BACKGROUND

[0001] There has been demand in the recent years for a low-temperature fixing of toner images in electrophotography, which enables the suppression of power consumption in order to save energy. In general, in order to fix toner particles at low temperatures to bases such as paper and the like, a measure is taken such that the glass transition temperature (Tg) or molecular weight of binder resins in toner particles is reduced. However, if binder resins with a low Tg are used, toner may be flocculated within the printer when transported or stored so as to affect storability. In addition, when the molecular weight of binder resins is reduced, exposure to physical stresses at the time of printing may cause reduction in durability and image deterioration may occur with sequential printing. Further, when the Tg or molecular weight is reduced, the viscosity of toner particles is reduced and the high-temperature offset by which toner particles adhere to a heat fixing drum when fusing and fixing to paper, is likely to occur so as to cause the narrowing of fixable temperature ranges. The narrowing of fixable temperature ranges results in a need for highly accurate control of heat fixing drum temperatures which may be more costly.

BRIEF DESCRIPTION OF DRAWINGS

[0002] FIG.1 is a differential scanning calorimetry (DSC) profile of an epoxy group-containing toner particle.

[0003] FIGS. 2A and 2B are gel permeation chromatographs (GPC) before and after the DSC measurement of the epoxy group-containing toner particle.

DETAILED DESCRIPTION

[0004] An example epoxy group-containing toner particle will be described. The example epoxy group-containing toner particle includes a binder resin, an epoxy group-containing resin, a catalyst, a colorant, and a mold release agent. The binder resin includes a pendant-type amorphous polyester resin and a crystalline polyester resin. The pendant-type amorphous polyester resin may contain 1 mol% to 15 mol% of a constituent unit having a pendant group with 3 to 32 carbons. The epoxy group-containing resin may have an epoxy group represented by the general formula (1): in which each of R ¹ , R ² and R ³ represents independently a hydrogen atom or an alkyl group with 1 to 4 carbons, and ^x represents a binding site. [0005] The binder resin includes the crystalline polyester resin and the pendant-type amorphous polyester resin. In order to better disperse the crystalline polyester resin in the pendant-type amorphous polyester resin, the amorphous polyester resin may contain the constituent unit having a pendant group with 3 to 32 carbons in an amount that is within a range having a minimum of 1 mol%, 1.5 mol%, or 2 mol%, and a maximum of 10 mol%, 9 mol%, or 8 mol% in all constituent units. Here, this mol% may be defined as mol% of a monomer serving as the constituent unit having a pendant group in all constituent monomers of the pendant-type amorphous polyester. [0006] The pendant-type amorphous polyester resin may be, for example, a polyester having no clear endothermic peak in a differential scanning calorimetry (DSC), and may also be defined as a polyester resin which indicates a stepwise change in endothermic energy amount or for which a half width of an endothermic peak is greater than 15°C when the measurement is performed at a rate of temperature increase (e.g., a heating rate) of 10°C/min in DSC. [0007] The crystalline polyester resin may be, for example, a polyester resin having a clear endothermic peak in DSC. [0008] The example epoxy group-containing toner particle may contain the binder resin in an amount that is within a range having a minimum of 40 mass%, or 45 mass% or 50 mass%, and a maximum of 90 mass%, or 85 mass% or 75 mass%.

[0009] The example epoxy group-containing toner particle may contain the pendant-type amorphous polyester resin in an amount that is within a range having a minimum of 48 mass% or 56 mass%, and a maximum of 72 mass% or 64 mass%.

[0010] The example epoxy group-containing toner particle may contain the crystalline polyester resin in an amount that is within a range having a minimum of 10 mass% or 15 mass%, and a maximum of 30 mass% or 20 mass%.

[0011 ] A method for producing the pendant-type amorphous polyester resin according to examples, will be described. The pendant-type amorphous polyester resin can be obtained by polycondensing a polyfunctional carboxylic acid and a polyol. In this case, a pendant group-containing polyfunctional carboxylic acid and a polyfunctional carboxylic acid having no pendant group are mixed as the polyfunctional carboxylic acid to be caused to react with the polyol, to obtain a mixture of an amorphous polyester having a pendant group containing the polyfunctional carboxylic acid units, and an amorphous polyester having no pendant group. The mixture obtained can be used as the pendant-type amorphous polyester resin. A content ratio of the amorphous polyester having a pendant group, i.e., a content ratio of the constituent component having a pendant group, can be adjusted by adjusting the usage amounts of the pendant group-containing polyfunctional carboxylic acid and polyfunctional carboxylic acid having no pendant group. Further, the pendant-group-containing amorphous polyester and the amorphous polyester having no pendant-type group can also be obtained in advance and separately from a polyfunctional carboxylic acid having a pendant group and a polyol, and from a polyfunctional carboxylic acid having no pendant group and a polyol, and subsequently mixed and used as the pendant-type amorphous polyester resin.

[0012] The pendant-type amorphous polyester resin can be obtained in some examples by using, as the pendant group-containing polyfunctional carboxylic acid, a succinic acid derivative represented by the general formula (2):

in which R ⁴ represents a hydrogen atom, a linear or branched alkyl group or alkenyl group with 3 to 32 carbons, or a phenyl group, and in which R ⁵ represents a linear or branched alkyl group or alkenyl group with 3 to 32 carbons, or a phenyl group.

In other examples, the pendant-type amorphous polyester resin can be obtained by using, as the pendant group-containing polyfunctional carboxylic acid, a succinic acid derivative anhydride represented by the general formula (3): in which R ⁴ and R ⁵ represent the same respective contents (or compounds) as those mentioned above, and a polyfunctional carboxylic acid having no pendant group other than these, and causing them to react with a polyol.

[0013] As R ⁴ of the succinic acid derivative and the succinic acid derivative anhydride represented respectively by the general formulas (2) and (3), a compound of a hydrogen atom can be used. In addition, as R ⁵ serving as a pendant group, a compound with 3 to 32 carbons, or 3 to 24 carbons or further 18 to 24 carbons can be used.

[0014] Examples of the succinic acid derivative and the succinic acid derivative anhydride represented respectively by the general formulas (2) and (3), include butylsuccinic acid, octylsuccinic acid, decylsuccinic acid, dodecylsuccinic acid, tetradecylsuccinic acid, hexadecylsuccinic acid, octadecylsuccinic acid, isooctadecylsuccinic acid (mixture of branched chain isomers), phenylsuccinic acid, 2-propene-1 -yl succinic acid, 2-methyl-2-propene-1-yl succinic acid, 2- butene-1 -yl succinic acid, 2-hexene-1 -yl succinic acid, 2-octene-1 -yl succinic acid, 2-nonene-1-yl succinic acid, 2-tetradecen-1-yl succinic acid, 2-octadecene-1 -yl succinic acid, isooctadecenylsuccinic acid (mixture of branched chain isomers), 2,7-octadien-1-yl succinic acid or the like, and an anhydride thereof. In some examples, two or more selected from the aforementioned compounds may be used.

[0015] The succinic acid derivative (2) can be used in the form of the succinic acid derivative anhydride (3), and can also be used, for example, in the form of an ester of (an alkyl with 1 to 8 carbons); a diimide obtained by a reaction with a 4,4-diaminophenylmethane or the like; or an isocyanate ring-containing polyimide obtained by a reaction with a trimerization reaction product of a tris-(β - carboxyethyl)isocyanurate, an isocyanurate ring-containing polyimide, a tolylene diisocyanate, a xylylene diisocyanate or an isophorone diisocyanate or the like. [0016] As the polyfunctional carboxylic acid having no pendant group, a polyfunctional aromatic carboxylic acid with 2 to 50 carbons and a polyfunctional aliphatic carboxylic acid can be used. Examples of the polyfunctional aromatic carboxylic acid include a bifunctional aromatic carboxylic acid such as phthalic acid, isophthalic acid, terephthalic acid, tert-butylisophthalic acid, naphthalene- 2,6-dicarboxylic acid, 4,4’-biphenyldicarboxylic acid or the like; a trifunctional aromatic carboxylic acid such as trimesic acid, trimellitic acid, hemimellitic acid or the like; a tetrafunctional aromatic carboxylic acid such as pyromellitic acid, mellophanic acid, prehnitic acid, pyromellitic acid, naphthalene-1 ,4,5,8- tetracarboxylic acid, naphthalene-2,3,6,7-tetracarboxylic acid, biphenyl-3,3’,4,4’- tetracarboxylic acid, perylene-3,4:9,10-tetracarboxylic acid or the like; a pentafunctional aromatic carboxylic acid such as benzenepentacarboxylic acid or the like; or a hexafunctional aromatic carboxylic acid such as mellitic acid or the like; etc..

[0017] Examples of the polyfunctional aliphatic carboxylic acid having no pendant group, include a bifunctional aliphatic carboxylic acid such as oxalic acid, malonic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, succinic acid, glutaric acid, adipic acid, sebacic acid, azelaic acid, isooctenylsuccinic acid, decylsuccinic acid, dodecylsuccinic acid, dodecenylsuccinic acid, pentadecenylsuccinic acid, octadecenylsuccinic acid, cyclohexane-1 ,4-dicarboxylic acid, dodecanedicarboxylic acid, octadecanedicarboxylic acid, dimer acid or the like; a trifunctional aliphatic carboxylic acid such as propane-1 ,2, 3-tricarboxylic acid, aconitic acid, butane- 1 ,2,4-tricarboxylic acid, hexane-1,3,6-tricarboxylic acid, cyclohexane-1 ,3,5- tricarboxylic acid, adamantane-1,3,5-tricarboxylic acid or the like; a tetrafunctional aliphatic carboxylic acid such as ethylenetetracarboxylic acid, butane-1 ,2,3,4-tetracarboxylic acid, butane-1 ,1 ,3, 4-tetracarboxylic acid, cyclobutane-1 ,2,3,4-tetracarboxylic acid, cyclopentane-1 ,2,3,4-tetracarboxylic acid, octahydropentalene-1 ,3,4,6-tetracarboxylic acid, cyclohexane-1 ,2,4,5- tetracarboxylic acid, bicyclo[2.2.2]oct-7-ene- 2,3,5,6-tetracarboxylic acid or the like; or a hexafunctional aliphatic carboxylic acid such as cyclohexane- 1 ,2,3,4,5,6-hexacarboxylic acid or the like; etc.. In some examples, two or more selected from them can also be used.

[0018] These polyfunctional carboxylic acids can be used in the form of: an anhydride; an ester of (an alkyl with 1 to 8 carbons); a diimide obtained by a reaction with a 4,4-diaminophenylmethane or the like; or an isocyanate ring- containing polyimide obtained by a reaction with a trimerization reaction product of a tris-(β -carboxyethyl)isocyanurate, an isocyanurate ring-containing polyimide, a tolylene diisocyanate, a xylylene diisocyanate or an isophorone diisocyanate or the like.

[0019] Examples of the polyfunctional aromatic carboxylic acid having no pendant group include isophthalic acid, terephthalic acid, trimellitic acid or pyromellitic acid, and examples of the polyfunctional aliphatic carboxylic acid include sebacic acid, azelaic acid or dodecanedioic acid, to obtain a pendant-type amorphous polyester resin having a suitable fixability. In some examples, two or more selected from these polyfunctional carboxylic acids may be used.

[0020] In some examples, a hydroxycarboxylic acid component such as, for example, p-oxybenzoic acid, vanillic acid, dimethylolpropionic acid, malic acid, tartaric acid, 5-hydroxyisophthalic acid or the like may be added to the aforementioned polyfunctional carboxylic acids, or a monovalent carboxylic acid or a monovalent alcohol may be included, in order to better adjust the molecular weight of the resin and/or to improve the high-temperature offset resistance of the toner.

[0021] An example polyol which can be used for producing the amorphous polyester resin, may be a bisphenol A derivative represented by the general formula (4): in which R ⁶ are the same or different from each other and represent an ethylene group or a methyl ethylene group; each of R ⁷ and R ⁸ represents independently a hydrogen atom or an alkyl group with 1 to 4 carbons; R ⁹ represents an ethylene group, a methyl ethylene group, a dimethylethylene group, a methylphenylethylene group, a di(trifluoromethyl)ethylene group, an ethylmethyl ethylene group, a diphenylethylene group or a p-xylylene group; and each of x and y represents an integer of 0 to 10 and an average value of the sum of x and y represents 1 to 10, and ethylene oxide and/or propylene oxide adducts thereof. In other examples, a linear or branched polyol with 2 to 36 carbons can be used. Examples of the linear or branched polyol with 2 to 36 carbons include an aromatic diol such as hydrogenated bisphenol A, bis(2- hydroxyethyl)terephthalate, xylylene glycol or the like; an aliphatic diol such as ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, dipropylene glycol, isopentylglycol, dipropylene glycol, isopentylglycol, 1 ,2-propanediol, 1 ,3-propanediol, 1 ,3-butanediol, 1 ,4-butanediol, 1 ,5-pentanediol, 1 ,6-hexanediol, 1 ,7-heptanediol, 1 ,8-octanediol, 1 ,9-nonanediol, 1 ,10-decanediol, 1,11 -undecanediol, 1,12-dodecanediol, 1 ,13-tridecanediol, 1 ,14-tetradecanediol, 1 ,18-octadecanediol, 1 ,20-eicosanediol, 1 ,4-butenediol, 2,2-dimethyl-1 ,3-propanediol, 1 ,4-cyclohexanedimethanol, 2,2,4-trimethy 1-1 ,3- pentanediol or the like; an aliphatic triol such as glycerin, trimethylolethane, trimethylolpropane or the like; or an aliphatic tetraol such as pentaerythritol or the like; etc.. In some examples, a saccharide such as sorbitol, sucrose or the like can also be used. Further, a polyethylene terephthalate having hydroxy groups at both terminals can also be used as the polyol. [0022] As the polyol, two or more selected from the aforementioned polyols may be used. To obtain a polyol with which the pendant-type amorphous polyester resin has a suitable fixability, two or more selected from bisphenol A and ethylene oxide and/or propylene oxide adducts thereof can be used.

[0023] The pendant-type amorphous polyester resin may have a glass transition temperature (Tg) that falls within a range of 50 to 80°C in some examples, or of 50 to 70°C in other examples. The pendant group-containing amorphous polyester and the amorphous polyester having no pendant group may be prepared separately to each have a glass transition temperature (Tg) that falls within the range.

[0024] A weight average molecular weight (Mw) of the pendant-type amorphous polyester resin may be within a range of 5,000 to 30,000 in some examples, within a range of 6,000 to 25,000 in other example, or within a range of 8,000 to 16,000 in yet other example, from the viewpoint of the dispersion of the crystalline polyester resin. The pendant group-containing amorphous polyester and the amorphous polyester having no pendant group may be prepared separately, in order to achieve a Mw that falls within the suitable range. [0025] The pendant-type amorphous polyester resin may have a melt viscosity at 120°C within a range of 50 to 20,000 Pa s in some examples, a range of 80 to 195,000 Pa s in other examples, or a range of 100 to 19,000 Pa s in yet other examples, from the viewpoint of the low-temperature fixability.

[0026] Examples of the melting point (Tm) of the amorphous polyester resin can include temperatures selected from 50 to 120°C. In order to reduce the viscosity and achieve a suitable heat-resistant storability of the toner, the examples can include temperatures selected from 55 to 100°C. The pendant group-containing amorphous polyester and the amorphous polyester having no pendant group may be prepared separately, in order to achieve a Tm that falls within the suitable range.

[0027] A method for producing the crystalline polyester resin will be described. Examples of a polyfunctional carboxylic acid which can be used for producing the crystalline polyester resin can include a polyfunctional aromatic carboxylic acid with 2 to 50 carbons and a polyfunctional aliphatic carboxylic acid. Examples of the polyfunctional aromatic carboxylic acid include a bifunctional aromatic carboxylic acid such as phthalic acid, isophthalic acid, terephthalic acid, tert-butylisophthalic acid, naphthalene-2,6-dicarboxylic acid, 4,4’- biphenyldicarboxylic acid or the like; a trifunctional aromatic carboxylic acid such as trimesic acid, trimellitic acid, hemimellitic acid or the like; a tetrafunctional aromatic carboxylic acid such as pyromellitic acid, mellophanic acid, prehnitic acid, pyromellitic acid, naphthalene-1 ,4,5,8-tetracarboxylic acid, naphthalene-

2.3.6.7-tetracarboxylic acid, biphenyl-3,3',4,4’-tetracarboxylic acid, perylene- 3,4:9, 10-tetracarboxylic acid or the like; a pentafunctional aromatic carboxylic acid such as benzenepentacarboxylic acid or the like; or a hexafunctional aromatic carboxylic acid such as mellitic acid or the like; etc..

[0028] Examples of the polyfunctional aliphatic carboxylic acid include a bifunctional aliphatic carboxylic acid such as oxalic acid, malonic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, succinic acid, glutaric acid, adipic acid, sebacic acid, azelaic acid, isooctenylsuccinic acid, decylsuccinic acid, dodecylsuccinic acid, dodecenylsuccinic acid, pentadecenylsuccinic acid, octadecenylsuccinic acid, cyclohexane-1 ,4-dicarboxylic acid, dodecanedicarboxylic acid, octadecanedicarboxylic acid, dimer acid, butylsuccinic acid, octylsuccinic acid, decylsuccinic acid, dodecylsuccinic acid, tetradecylsuccinic acid, hexadecylsuccinic acid, octadecylsuccinic acid, isooctadecylsuccinic acid (mixture of branched chain isomers), phenylsuccinic acid, 2-propene-1-yl succinic acid, 2-methyl-2-propene-1 -yl succinic acid, 2- butene-1 -yl succinic acid, 2-hexene-1 -yl succinic acid, 2-octene-1 -yl succinic acid, 2-nonene-1-yl succinic acid, 2-tetradecen-1 -yl succinic acid, 2-octadecene-1 -yl succinic acid, isooctadecenylsuccinic acid (mixture of branched chain isomers),

2.7-octadien-1-yl succinic acid or the like; a trifunctional aliphatic carboxylic acid such as propane-1, 2, 3-tricarboxylic acid, aconitic acid, butane-1 ,2,4-tricarboxylic acid, hexane- 1 ,3,6-tricarboxylic acid, cyclohexane-1 ,3, 5-tricarboxylic acid, adamantane-1 ,3,5-tricarboxylic acid or the like; a tetrafunctional aliphatic carboxylic acid such as ethylenetetracarboxylic acid, butane-1 ,2,3,4- tetracarboxylic acid, butane-1, 1, 3, 4-tetracarboxylic acid, cyclobutane-1 ,2,3,4- tetracarboxylic acid, cyclopentane-1 ,2, 3, 4-tetracarboxylic acid, octahydropentalene-1 ,3,4,6-tetracarboxylic acid, cyclohexane-1 ,2,4,5- tetracarboxylic acid, bicyclo[2.2.2]oct-7-ene- 2,3,5,6-tetracarboxylic acid or the like; or a hexafunctional aliphatic carboxylic acid such as cyclohexane- 1 ,2, 3,4,5, 6-hexacarboxylic acid or the like; etc.. In some examples, two or more selected from the above examples can also be used.

[0029] These polyfunctional carboxylic acids can be used in the form of: an anhydride; an ester of (an alkyl with 1 to 8 carbons); a diimide obtained by a reaction with a 4,4-diaminophenylmethane or the like; or an isocyanate ring- containing polyimide obtained by a reaction with a trimerization reaction product of a tris-(β -carboxyethyl)isocyanurate, an isocyanurate ring-containing polyimide, a tolylene diisocyanate, a xylylene diisocyanate or an isophorone diisocyanate or the like.

[0030] An alkane dicarboxylic acid and an alkene dicarboxylic acid may be selected among these polyfunctional carboxylic acids, in order to achieve suitable crystallinity, low-temperature fixability and heat-resistant storability. Examples thereof can include, for example, adipic acid, sebacic acid, azelaic acid, dodecanedicarboxylic acid, octadecanedicarboxylic acid, maleic acid and fumaric acid. As the polyfunctional carboxylic acid component, one of the above examples may be used or two or more of among these may be used together.

[0031] To the aforementioned polyfunctional carboxylic acids, a hydroxycarboxylic acid component such as, for example, p-oxybenzoic acid, vanillic acid, dimethylolpropionic acid, malic acid, tartaric acid, 5- hydroxyisophthalic acid or the like may be added, or a monovalent carboxylic acid or a monovalent alcohol may be included in order to adjust the molecular weight of the resin or to improve the high-temperature offset resistance of the toner.

[0032] A linear-type polyol with suitable crystallinity can be selected as a polyol for producing the crystalline polyester, and examples thereof include, for example, ethylene glycol, 1,3-propanediol, 1 ,4-butanediol, 1 ,5-pentanediol, 1,6- hexanediol, 1 ,7-heptanediol, 1 ,8-octanediol, 1 ,9-nonanediol, 1 ,10-decanediol, 1 ,11-undecanediol, 1,12-dodecanediol, 1,13-tridecanediol, 1,14-tetradecanediol, 1 ,18-octadecanediol, 1 ,20-eicosanediol and the like, and among them, ethylene glycol, 1,3-propanediol, 1 ,4-butanediol, 1 ,6-hexanediol, 1 ,9-nonanediol, 1,10- decanediol or 1,12-dodecanediol. As the polyol, one of the above examples may be used, or two or more of these may be used together.

[0033] The melting point (PT) of the crystalline polyester resin may be of 50 to 80°C in some examples, or may be of 50 to 70°C in other examples.

[0034] The Mw of the crystalline polyester resin may be within a range of 4,000 to 15,000 in some examples, of 4,100 to 10,000 in other examples, or of 4,200 to 8,000 in yet other examples.

[0035] The melt viscosity of the crystalline polyester at 120°C may be 200 to 20000 Pa s in some examples, or 400 to 195,000 Pa s in other examples, or 900 to 19,000 Pa-s in yet other examples, from the viewpoint of the low-temperature fixability.

[0036] Acid numbers of the amorphous polyester resin and the crystalline polyester resin are defined by the respective weights of potassium hydroxide (KOH) capable of neutralizing 1 g of these polyester resins. Examples of an acid number of a binder resin of the toner particle can include acid numbers selected from a range of 3 to 20 mgKOH/g in some examples, or 4 to 18 mgKOH/g in other examples, or further 5 to 16 mgKOH/g in yet other examples, in order to reduce a duration of the reaction with the epoxy group in the epoxy group-containing resin.

[0037] The binder resin of the epoxy group-containing toner particle has an endothermic energy amount at a second time of temperature increase represented by Tg2nd-dH, which may be within a range of 5 J/g to 50 J/g. The range for the Tg2nd-dH may have a minimum of 10 J/g in some examples, 14 J/g in other examples, or 15 J/g in yet other examples, and may have a maximum of 40 J/g in some examples, 25 J/g in other examples, 19 J/g in other examples, or 18 J/g in yet other examples. Tg2nd-dH of the binder resin may be regarded as, for example, an indicator of the compatibility of the pendant-type amorphous polyester resin and the crystalline polyester resin. Tg2nd-dH of the binder resin may also be defined in the same manner as mentioned above.

[0038] When the Tg2nd-dH of the binder resin falls within the aforementioned range, the glass transition temperature of the epoxy group- containing toner particle can be prevented from dropping while the fixing temperature is towered, so as to improve the storage stability of the epoxy group- containing toner particle.

[0039] The pendant-type amorphous polyester resin and the crystalline polyester resin can be produced by a condensation reaction of the aforementioned polyfunctional carboxylic acid and polyol. For example, they can be produced in such a manner that: the polyfunctional carboxylic acid and polyol, and in some examples, an esterification catalyst, are introduced into a reaction container provided with a thermometer, stirrer and flow down-type condenser, and blended therein; and are heated at 150 to 250°C under the presence of an inert gas (nitrogen gas or the like); a low-molecular weight compound generated as a by-product is continuously removed out of a reaction system; and the reaction is ceased at a time when a predetermined acid number is reached, and a resultant product is cooled to obtain a target product.

[0040] When a polymerizable monomer is not dissolved or compatible under reaction temperature, it may be dissolved by adding a high boiling point solvent as a solubilizing agent. In a polycondensation reaction, the reaction is performed while the solubilizing agent is removed by distillation. In a copolymerization reaction, when a polymerizable monomer having an unsuitable compatibility is present, the polymerizable monomer having the unsuitable compatibility can be condensed in advance with an acid or alcohol to be polycondensed with the polymerizable monomer, and then polycondensed together with main components.

[0041] Examples of the esterification catalyst include a compound including an alkali metal-based, alkaline earth metal-based, antimony-based, tin-based, germanium-based, titanium-based, zinc-based, aluminum-based, rare earth metal-based metal or the like. In addition, an organic metal such as dibutyltin, dilaurate, a dibutyltin oxide or the like, or a metal alkoxide such as tetrabutyl titanate or the like, etc. can be used. An acid such as phosphoric acid, sulfonic acid or the like; or an organic base such as amine, amide or the like may also be used.

[0042] Among these, examples of a tin(ll) compound having no Sn-C bonding include a tin(ll) compound having Sn-0 bonding, a tin(ll) compound having Sn-halogen bonding or the like. In some examples, a tin(ll) compound having Sn-0 bonding may be selected, from the viewpoint of environmental influence and/or safety. In addition, two or more esterification catalysts may be used by mixing. A usage amount of the esterification catalyst may be a so-called catalyst quantity.

[0043] A preparation ratio between the polyfunctional carboxylic acid and the polyol at the time of producing the pendant-type amorphous polyester resin or the crystalline polyester resin is not particularly limited. In some examples, the polyester resins obtained may further be caused to react with a polyfunctional carboxylic acid and/or polyol. As a polyfunctional carboxylic acid and/or polyol which can be used in this case, any of the examples above can be used, and the reaction can be performed in accordance with the aforementioned synthesizing conditions.

[0044] Note that the aforementioned pendant-type amorphous polyester resin and crystalline polyester resin may be a graft or block polyester resin with phenol, urethane or the like or a modified polyester resin such as a composite resin having two or more resin units including a polyester unit or the like to the extent that their properties are not substantially impaired.

[0045] The binder resin may also contain, for example, a styrene- (meth)acrylic copolymer or a styrene-butadiene copolymer, in addition to the aforementioned pendant-type amorphous polyester resin and crystalline polyester resin. Among these, a styrene-acrylic copolymer is suitable for directly producing a colored particle by a chemical method such as emulsion aggregation method or suspension polymerization method. Examples of a monomer for producing the styrene-acrylic copolymer, include styrene; a styrene-based monomer such as o-(m-, p-)methyl styrene, m-(p-)ethyl styrene or the like; a (meth)acrylic acid ester-based monomer such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, octyl (meth)acrylate, dodecyl (meth)acrylate, stearyl (meth)acrylate, behenyl (meth)acrylate, 2-ethyl hexyl (meth)acrylate, dimethylamino ethyl (meth)acrylate, diethylaminoethyl (meth)acrylate or the like; or an ene-based monomer such as butadiene, isoprene, cyclohexene, (meth)acrylonitrile, acrylic amide or the like. [0046] In some examples, a cross-linking agent may be used at the time of producing the binder resin. Examples of a bifunctional cross-linking agent as the cross-linking agent used at the time of producing the binder resin include, for example, divinylbenzene, bis(4-acryloxy polyethoxyphenyl)propane, ethylene glycol diacrylate, 1,3-butylene glycol diacrylate, 1 ,4-butanediol diacrylate, 1,5- pentanediol diacrylate, 1 ,6-hexanediol diacrylate, neo pentylglycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, the respective diacrylates of polyethylene glycols #200, #400 and #600, dipropylene glycol diacrylate, polypropylene glycol diacrylate, polyester-type diacrylate and products obtained by substituting dimethacrylates for the aforementioned diacrylates.

[0047] Examples of a trifunctional or more polyfunctional cross-linking agent include, for example, pentaerythritol triacrylate, trimethylolethane triacrylate, trimethylolpropane triacrylate, tetramethylolmethane tetracrylate, oligoester acrylate and methacrylates thereof, 2,2-bis(4-methacryloxy polyethoxyphenyl)propane, diallyl phthalate, triallyl cyanurate, triallyl isocyanurate and triallyl trimellitate.

[0048] These cross-linking agents can be used at a content ratio of 0.01 to 10 mass% in some examples, or 0.1 to 5 mass% in other examples, relative to the polymerizable monomers constituting the binder resin.

[0049] The epoxy group-containing toner particle includes an epoxy group- containing resin having an epoxy group capable of reacting with a carboxyl group and represented by the general formula (1): in which R ¹ , R ² , R ³ and ● represent the same contents as those mentioned above for the respective symbols.

[0050] The resin can be produced by causing an epihalohydrin derivative represented by the general formula (5) to react: in which R ¹ , R ² and R ³ represent the same contents as those mentioned above; and X represents a chlorine atom, a bromine atom or an iodine atom, and a polyol under the presence of acid and/or base catalysts.

[0051] As the polyol, a bisphenol A derivative represented by the general formula (6) may be selected: in which R ¹⁰ are the same or different from each other and represent an ethylene group or a methyl ethylene group; each of R ¹¹ and R ¹² independently represents a hydrogen atom or an alkyl group with 1 to 4 carbons; R ¹³ represents an ethylene group, a methyl ethylene group, a dimethylethylene group, a methylphenylethylene group, a di(trifluoromethyl)ethylene group, an ethylmethyl ethylene group, a diphenylethylene group or a p-xylylene group; and each of x’ and y ^: represents an integer of 0 to 10 and an average value of the sum of x’ and y’ represents 1 to 10, and ethylene oxide and/or propylene oxide adducts thereof; or a linear or branched polyol with 2 to 36 carbons can be used. Examples of the linear or branched polyol with 2 to 36 carbons can include aromatic diols such as hydrogenated bisphenol A, bis(2-hydroxyethyl) terephthalate, xylylene glycol and the like; aliphatic diols such as ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, dipropylene glycol, isopentylglycol, dipropylene glycol, isopentylglycol, 1,2-propanediol, 1 ,3-propanediol, 1,3- butanediol, 1 ,4-butanediol, 1 ,5-pentanediol, 1 ,6-hexanediol, 1,7-heptanediol, 1,8- octanediol, 1 ,9-nonanediol, 1,10-decanediol, 1 ,11 -undecanediol, 1,12- dodecanediol, 1,13-tridecanediol, 1 ,14-tetradecanediol, 1 ,18-octadecanediol, 1 ,20-eicosanediol, 1 ,4-butenediol, 2, 2-dimethyl-1 ,3-propanediol, 1,4- cyclohexanedimethanol, 2,2,4-trimethyl-1 ,3-pentanediol and the like; aliphatic triols such as glycerin, trimethylolethane, trimethylolpropane and the like; and aliphatic tetraols such as pentaerythritol and the like; etc. In addition, a saccharide such as sorbitol, sucrose or the like can also be used. Further, a polyethylene terephthalate having hydroxy groups at both terminals can also be used as the polyol. Moreover, as the polyol, two or more examples selected from the aforementioned polyols may be used. Two or more selected from bisphenol A and ethylene oxide and/or propylene oxide adducts thereof can be used.

[0052] As the epoxy group-containing resin obtained from the epihalohydrin derivative (5) and any of the aforementioned polyols, a bisphenol A-type epoxy resin, a halogenated bisphenol A-type epoxy resin, a novolac-type epoxy resin, a polyglycol-type epoxy resin, a bisphenol F-type epoxy resin, an epoxidized oil or the like can be used.

[0053] In addition, an epoxy ester compound obtained by a reaction of a polydiglycidyl ether of any of the aforementioned polyols and a polyfunctional carboxylic acid which can be used for synthesizing the crystalline and amorphous polyesters, can also be used as the epoxy group-containing resin. Further, a cresol novolac-type resin obtained by glycidy lating the hydroxy group of a novolac resin with the epihalohydrin derivative (5) can also be used as the epoxy group- containing resin.

[0054] Moreover, the epoxy resin-containing resin may be obtained by polymerizing the olefin moiety of an unsaturated carboxylic acid glycidyl ester such as glycidyl methacrylate, glycidyl acrylate, glycidyl 2-cyanoacrylate, diglycidyl itaconate, glycidyl sorbate, glycidyl methacrylate citric acid ester or the like. In this case, the content of the epoxy group in the resin can be adjusted by mixing to the unsaturated carboxylic acid glycidyl ester, for example, an unsaturated carboxylic acid having no glycidyl group or an ester thereof, such as an unsaturated carboxylic acid, an unsaturated carboxylic acid methyl ester, an unsaturated carboxylic acid ethyl ester or the like, or an olefin having no glycidyl group, and performing a copolymerization or a block polymerization.

[0055] In other examples, the epoxy group-containing resin may be obtained by polymerizing an olefin having a glycidyl group, such as 2-(1-propenyl)phenyl glycidyl ether, 2-ethenylphenyl(2-methylglycidyl) ether or the like. In this case, the content of the epoxy group in the resin can be adjusted by mixing to the oiefin having a glycidyl group an olefin having no glycidyl group and performing a copolymerization or a block polymerization.

[0056] In some examples, a commercially available product such as YD series of NIPPON STEEL Chemical & Material Co., Ltd., jER series of Mitsubishi Chemical Corporation, DENACOL of Nagase ChemteX Corporation or the like can also be used.

[0057] The content of the epoxy group in the epoxy group-containing resin may be set within a range of 0.6 to 5.0 mol per mol of the resin, to enhance the reactivity with the carboxyl group in the binder resin.

[0058] Mw of the epoxy group-containing resin may be a value selected from a range of 500 to 30,000 in some examples, a range of 800 to 20,000 in other examples, or a range of 1 ,000 to 10,000 in yet other examples.

[0059] A catalyst for a reaction of the carboxyl group of the polyesters may include an organic base included in the binder resin and the epoxy group in the epoxy group-containing resin. Examples of such an organic base include a trialkylamine such as tri(alkyl with 1 to 4 carbons)amine or the like; a quarternary ammonium salt such as tetra(alkyl with 1 to 4 carbons)ammoniumbromide, tetra(alkyl with 1 to 4 carbons)ammoniumchloride or the like; or a nitrogen- containing aromatic compound such as imidazole, N-(alkyl with 1 to 4 carbons)pyrrol, N-(alkyl with 1 to 4 carbons)indole, N-(alkyl with 1 to 4 carbons)carbazole, pyrazole, 1 ,2,3-triazole, 1,2,4- triazole, pyridine, 4- dimethylaminopyridine or the like. The content of the organic base used can be a so-called catalyst quantity.

[0060] Note that a hydroxyl group-containing resin, an amino group- containing resin or the like having a functional group capable of reacting with the carboxyl group other than the epoxy group can be used, and they may be used by mixing.

[0061] Examples of the hydroxyl group-containing resin can include polyethylene glycol, polypropylene glycol, polyoxypropylene triol, polyoxyethylene polyoxypropylene glycol, cellulose, amylose and the like. [0062] When the hydroxyl group-containing resin is used, an organic acid or an organic base may be included as a catalyst for a reaction of the carboxyl group of the polyesters included in the binder resin and the hydroxyl group in the resin. As the organic acid, a carboxylic acid such as acetic acid, propionic acid or the like can be used. As the organic base, any of the aforementioned organic bases can be used. The content of the organic acid or organic base used can be a so- called catalyst quantity. The organic acid may not be used in some examples, since the carboxyl group in the polyesters may act as a catalyst.

[0063] Examples of the amino group-containing resin can include polyethyleneimine, polyvinylpyridine, polyvinylcarbazole, DNA, RNA, polyurethane, polycaproamide, polyhexamethylene adipamide, aromatic polyimide and the like.

[0064] When the amino group-containing resin is used, any of the aforementioned organic acids or organic bases may be included as a catalyst for a reaction of the carboxyl group of the polyesters included in the binder resin and the amino group in the resin. The content of the organic acid or organic base used can be a so-called catalyst quantity. The organic acid may not be used in some examples, since the carboxyl group in the polyesters may act as a catalyst. In addition, the organic base may not be used in some examples, since the amino group in the amino group-containing resin may act as a catalyst.

[0065] The epoxy group and the carboxyl group are caused to react with the epoxy group-containing resin, at a temperature of about 90 to 110°C which is a DSC exothermic peak starting temperature of the binder resin to produce a polymer for improving the high-temperature offset resistance. For example, when R ¹ , R ² and R ³ in the general formula (1) are hydrogen atoms, the polymer is produced by a reaction of the formula (7):

[0066] A ratio of an amount of the epoxy group in the epoxy group-containing resin to that of the carboxyl group in the binder polyester resins, represented by [epoxy group]/[carboxyl group], may be a value within a range of 0.5 to 50 in some examples, of 0.7 to 30 in other examples, or of 1.0 to 10 in yet other examples, to increase the efficiency of the reaction of the formula (7).

[0067] The mold release agent in the epoxy group-containing toner particle may be selected to have a melting point at a temperature within a range of 60°C to 100°C, to improve the high-temperature offset resistance at the time of contact fixing.

[0068] Examples of the mold release agent can include, for example, wax esters, waxes and the like, such as: vegetable waxes such as carnauba wax, cotton wax, Japan wax, rice wax and the like; animal waxes such as beeswax, lanolin and the like; mineral waxes such as ozokerite, ceresin and the like; and petroleum waxes such as paraffin, micro crystalline, petrolatum and the like, etc. In addition to these natural waxes, synthetic hydrocarbon waxes such as Fischer- Tropsch wax, a low-molecular weight polyethylene wax, a low-molecular weight polypropylene wax and the like; and synthetic waxes such as an ether wax and the like can also be used.

[0069] In some examples, as a mold release agent having a suitable mold release property, the petroleum wax can be used. A petroleum wax which can be used is a paraffin wax composed mainly of a straight-chain hydrocarbon. For example, HNP-3, 5, 9, 10, 11, 12 or 51 manufactured by NIPPON SEIRO CO., LTD., C80 C80-G, C80N8, C80M, H1, H1N6, H1N8, H1N4, H1N4-G, Spray 30, Spray 30-G or Spray 30 G-EF manufactured by Sasol Limited, Trasol PF60 manufactured by Chukyo Yushi Co., Ltd or the like can be used. In addition, a microcrystalline wax including a large number of branched hydrocarbons or cyclic saturated hydrocarbons can be used. For example, Hi-Mic-2095, 1090, 1080, 1070, 2065, 1045 or 2045 manufactured by NIPPON SEIRO CO., LTD., 5803, 6403 or KTM23 manufactured by Sasol Limited or the like can be used.

[0070] In order to achieve a suitable epoxy group-containing toner particle, the paraffin wax may be selected among these petroleum waxes.

[0071] In other examples, an ester-based wax can also be used. The ester- based wax may be a mixture of a paraffin wax and a high-molecular weight ester; or an ester group-containing paraffin wax. The high-molecular weight ester may be, for example, behenyl behenate, stearyl stearate, a stearic acid ester of pentaerythritol, or an ester of a fatty acid with 15 to 30 carbons such as montanic acid glyceride or the like and a monohydric alcohol or a pentahydric alcohol. The alcohol component constituting the ester may be a monohydric alcohol with 10 to 30 carbons or a polyhydric alcohol with 3 to 30 carbons.

[0072] Examples thereof include a mixture of the high-molecular weight ester and a non-ester wax such as a polyethylene wax, a polypropylene wax, a silicon wax, a paraffin wax or the like or an ester group-containing wax which contains an ester group in the non-ester wax. Some examples thereof include, for example, product names P-212, P-280, P-318, P-319 and P-419 of Chukyo Yushi Co., Ltd. and the like.

[0073] In the case where the wax is a mixture of a paraffin wax and a high- molecular weight ester, the content of the ester wax may be within a range having a minimum of 1 mass% in some examples, 5 mass% in other examples, 10 mass% in other examples, or 15 mass% in yet other examples, and a maximum of 50 mass% relative to the total weight of the mixture of a paraffin wax and a high-molecular weight ester in some examples. The content of the high- molecular weight ester may be 1 mass% or more, to sufficiently maintain the compatibility with the latexes used at the time of producing the epoxy group- containing toner particle, and may be 50 mass% or less, to achieve a suitable plasticity of the epoxy group-containing toner particle and to maintain a suitable developing property for a prolonged duration.

[0074] A content ratio of the mold release agent in the epoxy group- containing toner particle can be a value within a range of 0.5 to 10 mass% in some examples, of 0.75 to 9.5 mass% in other examples or of 1.0 to 9.0 mass% in yet other examples.

[0075] According to examples, a dispersant may be used to achieve a suitable epoxy group-containing toner particle. The dispersant may be selected to have a melting point at a temperature within a range of 60°C to 100°C or less as a dispersant.

[0076] In some examples, a carbonyl compound can be used as the dispersant. As the carbonyl compound, a linear fatty acid ester, a linear aliphatic ketone or a linear fatty acid amide can be used. According to examples, the toner particle can be produced by using a linear fatty acid ester among these carbonyl compounds.

[0077] As the linear fatty acid ester, a monocarboxylic acid ester represented by the general formula (8): R ¹⁴ COOR ¹⁵ (in which R ¹⁴ represents a linear alkyl group with 18 to 25 carbons and R ¹⁵ represents a linear alkyl group with 18 to 30 carbons) can be used.

[0078] A commercial product may be used as the monocarboxylic acid ester of the general formula (8) in some examples, or in other examples, the monocarboxylic acid ester may be synthesized by an esterification using R ⁱ⁴ COOH or an acid anhydride or acid halide of R ¹⁴ COOH and R ¹⁵ OH. In other examples, the monocarboxylic acid ester can be synthesized by Baeyer-Villiger oxidation using a peroxy acid of R ¹⁴ -(C=O)-R ¹⁵ , alkylation using a diazoalkyl, a nucleophilic substitution reaction to an alkyl halide or the like using R ¹⁴ COO-, an addition reaction of an alkene or alkyne and R ¹⁴ COOH, or the like.

[0079] An example of the linear fatty acid ester includes a dicarboxylic acid diester represented by the general formula (9): R ¹⁷ O-(C=O)-R ¹⁶ -(C=O)-OR ¹⁷ (in which R ¹⁶ represents a linear alkylene group with 14 to 30 carbons and R ¹⁷ represents a linear alkyl group with 1 to 25 carbons).

[0080] A commercial product may be used as the dicarboxylic acid diester of the general formula (9) in some example, or in other examples, the dicarboxylic acid diester may also be synthesized by an esterification using HOOC-R ¹⁶ "COOH or an acid anhydride or acid halide of HOOC-R ¹⁶ -COOH and R ¹⁷ OH. In other examples, the dicarboxylic acid diester can be synthesized by Baeyer-Villiger oxidation using a peroxy acid of R ¹⁷ -(C=O)-R ¹⁶ -(C=O)-R ¹⁷ , alkylation using a diazoalkyl, a nucleophilic substitution reaction to an alkyl halide or the like using -OOC-R ¹⁶ -COO-, an addition reaction of an alkene or alkyne and HOOC-R ¹⁶ - COOH, or the like.

[0081] As the linear aliphatic ketone, a symmetrical ketone represented by the general formula (10): R ¹⁸ -(C=O)-R ¹⁸ (in which R ¹⁸ represents a linear alkyl group with 10 to 20 carbons) can be used. [0082] A commercial product may be used as the symmetrical ketone of the general formula (10) or it may also be synthesized by a reaction of R ¹⁸ -(CO)-CI or R ¹⁸ -CN and R ¹⁸ MgBr, catalytic dehydrogenation of R ¹⁸ -CH(OH)-R ¹⁸ , or the like. [0083] As the linear fatty acid amide, an amide represented by the general formula (11): R ¹⁹ -(C=O)-NH ₂ (in which R ¹⁹ represents a linear alkyl group with 6 to 15 carbons or a linear monoalkenyl group with 15 to 25 carbons) can be used. [0084] A commercial product may be used as the amide of the general formula (11) in some examples, or in other examples, the amide can be synthesized by a reaction of an acid anhydride, acid halide, acid azide or p- nitrophenyl ester of R ¹⁹ COOH or the like and ammonia, or the like.

[0085] In addition, as the linear fatty acid amide, an N-substituted amide represented by the general formula (12): R ²⁰ -(C=O)-NH-R ²¹ (in which R ²⁰ represents a linear alkyl group with 10 to 20 carbons or a linear monoalkenyl group with 15 to 25 carbons, and R ²¹ represents a linear alkyl group with 10 to 20 carbons or a linear monoalkenyl group with 15 to 25 carbons) can be used.

[0086] A commercial product may be used as the N-substituted amide of the general formula (12) in some examples, or in other examples, the N-substituted amide can also be synthesized by a reaction of an acid anhydride, acid halide, acid azide or p-nitrophenyl ester of R ²⁰ COOH or the like and NH ₂ -R ²¹ . In other examples, the N-substituted amide can be synthesized by a reaction of R ²⁰ -CN and R ²¹ -OH, a reaction of R ²⁰ -(C=O)-NH ₂ and R ²¹ -NH ₃ +, a reaction of R ²⁰ -(C=O)- R ²¹ and NH ₃ , Beckmann rearrangement of R ²⁰ -(C=N(OH))-R ²¹ , or the like.

[0087] In addition, as the linear fatty acid amide, an N-hydroxymethylamide represented by the general formula (13): R ²² -(C=O)-NH-CH ₂ OH (in which R ²² represents a linear alkyl group with 6 to 15 carbons) can also be used.

[0088] A commercial product may be used as the N-hydroxymethylamide of the general formula (13) in some examples, or in other examples, the N- hydroxymethylamide can be synthesized by a reaction of R ²² -(C=O)-NH ₂ and formaldehyde. In some examples, the N-hydroxymethylamide can be synthesized by a reaction of an acid anhydride, acid halide, acid azide or p- nitrophenyl ester of R ²² COOH or the like and NH ₂ -CH ₂ OH, or the like. [0089] Moreover, as the linear fatty acid amide, a hydroxy fatty acid amide represented by the general formula (14): HO-R ²³ -(C= O)-NH ₂ (in which R ²³ represents a linear alkylene group with 6 to 12 carbons) can be used.

[0090] A commercial product may be used as the hydroxy fatty acid amide of the general formula (14) in some examples, or in other examples, the hydroxy fatty acid amide can be synthesized by a reaction of an acid anhydride, acid halide, acid azide or p-nitrophenyl ester of HO-R ²³ COOH or the like and ammonia, or the like.

[0091] The dispersant can be used at a content ratio within a range of 2 to 15 mass% in some examples, of 2.5 to 12 mass% in other examples, or of 3.0 to 10 mass% in yet other examples, in the epoxy group-containing toner particle.

[0092] A mass ratio of the dispersant and the mold release agent can be a value within a range selected from, 50:50 to 95:5, 55:45 to 90: 10 or 60:40 to 85: 15. [0093] The epoxy group-containing toner particle may include a colorant. The colorant can include a colorant selected from, for example, black, cyan, magenta and yellow colorants. The black colorant may be carbon black or aniline black. The yellow colorant may be a condensed nitrogen compound, an isoindolinone compound, an anthraquinone compound, an azo metal complex or an allyl imide compound. Examples thereof include C.l. pigment yellow 12, 13, 14, 17, 62, 74, 83, 93, 94, 95, 109, 110, 111 , 128, 129, 147, 168, 180 and the like. The magenta colorant may be a condensed nitrogen compound, an anthraquinone, a quinacridone compound, a basic dye lake compound, a naphthol compound, a benzoimidazole compound, a thioindigo compound or a perylene compound. Examples thereof include, for example, C.l. pigment red 2, 3, 5, 6, 7, 23, 48:2, 48:3, 48:4, 57:1, 81:1, 122, 144, 146, 166, 169, 177, 184, 185, 202, 206, 220, 221, 254 and the like. The cyan colorant may be a copper phthalocyanine compound, a derivative thereof, an anthraquinone compound or the like. Examples thereof include, for example, C.l. pigment blue 1, 7, 15, 15:1, 15:2, 15:3, 15:4, 60, 62, 66 and the like.

[0094] Such a colorant may be obtained from a single component, for example, or in other examples, from a mixture of two or more of the compounds selected in consideration of a hue, a chroma, lightness, weather resistance, dispersibility in the epoxy group-containing toner particle and/or the like.

[0095] While the content of the colorant is not particularly limited as long as it is an amount sufficient to color the epoxy group-containing toner particle, the content of the colorant may be within a range having a minimum of 0.5 parts by mass, 1 part by mass or 2 parts by mass, depending on examples, and having a maximum of 15 parts by mass, 12 parts by mass, or 10 parts by mass depending on examples, relative to 100 parts by mass of the epoxy group-containing toner particle. The content of the colorant may be selected to be 0.5 parts by mass or more relative to 100 parts by mass of the epoxy group-containing toner particle, to exhibit a sufficient coloring effect, and to be 15 parts by mass or less, to obtain a sufficient triboelectric charge amount without having a significant effect on a cost increase for producing the epoxy group-containing toner particle.

[0096] An additive may be kneaded with the epoxy group-containing toner particle. Examples of the additive include a charge control agent, a magnetic powder, a fluidity improving agent, a conductivity adjusting agent, an extender pigment, a reinforcing filler such as a fibrous material or the like, an antioxidant, an anti-aging agent, a cleanliness improving agent or the like, etc..

[0097] The charge control agent is not particularly limited and may contain a positive electrified charge control agent or a negative electrified charge control agent. In addition, the charge control agent may be internally or externally added to the epoxy group-containing toner particle.

[0098] Examples of the positive electrified charge control agent include a nigrosine dye, for example, “NIGROSINE BASE EX, ^" “OIL BLACK BS,” “OIL BLACK SO,” “BONTRON N-01," “BONTRON N-04,” “BONTRON N-07,” “BONTRON N-09,” “BONTRON N-11” (all manufactured by ORIENT CHEMICAL INDUSTRIES CO., LTD.) or the like; a triphenylmethane dye containing a tertiary amine as a side chain, a quaternary ammonium salt compound, for example, “BONTRON P-51” (manufactured by ORIENT CHEMICAL INDUSTRIES CO., LTD.), cetyltrimethylammonium bromide, “COPY CHARGE PX VP 435” (manufactured by Clariant AG) or the like; a polyamine resin, for example, “AFP- B” (manufactured by ORIENT CHEMICAL INDUSTRIES CO., LTD.) or the like; an imidazole derivative, for example, “PLZ-2001,” “PLZ-8001” (all manufactured by SHIKOKU CHEMICALS CORPORATION) or the like; or a styrene acrylic resin, for example, “FCA-701PT” (manufactured by Fujikura Kasei Co., Ltd.) or the like. [0099] Examples of the negative electrified charge control agent include a metal-containing azo dye, for example, “VALIFAST BLACK 3804,” “BONTRON S- 31," “BONTRON S-32,” “BONTRON S-34,” “BONTRON S-36” (all manufactured by ORIENT CHEMICAL INDUSTRIES CO., LTD.), “Aizen Spilon Black TRH,” “T- 77” (manufactured by Hodogaya Chemical Co., Ltd.) or the like; a metal compound of a benzilic acid compound, for example, “LR-147,” “LR-297” (all manufactured by Japan Carlit Co., Ltd.) or the like; a metal compound of a salicylic acid compound, for example, “BONTRON E-81,” “BONTRON E-84,” “BONTRON E-88,” “BONTRON E-304” (all manufactured by ORIENT CHEMICAL INDUSTRIES CO., LTD.), “TN-105” (manufactured by Hodogaya Chemical Co., Ltd.) or the like; a copper phthalocyanine dye; a quaternary ammonium salt, for example, “COPY CHARGE NX VP 434” (manufactured by Clariant AG), a nitroimidazole derivative or the like; or an organic metal compound or the like. [0100] In addition, together with any of the aforementioned charge control agents, a metal soap, an inorganic or organic metal salt can be used as a cleaning assistant. Examples of such a cleaning assistant include a metal soap, aluminum tristearate, aluminum distearate, barium, calcium, lead and zinc stearates, or cobalt, manganese, lead and zinc linoleates, aluminum, calcium and cobalt octanoates, calcium and cobalt oleinates, zinc palmitate, calcium, cobalt, manganese, lead and zinc naphthenes, acid salts, calcium, cobalt, manganese, lead and zinc resinates, and the like. In addition, as to the inorganic and organic metal salts, for example, a cationic component in the metal salts is selected from the group consisting of the metals belonging to the la, Ila and Illa groups of the periodic table, and an anionic component of the acids thereof may be a salt selected from the group consisting of a halide ion, a carbonate ion, an acetate ion, a sulfate ion, a borate ion, a nitrate ion and a phosphate ion. In order to achieve a suitable effect, these charge control agent and cleaning assistant may be added at a content ratio within a range selected from 0.01 to 20 mass%, 0.1 to 5 mass%, or 0.5 to 2.5 mass% relative to the epoxy group-containing toner particle.

[0101] According to examples, the epoxy group-containing toner particle may contain a magnetic substance to become magnetized. A commercially available magnetic substance can be suitably used. For example, metals such as iron, cobalt, nickel and the like and alloys thereof; metal oxides such as Fe ₃ O ₄ , y-Fe ₂ O ₃ , a cobalt-added iron oxide and the like; products formed of various ferrites such as MnZn ferrite and NiZn ferrite and the like; and among them, Fe ₃ O ₄ of 0.05 to 0.5 pm can be used. These may be treated with various treating agents to have hydrophobicity and then used. Further, a plurality of these may be combined together. While the content can be selected as necessary, they can be added in an amount within a range selected from 0.2 to 2.0 mass%, 0.4 to 1.5 mass%, or 0.5 to 1.0 mass% relative to the epoxy group-containing toner particle to be used as magnetic toner.

[0102] According to examples, the epoxy group-containing toner particle may contain an inorganic micro particle. The inorganic micro particle may be internally added to the epoxy group-containing toner particle in some examples, or contained in the toner as an external additive in other examples. When contained as an external additive, the inorganic micro particle may be an inorganic micro particle such as a silica micro particle, a titanium-oxide micro particle or an aluminum-oxide micro particle. The inorganic micro particle may be hydrophobized by a hydrophobing agent such as, for example, a silane compound, a silicon oil or a mixture thereof. In order to improve the fluidity of the toner, the inorganic micro particle may have a specific surface area of 50 m ² /g to 400 m ² /g. In order to improve the durability of the epoxy group-containing toner, the inorganic micro particle may have a specific surface area of 10 m ² /g to 50 m ² /g. In order to improve both the fluidity and the durability at the same time, inorganic micro particles with the respective specific surface areas within the aforementioned ranges may be used together. When the inorganic micro particle is contained as an external additive, a proportion thereof may be 0.1 parts by mass to 10.0 parts by mass relative to 100 parts by mass of the epoxy group- containing toner particle. The epoxy group-containing toner particle and the inorganic micro particle can be mixed by using a mixer such as, for example, Henschel mixer.

[0103] A temperature at which the storage modulus of the epoxy group- containing toner reaches 0.1 MPa, may be 100°C or less. There is a substantially positive correlation between the storage modulus and the lowest fixing temperature and this correlation may be an indicator for a fixing property of the toner. Namely, a lower temperature at which the storage modulus reaches 0.1 MPa tends to correlate with a lower temperature of the lowest fixing temperature.

[0104] According to examples, the epoxy group-containing toner particle may have a sea-island structure including, for example, a matrix portion of the pendant-type amorphous polyester resin and a domain portion of the wax. For example, a longer diameter of the domain portion may be within a range of 0.3 pm to 1.5 pm. In some examples, the domain portion may be at least partially a two-layer domain portion with its circumference coated with a compatible layer of the crystalline polyester resin and the pendant-type amorphous polyester resin. The longer diameter of the domain portion may be set within the above-mentioned range, , in order to obtain a suitable particle size, to improve the high-temperature offset resistance, and to increase the durability.

[0105] In addition, a proportion of the two-layer domain portion may be within a range of 10 mass% to 50 mass% in the domain portion, so as to provide an adequate compatibility of the pendant-type amorphous polyester and the crystalline polyester resin and a suitable low-temperature fixability.

[0106] According to examples, the epoxy group-containing toner particle may have a structure in which the crystalline polyester resin is dispersed in the pendant-type amorphous polyester resin. An average particle size of the dispersed particle of the crystalline polyester resin in the pendant-type amorphous polyester resin may be within a range having a minimum of 5 nm, or 10 nm depending on examples, and having a maximum of 500 nm, or 250 nm depending on examples. This average particle size can be calculated from, for example, a TEM (transmission electron microscope) image. Additionally, this average particle size may be measured in such a state that the pendant-type amorphous polyester resin and the crystalline polyester resin are mixed prior to the production of the epoxy group-containing toner particle.

[0107] The epoxy group-containing toner particle may be produced by a crushing process or a polymerization process. In some examples, in order to achieve a predetermined sea-island structure as mentioned above, a polymerization process may be adopted to produce the epoxy group-containing toner particle.

[0108] A method for producing the epoxy group-containing toner particle by a polymerization process will be described based on an example.

[0109] A polycarboxylic acid including a polycarboxylic acid having a branched chain, a polyhydric alcohol, an esterification catalyst and the like are introduced into a reaction container and subjected to an esterification reaction to obtain the pendant-type amorphous polyester resin. The pendant-type amorphous polyester resin obtained is dissolved in a suitable solvent such as methyl ethyl ketone, isopropyl alcohol or the like, and a pH is adjusted, water is added, the solvent is removed and the like, to obtain a latex of a dispersion liquid of a predetermined concentration of the pendant-type amorphous polyester resin. [0110] According to examples, such an esterification reaction and a dispersion liquid latex preparation may also be performed for the crystalline polyester resin in a similar manner as for the pendant-type amorphous polyester resin.

[0111] In addition, a colorant dispersion liquid and a wax dispersion liquid are each prepared via a polymerization process. For example, in the preparation of the wax dispersion liquid, a wax, an anionic surfactant and water are initially introduced into a reaction container. A suitable content of the mold release agent in the mixture of the wax, the anionic surfactant and water is determined in view of a dispersion state and the like. Examples of the anionic surfactant include, for example, alkylbenzene sulfonates and the like. A content of the anionic surfactant in the mixture of the wax, the anionic surfactant and water is determined in view of a dispersion state and the like. A suitable content of water in the mixture of the mold release agent, the anionic surfactant and water is determined in view of a dispersion state, storability, economic efficiency and the like. Subsequently, the mixture of the mold release agent, the anionic surfactant and water is subjected to a dispersion process to obtain a mold release agent dispersion liquid. Examples of a method for subjecting the mixture to the dispersion process include a method using a homogenizer. In addition, a commercial product may be used for each of the colorant dispersion liquid and the wax dispersion liquid.

[0112] Initially, the latex of the pendant-type amorphous polyester resin, a latex of an amorphous polyester resin and the latex of the crystalline polyester resin are mixed, for example, in a water system. Next, a latex dispersion liquid including the epoxy group-containing resin and a catalyst Is mixed and the colorant dispersion liquid and the mold release agent dispersion liquid are further mixed with a homogenizer or the like (a mixed liquid formation process).

[0113] A flocculating agent is added to the mixture obtained in the mixed liquid formation process, and stirred with a Fullzone stirring blade at 500 to 700 rpm and the temperature is increased from room temperature to 45 to 55°C to obtain a flocculated particle containing: the binder resin including the pendant- type amorphous polyester resin and the crystalline polyester resin; the epoxy group-containing resin; and in some examples, the catalyst, the colorant and the wax (a flocculated particle formation process).

[0114] Next, the latex of the pendant-type amorphous polyester resin is further mixed to form a coating layer composed of the pendant-type amorphous polyester resin on the surface of the flocculated particle, to obtain a coated flocculated particle. At that time, the amorphous polyester resin latex may be added (a coated flocculated particle formation process).

[0115] Subsequently, the coated flocculated particle is heated to a temperature within a range of 55 to 85°C, to fuse and coalesce the particle within the coated flocculated particle, to obtain the epoxy group-containing toner particle (a fusion coalescence process).

[0116] Examples of the flocculating agent include ferrous metal salts. Examples thereof include poly silicate iron and polyaluminum chloride.

[0117] The flocculating agent can be used in an added amount within a range of 0.4 to 3.0 weight% or of 0.6 to 2.0 weight% of the total weight of the materials. According to examples, the added amount of the flocculating agent may be within the range of 0.4 to 3.0 weight%, to achieve a particle size of the epoxy group-containing toner particle that is within a suitable range mentioned below.

[0118] In the aforementioned method, a so-called core-shell type toner particle can be obtained by using the particle obtained in the flocculated particle formation process, as a core and coating it with a shell composed of the pendant- type amorphous polyester resin in the coated flocculated particle formation process.

[0119] A volume average particle size of the epoxy group-containing toner particle of this example can be with a range of 3 to 9 pm or of 2.5 to 8.5 pm. According to examples, the volume average particle size may be within the range of 3 to 9 pm, to more easily generate a detailed image.

[0120] In the example epoxy group-containing toner particle, an amount of particles having an average particle size of 3 pm or less, may be 3 % or less or 2.5 % or less, depending on examples. For example, the amount of particles having a particle size of 3 pm or less may be 3 number% or less, to achieve a sufficiently uniform particle size of the epoxy group-containing toner particle.

[0121] According to examples, the epoxy group-containing toner particle may include three or more elements including at least an iron atom, a silicon atom and a sulfur atom selected from the group consisting of an iron atom, a silicon atom, a sulfur atom and a fluorine atom. The content of an iron atom may be 1.0x10 ³ to 1.0x10 ⁴ ppm, the content of a silicon atom may be 1.0x10 ³ to 5.0x10 ³ ppm and the content of a sulfur atom may be 500 to 3,000 ppm. If a fluorine atom is included, the content of a fluorine atom may be 1.0x10 ³ to 1.0x10 ⁴ ppm. The contents of the iron atom, the silicon atom and the sulfur atom may be selected within the above-mentioned respective ranges, so as to generate a toner suitable for developing electrostatic charge images.

[0122] An iron atom and a silicon atom may be components derived from a flocculating agent and the like, a sulfur atom may be a component derived from a production catalyst for adhesive resins, a flocculating agent and the like, and a fluorine element may be a component derived from a production catalyst for adhesive resins and the like. Thus, the respective contents of an iron atom and a silicon atom in the epoxy group-containing toner particle can be controlled by adjusting the type and an amount of a flocculating agent used and the like, the content of a sulfur atom can be controlled by adjusting the types and amounts of a catalyst and flocculating agent used and the like, and the content of a fluorine atom can be controlled by adjusting the type and an amount of a catalyst used. [0123] The contents of the respective elements in the epoxy group- containing toner particle can be measured with, for example, x-ray fluorescence analysis. Specifically, for example, x-ray fluorescence spectrometer EDX-720 (manufactured by Shimadzu Corporation) can be used as a measurement device to perform measurement under the conditions of an x-ray tube voltage of 50 kV and a sample molding amount of 30.0 g. The content of each element can be determined by utilizing an intensity (cps/pA) from a quantitative result derived from the x-ray fluorescence measurement.

EXAMPLES AND COMPARATIVE EXAMPLES

[0124] Hereinafter, examples and comparative examples will be described, although the present disclosure is not restricted to the following examples.

[0125] Various measurement methods and evaluation methods related to the examples and comparative examples, will be described.

[0126] Measurement of weight molecular weight (Mw) of polyester resin and epoxy group-containing resin

Waters e2695 (manufactured by Nihon Waters K.K.) is used as a measurement device and Inertsil CN-3, 25 cm, dual (manufactured by GL Sciences Inc.) is used as a column. After 10 mg of the amorphous polyester resin is introduced into 10 mL of THF (stabilizer-containing, manufactured by Wako Pure Chemical Industries, Ltd.) and stirred for an hour, it is filtered with a 0.2 pm filter, and the filtrate is used as a sample. 20 pL of the THF sample solution is poured into the measurement device and subjected to the measurement under the conditions of 40°C and a flow rate of 1.0 mL/min.

[0127] Measurement of melt viscosity of polyester resin

Using a flow tester (SHIMADZU CORPORATION, “CFT-500D”), 1 g of the sample is molded at 20 MPa into a pellet, which is subjected to a load of 10 kg by a plunger at a constant temperature of 120°C to be squeezed out of a nozzle with a diameter of 1 mm and a length of 1 mm. The viscosity is calculated from a descent amount of the plunger of the flow tester relative to time.

[0128] Measurement of acid number of polyester resin

1 g of the polyester sample is weighed and introduced into a tall beaker, into which 100 cc of THF/MeOH at a ratio of 2/1 is added, and the sample is dissolved therein by stirring for 10 to 15 minutes with a stirrer. Subsequently, the 1/10N KOH MeOH titrant is placed on a potentiometric acid number measurement device (manufactured by Metrohm AG: C83-99 Metrohm 916 Ti- Touch) to perform the titration.

[0129] Measurement of Tg2nd-dH of polyester resin

Using a modulated differential scanning calorimeter named Q2000 (manufactured by TA Instruments), as a first temperature increase, the temperature was increased from room temperature to 140°C at a modulation amplitude of 0.1 °C, a modulation frequency of 10 seconds and a rate of 3°C per minute, and after the first temperature increase was finished, the temperature was decreased to 0°C at a rate of 20°C per minute. After the temperature was held at 0°C for 5 minutes, as a second temperature increase, the temperature was again increased from 0°C to 140°C at a modulation amplitude of 0.1° C, a modulation frequency of 10 seconds and a rate of 3°C per minute, and from a resultant differential scanning calorimetry curve, dH was obtained. Note that, when the crystalline polyester resin, the mold release agent and the dispersant were close in melting point, a portion obtained by subtracting endothermic energy amounts of the mold release agent and the dispersant from the total endothermic energy amount was defined as the endothermic energy amount of the crystalline polyester resin. Namely, endothermic energy amounts of the mold release agent and the dispersant were each measured and multiplied by the respective mass% by which they were included in the toner particle, and the products were subtracted from the total endothermic energy amount.

[0130] Measurement of epoxy group equivalent of epoxy group-containing resin The measurement of an epoxy group equivalent of the epoxy group- containing resin was performed in accordance with JISK7236:2001.

[0131] Measurement of the lowest fixing temperature of epoxy group- containing toner particle

Using a belt-type fixing device (manufactured by Samsung Electronics Co., Ltd., a fixing device for color laser 660 model (trade name)), an unfixed image for testing of a 100% solid pattern was fixed to test paper of 60 g paper (manufactured by Boise Inc., X-9 (trade name)) under the conditions of a fixing rate of 160 mm/sec and a fixing time of 0.08 seconds. The fixing of the unfixed image for testing was performed at each temperature at 1 °C intervals in the range of 110 ^c C to 170°C. An initial optical density of the fixed image was measured. Subsequently, 3M 810 tape was attached to the image area, over which 500 g of a weight was reciprocated 5 times, and the tape was subsequently removed. After removing the tape, an optical density was measured. The lowest temperature at which a fixability (%) determined from the following formula was 90% or more was taken as the lowest fixing temperature, taking into consideration the following relationship: fixability (%)~(initial optical density/optical density after removing tape)x100 [0132] Measurement of high-temperature offset temperature of epoxy group- containing toner particle

Using the belt-type fixing device (manufactured by Samsung Electronics Co., Ltd., color laser 660 model (trade name)), an unfixed image for testing of a 100% solid pattern was fixed to test paper of 60 g paper (manufactured by Boise Inc., X-9 (trade name)) under the conditions of a fixing rate of 160 mm/sec and a fixing time of 0.08 seconds. The fixing of the unfixed image for testing was performed at 5°C increments (e.g., at each temperature at 5°C intervals) in the range of 110°C to 180°C. The high-temperature offset was checked visually and the lowest temperature at which high-temperature offset occurred was taken as a high-temperature offset temperature.

[0133] Temperature at which storage modulus of epoxy group-containing toner particle reaches 0.1 MPa As a measurement device, a rotational plate-type rheometer named “ARES" (manufactured by TA Instruments) was used. As a measurement sample, a sample prepared by pressure-molding 0.25 g at 20 MPa for one minute using a tablet press machine was used. A storage modulus G’ when the temperature is increased from 40°C to 120°C under the conditions of a rate of temperature increase of 2°C/min, a frequency of 10 Hz and in a strain amount control mode (strain amount: 0.01 %-3%) is measured, and a change curve of G’ relative to temperature is obtained. The temperature when the storage modulus G’ reached 0.1 MPa was read.

[0134] Hereinafter, examples of the binder resin and the epoxy group- containing toner particle will be described, although the present disclosure is not limited to the following examples.

[0135] Production of polyester resin

[0136] A diol and a carboxylic acid in the respective preparation amounts shown in Table 1 and an esterification catalyst were introduced into a four-neck flask 5 L in capacity equipped with a nitrogen introducing pipe, a dehydrating pipe, a stirrer and a thermocouple, reacted under a nitrogen atmosphere at 230°C until the reaction ratio reached 90%, and subsequently reacted at 8.3 kPa until a targeted acid number was reached, thereby forming amorphous polyester resins A-1 to A-5 and a crystalline polyester resin C in Table 1.

[0137] Table 1 Production of polyester resin

BPA-2P0: propylene oxide adduct of bisphenol A (average added number 2)

BPA-2EO: ethylene oxide adduct of bisphenol A (average added number 2)

[0138] Production example of latex of pendant-type amorphous polyester resin

300 g of an amorphous polyester resin 1 , 250 g of methyl ethyl ketone and 50 g of isopropyl alcohol were introduced into a 3 L double-jacketed reactor, and the content of the reaction container was stirred by using a semi-moon type or Fullzone impeller under an environment at about 30 to 65°C to dissolve the resin. While the resin solution obtained was being stirred, 20 g of a 5% ammonia aqueous solution was gradually added into the reaction container, and subsequently, 1200 g of water was added at a rate of 20 g/min to produce an emulsion liquid. Subsequently, the mixed solvent of methyl ethyl ketone and isopropyl alcohol was removed from the emulsion liquid by distillation under reduced pressure until the concentration of the solid amorphous polyester resin 1 reached 20 mass%, to thereby obtain a resin latex.

[0139] Production example of latex of crystalline polyester resin

300 g of a crystalline polyester resin 1 , 250 g of methyl ethyl ketone and 50 g of isopropyl alcohol were introduced into a 3 L double-jacketed reaction container, and the content of the reaction container was stirred by using a semi- moon type impeller under an environment at about 30 to 65°C to dissolve the resin. While the resin solution obtained was being stirred, 25 g of a 5% ammonia aqueous solution was gradually added into the reaction container, and subsequently, 1200 g of water was added at a rate of 20 g/min to produce an emulsion liquid. Subsequently, the mixed solvent of methyl ethyl ketone and isopropyl alcohol was removed from the emulsion liquid by distillation under reduced pressure until the concentration of the solid crystalline polyester resin 1 reached 20 mass%, to thereby obtain a resin latex. Note that a commercial product having a physical property shown in Table 2 was used as the epoxy group-containing resin.

[0140] Table 2 Physical property of epoxy group-containing resin

[0141] Preparation example of dispersion liquid of colorant

A colorant, water and a surfactant are treated several times with a crusher until a targeted particle size is obtained.

[0142] Preparation example of dispersion liquid of catalyst

A selected proportion of polyester resin or the like, is mixed with the epoxy group-containing resin, to be emulsified so as to obtain a milky liquid.

[0143] Production of epoxy group-containing toner particle

500 g of deionized water, 630 g of the amorphous polyester resin latex 1 , 70 g of an amorphous polymer polyester resin latex, 143 g of the crystalline polyester resin latex, 630 g of an epoxy group-containing resin latex and 4.4 g of imidazole were introduced into a 3 L reactor, and subsequently, 60 g of the colorant dispersion liquid and 80 g of a wax dispersion liquid (Selosol P-212: manufactured by Chukyo Yushi Co., Ltd.) were added, and 70 g of a poly silicate iron (PSI-100, manufactured by SUIDO KIKO KAISHA, LTD. ) was added as a flocculating agent. A temperature of the mixed solution within the flask was increased at a rate of 1 °C/min to 45°C while stirring by using a homogenizer (T50 ULTRA-TURRAX (trade name) manufactured by IKA-Werke GmbH & Co. KG). Subsequently, the temperature of the flocculation reaction liquid was increased at a rate of 0.2°C/min to continue the flocculation reaction, to thereby obtain primary flocculated particles having a volume average particle size of 4 pm to 6 pm. Further, 210 g of the amorphous polyester resin latex 1 and 23 g of the amorphous polymer polyester resin latex for use in a shell layer were added to the reactor and flocculated for 30 minutes. Next, a 0.1 N NaOH aqueous solution was added and a pH of the mixed liquid was adjusted to 9.5. After 20 minutes passed, the mixed liquid was increased in temperature and fused for 3 hours to 5 hours, to thereby obtain secondary flocculated particles having a volume average particle size of 4 pm to 7 pm. Ice of deionized water was introduced into the flocculation reaction liquid at an adding rate of 100 ml/10sec to cool the liquid to 28°C or less, and subsequently, the particles underwent a filtration process to be separated and dried, to thereby obtain toner particles (a ratio of peak value of temperature increase/peak value of temperature decrease was 1.52 and peak temperature of temperature increase-peak temperature of temperature decrease was 8.7°C).

[0144] Table 3A Production of epoxy group-containing toner particle (unit: parts by weight)

Table 3B

[0145] Measurement of DSC profile of epoxy group-containing toner particle

10 mg±0.5 mg of a toner particle of example 1 was introduced into a sample pan, and DSC measurement was performed by increasing the temperature from 30 to 200°C at a rate of 3°C/min. An exothermic peak appears at 133°C, which suggests that the reaction of the formula (7) of the epoxy group and the carboxyl group is in progress. [0146] Molecular weight measurement of epoxy group-containing toner particle

A new peak appeared at a retention time near 4.3 minutes after the aforementioned DSC measurement when GPC measurement of the sample before and after the measurement was performed. It suggests that the reaction of the formula (7) proceeds due to heating, thereby producing a polymer. [0147] Evaluation of epoxy group-containing toner particle Table 4A

Table 4B [0148] Tables 4A and 4B show results of the measurement of low- temperature fixing temperatures and high-temperature offset temperatures of toner particles of examples 1 to 5 and comparative examples 1 to 6 shown in Tables 3A and 3B. In Tables 4A and 4B, the symbol represents a satisfactory low-temperature fixing performance and the symbol ‘X’ represents an insufficient low-temperature fixing performance. Each of the toner particle samples having a ratio of [epoxy group]/[carboxyl group] of 1.1 to 3.5, exhibited fixing at a low temperature of 133°C. In addition, these toner particle samples were found to have high-temperature offset temperatures of 163°C or more and exhibited fixing at a wide range of temperatures within a range of 30 to 45°C.

[0149] On the other hand, as to toner particles having a ratio of [epoxy group]/[carboxyl group] as low as 0.2 or 0.3 (e.g., comparative examples 1 and 2), while the lowest fixing temperature was 135°C, their high-temperature offset temperatures were 145°C and 150°C, and thus, a fixable temperature range was as narrow as 10°C or 15°C. In addition, as to the toner particles including no epoxy group-containing resin (e.g., comparative examples 3 to 6), low- temperature fixing temperatures were as high as 140°C or more.

[0150] According to the aforementioned results, by using the toner particle including the epoxy group-containing resin, a polymer is produced at the time of fixing by the reaction of the epoxy group and the carboxyl group represented by the formula (7) at approximately the lowest fixing temperature, so as to produce a suitable toner particle satisfying both the low-temperature fixability and the suppression of the high-temperature offset.

[0151] It is to be understood that not all aspects, advantages and features described herein may necessarily be achieved by, or included in, any one particular example. Indeed, having described various examples herein, it should be apparent that other examples may be modified in arrangement and detail is omitted.