Toner for developing electrostatic images

Abstract

This invention relates to a toner for electrostatic image development that produces printed materials with excellent image density. [Solution] A toner for developing electrostatic images, comprising toner particles and an external additive adhering to the surface of the toner particles, wherein the toner particles contain a binder resin comprising amorphous polyester resin A and crystalline polyester resin C, a colorant, and at least one resin B selected from amino resin, unsaturated polyester resin, and urethane resin, wherein amorphous polyester resin A is a polycondensate of an alcohol component, a carboxylic acid component, and polyethylene terephthalate, and crystalline polyester resin C is a polycondensate of an alcohol component containing ethylene glycol and a carboxylic acid component.

Description

[Technical Field]

[0001] The present invention relates to an electrostatic image developing toner used for developing latent images formed in electrophotography, electrostatic recording, electrostatic printing, and the like. [Background technology]

[0002] In the field of electrophotography, the demand for energy efficiency and higher image quality is increasing with the development of electrophotographic systems. Regarding energy conservation, toners using polyester resin as a binder are employed to fix the toner onto printing media such as paper with less energy. In recent years, toners using crystalline polyester resin in addition to amorphous polyester resin have been used to achieve even lower temperature fixing.

[0003] Patent Document 1 describes a toner containing a binder resin containing a crystalline polyester and an amorphous resin, and a phenylphosphonic acid metal salt, with the aim of providing a toner that has excellent low-temperature fixing properties, a wide fixing temperature range, durability, i.e., no sticking of the developing blade during printing, and excellent electrostatic stability during printing. Patent Document 2 describes an electrophotographic toner containing a binder resin composition for toner that has excellent low-temperature fixing properties, electrostatic rise properties, and dispersibility of colorants, a method for producing the polyester resin contained in the binder resin composition, and an electrophotographic toner containing the binder resin composition, with the aim of providing a toner binder resin composition that has excellent low-temperature fixing properties, electrostatic rise properties, and dispersibility of colorants, a method for producing the polyester resin contained in the binder resin composition, and an electrophotographic toner containing the binder resin composition. The toner binder resin composition contains a polyester resin that is a polycondensate of polyethylene terephthalate, a carboxylic acid component, and an alcohol component, wherein the polyethylene terephthalate is substantially polyethylene terephthalate with an IV value of 0.40 or more and 0.75 or less. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2010-224255 [Patent Document 2] Japanese Patent Publication No. 2017-45041 [Overview of the project] [Problems that the invention aims to solve]

[0005] Patent documents 1 and 2 describe toners that use both amorphous and crystalline polyester resins as binder resins. Using both amorphous and crystalline polyester resins enables low-temperature fixing of the toner to the printing medium. However, during storage or use, some of the toner particles tend to plasticize, causing embedding of external additives and a decrease in fluidity. As a result, the toner cannot be uniformly fixed to the printing medium, leading to a problem of reduced image density. This invention relates to a toner for electrostatic image development that can produce printed materials with excellent image density. [Means for solving the problem]

[0006] The inventors have found that the above problems can be solved by incorporating into toner particles an amorphous polyester resin having a structure derived from polyethylene terephthalate, a crystalline polyester resin having constituent units derived from ethylene glycol, a colorant, and a specific resin that does not melt even when kneaded at high temperatures during manufacturing. The present invention relates to the following [1]. [1] A toner for developing electrostatic images, comprising toner particles and an external additive adhering to the surface of the toner particles, The toner particles contain a binder resin comprising amorphous polyester resin A and crystalline polyester resin C, a colorant, and at least one resin B selected from amino resin, unsaturated polyester resin, and urethane resin. Amorphous polyester resin A is a polycondensate of an alcohol component, a carboxylic acid component, and polyethylene terephthalate. A toner for developing electrostatic images, wherein the crystalline polyester resin C is a polycondensate of an alcohol component containing ethylene glycol and a carboxylic acid component. [Effects of the Invention]

[0007] According to the present invention, a toner for electrostatic image development is provided that can produce printed materials with excellent image density. [Modes for carrying out the invention]

[0008] [Toner for developing electrostatic images] The electrostatic image developing toner of the present invention (hereinafter also simply referred to as "toner") comprises toner particles and an external additive adhering to the surface of the toner particles, wherein the toner particles contain a binder resin comprising amorphous polyester resin A and crystalline polyester resin C, a colorant, and at least one resin B selected from amino resin, unsaturated polyester resin, and urethane resin. Amorphous polyester resin A is a polycondensate of an alcohol component, a carboxylic acid component, and polyethylene terephthalate, while crystalline polyester resin C is a polycondensate of an alcohol component containing ethylene glycol and a carboxylic acid component.

[0009] The detailed mechanism by which the toner of the present invention yields printed materials with excellent image density is not yet clear, but it is thought to be as follows. The toner of the present invention contains an amorphous polyester resin A, which is a polycondensate of an alcohol component, a carboxylic acid component, and polyethylene terephthalate; a binder resin C, which is a polycondensate of an alcohol component and a carboxylic acid component containing ethylene glycol; and one or more resins B selected from amino resins, unsaturated polyester resins, and urethane resins. It is generally difficult to uniformly disperse resin B, which is relatively polar, hardened, and does not melt during kneading, in toner particles. However, it is believed that the relatively polar resin B can be well dispersed in toner particles because a relatively polar polyethylene terephthalate-derived structure is uniformly present in amorphous polyester resin A at a certain molecular weight, and furthermore, crystalline polyester resin C contains constituent units derived from ethylene glycol, which is a hydrophilic component. As a result, due to the filler effect of Resin B uniformly present throughout including the surface of the toner particles, the rigidity of the toner particles can be improved, the embedding of external additives adhering to the toner particles during storage and use is suppressed, and it is considered that a printed matter showing excellent image density can be obtained. Note that the above mechanism regarding the effects of the present invention is an estimation and is not limited thereto.

[0010] The definitions of various terms in this specification are shown below. In the specification, the carboxylic acid component of the polyester resin includes not only the compound itself, but also anhydrides that decompose during the reaction to generate carboxylic acids, and alkyl esters (alkyl groups having 1 to 3 carbon atoms) of each carboxylic acid. Whether the resin is crystalline or amorphous is determined by the crystallinity index. The crystallinity index is defined as the ratio of the softening point of the resin to the maximum peak temperature of endotherm in the measurement method described in the examples below (softening point (°C) / maximum peak temperature of endotherm (°C)). A crystalline resin is one having a crystallinity index of 0.6 or more and 1.4 or less. An amorphous resin is one in which no endothermic peak is observed, or if observed, having a crystallinity index of less than 0.6 or more than 1.4. The crystallinity index can be appropriately adjusted according to the type and ratio of the raw material monomers, and production conditions such as reaction temperature, reaction time, and cooling rate.

[0011] 〔Toner Particles〕 The toner particles contain a binder resin containing an amorphous polyester resin A and a crystalline polyester resin C, a colorant, and at least one resin B selected from an amino resin, an unsaturated polyester resin, and a urethane resin.

[0012] <Binder Resin> The binder resin contains an amorphous polyester resin A and a crystalline polyester resin C from the viewpoint of improving the image density of the printed matter. The binder resin preferably contains an amorphous polyester resin a which is a polycondensate of an alcohol component and a carboxylic acid component from the viewpoint of further improving the image density of the printed matter. Hereinafter, the amorphous polyester resin A may be referred to as "resin A", the amorphous polyester resin a may be referred to as "resin a", and the crystalline polyester resin C may be referred to as "resin C".

[0013] (Amorphous polyester resin A) The toner particles contain an amorphous polyester resin A (hereinafter, may also be referred to as "resin A") which is a polycondensate of an alcohol component, a carboxylic acid component, and polyethylene terephthalate (hereinafter, may also be referred to as "PET") from the viewpoint of improving the image density of the printed matter. PET, or ethylene glycol and terephthalic acid generated by partial depolymerization thereof, are used as raw materials and subjected to a polycondensation reaction and incorporated into the polyester resin. By the transesterification reaction and the polycondensation reaction, a part of PET is incorporated into the polyester resin. PET is a polycondensate of ethylene glycol and terephthalic acid, and is converted with 1 mol of the ethylene glycol - terephthalic acid unit (Mw: 192). Therefore, the number of moles of PET = the number of moles of ethylene glycol units = the number of moles of terephthalic acid units.

[0014] Examples of the alcohol component include alkylene oxide adducts of aromatic diols, aliphatic diols, alicyclic diols, and polyhydric alcohols having a valence of 3 or more. Among these, alkylene oxide adducts of aromatic diols are preferable from the viewpoint of improving the image density of the printed matter. Examples of the alkylene oxide adduct of the aromatic diol include formula (I): [Chemical formula] An example of an alkylene oxide adduct of bisphenol A is given by the formula (wherein OR and RO are oxyalkylene groups, R is independently an ethylene or propylene group, x and y represent the average number of moles of alkylene oxide added, each being a positive number, and the sum of x and y is 1 or more, preferably 1.5 or more, 16 or less, preferably 8 or less, and more preferably 4 or less). Examples of alkylene oxide adducts of bisphenol A represented by formula (I) include propylene oxide adducts of 2,2-bis(4-hydroxyphenyl)propane and ethylene oxide adducts of 2,2-bis(4-hydroxyphenyl)propane. The content of the bisphenol A alkylene oxide adduct in the alcohol component is preferably 85 mol% or more, more preferably 90 mol% or more, even more preferably 95 mol% or more, and 100 mol% or less, preferably 100 mol%. The content of the bisphenol A alkylene oxide adduct in the alcohol component is equivalent to the amount of constituent units derived from the bisphenol A alkylene oxide adduct in the constituent units derived from the alcohol component of resin A. The same applies to the content of each subsequent component.

[0015] The aliphatic diol has two or more carbon atoms, preferably 16 or fewer, more preferably 12 or fewer, even more preferably 8 or fewer, and still more preferably 4 or fewer. Examples of aliphatic diols include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, neopentyl glycol (2,2-dimethyl-1,3-propanediol), 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, and 1,12-dodecanediol.

[0016] Examples of alicyclic diols include hydrogenated bisphenol A [2,2-bis(4-hydroxycyclohexyl)propane] and alkylene oxide adducts of hydrogenated bisphenol A with 2 to 4 carbon atoms (average number of added moles: 2 to 12). Examples of polyhydric alcohols with a valency of 3 or higher include glycerin, pentaerythritol, trimethylolpropane, and sorbitol.

[0017] Examples of carboxylic acid components include dicarboxylic acids and polycarboxylic acids with a valency of three or more.

[0018] Examples of dicarboxylic acids include aliphatic dicarboxylic acids, aromatic dicarboxylic acids, and alicyclic dicarboxylic acids. Among these, aliphatic dicarboxylic acids are preferred.

[0019] The number of carbon atoms in the aliphatic dicarboxylic acid is preferably 2 or more, more preferably 3 or more, and preferably 30 or less, more preferably 20 or less. Examples of aliphatic dicarboxylic acids include oxalic acid, malonic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, succinic acid, adipic acid, sebacic acid, dodecanediic acid, azelaic acid, and succinic acid substituted with an aliphatic hydrocarbon group having 1 to 20 carbon atoms. Among these, succinic acid substituted with an aliphatic hydrocarbon group having 1 to 20 carbon atoms is preferred from the viewpoint of improving the image density of printed materials. For example, specific examples of succinic acid substituted with an aliphatic hydrocarbon group having 1 to 20 carbon atoms include dodecyl succinic acid, dodecenyl succinic acid, and octenyl succinic acid, with dodecenyl succinic acid being preferred. When the carboxylic acid component includes an aliphatic dicarboxylic acid, the content of the aliphatic dicarboxylic acid in the carboxylic acid component is preferably 25 mol% or more, more preferably 30 mol% or more, even more preferably 35 mol% or more, and preferably 55 mol% or less, more preferably 50 mol% or less, and even more preferably 45 mol% or less.

[0020] Examples of aromatic dicarboxylic acids include phthalic acid, isophthalic acid, and terephthalic acid. Among these, terephthalic acid is preferred. When the carboxylic acid component includes an aromatic dicarboxylic acid, the content of the aromatic dicarboxylic acid in the carboxylic acid component is preferably 50 mol% or more, more preferably 55 mol% or more, even more preferably 60 mol% or more, and preferably 80 mol% or less, more preferably 75 mol% or less, and even more preferably 70 mol% or less.

[0021] Examples of alicyclic dicarboxylic acids include cyclohexanedicarboxylic acid.

[0022] Preferably, the polycarboxylic acid with a valency of 3 or higher is a trivalent carboxylic acid, such as trimellitic acid. The content of trivalent or higher polycarboxylic acids in the carboxylic acid component is preferably 10 mol% or more, more preferably 30 mol% or more, even more preferably 50 mol% or more, and 100 mol% or less, preferably 85 mol% or less, and even more preferably 70 mol% or less.

[0023] PET can be either new PET (virgin PET) or recycled PET. Recycled PET refers to material obtained by collecting used PET, washing it as needed, separating it from other materials, crushing it, depolymerizing the crushed material to monomer units, and then resynthesizing it using these monomers as raw materials.

[0024] In the present invention, it is preferable that the PET has a relatively low IV value, i.e., a low molecular weight, compared to conventionally used PET. By introducing low IV value (low molecular weight) PET into the polyester resin, the depolymerization of PET proceeds more uniformly. The IV value of PET can be adjusted by the polycondensation time, the charging ratio of raw material monomers, etc.

[0025] From the viewpoint of the above, the IV value of PET is preferably 0.40 or higher, more preferably 0.45 or higher, even more preferably 0.50 or higher, and even more preferably 0.55 or higher. Furthermore, from the viewpoint of low-temperature fixability and uniformity of depolymerization, it is preferably 0.85 or lower, more preferably 0.75 or lower, and even more preferably 0.70 or lower.

[0026] The IV value can be measured, for example, by dissolving the sample at a concentration of 0.4 g / dL in a phenol / tetrachloroethane = 60 / 40 (mass ratio) mixed solvent, measuring it with an Ubbelohde viscometer, and calculating it according to the following formula.

number

[0027] Commercially available PET products with an IV value between 0.40 and 0.85 include RAMAPET L1 (manufactured by Indorama Ventures, IV value: 0.60), RAMAPET BF3067 (manufactured by Indorama Ventures, IV value: 0.65), RAMAPET N2G (manufactured by Indorama Ventures, IV value: 0.75), TRN-NTJ (manufactured by Teijin Limited, IV value: 0.53), TRN-RTJC (manufactured by Teijin Limited, IV value: 0.64), RAMAPET S1 (manufactured by Indorama Ventures, IV value: 0.84), and UK-31 (manufactured by Utsumi Recycling Systems Co., Ltd., IV value: 0.67).

[0028] The equivalent ratio [COOH group / OH group] of the carboxyl group of the carboxylic acid component to the hydroxyl group of the alcohol component is preferably 0.7 or higher, more preferably 0.8 or higher, and preferably 1.2 or lower, more preferably 1.1 or lower.

[0029] Furthermore, the "molar equivalent ratio (COOH group / OH group)" shall be calculated assuming that the alcohol component contains the same mole of ethylene glycol as the constituent units derived from ethylene glycol in the PET, and the carboxylic acid component contains the same mole of terephthalic acid as the constituent units derived from terephthalic acid in the PET.

[0030] The PET content is preferably 10 mol% or more, more preferably 25 mol% or more, even more preferably 40 mol% or more, and preferably 80 mol% or less, more preferably 65 mol% or less, and even more preferably 50 mol% or less, out of 100 mol% of the total amount of alcohol component, carboxylic acid component, and PET that are raw materials of resin A, from the viewpoint of improving the image density of the printed material.

[0031] From the viewpoint of improving the image density of printed materials, the content of PET-derived structures in resin A is preferably 5% by mass or more, more preferably 15% by mass or more, even more preferably 30% by mass or more, and preferably 55% by mass or less, more preferably 50% by mass or less, and even more preferably 45% by mass or less.

[0032] ≪Method for producing amorphous polyester resin A≫ Resin A is manufactured by polycondensation of an alcohol component, a carboxylic acid component, and polyethylene terephthalate. In this reaction, if necessary, an esterification catalyst such as tin(II) di(2-ethylhexanoate), dibutyltin oxide, or titanium diisopropylate bistriethanolamine may be used in an amount of 0.01 parts by mass to 5 parts by mass per 100 parts by mass of the total amount of raw materials for resin A; and an esterification co-catalyst such as gallic acid (same as 3,4,5-trihydroxybenzoic acid) may be used in an amount of 0.001 parts by mass to 0.5 parts by mass per 100 parts by mass of the total amount of raw materials for resin A. Furthermore, when using monomers having unsaturated bonds, such as fumaric acid, in polycondensation, a radical polymerization inhibitor may be used, preferably in an amount of 0.001 parts by mass or more and 0.5 parts by mass or less, per 100 parts by mass of the total amount of raw materials for resin A, as needed. An example of a radical polymerization inhibitor is 4-tert-butylcatechol. The reaction temperature is preferably 120°C or higher, more preferably 150°C or higher, even more preferably 170°C or higher, and preferably 250°C or lower, more preferably 240°C or lower. The reaction may also be carried out in an inert gas atmosphere.

[0033] ≪Physical properties of amorphous polyester resin A≫ The softening point of resin A is preferably 100°C or higher, more preferably 110°C or higher, and even more preferably 125°C or higher, from the viewpoint of heat-resistant storage of the toner, and preferably 160°C or lower, more preferably 150°C or lower, and even more preferably 140°C or lower, from the viewpoint of low-temperature fixing properties.

[0034] The glass transition temperature of resin A is preferably 45°C or higher, more preferably 50°C or higher, and even more preferably 55°C or higher, from the viewpoint of heat-resistant storage of the toner, and preferably 80°C or lower, more preferably 75°C or lower, and even more preferably 70°C or lower, from the viewpoint of low-temperature fixing properties.

[0035] The acid value of resin A is preferably 5 mg KOH / g or more, more preferably 10 mg KOH / g or more, even more preferably 15 mg KOH / g or more, and preferably 40 mg KOH / g or less, more preferably 35 mg KOH / g or less, and even more preferably 30 mg KOH / g or less, from the viewpoint of improving the image density of printed materials.

[0036] The weight-average molecular weight of resin A is preferably 5,000,000 or more, more preferably 10,000,000 or more, even more preferably 15,000,000 or more, and preferably 100,000,000 or less, more preferably 50,000,000 or less, and even more preferably 25,000,000 or less, from the viewpoint of improving the image density of printed materials.

[0037] The softening point, glass transition temperature, acid value, and weight-average molecular weight of resin A can be appropriately adjusted depending on the type and amount of raw material monomer used, as well as manufacturing conditions such as reaction temperature, reaction time, and cooling rate, and can be determined by the method described in the examples. Furthermore, when using two or more types of resin A in combination, it is preferable that the softening point, glass transition temperature, acid value, and weight-average molecular weight obtained from the mixture are all within the aforementioned ranges.

[0038] (Amorphous polyester resin a) Amorphous polyester resin a is a polycondensate of an alcohol component and a carboxylic acid component, and can be produced in the same manner as resin A, for example, using the alcohol component and carboxylic acid component of resin A described above.

[0039] ≪Physical properties of amorphous polyester resin a≫ The softening point of resin a is preferably 75°C or higher, more preferably 80°C or higher, even more preferably 85°C or higher, and preferably 105°C or lower, more preferably 100°C or lower, and even more preferably 95°C or lower, from the viewpoint of improving the image density of the printed material.

[0040] The glass transition temperature of resin a is preferably 35°C or higher, more preferably 40°C or higher, even more preferably 45°C or higher, and preferably 65°C or lower, more preferably 60°C or lower, and even more preferably 55°C or lower, from the viewpoint of improving the image density of the printed material.

[0041] The acid value of resin a is preferably 0.5 mg KOH / g or more, more preferably 1 mg KOH / g or more, and more preferably 7 mg KOH / g or less, more preferably 5 mg KOH / g or less, and even more preferably 3 mg KOH / g or less.

[0042] The weight-average molecular weight of resin a is preferably 1,000 or more, more preferably 2,000 or more, even more preferably 3,000 or more, and preferably 15,000 or less, more preferably 10,000 or less, and even more preferably 5,000 or less.

[0043] The softening point, glass transition temperature, acid value, and weight-average molecular weight of resin a can be appropriately adjusted depending on the type and amount of raw material monomer used, as well as manufacturing conditions such as reaction temperature, reaction time, and cooling rate, and can be determined by the method described in the examples. Furthermore, when using two or more types of resin a in combination, it is preferable that the softening point, glass transition temperature, acid value, and weight-average molecular weight obtained from the mixture thereof are all within the aforementioned ranges.

[0044] (Crystalline polyester resin C) Crystalline polyester resin C is a polycondensate of an alcohol component containing ethylene glycol and a carboxylic acid component. The amount of ethylene glycol in the alcohol component is preferably 80 mol% or more, more preferably 85 mol% or more, even more preferably 90 mol% or more, even more preferably 95 mol% or more, and 100 mol% or less, and preferably 100 mol%.

[0045] The alcohol component may contain alcohol components other than ethylene glycol. Examples of alcohol components other than ethylene glycol include aliphatic diols with 3 or more carbon atoms, aromatic diols, and trivalent or higher alcohols. The upper limit of the number of carbon atoms in an aliphatic diol with 3 or more carbon atoms is preferably 12 or less. Examples of aliphatic diols having three or more carbon atoms include 1,3-propanediol, 1,2-propanediol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, and 1,12-dodecanediol. Examples of aromatic diols include alkylene oxide adducts of bisphenol A. Examples of alcohols with a hydride of 3 or higher include glycerin, pentaerythritol, and trimethylolpropane.

[0046] As the carboxylic acid component, aliphatic dicarboxylic acids are preferred, and linear aliphatic dicarboxylic acids are more preferred. The number of carbon atoms in the aliphatic dicarboxylic acid is preferably 4 or more, more preferably 8 or more, even more preferably 10 or more, and preferably 14 or less, more preferably 12 or less. Examples of aliphatic dicarboxylic acids include fumaric acid, sebacic acid, dodecanediic acid, and tetradecanediic acid. Among these, sebacic acid is preferred.

[0047] The amount of aliphatic dicarboxylic acid in the carboxylic acid component is preferably 80 mol% or more, more preferably 85 mol% or more, even more preferably 90 mol% or more, even more preferably 95 mol% or more, and 100 mol% or less, preferably 100 mol%.

[0048] The carboxylic acid component may contain other carboxylic acid components other than aliphatic dicarboxylic acids. Examples of other carboxylic acid components include aromatic dicarboxylic acids such as terephthalic acid and isophthalic acid; and polycarboxylic acids with a valency of three or more.

[0049] The equivalent ratio [COOH group / OH group] of the carboxyl group of the carboxylic acid component to the hydroxyl group of the alcohol component is preferably 0.7 or higher, more preferably 0.8 or higher, even more preferably 0.9 or higher, and preferably 1.3 or lower, more preferably 1.2 or lower, and even more preferably 1.1 or lower.

[0050] A method for manufacturing resin C can be, for example, the same method as described above for resin A.

[0051] ≪Physical properties of crystalline polyester resin C≫ The softening point of resin C is preferably 60°C or higher, more preferably 70°C or higher, and even more preferably 80°C or higher, from the viewpoint of heat-resistant storage of the toner, and preferably 130°C or lower, more preferably 110°C or lower, and even more preferably 95°C or lower, from the viewpoint of further improving low-temperature fixation.

[0052] The melting point of resin C is preferably 50°C or higher, more preferably 60°C or higher, and even more preferably 70°C or higher, from the viewpoint of heat-resistant storage of the toner, and preferably 105°C or lower, more preferably 95°C or lower, and even more preferably 85°C or lower, from the viewpoint of further improving low-temperature fixing performance.

[0053] The acid value of resin C is preferably 5 mg KOH / g or more, more preferably 10 mg KOH / g or more, and more preferably 35 mg KOH / g or less, more preferably 25 mg KOH / g or less, and even more preferably 20 mg KOH / g or less.

[0054] The weight-average molecular weight of resin C is preferably 5,000 or more, more preferably 10,000 or more, even more preferably 15,000 or more, and preferably 60,000 or less, more preferably 40,000 or less, and even more preferably 20,000 or less.

[0055] The softening point, melting point, acid value, and weight-average molecular weight of resin C can be appropriately adjusted depending on the type and amount of raw material monomer used, as well as manufacturing conditions such as reaction temperature, reaction time, and cooling rate, and can be determined by the method described in the examples. Furthermore, when using two or more types of resin C in combination, it is preferable that the softening point, melting point, acid value, and weight-average molecular weight of the resulting mixture are all within the aforementioned ranges.

[0056] (Binding resin content) From the viewpoint of improving the image density of printed materials, the content of the binder resin in the toner particles is preferably 80% by mass or more, more preferably 85% by mass or more, even more preferably 90% by mass or more, and preferably 99% by mass or less, more preferably 97% by mass or less, and even more preferably 95% by mass or less.

[0057] From the viewpoint of improving the image density of the printed material, the content of resin A in the binder resin is preferably 55% by mass or more, more preferably 60% by mass or more, even more preferably 65% ​​by mass or more, and preferably 85% by mass or less, more preferably 80% by mass or less, and even more preferably 75% by mass or less.

[0058] (Content of PET-derived structures) In the amorphous polyester resin A used as the binder resin, the content of the polyethylene terephthalate-derived structure calculated by the following formula (1) is preferably 3% by mass or more, more preferably 5% by mass or more, even more preferably 10% by mass or more, even more preferably 15% by mass or more, even more preferably 20% by mass or more, and preferably 45% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less. The amount of polyethylene terephthalate-derived structure in the amorphous polyester resin A of the binder resin contained in the toner particles = Amount of amorphous polyester resin A in the binder resin contained in the toner particles (mass%) × {Mass of polyethylene terephthalate-derived structure in amorphous polyester resin A / (Mass of amorphous polyester resin A)} (1)

[0059] When the binder resin contains resin a, the content of resin a in the binder resin is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 15% by mass or more, and preferably 40% by mass or less, more preferably 35% by mass or less, and even more preferably 25% by mass or less, from the viewpoint of improving the image density of the printed material.

[0060] When the binder resin contains resin a, the mass ratio of resin a to resin A in the binder resin [resin a / resin A] is preferably 5 / 95 or more, more preferably 10 / 90 or more, even more preferably 15 / 85 or more, and preferably 35 / 65 or less, more preferably 30 / 70 or less, and even more preferably 25 / 75 or less, from the viewpoint of improving the image density of the printed material.

[0061] From the viewpoint of low-temperature fixation properties, the content of resin C in the binder resin is preferably 1% by mass or more, more preferably 4% by mass or more, even more preferably 7% by mass or more, and preferably 25% by mass or less, more preferably 20% by mass or less, and even more preferably 15% by mass or less.

[0062] When toner particles contain resin a, the mass ratio of resin C to the total of resin A and resin a in the toner particles [resin C / total of resin A and resin a] is preferably 3 / 97 or more, more preferably 5 / 95 or more, even more preferably 7 / 93 or more, and preferably 25 / 75 or less, more preferably 20 / 80 or less, and even more preferably 15 / 85 or less.

[0063] When toner particles contain resin a, the mass ratio of resin A, resin a, and resin C in the toner particles (resin S / resin C / resin A) is preferably 55-85 / 5-35 / 1-25, more preferably 60-80 / 10-30 / 3-20, and even more preferably 65-75 / 15-25 / 5-15.

[0064] <Resin B> Resin B is at least one selected from amino resin, unsaturated polyester resin, and urethane resin, from the viewpoint of improving the image density of printed materials, with amino resin being preferred. Resin B is a curing resin, and when the toner of the present invention is manufactured by a melt-kneading method, the binder resin melts, but resin B does not.

[0065] (Amino resin) The amino resin is preferably at least one selected from urea resin, melamine resin, aniline resin, and guanamine resin, and more preferably melamine resin. The amino resin is a thermosetting amino resin that is cured by heating a thermosetting amino resin, and when the toner of the present invention is manufactured by a melt-kneading method, it does not melt.

[0066] (Unsaturated polyester resin) The unsaturated polyester resin is a thermosetting resin obtained by heating and curing a polyester, which is produced by the condensation reaction of an unsaturated polycarboxylic acid such as maleic anhydride or fumaric acid with a glycol, dissolved in styrene or methyl methacrylate. When the toner of the present invention is manufactured by a melt-kneading method, the unsaturated polyester resin does not melt. Furthermore, the polyester may contain constituent units derived from saturated polycarboxylic acids, such as constituent units derived from terephthalic acid or isophthalic acid, for the purpose of adjusting its physical properties.

[0067] (urethane resin) The urethane resin is a thermosetting urethane resin that has been heated and cured, and when the toner of the present invention is manufactured by the melt-kneading method, it does not melt.

[0068] Resin B is preferably in the form of particles. The shape of the resin B particles is not particularly limited and may be spherical, ellipsoidal, or polygonal prism-shaped. The resin B particles may also have an irregular shape. The average particle size of resin B particles is preferably 0.05 μm or more, more preferably 0.07 μm or more, and preferably 3.5 μm or less, more preferably 2.5 μm or less, even more preferably 1.5 μm or less, even more preferably 1.0 μm or less, and even more preferably 0.6 μm or less, from the viewpoint of improving the image density of printed materials. The average particle size of resin B particles is determined by the method described in the examples.

[0069] (Content) In toner particles, the content of resin B (preferably amino resin) per 100 parts by mass of binder resin is preferably 0.5 parts by mass or more, more preferably 0.7 parts by mass or more, preferably 3 parts by mass or less, more preferably 2 parts by mass or less, and even more preferably 1.5 parts by mass or less, from the viewpoint of improving the image density of printed materials.

[0070] <Coloring agent> As a coloring agent, all dyes, pigments, etc. used as coloring agents for toners can be used. Examples of colorants include carbon black, phthalocyanine blue, permanent brown FG, brilliant first scarlet, pigment green B, rhodamine-B base, solvent red 49, solvent red 146, solvent blue 35, quinacridone, carmine 6B, disazo yellow, and pigment red 269. The toner may be either black toner or a color toner other than black. The colorant content in the toner particles is preferably 0.5% by mass or more, more preferably 1% by mass or more, and even more preferably 2% by mass or more, from the viewpoint of improving the image density of the printed material, and preferably 15% by mass or less, more preferably 10% by mass or less, and even more preferably 8% by mass or less, from the viewpoint of print quality and economic efficiency.

[0071] In addition to the resin and colorant mentioned above, the toner particles preferably contain a release agent. Furthermore, the toner particles may also contain additives such as charge control agents, magnetic powders, flowability enhancers, conductivity modifiers, reinforcing fillers such as fibrous materials, antioxidants, anti-aging agents, and cleaning properties enhancers.

[0072] <Release agent> Examples of release agents include hydrocarbon waxes or oxides thereof such as polypropylene wax, polyethylene wax, ethylene propylene copolymer wax, microcrystalline wax, paraffin wax, and Fischer-Tropsch wax; ester waxes such as carnauba wax, montane wax or their deoxidizing waxes, and fatty acid ester waxes; and fatty acid amides, fatty acids, higher alcohols, and fatty acid metal salts.

[0073] The melting point of the release agent is preferably 60°C or higher, more preferably 70°C or higher, and more preferably 160°C or lower, more preferably 140°C or lower, and even more preferably 120°C or lower.

[0074] The release agent content in the toner particles is preferably 0.5% by mass or more, more preferably 1% by mass or more, and preferably 8% by mass or less, more preferably 4% by mass or less.

[0075] <Physical properties of toner particles> Volume-intermediate particle size D of toner particles 50 From the viewpoint of obtaining printed materials with good image quality and further improving the cleaning performance of the toner, the thickness is preferably 2 μm or more, more preferably 4 μm or more, even more preferably 6 μm or more, and preferably 15 μm or less, more preferably 12 μm or less, and even more preferably 10 μm or less.

[0076] Volume-intermediate particle size D of toner particles 50 This can be measured by the method described in the examples.

[0077] [Method for manufacturing toner for electrostatic image development] The method for producing electrostatic image developing toner of the present invention (hereinafter also referred to as "toner production method") may be any known method such as melt kneading, emulsion phase inversion, suspension polymerization, or emulsion agglomeration, but the melt kneading method is preferred.

[0078] <Melting and mixing method> In the melt-kneading method, for example, resin A, resin C, colorant, resin B, and optionally resin a, release agent, charge control agent, and other additives are pre-mixed in a mixer such as a Henschel mixer, and then melt-kneaded in a closed-type kneader, a single-screw or twin-screw extruder, or an open-roll type kneader. Subsequently, toner particles can be obtained by cooling, grinding, and classifying the mixture.

[0079] [External additives] Toner is formed when an external additive adheres to the surface of toner particles. Examples of external additives include fine particles of inorganic materials such as hydrophobic silica, titanium dioxide, alumina, cerium oxide, and carbon black, as well as polymer fine particles such as polycarbonate, polymethyl methacrylate, and silicone resin. Among these, hydrophobic silica is preferred. External additives may be used individually or in combination of two or more. In addition, two or more types of hydrophobic silica with different particle sizes may be used. When surface treatment of toner particles is performed using an external additive, the amount of external additive added is preferably 0.2 parts by mass or more, more preferably 0.5 parts by mass or more, and preferably 3 parts by mass or less, more preferably 2 parts by mass or less, and even more preferably 1.5 parts by mass or less, per 100 parts by mass of toner particles.

[0080] Toner is used in electrophotographic printing for electrostatic image development. Toner can be used, for example, as a one-component developer, or mixed with a carrier to form a two-component developer. [Examples]

[0081] The present invention will be specifically described below with reference to examples, but the present invention is not limited in any way by these examples. Each physical property was measured and evaluated by the following method. In notations such as "alkylene oxide (X)," the number X in parentheses represents the average number of moles of alkylene oxide added.

[0082] [Measurement method] [Softening point, crystallinity index, melting point, and glass transition temperature of resins] (1) Softening point Using a flow tester "CFT-500EX" (manufactured by Shimadzu Corporation), 1 g of sample was heated at a heating rate of 6°C / min while a load of 1.96 MPa was applied by a plunger, and the sample was extruded from a nozzle with a diameter of 1 mm and a length of 1 mm. The amount of plunger descent of the flow tester was plotted against temperature, and the temperature at which half of the sample flowed out was defined as the softening point. (2) Crystallinity index Using a differential scanning calorimeter "Q-20" (manufactured by T.A. Instruments Japan Co., Ltd.), 0.01 to 0.02 g of the sample was weighed into an aluminum pan and cooled to 0°C at a cooling rate of 10°C / min. The sample was then left to stand still for 1 minute, and then heated to 180°C at a heating rate of 10°C / min, and the amount of heat was measured. Among the observed endothermic peaks, the temperature of the peak with the largest peak area was defined as the maximum endothermic peak temperature (1), and the crystallinity index was determined by (softening point (°C)) / (maximum endothermic peak temperature (1) (°C)). (3) Melting point and glass transition temperature Using a differential scanning calorimeter "Q-20" (manufactured by T.A. Instruments Japan Co., Ltd.), 0.01 to 0.02 g of the sample was weighed into an aluminum pan and heated from room temperature (20°C) to 200°C at a heating rate of 10°C / min, and then cooled to 0°C at a cooling rate of 10°C / min. Next, the sample was heated to 180°C at a heating rate of 10°C / min, and the endothermic peak was measured. Among the observed endothermic peaks, the temperature of the peak with the largest peak area was defined as the maximum endothermic peak temperature (2), and in the case of crystalline resins, this peak temperature was defined as the melting point. Furthermore, in the case of amorphous resins, if a peak was observed, the temperature of that peak was defined as the glass transition temperature. If no peak was observed but a step was observed, the temperature at the intersection of the tangent line showing the maximum slope of the curve in the step portion and the extension of the baseline on the low-temperature side of the step was defined as the glass transition temperature.

[0083] [Acid value of resin] The acid value of the resin was measured according to the neutral titration method described in JIS K 0070:1992. However, for the amorphous resin, the measurement solvent was changed from the mixed solvent of ethanol and ether specified in JIS K 0070:1992 to a mixed solvent of acetone and toluene (acetone:toluene = 1:1 (volume ratio)), and for the crystalline resin, it was changed to tetrahydrofuran.

[0084] [Weight-average molecular weight of resin] The molecular weight distribution was measured by gel permeation chromatography (GPC) method obtained by the following method, and the weight-average molecular weight of the resin was determined. (1) Preparation of sample solution The sample was dissolved in tetrahydrofuran for the amorphous resin and chloroform for the crystalline resin at 25 °C so that the concentration became 0.5 g / 100 mL. Then, this solution was filtered using a fluororesin filter "DISMIC-25JP" (manufactured by ADVANTEC) with a pore size of 0.2 μm for the amorphous resin and a fluororesin filter "FP-200" (manufactured by Sumitomo Electric Industries, Ltd.) with a pore size of 2 μm for the crystalline resin to remove insoluble components, and used as a sample solution. (2) Molecular weight measurement Using the following measuring device and analytical column, tetrahydrofuran was used as the eluent for the amorphous resin and chloroform for the crystalline resin, and flowed at a flow rate of 1 mL per minute to stabilize the column in a thermostat at 40 °C. Then, 100 μL of the sample solution was injected for measurement. The molecular weight of the sample was calculated based on a calibration curve prepared in advance. The calibration curve at this time included several types of monodisperse polystyrene "A-500" (5.0×10 2 ), "A-1000" (1.01×10 3 ), "A-2500" (2.63×10 3 ), "A-5000" (5.97×10 3 ), "F-1" (1.02×10 4 ), "F-2" (1.81×10 4 ), "F-4" (3.97×10 4), "F-10" (9.64×10 4 ), "F-20" (1.90×10 5 ), "F-40" (4.27×10 5 ), "F-80" (7.06×10 5 ), "F-128" (1.09×10 6 The following samples were prepared using the following product (manufactured by Tosoh Corporation) as a standard sample. The values ​​in parentheses indicate the molecular weight. Measuring device: "HLC-8420CPC" (manufactured by Tosoh Corporation) (for amorphous resins) or "HLC-8320CPC" (manufactured by Tosoh Corporation) (for crystalline resins) Analysis columns: "GMHXL" + "G3000HXL" (manufactured by Tosoh Corporation)

[0085] [Melting point of release agent] Using a differential scanning calorimeter "Q-20" (manufactured by T.A. Instruments Japan Co., Ltd.), 0.01 to 0.02 g of the sample was weighed into an aluminum pan, heated to 200°C at a heating rate of 10°C / min, and then cooled from 200°C to -10°C at a cooling rate of 5°C / min. Next, the sample was heated to 180°C at a heating rate of 10°C / min. The maximum endothermic peak temperature observed from the melting endothermic curve was defined as the melting point of the release agent.

[0086] [Average particle size of resin B particles and external additive] Using a field emission scanning electron microscope (FE-SEM) (Hitachi High-Tech Corporation, "S-4800"), the particle size (average value of the major and minor axes of the particles) of 500 particles was measured, and the number-average value of the particle sizes was used as the average particle size.

[0087] [Toner particle volume medium particle size D] 50 ] Volume-intermediate particle size D of toner particles 50 The following measurements were taken: • Measuring instrument: "Coulter Multisizer (registered trademark) III" (manufactured by Beckman Coulter, Inc.) • Aperture diameter: 50 μm • Analysis software: "Multisizer (registered trademark) III version 3.51" (manufactured by Beckman Coulter, Inc.) • Electrolyte: "Isoton (registered trademark) II" (manufactured by Beckman Coulter, Inc.) • Dispersion: Dissolve polyoxyethylene lauryl ether "Emulgen® 109P" (manufactured by Kao Corporation, HLB (Hydrophile-Lipophile Balance) = 13.6) in the electrolyte and adjust to a concentration of 5% by mass. • Dispersion conditions: 10 mg of the measurement sample of dried toner particles was added to 5 mL of the dispersion, and dispersed for 1 minute using an ultrasonic disperser (US-1, manufactured by SND Corporation, output 80W). Then, 25 mL of the electrolyte was added, and dispersed for another minute using the ultrasonic disperser to prepare the sample dispersion. • Measurement conditions: The sample dispersion was added to 100 mL of the electrolyte to adjust the concentration to one that could measure the particle size of 30,000 particles in 20 seconds. Then, the 30,000 particles were measured, and the volume median particle size D of the toner particles was determined from the particle size distribution. 50 They sought it.

[0088] [Resin manufacturing] [Manufacturing of amorphous polyester resin] Manufacturing Example A1 (Manufacturing of Amorphous Polyester Resin A-1) Of the polyester resin raw materials shown in Table 1, all raw materials except succinic anhydride (DDSA-C) and trimellitic anhydride substituted with branched C12 alkenyl groups, an esterification catalyst, and an esterification co-catalyst were placed in a 10-liter four-necked flask equipped with a thermometer, stainless steel stirring rod, dehydration tube, condenser, and nitrogen inlet tube, and heated to 235°C over 2 hours in a mantle heater under a nitrogen atmosphere. After confirming that the reaction rate reached 95% or more at 235°C, the mixture was cooled to 180°C. Then, DDSA-C and trimellitic anhydride were added, and the mixture was heated to 210°C over 2 hours. After reacting at 210°C for 1 hour, the reaction was carried out under reduced pressure of 40 kPa until the softening point shown in Table 1 was reached, yielding amorphous polyester resin A-1. The physical properties are shown in Table 1. The reaction rate is calculated from the formula: "100 × amount of water produced (moles) / theoretical amount of water produced (moles)". The theoretical amount of water produced (in moles) is the smaller of the following two values: "the sum of the values ​​obtained by calculating (amount in charge (in moles) × number of hydroxyl groups per molecule) for each alcohol component" and "the sum of the values ​​obtained by calculating (amount in charge (in moles) × number of carboxyl groups per molecule) for each carboxylic acid component." PET is not considered because its molecular weight is sufficiently large, and the amount of water produced from PET during the reaction is negligible. The number of carboxyl groups in carboxylic acid anhydrides, such as trimellitic anhydride, is considered to be 1 in the anhydride portion.

[0089] Manufacturing Example A2 (Manufacturing of Amorphous Polyester Resin A-2) Of the polyester resin raw materials shown in Table 1, all raw materials except trimellitic anhydride, the esterification catalyst, and the esterification co-catalyst were placed in a 10-liter four-necked flask equipped with a thermometer, stainless steel stirring rod, dehydration tube, condenser, and nitrogen inlet tube. The mixture was heated to 235°C over 2 hours in a mantle heater under a nitrogen atmosphere. After confirming that the reaction rate reached over 95% at 235°C, the mixture was cooled to 180°C. Then, trimellitic anhydride was added, and the mixture was heated to 210°C over 2 hours. After reacting at 210°C for 1 hour, the reaction was carried out under reduced pressure of 40 kPa until the softening point shown in Table 1 was reached, yielding amorphous polyester resin A-2. The physical properties are shown in Table 1.

[0090] Manufacturing Example A3 (Manufacturing of Amorphous Polyester Resin A-3) Amorphous polyester resin A-3 was obtained in the same manner as in manufacturing example A2, except that the raw material composition was changed as shown in Table 1. The physical properties are shown in Table 1.

[0091] Manufacturing example a4 (Manufacturing of amorphous polyester resin a-4) The raw materials for the polyester resin, the esterification catalyst, and the esterification co-catalyst shown in Table 1 were placed in a 10-liter four-necked flask equipped with a thermometer, stainless steel stirring rod, dehydration tube, condenser, and nitrogen inlet tube. The mixture was heated to 235°C over 2 hours in a mantle heater under a nitrogen atmosphere. After reacting at 235°C for 8 hours, the reaction was carried out under reduced pressure of 40 kPa until the softening point shown in Table 1 was reached, yielding amorphous polyester resin a-4. The physical properties are shown in Table 1.

[0092] Manufacturing Example A'5 (Manufacturing of Amorphous Polyester Resin A'-5) Of the polyester resin raw materials shown in Table 1, all raw materials except trimellitic anhydride, the esterification catalyst, and the esterification co-catalyst were placed in a 10-liter four-necked flask equipped with a thermometer, stainless steel stirring rod, fractionation column, dehydration tube, condenser, and nitrogen inlet tube. The mixture was heated in a mantle heater under a nitrogen atmosphere at 180°C for 1 hour, and then the temperature was raised from 180°C to 230°C over 8 hours. After confirming that the reaction rate reached 95% or more at 230°C, the mixture was cooled to 180°C, trimellitic anhydride was added, and the temperature was raised to 210°C over 2 hours. After reacting at 210°C for 1 hour, the reaction was carried out under reduced pressure of 40 kPa until the softening point shown in Table 1 was reached, yielding amorphous polyester resin A'-5. The physical properties are shown in Table 1.

[0093] [Table 1]

[0094] <Manufacturing of crystalline polyester resin> Manufacturing Example C1 (Manufacturing of Crystalline Polyester Resin C-1) The raw material monomers for the polyester resin shown in Table 2 were placed in a 10-liter four-necked flask equipped with a thermometer, stainless steel stirring rod, dehydration tube, condenser, and nitrogen inlet tube. The mixture was heated in a mantle heater under a nitrogen atmosphere from 130°C to 200°C over 8 hours, then reacted at 200°C for 2 hours. After adding the esterification catalyst, the reaction was carried out under reduced pressure of 8 kPa until the acid value shown in Table 2 was reached, yielding crystalline polyester resin C-1. The physical properties are shown in Table 2.

[0095] Manufacturing Example C'2 (Manufacturing of Crystalline Polyester Resin C'-2) Crystalline polyester resin C'-2 was obtained in the same manner as in manufacturing example C1, except that the raw material composition was changed as shown in Table 2. The physical properties are shown in Table 2.

[0096] [Table 2]

[0097] [Toner manufacturing] Example 1 (Manufacturing of toner particles 1 and toner 1) 100 parts by mass of the binder resin shown in Table 3 (70 parts by mass of amorphous polyester resin A-1, 20 parts by mass of amorphous polyester resin a-4, and 10 parts by mass of crystalline polyester resin C-1), 1 part by mass of the negative charge control agent "Bontron E-81" (manufactured by Orient Chemical Industry Co., Ltd.), 5 parts by mass of the coloring agent "Pigment blue 15:3" (manufactured by Dainichi Seika Kogyo Co., Ltd., phthalocyanine blue), 2 parts by mass of the release agent "HNP-9" (manufactured by Nippon Seiro Co., Ltd., paraffin wax, melting point: 80℃), and 1 part by mass of resin B particles shown in Table 3 were thoroughly mixed in a Henschel mixer. Then, the mixture was melt-kneaded using a co-rotating twin-screw extruder with a total length of 1560 mm, a screw diameter of 42 mm, and a barrel inner diameter of 43 mm, at a roll rotation speed of 200 r / min and a heating temperature in the rolls of 100℃. The feed rate of the mixture was 20 kg / h, and the average residence time was approximately 18 seconds. The resulting molten mixture was cooled and coarsely ground, then ground in a jet mill and classified to obtain the medium volume particle size D. 50 This yielded toner particles 1 with a diameter of 8 μm. To 100 parts by mass of the obtained toner particles 1, 1 part by mass of hydrophobic silica (AEROSIL NAX50 (manufactured by Nippon Aerosil Co., Ltd., hydrophobic treatment agent: hexamethyldisilazane (HMDS), average particle size: approximately 30 nm)) was added to a 10-liter Henschel mixer (manufactured by Nippon Coke Industries Co., Ltd.) equipped with a stirring blade, and stirred at 3000 r / min for 2 minutes to obtain toner 1. The image density of the obtained toner 1 was evaluated using the following evaluation method. The results are shown in Table 3.

[0098] [Evaluation Method] [Image density] Using high-quality paper "J Paper A4 size" (manufactured by Fujifilm Business Innovation Co., Ltd.) and a commercially available printer "HL-2040" (manufactured by Brother Industries, Ltd.), the amount of toner adhering to the paper was measured at 0.42-0.48 mg / cm². 2 A solid image was output, and a printed copy was obtained. Next, the fuser temperature was set to 130°C, and the toner was fixed at a rate of 1.5 seconds per sheet in the A4 portrait direction to obtain the printed material. The reflected image density of the fixed image portion of the printed output was measured using a SpectroEye colorimeter (GretagMacbeth, light emission conditions: standard light source D50, observation field of view 2°, density reference DINNB, absolute white reference). A higher reflected image density value indicates better image density. The results are shown in Table 3.

[0099] Examples 2-7, Examples 1, 2, 3, 5 (Manufacturing of toner particles 2-7, c1, c2, c3, c5, toner 2-7, c1, c2, c3, c5) Except for using the binder resin and resin B particles as shown in Table 3, toner particles 2-7, c1, c2, c3, and c5 were obtained in the same manner as in Example 1. The resin B particles or resin B' particles were used as shown in Table 3. The evaluation results for toner particles 2-7, c1, c2, c3, and c5 are shown in Table 3.

[0100] Comparative Example 4 (Toner Particle C4, Manufacturing of Toner C4) Toner particles c4 were obtained in the same manner as in Comparative Example 1. To 100 parts by mass of the obtained toner particles c4, 1 part by mass of hydrophobic silica (AEROSIL NAX50 (manufactured by Nippon Aerosil Co., Ltd., hydrophobic treatment agent: HMDS, average particle size: approximately 30 nm)) and 1 part by mass of melamine-formaldehyde resin "Epostor SS" (manufactured by Nippon Shokubai Co., Ltd., average particle size: approximately 100 nm) were added to a 10-liter Henschel mixer (manufactured by Nippon Coke Industries Co., Ltd.) equipped with a stirring blade, and stirred at 3000 r / min for 2 minutes to obtain toner c4. The evaluation results of toner c4 are shown in Table 3.

[0101] [Table 3]

[0102] Compared to toners that do not contain resin B in the toner particles (Comparative Examples 1 and 5), toners that do not contain resin B in the toner particles but use resin B as an external additive (Comparative Example 4), toners manufactured using amorphous polyester resin that does not have a PET-derived structure (Comparative Example 2), and toners manufactured using crystalline polyester resin that does not have ethylene glycol-derived constituent units (Comparative Example 3), the toners of the Examples show superior image density (Examples 1 to 7).

Claims

1. A toner for developing electrostatic images, comprising toner particles and an external additive adhering to the surface of the toner particles, The toner particles contain a binder resin comprising amorphous polyester resin A and crystalline polyester resin C, a colorant, and at least one resin B selected from amino resin, unsaturated polyester resin, and urethane resin. Amorphous polyester resin A is a polycondensate of an alcohol component, a carboxylic acid component, and polyethylene terephthalate. A toner for developing electrostatic images, wherein the crystalline polyester resin C is a polycondensate of an alcohol component containing ethylene glycol and a carboxylic acid component.

2. The electrostatic image developing toner according to claim 1, wherein, in a total of 100 mol% of the alcohol component, carboxylic acid component, and polyethylene terephthalate that are raw materials of amorphous polyester resin A, the content of polyethylene terephthalate is 10 mol% or more and 80 mol% or less, with ethylene glycol-terephthalic acid units considered as 1 mole.

3. The electrostatic image developing toner according to claim 1 or 2, wherein resin B consists of particles with an average particle size of 0.05 μm or more and 3.5 μm or less.

4. The electrostatic image developing toner according to claim 1 or 2, wherein the content of resin B in the toner particles is 0.5 parts by mass or more and 3 parts by mass or less per 100 parts by mass of binder resin.

5. The electrostatic image developing toner according to claim 1 or 2, wherein resin B is an amino resin.

6. The electrostatic image developing toner according to claim 1 or 2, wherein the amorphous polyester resin A of the binder resin contained in the toner particles contains a polyethylene terephthalate-derived structure calculated by the following formula (1) to be 3% by mass or more and 40% by mass or less. The amount of polyethylene terephthalate-derived structure in the amorphous polyester resin A of the binder resin contained in the toner particles = The amount of amorphous polyester resin A contained in the binder resin contained in the toner particles (mass %) × {Mass of polyethylene terephthalate-derived structure in amorphous polyester resin A / Mass of amorphous polyester resin A} (1)

7. The electrostatic image developing toner according to claim 1 or 2, wherein the amino resin is a melamine resin.

8. The electrostatic image developing toner according to claim 1 or 2, wherein the amorphous polyester resin A contains constituent units derived from succinic acid substituted with aliphatic hydrocarbon groups having 1 to 20 carbon atoms.

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