Ink-jet printing (IJP) is a non-impact printing technique in which droplets of ink are ejected through a fine nozzle onto a substrate without bringing the nozzle into contact with the substrate.

There are many demanding performance requirements for dyes and inks used in IJP. For example they desirably provide sharp, non-feathered images having good water, light and ozone fastness and high optical density. The inks are often required to dry quickly when applied to a substrate to prevent smudging, but they should not form a crust over the tip of an ink-jet nozzle because this will stop the printer from working. The inks should also be stable to storage over time without decomposing or forming a precipitate which could block the fine nozzle.

Water-fastness is a particular problem with aqueous ink-jet printing inks. For maximum stability in the cartridge the dye should be as soluble as possible to minimise the risk of blockage of the ink-jet nozzle. On the other hand, high solubility in water is responsible for poor water fastness on paper. Prints formed using dyes with poor water- fastness readily smudge when handled with moist fingers or if tea, coffee or water is accidentally spilled on them.

Dyes containing a single copper phthalocyanine group and their use in ink-jet printing are known. For example, C. I. Direct Blue 199 and C. l. Direct Blue 86 are copper phthalocyanine dyes used as colorants in commercial ink-jet printing inks.

Certain azaphthalocyanine compounds are known from Canadian Patent 2133284 to be useful for photodyamic therapy of cancer and treatment of blood products. Japanese Patent publications JP2129650 and JP4124188 describe the use of certain insoluble azaphthalocyanines in electrophotography. European patent publication EP965874 describes the use of various azaphthalocyanines in the manufacture of colour filters.

According to the present invention there is provided a process for coloration of paper comprising applying thereto a composition comprising a medium and an. azaphthalocyanine compound.

Preferably the composition is applied to the paper by means of a printing process, more preferably by means of an ink-jet printer.

The ink-jet printer preferably applies the composition to the paper in the form of droplets which are ejected through a small orifice onto the substrate. Preferred ink-jet printers are piezoelectric ink-jet printers and thermal ink-jet printers. In thermal ink-jet printers, programmed pulses of heat are applied to the composition in a reservoir by means of a resistor adjacent to the orifice, thereby causing the composition to be ejected in the form

of small droplets directed towards the paper during relative movement between the substrate and the orifice. In piezoelectric ink-jet printers the oscillation of a small crystal causes ejection of the composition from the orifice. Alternately the ink can be ejected by an electromechanical actuator connected to a moveable paddle or plunger as for example described in International Patent Applications WO 00/48938 and WO 00/55089.

Preferred papers are plain, treated or coated papers which may have an acid, alkaline or neutral character.

The azaphthalocyanine compound is preferably water-soluble, more preferably it has from 1 to 8 water-solubilising groups.

Preferred azaphthalocyanine compounds are of Formula (1): Formula (1) wherein: each A independently is CH or N; M is 2H, Si, a metal, an oxymetal group, a hydroxymetal group or a halometal group; each D independently is an acidic water solubilising group; each E independently is an optional substituent; m is 0 to 8; and n is 0 to 8.

Preferably all groups represented by A are CH or all groups represented by A are N.

M is preferably 2Li, 2Na, 2K, Mg, Ca, Ba, Al, Si, Sn, Pb, Rh, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, AIX, GaX, InX or SiX2, where in X is OH or Cl, more preferably Sc, Ti, Va, Cr, Mn, Fe, Co, Zn, Ni and Cu especially Cu or Ni.

Preferably each D independently is carboxy, phosphato, sulpho or hydrocarbyl carrying at least one group selected from carboxy, phosphato and sulpho. It is especially preferred that each D independently is carboxy or hydrocarbyl carrying at least one group selected from carboxy, sulpho and phosphato (particularly carboxy and sulpho).

Hydrocarbyl groups include alkyl, alkenyl, alkynyl and aryl groups and any combination thereof (such as aralkyl and alkaryl) optionally interrupted by one or more bivalent radicals such as-COZ-,-CONR'-,-NR'-,-O-,-SO-,-SO2-or-S-wherein R'is H or optionally substituted Cl-4 alkyl. More preferably each D independently is carboxy, alkyl carrying at

least one group selected from carboxy and sulpho or aryl carrying at least one group selected from carboxy and sulpho.

It is also preferred that all the groups represented by D are the same as each other.

It is especially preferred that each D is carboxy or each D is aryl (especially phenyl) carrying at least one sulpho group.

Preferably each E independently is H, optionally substituted alkyl (preferably C14- alkyl), optionally substituted alkoxy (preferably C14-alkoxy), optionally substituted aryl (preferably phenyl), optionally substituted aryloxy (preferably phenoxy), optionally substituted polyalkylene oxide (preferably polyethylene oxide or polypropylene oxide), nitro, cyano, halo, ureido, SOIF, hydroxy, ester,-NR2R3,-COR2,-CoNR2R3,-NHCOR2, carboxyester, sulphone, and-So2NR2R3, wherein R2 and R3 are each independently H or optionally substituted alkyl (especially C, 4-alkyl).

Preferably m is 0 to 7, more preferably 0 to 4.

Preferably n is 1 to 8, more preferably 4 to 8, especially 4.

When D is a hydrocarbyl group carrying at least one group selected from carboxy, phosphato and sulpho it optionally carries further substituents. These substituents and also the optional substituents which may be present on E, are each independently selected from alkyl (preferably C14-alkyl), alkoxy (preferably C14-alkoxy), aryl (preferably phenyl), aryloxy (preferably phenoxy), polyalkylene oxide (preferably polyethylene oxide or polypropylene oxide), nitro, cyano, halo, ureido, SOIF, hydroxy, ester,-NR4R5,-COR4,-CONR4R5,- NHCOR4, carboxyester, sulphone and-So2NR4R5, wherein R4 and R5 are each independently H or alkyl (especially Cl-4-alkyl). It is more preferred that the further substituents which may be present on D and the optional substituents which may be present on E are each independently selected from methyl, ethyl, propyl, butyl, phenyl, methoxy, ethoxy, butoxy, nitro, phenoxy, cyano, carboxyester, sulphone, sulphonamide, ureido,- SO2NR4R5 and NHCOR4, wherein R4 and R5 are as hereinbefore defined.

In view of the foregoing preferences, in a particularly preferred process the azaphthalocyanine compound is of Formula (1) wherein A is CH or N; M is Cu or Ni; each D is carboxy or each D is aryl (especially phenyl) carrying at least one sulpho group and optionally one or more further substituents; each E independently is an optional substituent; misOto4 ; andnis4to8.

When all the groups represented by A are N and n is 8, D is preferably aryl (especially phenyl) carrying a sulphonic acid group and optionally one or more further substituents.

Any acid or basic groups on the azaphtholocyanine compound, particularly acid groups, are preferably in the form of a salt. Thus, the Formulae shown herein include the compounds in free acid and in salt form.

Preferred salts are alkali metal salts, especially lithium, sodium and potassium, ammonium and substituted ammonium salts (including quaternary amines such as

((CH3) 4N+) and mixtures thereof. Especially preferred are salts with sodium, lithium, ammonia and volatile amines, more especially sodium salts. The compounds may be converted into a salt using known techniques.

Preferably the azaphthalocyanine compound used in the process is able to form a zwitterion or is in zwitterionic form. Zwitterions bear both positive and negative charges and are overall neutral. Thus, they tend to have much lower aqueous solubility than the parent cation or anion. It is believed that the excellent solubility and water-fastness of certain of the azaphthalocyanines is due to them having an overall negative charge in an alkaline composition, thus enhancing solubility. On application by the process to a more acidic paper, nitrogen atoms in the azaphthalocyanine ring system may become protonated, resulting in its solubility decreasing and water-fastness increasing.

In an alternative embodiment the composition used in the process is more acidic than the paper.

Thus, in one embodiment of the present invention the composition has a pH >7, preferably >7.5, more preferably >8 and in each case the paper has a lower pH than the composition. While in another embodiment of the present invention the composition has a pH <7, preferably <6.5, more preferably <6 and in each case the paper has a higher pH than the composition.

From the above it will be appreciated that the process may be fine tuned to give optimum performance by careful selection of the nature and number of acid and basic groups present on the azaphthalocyanine, the pH of the composition and the pH of the paper.

In some azaphthalocyanine compounds having multiple anionic and cationic groups a true zwitterion may not be formed on application to the substrate. However, as the pH approaches the molecules isoelectric point a significant decrease in solubility may still be seen.

The compounds of Formula (1) may exist in tautomeric forms other than those shown in this specification. These tautomers are included within the scope of the present invention.

Preferably the composition to be applied by the process comprises: (a) from 0.01 to 30 parts of a azaphthalocyanine compound, preferably of Formula (1) as hereinbefore defined; and (b) from 70 to 99.99 parts of a medium; wherein all parts are by weight and the number of parts of (a) + (b) =100.

Preferably the medium is a liquid medium.

The number of parts of component (a) is preferably from 0.1 to 20, more preferably from 0.5 to 15, especially from 1 to 5 parts. The number of parts of component (b) is preferably from 99.9 to 80, more preferably from 99.5 to 85, especially from 99 to 95 parts.

The composition may of course contain further ingredients in addition to (a) and (b).

Preferably component (a) is completely dissolved in component (b). Preferably component (a) has a solubility in component (b) at 20°C of at least 10%. This allows the preparation of liquid concentrates which may be used to prepare more dilute inks and also reduces the chance of component (a) precipitating if evaporation of the liquid medium occurs during storage.

Preferred liquid media include water, a mixture of water and organic solvent and organic solvent free from water.

When the liquid medium comprises a mixture of water and an organic solvent, the weight ratio of water to organic solvent is preferably from 99: 1 to 1: 99, more preferably from 99: 1 to 50: 50 and especially from 95: 5 to 80: 20.

It is preferred that the organic solvent present in the mixture of water and organic solvent is a water-miscible organic solvent or a mixture of such solvents. Preferred water- miscible organic solvents include C14-alkanols, preferably methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol, tert-butanol, n-pentanol, cyclopentanol and cyclohexanol ; linear amides, preferably dimethylformamide or dimethylacetamide ; ketones and ketone-alcohols, preferably acetone, methyl ether ketone, cyclohexanone and diacetone alcohol ; water-miscible ethers, preferably tetrahydrofuran and dioxane; diols, preferably diols having from 2 to 12 carbon atoms, for example pentane-1,5-diol, ethylene glycol, propylene glycol, butylene glycol, pentylene glycol, hexylene glycol and thiodiglycol and oligo-and poly-alkyleneglycols, preferably diethylene glycol, triethylene glycol, polyethylene glycol and polypropylene glycol ; triols, preferably glycerol and 1,2,6-hexanetriol; mono-C14-alkyl ethers of diols, preferably mono-C14-alkyl ethers of diols having 2 to 12 carbon atoms, especially 2-methoxyethanol, 2- (2-methoxyethoxy) ethanol, 2- (2-ethoxyethoxy)-ethanol, 2- [2- (2- methoxyethoxy) ethoxy] ethanol, 2- [2- (2-ethoxyethoxy)-ethoxy]-ethanol and ethyleneglycol monoallylether ; cyclic amides, preferably 2-pyrrolidone, N-methyl-2-pyrrolidone, N-ethyl-2- pyrrolidone, caprolactam and 1,3-dimethylimidazolidone; cyclic esters, preferably caprolactone ; sulphoxides, preferably dimethyl sulphoxide and sulpholane. Preferably the liquid medium comprises water and 2 or more, especially from 2 to 8, water-soluble organic solvents.

Especially preferred water-soluble organic solvents are cyclic amides, especially 2- pyrrolidone, N-methyl-pyrrolidone and N-ethyl-pyrrolidone ; diols, especially pentane-nb1, 5- diol, ethyleneglycol, thiodiglycol, diethyleneglycol and triethyleneglycol ; and mono-C14-alkyl and C1g-alkyl ethers of diols, more preferably mono-C14-alkyl ethers of diols having 2 to 12 carbon atoms, especially 2-methoxy-2-ethoxy-2-ethoxyethanol.

Although not usually necessary, further colorants may be included in the composition medium to modify the shade and performance properties of the composition. Examples of such colorants include C. I. Direct Yellow 86,132,142 and 173; C. I. Direct Blue 199, and 307; C. I. Food Black 2; C. I. Direct Black 168 and 195; C. l. Acid Yellow 23; and any of the dyes used in ink-jet printers sold by Seiko Epson Corporation, Hewlett Packard Company,

Canon Inc. & Lexmark International. Addition of such further colorants can increase overall solubility leading to less kogation (nozzle blockage) for the resultant composition.

Examples of further suitable liquid media comprising a mixture of water and one or more organic solvents are described in US 4,963,189, US 4,703,113, US 4,626,284 and EP 4,251,50A.

When the liquid medium comprises an organic solvent free from water, (i. e. less than 1% water by weight) the solvent preferably has a boiling point of from 30° to 200°C, more preferably of from 40° to 150°C, especially from 50 to 125°C. The organic solvent may be water-immiscible, water-miscible or a mixture of such solvents. Preferred water-miscible organic solvents are any of the hereinbefore described water-miscible organic solvents and mixtures thereof. Preferred water-immiscible solvents include, for example, aliphatic hydrocarbons; esters, preferably ethyl acetate; chlorinated hydrocarbons, preferably CH2CI2 ; and ethers, preferably diethyl ether; and mixtures thereof.

When the liquid medium comprises a water-immiscible organic solvent, preferably a polar solvent is included because this enhances solubility of the dye in the liquid medium.

Examples of polar solvents include C14-alcohols. In view of the foregoing preferences it is especially preferred that where the liquid medium is an organic solvent free from water it comprises a ketone (especially methyl ethyl ketone) and/or an alcohol (especially a C14- alkanol, more especially ethanol or propanol).

The organic solvent free from water may be a single organic solvent or a mixture of two or more organic solvents. It is preferred that when the medium is an organic solvent free from water it is a mixture of 2 to 5 different organic solvents. This allows a medium to be selected which gives good control over the drying characteristics and storage stability of the composition.

Liquid media comprising an organic solvent free from water are particularly useful where fast drying times are required and particularly when printing onto hydrophobic and non-absorbent substrates, for example plastics, metal and glass.

Preferably the composition has been filtered through a filter having a mean pore size below 10, um, more preferably below 3, um, especially below 2pm, more especially below 1, um. This filtration removes particulate matter which could otherwise block the fine nozzles found in many ink-jet printers.

The composition preferably has a total concentration of divalent and trivalent metal ions (other than those bound to the nitrogen atoms at the azaphthalocyanine nucleus) of below 1000, more preferably below 100, especially below 20, more especially below 10 parts per million by weight relative to the total weight of the composition. Pure compositions of this type may be prepared by using high purity ingredients and/or by purifying the composition after it has been prepared. Suitable purification techniques are well known, e. g. ultrafiltration, reverse osmosis, ion exchange and combinations thereof.

The liquid medium may also of course contain further additives which are conventionally used in ink-jet printing inks, for example viscosity and surface tension modifiers, corrosion inhibitors, biocides, kogation reducing additives and surfactants which may be ionic or non-ionic.

According to a second aspect of the invention there is provided a composition comprising a medium and a compound of Formula (1) as hereinbefore defined, with the proviso that n is 1 to 8 and each D independently is carboxy or hydrocarbyl carrying at least one group selected from carboxy, sulpho, and phosphato (preferably from carboxy and sulpho).

Preferably the medium is as hereinbefore described in the first aspect of the invention.

The composition is preferably an ink, especially an ink-jet printing ink, or a liquid dye concentrate which is used to prepare inks. The concentrates are useful as a means for transporting colorant and so minimising costs associated drying the dye and transporting excess liquid.

Each D independently is preferably carboxy, alkyl carrying at least one group selected from carboxy and sulpho or aryl (especially phenyl) carrying at least one group selected from carboxy and sulpho. The further substituents which D may also carry are as hereinbefore described in relation to the first aspect of the present invention.

It is also preferred that all groups represented by D are identical to each other, e. g. all groups represented by D are carboxy or all groups represented by D are aryl carrying at least one sulpho group.

In preferred compositions of the second aspect of the invention the compound of Formula (1) is able to form a zwitterion or is in zwitterion form.

In the second aspect of the invention the preferences for M, m, A and E and salt forms are as hereinbefore described in the first aspect of the invention.

In the second aspect of the invention n is preferably 4 to 8.

The preferred ratio of compound of liquid medium and the preferred liquid media for the composition are as hereinbefore described in relation to the composition used in the process of the present invention.

In a particularly preferred composition according to the second aspect of the present invention each A is CH or N; M is Cu or Ni; each D is carboxy or each D is aryl (especially phenyl) carrying at least one sulpho group; each E is independently an optional substituent; m is 0 to 4 ; n is 4 to 8.

When each A is N and n is 8, D is preferably optionally substituted aryl sulphonic acid.

A third aspect of the invention provides a compound of Formula (1) as hereinbefore defined in the first aspect of the invention, with the provisos that: (i) n is 1 to 8 and each D independently is carboxy or hydrocarbyl carrying at least one group selected from carboxy,

sulpho and phosphato, and (ii) when all groups represented by A are N and D is carboxy, n is 1 to 7.

In the third aspect of the invention the preferences for M, A, m and E the salts and zwitterion are as hereinbefore described in the first aspect of the present invention.

Preferably each D in the third aspect of the invention independently is carboxy, or hydrocarbyl (especially C110 hydrocarbyl) carrying at least one group selected from carboxy and sulpho. Hydrocarbyl groups include alkyl (especially C14 alkyl), alkenyl (especially C36 alkenyl), alkynyl (especially C36 alkynyl) and aryl (especially C610 aryl) groups, and any combination thereof, such as aralkyl and alkaryl optionally interrupted by one or more bivalent radicals such as-CO2-,-CONR'-,-NR'-,-O-,-SO-,-SO2-or-S-wherein R'is H or optionally substituted C14 alkyl. More preferably each D independently is carboxy, alkyl (especially C14 alkyl) carrying at least one group selected from carboxy and sulpho or aryl carrying at least one group selected from carboxy and sulpho.

It is also preferred that all groups represented by D are the same as each other. It is especially preferred that each D is carboxy or each D is aryl (especially phenyl) carrying at least one sulpho group.

In the third aspect of the invention n is preferably 4 to 8.

In the third aspect of the invention when A is N and n is 8, D is preferably aryl (especially phenyl) carrying a sulpho group.

In view of the foregoing preferences a preferred compound according to the third aspect of the invention is of Formula (1) as hereinbefore defined with the provisos that M is Cu or Ni; each D is carboxy or each D is aryl (preferably phenyl) carrying at least one sulpho group; n is 4 to 8; and when all groups represented by A are N and D is carboxy, n is 1 to7.

Preferably the novel compounds of Formula (1) in the third aspect of the invention are water-soluble.

The compounds of the present invention have attractive, strong green/cyan/blue shades and are valuable colorants for ink-jet printing inks. They benefit from a good balance of solubility, storage stability and fastness to water and light. In particular the compounds of the present invention display good solubility and water-fastness.

A fourth aspect of the invention provides a process for printing an image on a substrate other than paper comprising applying thereto a composition according to the second aspect of the invention by means of an ink-jet printer.

The substrate other than paper is preferably, plastic, a textile, metal or glass, an overhead projector slide or a textile material. The ink-jet printer preferably applies the composition to the substrate in an analogous manner to that as described above in relation to the first aspect of the present invention.

A fifth aspect of the present invention provides a substrate printed with a azaphthalocyanine compound according to a process of the first or fourth aspects of the present invention.

A sixth aspect of the present invention provides an ink-jet printer cartridge comprising a chamber and a composition, wherein the composition is in the chamber and the composition is as described in the second aspect of the present invention.

The invention is further illustrated by the following Examples in which all parts and percentages are by weight unless otherwise stated.

Example 1 Preparation of Stage 1 Preparation of 2s3-dicyano-5s6-diphenylpyrazine Benzil (42g, 0.2mol) and diaminomaleonitrile (DAMN, 21.6g, 0.2mol) were suspended in a solution of water (200ml), methylated spirit (200ml) and acetic acid (20ml). The mixture was boiled under reflux for 2 hours. After cooling a beige precipitate (56g) of 2,3-dicyano-5,6-diphenylpyrazine was collected. The sample was homogeneous by TLC.

Stage 2 The product of stage 1 (10g, 35.5mmol) and nickel chloride (1.15g, 8.86mmol) were suspended in quinoline (100ml) and the mixture was heated to 170°C. The reaction mixture turned brown and then green. The reaction was stopped after 2 hours cooled. A solid was collected by filtration, washed with quinoline, ethanol, water and then ethanol once more to give a jade solid (4.3g).

Stage 3 The jade solid (1.5g) from stage 2 was added to a stirred solution of 10% fuming sulfuric acid (30moi) at 0°C over a period of 5-10 minutes. The mixture was stirred for 1 hour

then carefully poured onto ice. Acetone (approx. 6 volume equivalents) was added and the precipitate was collected by filtration. The precipitate was taken up in water and desalted to give 1. 4g of the title product having % maux in water at 603 and 638 nm.

Example 2 Preparation of

2,3,5-Pyridinetricarboxylic acid (3.37g), urea (3.83g), nickel chloride (519mg), ammonium molybdat (100mg) and 1,2,4-trichlorobenzene (100ml) were stirred at 140°C for 1.5 hours.

The temperature was raised to 165°C for a further hour and then briefly to 180°C. A deep blue coloration was noted, and the mixture left to cool, whereupon the title product was collected by filtration. The title product was washed with trichlorobenzene, ethanol and acetone and an aqueous solution of the title product was dialysed. The resultant solution of the title compound in water had kmax in water at 593 and 640nm.

Example 3 Preparation of

The method of Example 2 was repeated except that copper (II) acetate was used in place of nickel chloride. The title product had a k max in water of 605 and 660nm.

Example 4 Preparation of

Example 4 was prepared according to the method described by Kudrevich, Galpern and van Lier; in Synthesis (1994), page 779.

Example 5 Preparation of inks Inks were prepared by dissolving 3% by weight of dye in an ink vehicle comprising 5% 2- pyrrolidone, 5% thiodiglycol, 2% Surfynol 465 and the balance water. The pH was adjusted to 8.5-10 using sodium hydroxide solution (2M). The resultant inks were as follows : Ink (1) contained the dye from Example 1.

Ink (2) contained the dye from Example 2.

Ink (3) contained the dye from Example 3.

Ink (4) contained the dye from Example 4.

Each ink was filtered through a 0.45, 1m filter and put into the chamber of a monochrome cartridge designed for the Hewlett Packard 550 printer. ink-jet Printing Inks (1) to (4) were then ink-jet printed onto Xerox acid and Gilbert Bond papers using a Hewlett Packard DeskJet 550C. The properties of the resultant prints are summarised in Table 1.

The CIE colour co-ordinates of each print (a, b, L, Chroma and hue) were measured using a Xrite 983 Spectrodensitometer with 0°/45° measuring geometry with a spectral range of 400-700nm at 20nm spectral intervals, using illuminant C with a 2° (CIE 1931) observer angle and a density operation of status T. No less than 2 measurements were taken diagonally across a solid colour block on the print with a size greater than 10mm x 1 Omm.

To evaluate light fastness the prints were faded in an Atlas Ci35 Weatherometer for 50 hours. The degree of fade is expressed as AE where a lower figure indicates higher light

fastness. AE is defined as the overall change in the CIE colour co-ordinates L*, a*, b* of the print and is expressed by the equation AE = (AL + A a2 + Ab2) 05.

Water fastness was assessed five minutes post-printing by suspending the print at 45° and running 0.5 ml of water down a section of print comprising 12 printed lines. Each line was approximately 3 mm wide and spaced approximately 5mm apart. When the water had dried the extent of ink staining on the unprinted areas was assessed by reference to a standard scale. A value of 10 would be classed as excellent water fastness and a value of 6 would be classed as very poor water fastness.

Table 1 Ink Paper L a b C h WF DEsohr Ink (1) X. Acid 58. 48-25.88 5. 86 26. 54 167. 2 5 6.07 G. Bond 57. 01-25.05 3. 67 25. 32 171. 7 5 3.95 Ink (2) X. Acid 65. 40-9.66-8. 77 13. 05 222. 2 10 1.71 G. Bond 66. 61-8.21-10.28 13. 16 231. 4 10 2. 29 Ink (3) X. Acid 71. 23-1.16-23.37 23. 40 267. 2 10 5.15 G. Bond 70. 41-0.33-26.74 26. 74 269. 3 10 5.39 Ink (4) X. Acid 67. 01-13.5-24.8 28. 2 241. 5 9 13.7 G. Bond 65. 74-12.1-26. 7 29.3 245.6 9.5 11.1 Further Inks The inks described in Tables I and 11 may be prepared wherein the Dye described in the first column is the compound made in the above example of the same number. Numbers quoted in the second column onwards refer to the number of parts of the relevant ingredient and all parts are by weight. The inks may be applied to paper by thermal or piezo ink-jet printing.

The following abbreviations are used in Table I and)) : PG = propylene glycol DEG = diethylene glycol NMP = N-methyl pyrollidone DMK = dimethylketone IPA = isopropanol MEOH = methanol 2P = 2-pyrollidone MIBK = methylisobutyl ketone P12 = propane-1, 2-diol BDL = butane-2, 3-diol CET= cetyl ammonium bromide PHO = Na2HPO4 TBT = tertiary butanol TDG = thiodiglycol TABLE I Example Dye Water PG DEG NMP DMK NaOH Na IPA MEOH 2P MIBK Content Stearate 1 2.0 80 5 6 4 5 2 3.0 90 5 5 0.2 3 10.0 85 3 3 3 5 1 4 2.1 91 8 1 1 3.1 86 5 0.2 4 5 2 1.1 81 9 0.5 0.5 9 3 2.5 60 4 15 3 3 6 10 5 4 4 5 65 20 10 1 2.4 75 5 4 5 6 5 2 4.1 80 3 5 2 10 0.3 3 3.2 65 5 4 6 5 4 6 5 4 5.1 96 4 1 10.8 90 5 5 2 10.0 80 2 6 2 5 1 4 3 1.8 80 5 15 4 2.6 84 11 5 1 3.3 80 2 10 2 6 1 12.0 90 7 0.3 3 1 5.4 69 2 20 2 1 3 3 1 6.0 91 4 5 TABLE II Example Dye Water PG DEG NMP CET TBT TDG BDL PHO 2P PI2 Content 1 3.0 80 15 0.2 5 2 9.0 90 5 1.2 5 3 1.5 85 5 5 0.15 5.0 0.2 4 2.5 90 6 4 0.12 1 3.1 82 4 8 0.3 6 2 0.9 85 10 5 0.2 3 8.0 90 5 5 03 4 4.0 70 10 4 1 4 11 1 2.2 75 4 10 3 2 6 2 10.0 91 6 3 3 9.0 76 9 7 3.0 0.95 5 4 5.0 78 5 11 6 1 5.4 86 7 7 2 2.1 70 5 5 6 0.1 0.2 0.1 5 0.1 5 3 2.0 90 10 4 2 88 10 1 5 78 5 12 5 1 8 70 2 8 15 5 1 10 80 8 12 1 10 80 10