material, small outdoor decoration articles (ornament, doll, etc. ) and members of outdoor lighting fixture. In the case where the dye of the invention is used as an image- forming material, the term"image"as used herein means an image in a narrow sense as well as all dye patterns perceivable by human being such as abstract design, letter and geometrical pattern.

Examples of the media on which patterns are formed in these uses include various materials such as paper, fiber, cloth (including nonwoven cloth), plastic, metal and ceramics. Dyeing can be carried out by mordanting or printing. Alternatively, a dye can be fixed in the form of reactive dye having a reactive group incorporated therein. Preferred among these dyeing methods is mordanting.

(Example) The first embodiment of the invention will be further described in the following examples, but the invention is not construed as being limited thereto.

(Example 1-1) To the following components was added ultrapure water having a resistivity of 18 MQ or more to make 11. The mixture was then heated to a temperature of from 30°C to 40°C with stirring for 1 hour. Thereafter, the solution was filtered through a microfilter having an average pore diameter of 0.25 jjm under reduced pressure to prepare various color ink solutions.

[Formulation of light cyan ink] (Solid component) Cyan dye (C-1-1) shown below 20 g/1 Urea (UR) 15 g/1 Benzotriazole (BTZ) 0.08 g/1 PROXEL XL2 (PXL) 3.5 g/l (Liquid component) Triethylene glycol (TEG) 110 g/1 Glycerin (GR) 130 g/1 Triethylene glycol monobutyl ether (TGB) 110 g/1 2-Pyrrolidone (PRD) 60 g/1 Triethanolamine (TEA) 7 g/1 Surfynol STG (SW) 10 g/1 [Formulation of cyan ink] (Solid component) Cyan dye (C-1-1) shown above 60 g/1 Urea (UR) 30 g/1 Benzotriazole (BTZ) 0.08 g/1 PROXEL XL2 (PXL) 3.5 g/l (Liquid component) Triethylene glycol (TEG) 110 g/1 Glycerin (GR) 130 g/1 Triethylene glycol monobutyl ether (TGB) 130 g/1 2-Pyrrolidone (PRD) 60 g/l Triethanolamine (TEA) 7 g/l Surfynol STG (SW) 10 g/1 [Formulation of light magenta ink] (Solid component) Cyan dye (C-1) shown below 7.5 g/1 Urea (UR) 10 g/l PROXELXL2 (PXL) 5g/l (Liquid component) Triethylene glycol (TEG) 90 g/1 Glycerin (GR) 70 g/1 Triethylene glycol monobutyl ether (TGB) 70 g/1 Triethanolamine (TEA) 6.9 gll Surfynol STG (SW) 10 g/1 [Formulation of magenta ink] (Solid component) Magenta dye-1) shown above 23 g/1 Urea (UR) 15 g/l PROXEL XL2 (PXL) 5 g/1 (Liquid component) Diethylene glycol (DEG) 90 g/1 Glycerin (GR) 70 g/l (GR) 70 g/l Triethylene glycol monobutyl ether (TGB) 70 g/1 Triethanolamine (TEA) 6.9 g/l Surfynol STG (SW) 10 g/1 [Formulation of yellow ink] (Solid component) Yellow dyes (Y-1-Y-8)) shown below 35 g/l PROXEL XL2 (PXL) 3.5 g/l Benzotriazole 0.08 g/1 Urea 10 g/1 (Liquid component) Triethylene glycol monobutyl etlier (TGB) 130 g/l Glycerin (GR) 115 g/1 Diethylene glycol (DEG) 120 g/1 2-Pyrrolidone (PRD) 35 g/1 Triethanolamine (TEA) 8 g/1 Surfynol STG (SW) 10 g/1 [Formulation of black ink] (Solid component) Black dye (Bk-1) shown below 75 g/l Black dye (Bk-2) shown below 30 g/l PROXEL XL2 (PXL) 5 g/l Urea 10 g/1 Benzotriazole 3 g/l (Liquid component) Diethylene glycol monobutyl ether (DGB) 120 g/l Glycerin (GR) 125 g/l Diethylene glycol (DEG) 100 g/1 2-Pyrrolidone (PRD) 35 g/1 Triethanolamine (TEA) 8 g/l Surfynol STG (SW) 10 g/1 An ink set comprising these inks was referred to as"IS-101". Ink sets IS-102 to 108 shown below were then prepared from the same inks except that the dye for yellow ink was changed to one according to the invention or other compounds.

Table 1-1 Yellow dye Hydrogen-bonding group IS-101 (comparative) Y-l-11 IS-102 (comparative) Y-1-2 2 IS-103 (inventive) Y-1-3 4 IS-104 (inventive) Y-1-4 6 IS-105 (inventive) Y-1-5 8 IS-106 (inventive) Y-1-6 6 IS-107 (inventive) Y-1-7 16 IS-108 (inventive) Y-1-8 16 <Examples of comparative dye> <Examples of inventive dye> <Examples of inventive dye> The aforementioned dyes of the invention were each measured for potential in the form of 1 mmol/1 aqueous solution by dropping mercury electrode polarography. As a result, all these dyes showed a higher potential than 1.2 V/vsSCE.

These inks were each packed in the ink cartridge of a Type PM-980C ink jet printer (produced by EPSON Co. , Ltd. ). Using this ink jet printer, a standard image pattern was printed in a 6-color mode.

The image sheet used herein was prepared according to the following formulation.

(Preparation of coating solution A for coloring material-receiving layer) The gas phase process particulate silica (1), the ion-exchanged water (2) and"PAS-M-1" (3) in the following formulation were mixed, and then subjected to dispersion at a rotary speed of 10,000 rpm using KD-P (produced by SEINMARU ENTERPRISES CORPORATION) for 20 minutes. To the dispersion a solution of a polyvinyl alcohol (4), boric acid (5) and a polyoxyethylene lauryl ether (6) in ion-exchanged water (7). The mixture was then again subjected to dispersion at a rotary speed of 10,000 rpm for 20 minutes to prepare a coating solution A for coloring material-receiving layer.

The weight ratio (PB ratio = (1): (4) ) of particulate silica to water-soluble resin was 4.5 : 1. The pH value of the coating solution A for coloring material-receiving layer was 3.5, which is acidic.

<Formulation of coating solution A for coloring material-receiving layer> (1) Gas phase process particulate silica (inorganic particulate material) (Reolosil QS-30; average primary particle diameter: 7 nm ; produced by TOKUYAMA CORP. ) 10.0 parts (2) Ion-exchanged water 51.7 parts (3) "PAS-M-1" (60% aqueous solution) 0.83 parts (dispersant produced by Nitto Boseki Co. , Ltd.) (4) 8% Aqueous solution of polyvinyl alcohol 27.8 parts ("PVA124", produced by KURARAY CO. , LTD.; saponification degree: 98.5% ; polymerization degree: 2,400) (5) Boric acid (crosslinking agent) 0.4 parts (6) Polyoxyethylene lauryl ether (surface 1. 2 parts active agent) ("Emulgen 109P; produced by Kao Corp; 10% aqueous solution; HLB value: 13.6) (7) Ion-exchanged water 33.0 parts (Preparation of ink jet recording sheet) A 200-pm thick paper support laminated with a polyethylene was subjected to corona discharge treatment on one surface thereof. The coating solution A for coloring material-receiving layer obtained above was spread over the same surface of the support at a rate of 200 rnl/m2 (coating step), and then dried at 80°C in a hot air drier (wind velocity: 3 to 8 second) until the solid concentration of the coat layer reached 20%. The coat layer exhibited a constant drying rate. The coated support was immediately dipped in a mordant solution B having the following formulation for 30 seconds so that the mordant solution B was attached to the coat layer in an amount of 20 glxw (step of providing a mordant solution), and then dried at 80°C for 10 minutes (drying step). In this manner, an inventive ink jet recording sheet R-1 having a coloring material-receiving layer provided thereon to a dried thickness of 32 Fm was prepared.

<Formulation of mordant coating solution B> (1) Boric acid (crosslinking agent) 0.65 parts (2) 10% Aqueous solution of polyallylamine l'PAA-10C" (mordant produced by Nitto Boseki Co. , Ltd.) 25 parts (3) Ion-exchanged water 59.7 parts (4) Ammonium chloride (surface pH adjustor) 0.8 parts (5) Polyoxyethylene lauryl ether (surface 10 parts active agent) ("Emulgen 109P; produced by Kao Corp; 2% aqueous solution; HLB value: 13.6) (6) 10% Aqueous solution of Megafac"F1405" (fluorine-based surface active agent produced by DAINIPPON INK AND CHEMICALS, INCORPORATED) 2.0 parts Image-receiving papers R-2 and R-3 were prepared in the same manner as the ink jet recording sheet R- 1 except that the mordant polymer was changed from the polyarylamine to the inventive polymers P-1 and P-3, respectively.

<Evaluation of image bleeding> For the evaluation of image bleeding under high humidity conditions, the image sample printed on the image-receiving material was stored at 25°C and 90% RH for 7 days relative to the aforementioned standard image. Those showing bleeding of yellow dye on the white background were judged poor. Those showing no yellow bleeding were judged good.

The results of evaluation are set forth in the table below.

Table 1-2 Ink set No. Evaluation of resistance to bleeding R-1 R-2 R-3 IS-101 (comparative) Poor Poor Poor IS-102 (comparative) Poor Poor Poor IS-103 (inventive) Poor Good Good IS-104 (inventive) Poor Good Good IS-105 (inventive) Poor Good Good IS-106 (inventive) Poor Good Good IS-107 (inventive) Poor Good Good IS-108 (inventive) Poor Good Good As can be seen in the table above, the samples according to the invention showed no dye bleeding.

The second embodiment of the invention will be further described in the following examples, but the invention is not construed as being limited thereto.

(Example 2-1) To the following components was added deionized water to make 1 liter. The mixture was then heated to a temperature of from 30°C to 40°C with stirring for 1 hour. Thereafter, the solution was adjusted with 10 ml/1 of KOH to pH 9, and then filtered through a microfilter having an average pore diameter of 0. 25 zum under reduced pressure to prepare a light magenta ink solution.

Magenta dye (a-36) 8.2 g/L Diethylene glycol 43 g/L Urea 4 g/L Glycerin 124 g/L Triethylene glycol monobutyl ether 114 g/L 2-Pyrrolidone 3 g/L Triethanolamine 3 g/L Benzotriazole 0.02 g/L PROXEL XL2 2 g/L Surface active agent (w-1) 10 g/L Further, the kind of dyes and additives were changed to prepare a magenta ink, a light cyan ink, a cyan ink, a yellow ink, a dark yellow ink and a black ink from which an ink set 101 set forth in Table 2-1 was then prepared.

[Table 2-1] Light cyan Light Magenta Yellow Dark Black cyan magenta yellow Dye (g/l) No. 154 No. 154 a-36 a-36 Y-2-1 Y-2-1 B-1 15. 0 50.0 8.2 24.4 65.0 49.0 55.0 No. 154 B-2 5.1 20.0 a-36 Y-2-1 8.9 20.0 Diethylene glycol (g/1) 167 110 43 76 85 20 Urea (g/l) 4 4 Glycerin (g/l) 164 148 124 150 154 147 120 Triethylene glycol 125 132 114 107 130 127 230 monobutyl ether (g/1) 2-Pyrrolidone (g/l) - 2 3 Triethanolamine (g/l) 6.5 10 3 3 1 1 18 Benzotriazole (g/l) 0.02 0.02 0.02 0.02 0.03 0.03 0.03 Proxel XL2 (g/l) 2 3 2 3 3 3 4 Surface active agent (g/1) 10 10 10 10 10 10 10 Deionized water added to make 1 liter Ink sets 102 to 107 were then prepared in the same manner as the ink set 101 except that the surface active agent, the water-miscible organic solvent and the dye were changed as set forth in Table 2-2.

[Table 2-2] Surface Dye (oxidation potential) Ink set active Water-miscible organic solvent Remaxks agent LC C LM, M Y DY BK 101 W-1 Triethylene No. 154 a-6 Y-2-1 Y-2-1 (1. 03) B-1 (1. 3) Comparative 10 g/L glycol (1. 11) (1. 35) (1. 03) No. 154 (1. 11) B-2 (1. 31) monobutyl a-36 (1. 35) Y-2- ether 1 (1. 03) 102 Xl-1 Triethylene No. 154 a-36 Y-2-1 Y-2-1 (1. 03) B-1 (1. 3) Inventive 20 g/L glycol (1. 11) (1. 35) (1. 03) No. 154 (1. 11) B-2 (1. 31) monobutyl a-36 (1. 35) Y-2- ether 1 (1. 03) 103 Xl-1 Tripropylene No. 154 a-36 Y-2-1 Y-2-1 (1. 03) B-1 (1. 3) Inventive 20 g/L glycol (1. 11) (1. 35) (1. 03) No. 154 (1. 11) B-2 (1. 31) monomethyl a-36 (1. 35) Y-2- ether 1 (1. 03) 104 Xl-1 Triethylene No. 154 a-36 Y-2-1 Y-2-1 (1. 03) B-1 (1. 3) Inventive 20 g/L glycol (1. 11) (1. 35) (1. 03) No. 154 (1. 11) B-2 (1. 31) monobutyl a-36 (1. 35) Y-2- ether 1 (1. 03) 105 Xl-1 Tripropylene Direct a-36 Y-2-2 Y-2-1 (1. 03) PM920BK Comparative 20 g/L glycol Blue 87 (1. 35) (1. 04) No. 154 (1. 11) monomethyl (0. 75) a-36 (1. 35) ether 106 X2-3 Triethylene C-2-1 (1. 1) a-36 Y-2-3 Y-2-1 (1. 03) B-1 (1. 3) Inventive 20 g/L glycol (1. 35) (1. 3) No. 154 (1. 11) B-2 (1. 31) monobutyl a-36 (1. 35) Y-2- ether 1 (1. 03) 107 X2-3 Propylene No. 154 a-36 Y-2-1 Y-2-1 (1. 03) B-1 (1. 3) Comparative 20 g/L glycol (1. 11) (1. 35) (1. 03) No. 154 (1. 11) B-2 (1. 31) monomethyl a-36 (1. 35) Y-2- ether 1 (1. 03) W-1 : (n-C5H11)2CHO(CH2CH2O)10H Subsequently, these ink sets 101 to 107 were each packed in the cartridge of a Type PM920C ink jet printer (produced by EPSON CO. , LTD. ) by which an image was then printed on an ink jet paper photographic gloss paper produced by Fuji Photo Film Co. , Ltd. and evaluated for the following properties.

1) For the evaluation of printing properties, the cartridge was mounted on the printer. The ejection of ink from all the nozzles was then confirmed. Thereafter, the nozzles were allowed to stand with their cap removed for 3 days. The nozzle check pattern was then printed. The number of times of cleaning required until no ejection was observed on the nozzle check pattern thus printed was then counted.

2) For the evaluation of image storage properties (light-fastness), a solid gray print image sample was prepared.

The sample thus prepared was then evaluated as follows. The image density Ci of the image which had been just printed on the sample was measured using X-rite 310. The image was irradiated with xenon light (85,000 lux) for 7 days, and then again measured for image density Cf to determine percent remaining of dye (Cf/Ci x 100). The percent remaining of dye was evaluated at three initial reflection density points of 1,1. 5 and 2.

Those showing a percent dye remaining of 85% or more at any density point were ranked A, those showing a percent dye remaining of less than 85% at two of these density points were ranked B, and those showing a percent dye remaining of less than 85% at all the density points were ranked C.

3) For the evaluation of ozone resistance, the sample was allowed to stand in a box having an ozone gas concentration predetermined to 5 ppm for 3 days. The image density before and after aging in the presence of ozone gas was measured using a reflection densitometer (X-Rite 310TR) to determine percent dye remaining which was then evaluated. The percent remaining of dye was evaluated at three initial reflection density points of 1,1. 5 and 2. Those showing a percent dye remaining of 80% or more at any density point were ranked A, those showing a percent dye remaining of less than 85% at two of these density points were ranked B, and those showing a percent dye remaining of less than 70% at all the density points were ranked C.

4) For the evaluation of percent bleeding, a neutral gray data comprising a white line having a width of 0.2 mm extending through the center of a 10 mm square prepared using an imaging software (Adobe Photoshop) was outputted to a color printer which then printed a gray image having a reflection density of 1.5 (neutral color according to CIE) using a plurality of color inks. The percent bleeding is represented by the following equation: % Bleeding = (DC-Db) /Da x 100 where Da represents the density of the gray image which has been just printed; Db represents the density of the white line which has been just printed; and Dc represents the density of the white line which has been allowed to stand at 23°C and 90% RH for 7 days shortly after printing. The density was measured using a microdensitometer.

A percent bleeding of cyan, magenta, yellow and visual of gray image sites having a reflection density of 1. 5.

The results of the evaluations (1) to (4) are set forth in Table 2-3.

[Table 2-3] Ink Number of times Light-Ozone-Remarks set of cleaning for fastness fatness Bleeding Bleeding Bleeding Bleeding desired printing Cyan Magenta Yellow Visual properties 101 1 A A 1 35 12 2 Comparative 102 2 A A 0 10 13 1 Inventive 103 1 A A 0 5 10 1 Inventive 104 1 A A 0 8 12 1 Inventive 105 2 B B 1 9 45 32 Comparative 106 2 A A 1 8 13 1 Inventive 107 5 A A 0 4 7 0 Comparative As can be seen in the results of Table 33, the ink sets comprising the ink compositions of the invention exhibit an excellent ejection stability and image fastness.

Even when the image-receiving paper to be used in the invention was changed to PM photographic paper produced by EPSON Co. , LTD. or PR101 (produced by Canon Inc. ), the same effect as in the aforementioned results was exerted.

[Example 2-2] The inks prepared in Example 2-1 were each packed in the cartridge of a Type BJ-F850 ink jet printer (produced by Canon Inc. ). Using this ink jet printer, an image was then printed on an ink jet photographic gloss paper EX produced by Fuji Photo Film Co. , Ltd. The image thus printed was then evaluated in the same manner as in Example 2-1. The results thus obtained were similar to that of Example 2-1. Similar effects were exerted also with PM photographic paper produced by EPSON CO. , LTD. or PR101 (produced by Canon Inc.).

In accordance with the invention, an ink set for ink jet recording in the form of aqueous ink advantageous from the standpoint of handleability, odor, safety, etc. can be provided which exhibits a high ejection stability and can provide an image having an excellent weather resistance.

Industrial Applicability In accordance with the invention, an ink jet recording method can be provided which is little subject to image bleeding even under high humidity conditions.

The invention can provide a recording method (preferably ink jet recording method) which exhibits a high ejection stability and gives an image having an excellent hue and little bleeding and thus can be expected to be widely spread for office use.