Manufacturing method of toner for electrostatic charge image development

Abstract

To provide a manufacturing method of a toner for electrostatic charge image development, which can suppress the generation of fogging.SOLUTION: A manufacturing method of a toner for electrostatic charge image development includes the following steps 1 to 3 in this order: a step 1 of aggregating resin particles containing an amorphous polyester resin A in an aqueous medium so as to acquire an aggregated particle 1; a step 2 of aggregating resin particles which contain an amorphous polyester resin B and a styrene resin with an acid value of 60 mgKOH / g or more relative to the acquired aggregated particle 1, so as to acquire an aggregated particle 2; and a step 3 of fusing the acquired aggregated particle 2 so as to acquire a fused particle.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing a toner for developing electrostatic images, which is used for developing latent images formed in electrophotography, electrostatic recording, electrostatic printing, and the like. [Background technology]

[0002] In the field of electrophotography, with the advancement of electrophotographic systems, there is a demand for the development of electrophotographic toners that can meet the demands for higher image quality and higher speeds.In order to meet the demands for higher image quality, so-called chemical toners are produced by an aggregation and fusion method (emulsion aggregation method, aggregation and coalescence method) in which fine resin particles or the like are aggregated and fused in an aqueous medium to obtain a toner, in order to obtain a toner that has a narrow particle size distribution, a small particle size, and a fixing property that can meet the demands for higher speeds.

[0003] Patent Document 1 describes a method for producing a toner containing at least a polyester resin and a colorant, with the aim of providing a method for producing a toner that is excellent in image quality, has a sufficient low-temperature fixability and offset resistance, i.e., has a sufficient fixable temperature range, is obtainable by a simple operation, and is advantageous in terms of cost, and is characterized by comprising: (A) a step of dissolving a polyester resin and an ultra-high molecular weight styrene-based resin, the molecular weight distribution of which has a peak in the range of more than 500,000 and less than 3,000,000, in an organic solvent to prepare a binder resin solution; (B) a step of dispersing the binder resin solution in an aqueous medium as binder resin solution droplets; (C) a step of removing the organic solvent from the binder resin solution droplets to prepare a resin particle dispersion; and (D) a step of forming toner particles by aggregating the resin particles from which the organic solvent has been removed and colorant particles containing the colorant. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-42930 Summary of the Invention [Problem to be solved by the invention]

[0005] When forming a core-shell structure of toner particles by emulsion aggregation, it is known to improve the dispersion stability of shell resin particles in water by preparing an aqueous dispersion of shell resin particles using a surfactant to prevent aggregation of shell resin particles, as in the technology described in Patent Document 1. However, if the surfactant remains, particularly on the surface of the toner particles, it can cause problems such as reduced charging ability and fogging. The present invention relates to a method for producing a toner for developing electrostatic images, which can suppress the occurrence of fogging. [Means for solving the problem]

[0006] The present inventors have found that a toner for developing electrostatic images produced by a method (emulsion aggregation method) for producing a toner for developing electrostatic images, which includes a step of aggregating aggregate particles 1 containing an amorphous polyester resin that forms a core, and amorphous polyester resin particles for a shell, which are obtained by using styrene-based resin particles having an acid value of 60 mgKOH / g or more as a dispersant, to obtain aggregate particles 2 having a core-shell structure, can suppress the occurrence of fogging. The present invention relates to the following [1]. [1] A method for producing a toner for developing electrostatic images, comprising the following steps 1 to 3 in this order: Step 1: A step of aggregating resin particles containing an amorphous polyester resin A in an aqueous medium to obtain aggregated particles 1 Step 2: A step of aggregating resin particles containing amorphous polyester resin B and a styrene-based resin having an acid value of 60 mgKOH / g or more to the obtained aggregated particles 1 to obtain aggregated particles 2. Step 3: A step of fusing the obtained aggregated particles 2 to obtain fused particles [Effects of the Invention]

[0007] According to the present invention, there is provided a method for producing a toner for developing electrostatic images, which can suppress the occurrence of fogging. DETAILED DESCRIPTION OF THE INVENTION

[0008] [Method of manufacturing electrostatic image developing toner] The method for producing the toner for developing electrostatic images of the present invention includes the following steps 1 to 3 in this order. Step 1: A step of aggregating resin particles containing an amorphous polyester resin A in an aqueous medium to obtain aggregated particles 1 Step 2: A step of aggregating resin particles containing amorphous polyester resin B and a styrene-based resin having an acid value of 60 mgKOH / g or more to the obtained aggregated particles 1 to obtain aggregated particles 2. Step 3: A step of fusing the obtained aggregated particles 2 to obtain fused particles

[0009] Hereinafter, "toner for developing electrostatic images" may be simply referred to as "toner," and "method for producing toner for developing electrostatic images" may be simply referred to as "method for producing toner."

[0010] Although the detailed mechanism by which the toner production method of the present invention can produce a toner capable of suppressing the occurrence of fog is not clear, it is believed to be as follows. In preparing an aqueous dispersion of amorphous polyester resin particles for shell use, a styrene-based resin with an acid value of 60 mgKOH / g or more is used instead of a surfactant. The styrene-derived structural units interact with the amorphous polyester resin, causing the styrene-based resin to adsorb to the surface of the amorphous polyester resin particles for shell use. Furthermore, the high acid value of the styrene-based resin enhances the charge repulsion of the amorphous polyester resin particles for shell use in water, improving the dispersion stability of the amorphous polyester resin particles for shell use in an aqueous medium, similar to when a surfactant is used. Therefore, in the toner manufacturing method of the present invention, toner particles having a shell layer with a uniform thickness can be obtained using amorphous polyester resin particles for shell use prepared without using a surfactant, which is thought to stabilize the chargeability of the toner and suppress the occurrence of fog. Furthermore, it is believed that the toner particles have a shell layer of uniform thickness, which reduces the surface exposure of the release agent from the core portion, and thus makes it possible to obtain a toner with excellent durability. The above-mentioned mechanism regarding the effects of the present invention is only a supposition, and the present invention is not limited to this.

[0011] The definitions of various terms used 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 produce carboxylic acids, and alkyl esters of each carboxylic acid (alkyl groups having 1 to 3 carbon atoms). Whether a resin is crystalline or amorphous is determined by its crystallinity index. The crystallinity index is defined as the ratio of the softening point of the resin to the endothermic maximum peak temperature (softening point (°C) / endothermic maximum peak temperature (°C)) measured by the method described in the Examples below. A crystalline resin is one with 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 an endothermic peak is observed, one with a crystallinity index of less than 0.6 or more than 1.4. The crystallinity index can be adjusted appropriately by adjusting the types and ratios of raw material monomers, as well as production conditions such as reaction temperature, reaction time, and cooling rate. "(Meth)acrylic acid" means at least one selected from acrylic acid and methacrylic acid. "Styrenic compound" means unsubstituted or substituted styrene. The components used in the method for producing the toner of the present invention may each be used alone or in combination of two or more.

[0012] The method for producing the toner of the present invention includes the following steps 1 to 3 in this order. [Process 1] In step 1, resin particles containing an amorphous polyester resin A are aggregated in an aqueous medium to obtain aggregated particles 1. In step 1, it is preferable to aggregate resin particles containing amorphous polyester resin A and crystalline polyester resin C in the same or different particles to obtain aggregated particles 1. In step 1, it is also preferable to further aggregate at least one of a colorant and a release agent in addition to the resin particles, and it is more preferable to mix an aqueous dispersion of resin particles with an aqueous dispersion of colorant particles and / or an aqueous dispersion of release agent particles to aggregate these particles. Hereinafter, the "aqueous dispersion of resin particles," "aqueous dispersion of colorant particles," and "aqueous dispersion of release agent particles" may also be referred to as "resin particle dispersion," "colorant particle dispersion," and "release agent particle dispersion," respectively.

[0013] In the present invention, the aqueous medium is a medium containing water as a main component, and the water content in the aqueous medium is preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more, and 100% by mass or less. The water is preferably deionized water or distilled water. Examples of components other than water that can constitute the aqueous medium together with water include water-soluble organic solvents such as alkyl alcohols having 1 to 5 carbon atoms; dialkyl ketones having 3 to 5 carbon atoms, such as acetone and methyl ethyl ketone; and cyclic ethers, such as tetrahydrofuran.

[0014] -Amorphous polyester resin A- The amorphous polyester resin A (hereinafter sometimes simply referred to as "resin A") is, for example, a condensate of an alcohol component and a carboxylic acid component, and a condensate of an alcohol component, a carboxylic acid component and polyethylene terephthalate. Resin A may be a modified polyester resin. Examples of modified polyester resins include urethane-modified polyester resins, epoxy-modified polyester resins, and composite resins containing polyester resin segments and addition-polymerized resin segments.

[0015] Examples of the alcohol component include alkylene oxide adducts of aromatic diols, aliphatic diols, alicyclic diols, and trihydric or higher polyhydric alcohols. Among these, alkylene oxide adducts of aromatic diols and aliphatic diols are preferred from the viewpoint of obtaining a toner that can further suppress the occurrence of fogging. Examples of alkylene oxide adducts of aromatic diols include those represented by formula (I): [ka] (wherein OR and RO are oxyalkylene groups, each R is independently an ethylene or propylene group, x and y are positive numbers indicating the average number of moles of alkylene oxide added, and the sum of x and y is 1 or more, preferably 1.5 or more, and 16 or less, preferably 8 or less, and more preferably 4 or less). Examples of the alkylene oxide adduct of bisphenol A represented by formula (I) include a propylene oxide adduct of 2,2-bis(4-hydroxyphenyl)propane, an ethylene oxide adduct of 2,2-bis(4-hydroxyphenyl)propane, etc. Among these, it is preferable to contain at least a propylene oxide adduct of bisphenol A. When an alkylene oxide adduct of bisphenol A is used as the alcohol component, the amount thereof in the alcohol component is preferably 5 mol% or more, more preferably 10 mol% or more, even more preferably 15 mol% or more, and 100 mol% or less, preferably 80 mol% or less, more preferably 60 mol% or less, even more preferably 40 mol% or less, and even more preferably 30 mol% or less. The amount of alkylene oxide adduct of bisphenol A in the alcohol component is synonymous with the amount of structural units derived from alkylene oxide adduct of bisphenol A in the structural units derived from the alcohol component of resin A. The same applies to the amounts of each of the following components.

[0016] The aliphatic diol preferably has 2 or more carbon atoms and preferably 16 or less, more preferably 12 or less, even more preferably 8 or less, and still more preferably 4 or less. 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, with ethylene glycol and 1,2-propanediol being preferred. When an aliphatic diol is used as the alcohol component, the amount thereof in the alcohol component is preferably 50 mol% or more, more preferably 60 mol% or more, even more preferably 70 mol% or more, and 100 mol% or less, preferably 95 mol% or less, more preferably 90 mol% or less, even more preferably 85 mol% or less.

[0017] Examples of alicyclic diols include hydrogenated bisphenol A [2,2-bis(4-hydroxycyclohexyl)propane] and adducts of hydrogenated bisphenol A with alkylene oxides having 2 to 4 carbon atoms (average number of added moles: 2 to 12). Examples of trihydric or higher polyhydric alcohols include glycerin, pentaerythritol, trimethylolpropane, and sorbitol. These alcohol components may be used alone or in combination of two or more.

[0018] Examples of the carboxylic acid component include dicarboxylic acids and trivalent or higher polycarboxylic acids.

[0019] Examples of dicarboxylic acids include aromatic dicarboxylic acids, aliphatic dicarboxylic acids, and alicyclic dicarboxylic acids. Among these, aromatic dicarboxylic acids are preferred.

[0020] Examples of aromatic dicarboxylic acids include phthalic acid, isophthalic acid, and terephthalic acid. Of these, isophthalic acid and terephthalic acid are preferred. The amount of aromatic dicarboxylic acid in the carboxylic acid component is preferably 60 mol % or more, more preferably 70 mol % or more, and even more preferably 80 mol % or more, and is 100 mol % or less, preferably 95 mol % or less.

[0021] The aliphatic dicarboxylic acid preferably has 2 or more carbon atoms, more preferably 3 or more carbon atoms, and preferably has 30 or less carbon atoms, more preferably 20 or less carbon atoms. 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, dodecanedioic acid, azelaic acid, and succinic acids substituted with an aliphatic hydrocarbon group having from 1 to 20 carbon atoms. Examples of succinic acids substituted with an aliphatic hydrocarbon group having from 1 to 20 carbon atoms include dodecylsuccinic acid, dodecenylsuccinic acid, and octenylsuccinic acid. The amount of the aliphatic dicarboxylic acid in the carboxylic acid component is preferably 2 mol% or more, more preferably 4 mol% or more, even more preferably 6 mol% or more, and is preferably 25 mol% or less, more preferably 20 mol% or less, even more preferably 15 mol% or less.

[0022] An example of the alicyclic dicarboxylic acid is cyclohexanedicarboxylic acid.

[0023] The trivalent or higher polyvalent carboxylic acid is preferably a trivalent carboxylic acid, such as trimellitic acid. The trivalent or higher polycarboxylic acid is preferably 1 mol % or more, more preferably 2 mol % or more, and preferably 20 mol % or less, more preferably 15 mol % or less, and even more preferably 10 mol % or less, of the carboxylic acid component. One or more carboxylic acid components may be used.

[0024] From the viewpoint of obtaining a toner that can further suppress the occurrence of fogging, resin A is preferably a resin obtained by polycondensing a polycondensable monomer containing an alcohol component and a carboxylic acid component with polyethylene terephthalate (PET). PET, or ethylene glycol and terephthalic acid produced by depolymerization of a portion thereof, are used as raw material monomers in a polycondensation reaction and incorporated into the polyester resin. PET is an equimolar polycondensate of ethylene glycol and terephthalic acid, and in this specification, the ethylene glycol-derived structural units and terephthalic acid-derived structural units derived from PET are converted into structural units derived from the alcohol component and structural units derived from the carboxylic acid component, respectively.

[0025] The PET may be new PET (virgin PET) or recycled PET. Recycled PET is made by collecting used PET, washing it as necessary, separating it from other materials, and then crushing it. The crushed material is then depolymerized to break it down into monomer units, which are then used as raw materials for resynthesis.

[0026] In the present invention, the PET preferably has a relatively low IV value, i.e., a low molecular weight, compared to conventionally used PET. By introducing a low IV value (low molecular weight) PET into the polyester resin, depolymerization of the PET proceeds more uniformly.

[0027] From the above viewpoints, the IV value of PET is preferably 0.40 or more, more preferably 0.45 or more, even more preferably 0.50 or more, and even more preferably 0.55 or more. From the viewpoints of low-temperature fixability and uniform depolymerization, it is preferably 0.85 or less, more preferably 0.75 or less, and even more preferably 0.70 or less. The IV value is an intrinsic viscosity and serves as an index of molecular weight. The IV value of PET can be adjusted by the polycondensation time, etc.

[0028] The IV value can be measured, for example, by dissolving a sample in a mixed solvent of phenol / tetrachloroethane = 60 / 40 (mass ratio) at a concentration of 0.4 g / dL, measuring with an Ubbelohde viscometer, and calculating according to the following formula.

number

[0029] Commercially available PET products with an IV value of 0.40 or more and 0.85 or less 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 Recycle Systems Co., Ltd., IV value: 0.67), with UK-31 being preferred.

[0030] The equivalent ratio of the carboxyl groups of the carboxylic acid component to the hydroxyl groups of the alcohol component [COOH groups / OH groups] is preferably 0.7 or more, more preferably 0.8 or more, and is preferably 1.3 or less, more preferably 1.2 or less. When PET is used, the "molar equivalent ratio (COOH group / OH group)" is calculated assuming that the alcohol component contains the same mole of ethylene glycol as the ethylene glycol-derived structural unit derived from PET, and that the carboxylic acid component contains the same mole of terephthalic acid as the terephthalic acid-derived structural unit derived from PET.

[0031] When PET is used, the content of PET is preferably 30 mol% or more, more preferably 40 mol% or more, even more preferably 50 mol% or more, and is preferably 80 mol% or less, more preferably 75 mol% or less, even more preferably 70 mol% or less, from the viewpoint of obtaining a toner that can further suppress the occurrence of fogging, based on a total amount of 100 mol% of the alcohol component, carboxylic acid component, and PET that are raw materials for Resin A. Since PET is a polycondensation product of ethylene glycol, terephthalic acid, dimethyl terephthalate, etc., the terephthalic acid-ethylene glycol unit (Mw: 192) is considered to be 1 mol. Therefore, moles of PET = moles of ethylene glycol = moles of terephthalic acid.

[0032] -Method for producing amorphous polyester resin A- Resin A is produced by polycondensing an alcohol component, a carboxylic acid component, and, if necessary, 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 to 5 parts by mass per 100 parts by mass of the total amount of the raw materials for Resin A; or an esterification promoter such as gallic acid (equivalent to 3,4,5-trihydroxybenzoic acid) may be used in an amount of 0.001 to 0.5 parts by mass per 100 parts by mass of the total amount of the raw materials for Resin A. Furthermore, when a monomer having an unsaturated bond such as fumaric acid is used in polycondensation, a radical polymerization inhibitor may be used, if necessary, in an amount of preferably 0.001 to 0.5 parts by mass per 100 parts by mass of the total amount of the raw materials for Resin A. An example of the 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 is preferably 250°C or lower, more preferably 240°C or lower. The reaction may be carried out in an inert gas atmosphere.

[0033] -Physical properties of amorphous polyester resin A- The softening point of Resin A is preferably 70°C or higher, more preferably 80°C or higher, and even more preferably 90°C or higher from the viewpoint of heat-resistant storage stability of the toner, and is preferably 130°C or lower, more preferably 120°C or lower, and even more preferably 110°C or lower from the viewpoint of low-temperature fixability. The glass transition temperature of Resin A is preferably 30°C or higher, more preferably 35°C or higher, and even more preferably 40°C or higher from the viewpoint of heat-resistant storage stability of the toner, and is preferably 80°C or lower, more preferably 70°C or lower, and even more preferably 65°C or lower from the viewpoint of low-temperature fixability.

[0034] The acid value of Resin A is preferably 5 mgKOH / g or more, more preferably 10 mgKOH / g or more, even more preferably 15 mgKOH / g or more, and preferably 40 mgKOH / g or less, more preferably 35 mgKOH / g or less, even more preferably 30 mgKOH / g or less.

[0035] The softening point, glass transition temperature, and acid value of Resin A can be appropriately adjusted by the types and amounts of raw material monomers used, as well as production conditions such as reaction temperature, reaction time, and cooling rate, and are determined by the methods described in the Examples. When two or more types of Resin A are used in combination, it is preferable that the softening point, glass transition temperature, and acid value of the mixture thereof each fall within the above-mentioned ranges.

[0036] From the viewpoint of obtaining a toner having excellent durability, the content of resin A in the toner particles is preferably 55% by mass or more, more preferably 65% ​​by mass or more, even more preferably 75% by mass or more, and is preferably 98% by mass or less, more preferably 95% by mass or less, even more preferably 90% by mass or less.

[0037] -Crystalline polyester resin C- The crystalline polyester resin C (hereinafter sometimes simply referred to as "resin C") is a polycondensate of an alcohol component and a carboxylic acid component. The alcohol component is preferably an α,ω-aliphatic diol. The α,ω-aliphatic diol preferably has 2 or more carbon atoms, and preferably 16 or less, more preferably 12 or less, and even more preferably 8 or less. Examples of α,ω-aliphatic diols include 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, and 1,14-tetradecanediol. Among these, ethylene glycol, 1,6-hexanediol, 1,10-decanediol, and 1,12-dodecanediol are preferred, ethylene glycol and 1,6-hexanediol are more preferred, and 1,6-hexanediol is even more preferred.

[0038] The amount of the α,ω-aliphatic diol in the alcohol component is preferably 80 mol% or more, more preferably 85 mol% or more, even more preferably 90 mol% or more, still more preferably 95 mol% or more, and is 100 mol% or less, preferably 100 mol%.

[0039] The alcohol component may contain an alcohol component other than the α,ω-aliphatic diol. Examples of the other alcohol component include aliphatic diols other than α,ω-aliphatic diols, such as 1,2-propanediol and neopentyl glycol; alkylene oxide adducts of aromatic diols, such as alkylene oxide adducts of bisphenol A; and trihydric or higher alcohols, such as glycerin, pentaerythritol, and trimethylolpropane. These alcohol components may be used alone or in combination.

[0040] The carboxylic acid component is preferably an aliphatic dicarboxylic acid, more preferably a straight-chain aliphatic dicarboxylic acid. The aliphatic dicarboxylic acid preferably has 4 or more carbon atoms, more preferably 8 or more carbon atoms, and even more preferably 10 or more carbon atoms, and preferably 14 or less carbon atoms. Examples of aliphatic dicarboxylic acids include fumaric acid, sebacic acid, dodecanedioic acid, and tetradecanedioic acid. Among these, sebacic acid, dodecanedioic acid, and tetradecanedioic acid are preferred, sebacic acid and tetradecanedioic acid are more preferred, and sebacic acid is even more preferred. These carboxylic acid components may be used alone or in combination.

[0041] The amount of the aliphatic dicarboxylic acid in the carboxylic acid component is preferably 70 mol % or more, more preferably 80 mol % or more, even more preferably 85 mol % or more, and is 100 mol % or less, preferably 100 mol %.

[0042] The carboxylic acid component may contain other carboxylic acid components different from the aliphatic dicarboxylic acid. Examples of other carboxylic acid components include monocarboxylic acids such as palmitic acid and stearic acid; aromatic dicarboxylic acids such as terephthalic acid and isophthalic acid; and trivalent or higher polycarboxylic acids. These carboxylic acid components may be used alone or in combination.

[0043] The equivalent ratio of the carboxyl groups of the carboxylic acid component to the hydroxyl groups of the alcohol component [COOH groups / OH groups] is preferably 0.7 or more, more preferably 0.8 or more, and is preferably 1.3 or less, more preferably 1.2 or less.

[0044] Resin C can be produced, for example, by polycondensing raw material monomers containing an alcohol component and a carboxylic acid component in the same manner as for Resin A.

[0045] -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, and from the viewpoint of low-temperature fixability, is preferably 140°C or lower, more preferably 120°C or lower, and even more preferably 100°C or lower. The melting point of Resin C is preferably 55°C or higher, more preferably 60°C or higher, and even more preferably 65°C or higher, and from the viewpoint of low-temperature fixability, is preferably 100°C or lower, more preferably 90°C or lower, and even more preferably 85°C or lower.

[0046] The acid value of Resin C is preferably 5 mgKOH / g or more, more preferably 10 mgKOH / g or more, and preferably 35 mgKOH / g or less, more preferably 25 mgKOH / g or less, and even more preferably 20 mgKOH / g or less. The softening point, melting point, and acid value of Resin C can be appropriately adjusted by the type and amount of raw material monomers used, as well as production conditions such as reaction temperature, reaction time, and cooling rate, and are determined by the method described in the Examples below. When two or more types of Resin C are used in combination, it is preferable that the softening point, melting point, and acid value obtained as a mixture thereof each fall within the above-mentioned ranges.

[0047] When resin C is used in step 1, the content of resin C in the toner particles is preferably 1% by mass or more, more preferably 3% by mass or more, even more preferably 5% by mass or more, from the viewpoint of low-temperature fixability of the toner, and is preferably 20% by mass or less, more preferably 15% by mass or less, even more preferably 10% by mass or less.

[0048] When resin C is used in step 1, the mass ratio of resin C to resin A in the resin particles [resin C / resin A] is preferably 5 / 95 or more, more preferably 10 / 90 or more, and is preferably 40 / 60 or less, more preferably 30 / 70 or less, and even more preferably 20 / 80 or less, from the viewpoint of low-temperature fixability of the toner.

[0049] <Water-based dispersion of resin particles> The dispersion of resin particles in an aqueous medium can be carried out using a known method, but is preferably carried out by a phase inversion emulsification method. Examples of the phase inversion emulsification method include a method in which an aqueous medium is added to an organic solvent solution of a resin or a molten resin to effect phase inversion emulsification. Among these, a method in which an aqueous medium is added to an organic solvent solution of a resin to effect phase inversion emulsification is preferred. The organic solvent used for phase inversion emulsification is not particularly limited as long as it dissolves the resin and is water-soluble, and examples thereof include methyl ethyl ketone. A neutralizing agent may be added to the organic solvent solution. Examples of the neutralizing agent include basic substances. Examples of the basic substance include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide; and nitrogen-containing basic substances such as ammonia, trimethylamine, and diethanolamine. Among these, alkali metal hydroxides such as sodium hydroxide and potassium hydroxide are preferred. The degree of neutralization of the resin constituting the resin particles is preferably 40 mol% or more, more preferably 45 mol% or more, even more preferably 50 mol% or more, even more preferably 55 mol% or more, and preferably 75 mol% or less, more preferably 70 mol% or less, even more preferably 65 mol% or less. The degree of neutralization of the resin constituting the resin particles can be determined by the following formula. Degree of neutralization (mol %)=[{weight (g) of neutralizing agent added / equivalent weight of neutralizing agent} / [{weighted average acid value (mg KOH / g) of resin constituting resin particles × weight (g) of resin constituting resin particles} / (56 × 1000)]] × 100

[0050] Phase inversion emulsification is carried out by gradually adding an aqueous medium to a solution of a resin in an organic solvent or a molten resin while stirring the solution to cause phase inversion. From the viewpoint of improving the dispersion stability of the resin particles, the temperature of the organic solvent solution when the aqueous medium is added is preferably equal to or higher than the glass transition temperature of Resin A, for example, 60°C or higher, preferably 65°C or higher, and is preferably equal to or lower than 100°C, more preferably equal to or lower than 90°C, and even more preferably equal to or lower than 85°C.

[0051] After the phase inversion emulsification, the organic solvent may be removed from the resulting dispersion by distillation or the like, if necessary. Alternatively, the resin particles may be isolated by filtration or the like. It is preferable to use a resin particle dispersion obtained by removing the organic solvent from the dispersion obtained after the phase inversion emulsification. In this case, the amount of the remaining organic solvent in the dispersion is preferably 1% by mass or less, more preferably 0.5% by mass or less, and even more preferably substantially 0% by mass.

[0052] Resin particle volume median diameter D 50 is preferably 0.08 μm or more, more preferably 0.12 μm or more, and is preferably 1 μm or less, more preferably 0.5 μm or less, and even more preferably 0.3 μm or less. From the viewpoint of improving the dispersibility of the resin particles in the toner particles, the CV value of the resin particles is preferably 10% or more, more preferably 15% or more, even more preferably 20% or more, and is preferably 45% or less, more preferably 40% or less, even more preferably 35% or less. Resin particle volume median diameter D 50 The CV value is measured by the method described in the Examples.

[0053] From the viewpoint of improving the productivity of the toner and the dispersion stability of the resin particles, the solid content concentration of the resin particle dispersion X is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 15% by mass or more, and is preferably 35% by mass or less, more preferably 30% by mass or less, even more preferably 25% by mass or less. The solid content is the total amount of non-volatile components.

[0054] -Coloring agent- The colorant is preferably contained in the aggregated particles 1 by mixing it with resin particles as colorant particles and aggregating them. As the colorant, any dye, pigment, etc. that is used as a colorant for toner can be used. Examples of colorants include carbon black, phthalocyanine blue, permanent brown FG, brilliant fast 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.

[0055] <Colorant particle dispersion> The colorant particles are preferably obtained as an aqueous dispersion of colorant particles by dispersing a colorant and an aqueous medium using a disperser such as a homogenizer, an ultrasonic disperser, etc. From the viewpoint of improving the dispersion stability of the colorant, the dispersion is preferably carried out in the presence of a surfactant or an addition polymer (hereinafter, the addition polymer used to disperse the colorant is also referred to as "addition polymer E"). Examples of the surfactant include a nonionic surfactant, an anionic surfactant, and a cationic surfactant. The addition polymer E preferably has a constituent unit derived from an addition polymerizable monomer a having an aromatic group, and preferably further contains at least one selected from the group consisting of an addition polymerizable monomer b having an ionic group, an addition polymerizable monomer c having a polyalkylene oxide group, and a macromonomer d. For details of a colorant particle dispersion using the addition polymer E, see JP 2021-026129 A.

[0056] From the viewpoint of image density of printed matter, the content of the colorant in the colorant particle dispersion is preferably 2% by mass or more, more preferably 5% by mass or more, even more preferably 10% by mass or more, and is preferably 40% by mass or less, more preferably 30% by mass or less, even more preferably 20% by mass or less. The solid content of the colorant particle dispersion is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more, and is preferably 40% by mass or less, and more preferably 30% by mass or less.

[0057] Volume median particle size D of colorant particles 50 From the viewpoint of improving the dispersibility of the colorant in the toner particles, the particle size is preferably 0.05 μm or more, more preferably 0.08 μm or more, and is preferably 0.4 μm or less, more preferably 0.3 μm or less, and even more preferably 0.2 μm or less. From the viewpoint of improving the dispersibility of the colorant in the toner particles, the CV value of the colorant particles is preferably 10% or more, more preferably 15% or more, and is preferably 40% or less, more preferably 35% or less, and even more preferably 30% or less. Volume median particle size D of colorant particles 50 and CV values ​​are measured by the methods in the Examples.

[0058] From the viewpoint of image density of printed matter, the content of the colorant in the toner particles is preferably 1% by mass or more, more preferably 2% by mass or more, and preferably 10% by mass or less, more preferably 8% by mass or less, and even more preferably 6% by mass or less.

[0059] -Mold release agent- The release agent is preferably contained in the aggregated particles 1 by mixing it with the resin particles as release agent particles and aggregating them. Examples of the release agent include hydrocarbon waxes such as polypropylene wax, polyethylene wax, ethylene-propylene copolymer wax, microcrystalline wax, paraffin wax, and Fischer-Tropsch wax, or oxides thereof; ester waxes such as carnauba wax, montan wax, or deacidified waxes thereof, and fatty acid ester wax; fatty acid amides, fatty acids, higher alcohols, and fatty acid metal salts. These may be used alone or in combination of two or more.

[0060] The melting point of the release agent is preferably 60°C or higher, more preferably 70°C or higher, and preferably 160°C or lower, more preferably 140°C or lower, and even more preferably 120°C or lower. The content of the release agent in the toner particles is preferably 1% by mass or more, more preferably 2% by mass or more, and preferably 10% by mass or less, more preferably 8% by mass or less, and even more preferably 6% by mass or less.

[0061] <Release agent particle dispersion> The release agent particle dispersion can be obtained using a surfactant, but is preferably obtained by mixing the release agent and resin particles. By preparing the release agent particles using the release agent and resin particles, the release agent particles are stabilized by the resin that constitutes the resin particles, and it becomes possible to disperse the release agent in an aqueous medium without using a surfactant. It is believed that the release agent particle dispersion has a structure in which a large number of resin particles adhere to the surfaces of the release agent particles. The resin constituting the resin particles in which the release agent is dispersed is preferably a polyester resin, and it is more preferable to use a composite resin D having a polyester resin segment and an addition polymerization resin segment. For details about the release agent particle dispersion and composite resin D, see JP 2021-182045 A.

[0062] Volume median particle size D of release agent particles 50 From the viewpoint of obtaining uniform aggregated particles 1 by aggregation, the average particle size is preferably 0.05 μm or more, more preferably 0.1 μm or more, even more preferably 0.2 μm or more, and is preferably 1 μm or less, more preferably 0.8 μm or less, even more preferably 0.6 μm or less. The CV value of the release agent particles is preferably 10% or more, more preferably 15% or more, and is preferably 40% or less, more preferably 35% or less, and even more preferably 30% or less. Volume median particle size D of release agent particles 50 The CV value is measured by the method described in the Examples.

[0063] Aggregated particles 1 may also contain additives such as charge control agents, magnetic powders, flowability improvers, conductivity adjusters, reinforcing fillers such as fibrous substances, antioxidants, antiaging agents, and cleaning property improvers.

[0064] <Surfactants> In step 1, when the dispersions of the respective particles are mixed to prepare the mixed dispersion, the process may be carried out in the presence of a surfactant in order to improve the dispersion stability of the resin particles, release agent particles, colorant particles, etc. Examples of the surfactant include anionic surfactants such as alkylbenzene sulfonates and alkyl ether sulfates; and nonionic surfactants such as polyoxyethylene alkyl ethers and polyoxyethylene alkenyl ethers. When a surfactant is used, the total amount used is preferably 0.1 parts by mass or more, more preferably 0.3 parts by mass or more, and preferably 10 parts by mass or less, more preferably 5 parts by mass or less, and even more preferably 3 parts by mass or less, relative to 100 parts by mass of the total of the amorphous polyester resin A and the crystalline polyester resin C.

[0065] <Flocculant> In step 1, it is preferable to add a flocculant from the viewpoint of efficient flocculation. Examples of the flocculant include cationic surfactants such as quaternary salts, organic flocculants such as polyethyleneimine, and inorganic flocculants. Examples of the inorganic flocculant include inorganic metal salts such as sodium sulfate, sodium nitrate, sodium chloride, calcium chloride, and calcium nitrate; inorganic ammonium salts such as ammonium sulfate, ammonium chloride, and ammonium nitrate; and divalent or higher metal complexes. From the viewpoint of improving the aggregating property and obtaining uniform aggregated particles 1, inorganic aggregating agents having a valence of 1 to 5 are preferred, inorganic metal salts having a valence of 1 to 2 and inorganic ammonium salts are more preferred, inorganic ammonium salts are even more preferred, and ammonium sulfate is even more preferred.

[0066] For example, 5 to 50 parts by mass of the aggregating agent is added to a mixed dispersion containing resin particles, release agent particles, and colorant particles at a temperature of 0° C. to 40° C., relative to a total of 100 parts by mass of amorphous polyester resin A and crystalline polyester resin C, and the resin particles, release agent particles, and colorant particles are aggregated in an aqueous medium to obtain aggregated particles 1. Furthermore, from the viewpoint of promoting aggregation, it is preferable to increase the temperature of the dispersion after adding the aggregating agent.

[0067] Volume median particle size D of aggregated particles 1 50 is preferably 3 μm or more, more preferably 4 μm or more, even more preferably 5 μm or more, and is preferably 10 μm or less, more preferably 9 μm or less, even more preferably 8 μm or less.

[0068] [Process 2] Step 2 is a step of aggregating resin particles containing amorphous polyester resin B and a styrene-based resin having an acid value of 60 mgKOH / g or more into aggregated particles 1 obtained in step 1 to obtain aggregated particles 2. In step 2, it is preferable to mix an aqueous dispersion of aggregated particles 1 obtained in step 1 with an aqueous dispersion of resin particles containing amorphous polyester resin B and a styrene-based resin having an acid value of 60 mgKOH / g or more, and aggregating the resin particles containing amorphous polyester resin B and a styrene-based resin having an acid value of 60 mgKOH / g or more into aggregated particles 1 to obtain aggregated particles 2. The temperature at which the aqueous dispersion of aggregated particles 1 and the aqueous dispersion of resin particles containing amorphous polyester resin B and a styrene-based resin having an acid value of 60 mgKOH / g or more are mixed is preferably 25°C or higher, more preferably 35°C or higher, even more preferably 40°C or higher, and preferably 65°C or lower, even more preferably 60°C or lower. The resin particles containing the amorphous polyester resin B and the styrene-based resin having an acid value of 60 mgKOH / g or more are preferably obtained by either of the following steps a and b, and from the viewpoint of obtaining a toner that can further suppress the occurrence of fogging, are more preferably obtained by the following step a.

[0069] <Process a> In step a, an aqueous dispersion of styrene-based resin particles having an acid value of 60 mgKOH / g or more is added to an aqueous organic solvent solution of amorphous polyester resin B, and phase inversion emulsification is performed to obtain resin particles containing amorphous polyester resin B and a styrene-based resin having an acid value of 60 mgKOH / g or more.

[0070] -Amorphous polyester resin B- The amorphous polyester resin B (hereinafter sometimes simply referred to as "resin B") is, for example, a condensate of an alcohol component and a carboxylic acid component, or a condensate of an alcohol component, a carboxylic acid component, and polyethylene terephthalate. As the resin B, for example, the above-mentioned resin A can be used. From the viewpoint of obtaining a toner that can further suppress the occurrence of fogging, Resin B is preferably a resin obtained by polycondensing a polycondensable monomer containing a carboxylic acid component and an alcohol component with polyethylene terephthalate.

[0071] In the toner production method of the present invention, from the viewpoint of further suppressing the occurrence of fogging and obtaining a toner having excellent durability, it is preferable that the amorphous polyester resin A and / or the amorphous polyester resin B contain a structural unit derived from polyethylene terephthalate.

[0072] <Amorphous polyester resin B in aqueous organic solvent> The aqueous organic solvent is not particularly limited as long as it can dissolve the resin B, and examples thereof include methyl ethyl ketone. From the viewpoint of efficiently carrying out phase inversion emulsification, the solids concentration of the aqueous organic solvent for Resin B is preferably 35% by mass or more, more preferably 40% by mass or more, even more preferably 45% by mass or more, and is preferably 65% ​​by mass or less, more preferably 60% by mass or less, even more preferably 55% by mass or less.

[0073] - Styrene-based resin with an acid value of 60 mg KOH / g or more - The raw material monomers for a styrene-based resin having an acid value of 60 mgKOH / g or more (hereinafter, sometimes simply referred to as a "styrene-based resin") contain, in addition to a styrene-based compound a, an addition-polymerizable monomer b having an ionic group (hereinafter, sometimes simply referred to as a "monomer b").

[0074] The styrene-based compound a may be, for example, substituted or unsubstituted styrene. Examples of the substituent substituted on the styrene include an alkyl group having 1 to 5 carbon atoms, a halogen atom, an alkoxy group having 1 to 5 carbon atoms, a sulfo group, or a salt thereof. The molecular weight of the styrene-based compound a is preferably less than 1,000, more preferably 800 or less, and even more preferably 500 or less. Examples of the styrene-based compound a include styrene, methylstyrene, α-methylstyrene, β-methylstyrene, tert-butylstyrene, chlorostyrene, chloromethylstyrene, methoxystyrene, styrenesulfonic acid, and salts thereof. Among these, styrene and α-methylstyrene are preferred. The styrene-based compound a may be used alone or in combination of two or more kinds. From the viewpoint of obtaining a toner that can further suppress the occurrence of fogging, the amount of the styrene-based compound a is preferably 40% by mass or more, more preferably 50% by mass or more, even more preferably 60% by mass or more, and is preferably 95% by mass or less, more preferably 90% by mass or less, even more preferably 85% by mass or less, even more preferably 75% by mass or less, based on the raw material monomers of the styrene-based resin.

[0075] The ionic group in the monomer b means a group that undergoes ionic dissociation in water. Examples of the ionic group include anionic or cationic groups such as a carboxy group, a sulfo group, a phosphate group, an amino group, or salts thereof. The anionic group is preferably an acidic group or a salt thereof, more preferably a carboxy group, a sulfo group, or a salt thereof, and even more preferably a carboxy group or a salt thereof. Examples of addition polymerizable monomers having a carboxy group include (meth)acrylic acid, itaconic acid, maleic acid, fumaric acid, and 2-methacryloyloxymethylsuccinic acid. Among these, addition polymerizable monomers having an anionic group are preferred, (meth)acrylic acid is more preferred, and acrylic acid is even more preferred. The amount of monomer b in the raw material monomers of the styrene-based resin is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 15% by mass or more, even more preferably 25% by mass or more, and is preferably 45% by mass or less, more preferably 35% by mass or less.

[0076] In the present invention, the styrene-based resin is preferably a copolymer (styrene-acrylic polymer) of a styrene-based compound a and (meth)acrylic acid.

[0077] Furthermore, the raw material monomers of the styrene-based resin may contain addition-polymerizable monomers (other monomers) other than the styrene-based compound a and the monomer b. Examples of other monomers include addition-polymerizable monomers having a polyalkylene oxide group, such as polyalkylene glycol (meth)acrylate and methoxypolyethylene glycol (meth)acrylate, styrene-based macromonomers having an addition-polymerizable functional group at one end, alkyl (meth)acrylates having an alkyl group having 1 to 22 carbon atoms (preferably 6 to 18 carbon atoms), and aromatic group-containing (meth)acrylates. Examples of aromatic group-containing (meth)acrylates include benzyl (meth)acrylate and phenoxyethyl (meth)acrylate.

[0078] From the viewpoint of obtaining a toner that can further suppress the occurrence of fog, the weight average molecular weight of the styrene resin is preferably 7,000 or more, more preferably 8,000 or more, even more preferably 10,000 or more, even more preferably 13,000 or more, even more preferably 15,000 or more, and is preferably 100,000 or less, more preferably 50,000 or less, even more preferably 30,000 or less, even more preferably 20,000 or less. The weight average molecular weight can be measured by the method described in the examples.

[0079] The acid value of the styrene-based resin is 60 mgKOH / g or more, preferably 90 mgKOH / g or more, more preferably 130 mgKOH / g or more, even more preferably 160 mgKOH / g or more, even more preferably 190 mgKOH / g or more, even more preferably 220 mgKOH / g or more, and preferably 300 mgKOH / g or less, more preferably 280 mgKOH / g or less, even more preferably 260 mgKOH / g or less. The acid value of the styrene-based resin can be appropriately adjusted by the type and amount of raw material monomers used, as well as production conditions such as reaction temperature, reaction time, cooling rate, etc., and can be determined by the method described in the Examples. When two or more styrene-based resins are used in combination, it is preferable that the acid value of the mixture thereof is within the above-mentioned range. As will be described later, when a neutralizing agent is added to the styrene-based resin dispersion, the acid value of the styrene-based resin means the acid value before neutralization.

[0080] From the viewpoint of ease of control of molecular weight, molecular weight distribution, and copolymerizability of monomers, the styrene-based resin is preferably formed by bulk polymerization or solution polymerization, more preferably by bulk polymerization.

[0081] In the present invention, "bulk polymerization" refers to addition polymerization carried out under conditions where substantially no solvent is present in the reaction system, i.e., under solvent-free conditions. The bulk polymerization may be carried out using a radical generator. Examples of the radical generator include peroxides such as di-tert-butyl peroxide, persulfates such as sodium persulfate, and azo compounds such as 2,2'-azobis(2,4-dimethylvaleronitrile). When a radical generator is used in bulk polymerization, the amount used is preferably 0.1 parts by mass or more and 10 parts by mass or less relative to 100 parts by mass of the total amount of raw material monomers of the styrene-based resin, from the viewpoint of controlling the molecular weight, molecular weight distribution, and copolymerizability and obtaining a toner that can further suppress the occurrence of fog.

[0082] The bulk polymerization is preferably carried out at a high temperature under a pressurized state equal to or higher than atmospheric pressure, and continuous bulk polymerization under high temperature and pressure is more preferred. In the present invention, the pressurized state refers to a state in which the contents of a sealed container such as an autoclave are heated to a temperature equal to or higher than the boiling point under normal pressure. Radicals generated by the thermally initiated reaction of raw material monomers under high temperature and pressure equal to or higher than atmospheric pressure function as a polymerization initiator, allowing addition polymerization to proceed even under conditions in which the amount of radical generator is relatively small, and a styrene-based resin with a narrow molecular weight distribution can be obtained. Furthermore, when continuous bulk polymerization is used, it is possible to control not only the molecular weight distribution but also the monomer composition distribution, and to obtain a styrene-based resin with a narrower and more uniform monomer composition distribution, thereby obtaining a toner that can further suppress the occurrence of fogging. From the above viewpoints, the temperature of the bulk polymerization is preferably 160°C or higher, more preferably 170°C or higher, even more preferably 180°C or higher, and even more preferably 190°C or higher, and is preferably 350°C or lower, more preferably 320°C or lower.

[0083] <Aqueous dispersion of styrene resin with an acid value of 60 mg KOH / g or more> The solids concentration of an aqueous dispersion of a styrene-based resin having an acid value of 60 mgKOH / g or more (hereinafter also simply referred to as "styrene-based resin dispersion") is preferably 4% by mass or more, more preferably 7% by mass or more, and even more preferably 10% by mass or more, from the viewpoint of efficiently carrying out phase inversion emulsification, and is preferably 30% by mass or less, and more preferably 25% by mass or less.

[0084] A neutralizing agent may be added to the styrene-based resin dispersion. Examples of the neutralizing agent include basic substances. Examples of the basic substance include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide; and nitrogen-containing basic substances such as ammonia, trimethylamine, and diethanolamine. Among these, alkali metal hydroxides such as sodium hydroxide and potassium hydroxide are preferred. The degree of neutralization of the styrene-based resin is preferably 40 mol% or more, more preferably 45 mol% or more, even more preferably 50 mol% or more, even more preferably 55 mol% or more, and is preferably 75 mol% or less, more preferably 70 mol% or less, even more preferably 65 mol% or less. The degree of neutralization of the styrene-based resin can be calculated by the above formula.

[0085] In step a, the styrene resin dispersion is gradually added to the aqueous organic solvent solution of resin B while stirring, to effect phase inversion emulsification.

[0086] Before adding the styrene-based resin dispersion, a neutralizing agent may be added to the aqueous organic solvent solution of resin B. Examples of neutralizing agents include basic substances. Examples of basic substances include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide; and nitrogen-containing basic substances such as ammonia, trimethylamine, and diethanolamine. Among these, alkali metal hydroxides such as sodium hydroxide and potassium hydroxide are preferred. The neutralization degree of Resin B is preferably 40 mol% or more, more preferably 45 mol% or more, even more preferably 50 mol% or more, even more preferably 55 mol% or more, and is preferably 75 mol% or less, more preferably 70 mol% or less, even more preferably 65 mol% or less. The neutralization degree of Resin B can be calculated by the above formula.

[0087] From the viewpoint of improving the dispersion stability of the resin particles, the temperature of the organic solvent solution when the styrene-based resin dispersion is added is preferably not less than the glass transition temperature of Resin B, for example, not less than 60°C, preferably not less than 65°C, and is preferably not more than 100°C, more preferably not more than 90°C, and even more preferably not more than 80°C.

[0088] From the viewpoint of obtaining a toner that can further suppress the occurrence of fogging, the mixing mass ratio of the styrene-based resin particles to the resin B (mass of the styrene-based resin particles / mass of the resin B) is preferably 1 / 99 or more, more preferably 3 / 97 or more, even more preferably 5 / 95 or more, and is preferably 30 / 70 or less, more preferably 25 / 75 or less, even more preferably 20 / 80 or less.

[0089] From the viewpoint of efficiently adhering the styrene resin to Resin B, the addition rate when adding the styrene resin dispersion is preferably 1 g / min or more, more preferably 3 g / min or more, even more preferably 5 g / min or more, and is preferably 30 g / min or less, more preferably 20 g / min or less, even more preferably 10 g / min or less.

[0090] After the phase inversion emulsification, the organic solvent may be removed from the resulting dispersion by distillation or the like, if necessary. Alternatively, resin particles containing the amorphous polyester resin B and the styrene-based resin having an acid value of 60 mgKOH / g or more may be isolated by filtration or the like. In step 2, it is preferable to use an aqueous dispersion of resin particles containing the amorphous polyester resin B and the styrene-based resin having an acid value of 60 mgKOH / g or more, obtained by removing the organic solvent from the dispersion obtained after the phase inversion emulsification. In this case, the residual amount of the organic solvent in the dispersion is preferably 1% by mass or less, more preferably 0.5% by mass or less, and even more preferably substantially 0% by mass.

[0091] Volume median particle size D of resin particles containing amorphous polyester resin B and styrene-based resin with an acid value of 60 mg KOH / g or more 50 is preferably 0.08 μm or more, more preferably 0.12 μm or more, and is preferably 1 μm or less, more preferably 0.5 μm or less, and even more preferably 0.3 μm or less. The CV value of the resin particles containing amorphous polyester resin B and a styrene-based resin having an acid value of 60 mgKOH / g or more is preferably 10% or more, more preferably 15% or more, even more preferably 20% or more, from the viewpoint of improving the dispersibility of the resin particles in the toner particles, and is preferably 45% or less, more preferably 40% or less, even more preferably 35% or less. Volume median particle size D of resin particles containing amorphous polyester resin B and styrene-based resin with an acid value of 60 mg KOH / g or more 50 The CV value is measured by the method described in the Examples.

[0092] The solids concentration of the aqueous dispersion of resin particles containing amorphous polyester resin B and a styrene-based resin having an acid value of 60 mgKOH / g or more is, from the viewpoint of improving toner productivity and improving the dispersion stability of the resin particles, preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 15% by mass or more, and is preferably 35% by mass or less, more preferably 30% by mass or less, even more preferably 25% by mass or less.

[0093] <Process b> In step b, an aqueous medium is added to an aqueous organic solvent solution of amorphous polyester resin B, followed by phase inversion emulsification, and then an aqueous dispersion of styrene-based resin particles having an acid value of 60 mgKOH / g or more is added and mixed to obtain resin particles containing amorphous polyester resin B and a styrene-based resin having an acid value of 60 mgKOH / g or more. The aqueous organic solvent solution of amorphous polyester resin B and the aqueous dispersion of styrene-based resin particles having an acid value of 60 mgKOH / g or more are the same as the aqueous organic solvent solution of amorphous polyester resin B and the aqueous dispersion of styrene-based resin particles having an acid value of 60 mgKOH / g or more in step a. The amorphous polyester resin B can be subjected to phase inversion emulsification in the same manner as in step 1 <<aqueous dispersion of resin particles>>.

[0094] In step 2, from the viewpoint of preventing unnecessary aggregation, the dispersion of aggregated particles 2 may be cooled when aggregated particles 2 have grown to a particle size appropriate for toner particles, or an aggregation terminator may be added to the dispersion of aggregated particles 2. From the viewpoint of reliably preventing unnecessary aggregation, it is preferable to add an aggregation terminator.

[0095] (Aggregation stopper) The aggregation terminator is preferably a surfactant, more preferably an anionic surfactant. Examples of anionic surfactants include alkylbenzenesulfonates, alkyl sulfates, alkyl ether sulfates, polyoxyalkylene alkyl ether sulfates, arylsulfonates, and arylsulfonic acid-formalin condensates, and are preferably alkali metal salts of arylsulfonic acid-formalin condensates, and more preferably sodium salts of naphthalenesulfonic acid-formalin condensates. These may be used alone or in combination. The aggregation terminator may be added in the form of an aqueous solution. From the viewpoint of reliably preventing unnecessary aggregation, the amount of the aggregation terminator added is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and preferably 12 parts by mass or less, more preferably 10 parts by mass or less, and even more preferably 8 parts by mass or less, relative to 100 parts by mass of the total of the amorphous polyester resin and the crystalline polyester resin in the aggregated particles 2.

[0096] [Step 3] In step 3, for example, the aggregated particles 2 obtained in step 2 are fused in an aqueous medium. By fusion, the particles contained in aggregated particles 2 are fused together to obtain fused particles having a core-shell structure. In step 3, from the viewpoint of improving the fusibility of aggregated particles 2, aggregated particles 2 are maintained at a temperature equal to or higher than the glass transition temperature of the resin contained in aggregated particles 2 that has the highest glass transition temperature. From the viewpoint of improving toner productivity, the holding (heating) temperature when fusing aggregated particles 2 is preferably equal to or higher than the glass transition temperature of the resin having the highest glass transition temperature among the amorphous polyester resins, more preferably equal to or higher than the glass transition temperature of the resin by 2°C, even more preferably equal to or higher than the glass transition temperature of the resin by 5°C, and is preferably equal to or lower than a temperature by 25°C, more preferably equal to or lower than a temperature by 20°C, even more preferably equal to or lower than a temperature by 15°C, above the glass transition temperature of the resin having the highest glass transition temperature among the amorphous polyester resins. In this case, it is preferable to maintain the temperature at the above temperature until the desired circularity is achieved.

[0097] The volume median particle size D of the fused particles obtained by fusion 50 is preferably 2 μm or more, more preferably 3 μm or more, even more preferably 4 μm or more, and is preferably 10 μm or less, more preferably 8 μm or less, even more preferably 7 μm or less.

[0098] The circularity of the fused particles obtained by fusion is preferably 0.955 or more, more preferably 0.960 or more, and is preferably 0.990 or less, more preferably 0.985 or less, and even more preferably 0.980 or less. The fusion is preferably terminated after the desired circularity is reached. The circularity is measured by the method described in the Examples.

[0099] [Post-processing process] A post-treatment step may be carried out after step 3, and the fused particles are isolated to obtain toner particles. Since the fused particles obtained in the fusion step are present in an aqueous medium, it is preferable to first carry out solid-liquid separation. For solid-liquid separation, a suction filtration method or the like is preferably used. After solid-liquid separation, it is preferable to wash with an aqueous medium. Next, it is preferable to carry out drying. Examples of drying methods include vacuum constant temperature drying, vibration fluidized bed drying, spray drying, freeze drying, and flash jet drying.

[0100] [Toner particles] Volume median particle size D of toner particles 50 From the viewpoint of further improving the cleaning properties of the toner, the particle size is preferably 2 μm or more, more preferably 3 μm or more, even more preferably 4 μm or more, and is preferably 10 μm or less, more preferably 8 μm or less, even more preferably 7 μm or less.

[0101] The circularity of the toner particles is preferably 0.955 or more, more preferably 0.960 or more, from the viewpoint of obtaining high-quality images, and is preferably 0.990 or less, more preferably 0.985 or less, and even more preferably 0.980 or less, from the viewpoint of cleanability.

[0102] The CV value of the toner particles is preferably 10% or more, more preferably 15% or more, and even more preferably 20% or more from the viewpoint of improving toner productivity, and is preferably 40% or less, more preferably 35% or less, and even more preferably 30% or less from the viewpoint of obtaining high-quality images. Volume median particle size D of toner particles 50 The CV value can be measured by the method described in the Examples.

[0103] [Electrostatic image developing toner] The toner for developing electrostatic images obtained by the method for producing the toner for developing electrostatic images of the present invention contains toner particles having a core-shell structure. Although toner particles having a core-shell structure can be used as they are, it is preferable to use toner particles in which a fluidizing agent or the like is added as an external additive to the surface of the toner particles.

[0104] [External additives] Examples of external additives include fine particles of inorganic materials such as hydrophobic silica, titanium oxide, alumina, cerium oxide, and carbon black, and fine particles of polymers such as polycarbonate, polymethyl methacrylate, and silicone resin. Among these, hydrophobic silica is preferred. One type of external additive may be used alone, or two or more types may be used. Two or more types of hydrophobic silica having different particle sizes may also be used. When the surface treatment of the toner particles is performed using an external additive, the amount of the external additive added is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and preferably 5 parts by mass or less, more preferably 4.5 parts by mass or less, and even more preferably 4 parts by mass or less, relative to 100 parts by mass of the toner particles.

[0105] Toners are used to develop electrostatic images in electrophotographic printing. Toners can be used, for example, as a one-component developer or as a two-component developer mixed with a carrier.

[0106] The present invention includes the following aspects. <1> A method for producing a toner for developing electrostatic images, comprising the following steps 1 to 3 in this order: Step 1: A step of aggregating resin particles containing an amorphous polyester resin A in an aqueous medium to obtain aggregated particles 1 Step 2: A step of aggregating resin particles containing amorphous polyester resin B and a styrene-based resin having an acid value of 60 mgKOH / g or more to the obtained aggregated particles 1 to obtain aggregated particles 2. Step 3: A step of fusing the obtained aggregated particles 2 to obtain fused particles [Example]

[0107] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. Each property value was measured and evaluated by the following methods. In the notation "alkylene oxide (X)" and the like, the number X in parentheses means the average number of moles of alkylene oxide added.

[0108] [Measurement method] [Softening point, crystallinity index, melting point and glass transition temperature of resin] (1) Softening point Using a flow tester "CFT-500D" (Shimadzu Corporation), 1 g of sample was heated at a temperature increase rate of 6°C / min, while a load of 1.96 MPa was applied by the plunger, and the sample was extruded from a nozzle 1 mm in diameter and 1 mm in length. The plunger depression distance of the flow tester was plotted against the temperature, and the temperature at which half of the sample flowed out was taken as the softening point. (2) Crystallinity index Using a differential scanning calorimeter "Q-100" (TA Instruments Japan), 0.02 g of sample was weighed into an aluminum pan and cooled to 0°C at a rate of 10°C / min. The sample was then left to stand for 1 minute, after which it was heated to 180°C at a rate of 10°C / min and the calorific value was measured. The temperature of the endothermic peak with the largest area was defined as the endothermic maximum peak temperature (1), and the crystallinity index was calculated by (softening point (°C)) / (endothermic maximum peak temperature (1) (°C)). (3) Melting point and glass transition temperature Using a differential scanning calorimeter "Q-100" (TA Instruments Japan), 0.02 g of sample was weighed into an aluminum pan, heated to 200°C, and cooled to 0°C at a rate of 10°C / min. The sample was then heated at a rate of 10°C / min, and the calorific value was measured. The temperature of the endothermic peak with the largest peak area was taken as the maximum endothermic peak temperature (2). For crystalline resins, this peak temperature was taken as the melting point. For amorphous resins, if a peak was observed, the peak temperature was used; if no peak was observed but a step was observed, the glass transition temperature was taken as the temperature at the intersection of the tangent line showing the maximum slope of the curve at the step and an extension of the baseline on the low-temperature side of the step.

[0109] [Acid value of resin] The acid value of the resin was measured according to the neutralization titration method described in JIS K 0070: 1992. The measurement solvent was a mixed solvent of acetone and toluene (acetone:toluene=1:1 (volume ratio)).

[0110] [Melting point of release agent] Using a differential scanning calorimeter "Q-100" (TA Instruments Japan Co., Ltd.), 0.02 g of sample was weighed into an aluminum pan, heated to 200°C, and then cooled from 200°C to 0°C at a rate of 10°C / min. The sample was then heated at a rate of 10°C / min, the calorific value was measured, and the maximum endothermic peak temperature was taken as the melting point.

[0111] [Volume median particle diameter D of resin particles, colorant particles, and release agent particles 50 and CV value) (1) Measuring device: Laser diffraction particle size measuring instrument "LA-920" (manufactured by Horiba Ltd.) (2) Measurement conditions: Put the sample dispersion in a measurement cell, add distilled water, and measure the volume median particle size D at a concentration where the absorbance is in the appropriate range. 50 The volume average particle diameter Dv was measured, and the CV value was calculated according to the following formula. CV value (%) = (standard deviation of particle size distribution / volume average particle size Dv) x 100

[0112] [Solid Content Concentration of Resin Particle Dispersion, Colorant Particle Dispersion, and Release Agent Particle Dispersion] Using an infrared moisture meter "FD-230" (Kett Electric Laboratory Co., Ltd.), the moisture content (mass%) of 5 g of the measurement sample was measured at a drying temperature of 150°C and measurement mode 96 (monitoring time 2.5 minutes, moisture content fluctuation range 0.05%). The solid content concentration was calculated according to the following formula. Solid concentration (mass%) = 100-moisture (mass%)

[0113] [Volume median particle size of agglomerated particles D 50 〕 Volume median particle size of agglomerated particles D 50 was measured as follows: 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" (Beckman Coulter, Inc.) Electrolyte: "Isoton (registered trademark) II" (Beckman Coulter, Inc.) Measurement conditions: The sample dispersion is added to 100 mL of the electrolyte to adjust the concentration so that the particle size of 30,000 particles can be measured in 20 seconds. Then, 30,000 particles are measured again, and the volume median particle size D is calculated from the particle size distribution. 50 asked for.

[0114] [Circularity of fused particles] The circularity of the fused particles was measured under the following conditions. Measurement equipment: Flow particle image analyzer "FPIA-3000" (Sysmex Corporation) Preparation of dispersion: The dispersion of fused particles was diluted with deionized water to a solids concentration of 0.001 to 0.05% by mass. Measurement mode: HPF measurement mode

[0115] [Volume median particle size D of toner particles 50 and CV value) Volume median particle size D of toner particles 50 was measured as follows: The measurement device, aperture diameter, analysis software, and electrolyte were determined based on the volume median particle diameter D 50 The same material as that used in the measurement was used. Dispersion: Polyoxyethylene lauryl ether "EMULGEN (registered trademark) 109P" (manufactured by Kao Corporation, HLB (Hydrophile-Lipophile Balance) = 13.6) was dissolved in the electrolyte solution to obtain a dispersion with a concentration of 5 mass %. Dispersion conditions: 10 mg of a measurement sample of dried toner particles was added to 5 mL of the dispersion liquid, and the mixture was dispersed for 1 minute using an ultrasonic disperser. Thereafter, 25 mL of the electrolyte solution was added, and the mixture was further dispersed for 1 minute using the ultrasonic disperser to prepare a sample dispersion liquid. Measurement conditions: The sample dispersion is added to 100 mL of the electrolyte to adjust the concentration so that the particle size of 30,000 particles can be measured in 20 seconds. Then, 30,000 particles are measured and the volume median particle size D is calculated from the particle size distribution. 50 and volume average particle size D V asked for. The CV value (%) was calculated according to the following formula: CV value (%) = (standard deviation of particle size distribution) / volume average particle size D V ) x 100

[0116] [Weight average molecular weight of styrene-based resin] The measurements were performed by gel permeation chromatography (GPC) using a Tosoh HLC-8320GPC gel permeation chromatography system with Tosoh TSKgel SuperAWM-H, Tosoh SuperAW3000, and Tosoh TSKgel guardcolumn Super AW-H columns at a flow rate of 0.5 mL / min. The eluent was a solution of 60 mmol / L phosphoric acid and 50 mmol / L lithium bromide dissolved in N,N-dimethylformamide. The standard samples were monodisperse polystyrene kits with known molecular weights (PStQuick B (F-550, F-80, F-10, F-1, A-1000), PStQuick C (F-288, F-40, F-4, A-5000, A-500), Tosoh PStQuick C).

[0117] [Resin manufacturing] [Production of amorphous polyester resin for core] Production Example A1 (Production of Amorphous Polyester Resin A-1) The raw material monomers for polyester resins other than trimellitic anhydride and the esterification catalyst shown in Table 1 were placed in a 10-L four-neck flask equipped with a thermometer, a stainless steel stirring rod, a downflow condenser equipped with a dehydration tube, and a nitrogen inlet tube, and the mixture was heated from 180°C to 230°C over 6 hours in a nitrogen atmosphere in a mantle heater, and reacted at 230°C for 3 hours. After cooling to 210°C, trimellitic anhydride was added, the mixture was heated to 220°C, and the reaction was continued at 8 kPa until the softening point shown in Table 1 was reached, yielding amorphous polyester resin A-1.

[0118] Production Example A2 (Production of amorphous polyester resin A-2) The raw material monomers for polyester resin other than trimellitic anhydride shown in Table 1, the esterification catalyst, a thermometer, a stainless steel stirring rod, a dehydration tube equipped with a fractionating column through which hot water of 98°C had passed, and a nitrogen inlet tube were placed in a 10-L four-neck flask. The mixture was kept at 180°C in a mantle heater under a nitrogen atmosphere for 1 hour, and then heated from 180°C to 220°C at a rate of 10°C / h. After cooling to 210°C, trimellitic anhydride was added, the temperature was raised to 220°C, and the reaction was continued at 8 kPa until the softening point shown in Table 1 was reached, yielding amorphous polyester resin A-2.

[0119] Production Example A3 (Production of amorphous polyester resin A-3) Amorphous polyester resin A-3 was obtained in the same manner as in Production Example A2, except that the raw material monomers and esterification catalyst for the polyester resin shown in Table 1 were used in the amounts shown in Table 1.

[0120] [Table 1]

[0121] [Production of amorphous polyester resin for shell] Production Example B1 (Production of Amorphous Polyester Resin B-1) The raw material monomers for polyester resins other than trimellitic anhydride and the esterification catalyst shown in Table 2 were placed in a 10-L four-neck flask equipped with a thermometer, a stainless steel stirring rod, a downflow condenser equipped with a dehydration tube, and a nitrogen inlet tube, and the mixture was heated from 180°C to 230°C over 6 hours in a nitrogen atmosphere in a mantle heater, and reacted at 230°C for 3 hours. After cooling to 210°C, trimellitic anhydride was added, the mixture was heated to 220°C, and the reaction was continued at 8 kPa until the softening point shown in Table 2 was reached, yielding amorphous polyester resin B-1.

[0122] Manufacturing Example B2 (Manufacturing of Resin B-2) The raw material monomers for polyester resin other than trimellitic anhydride shown in Table 2, the esterification catalyst, a thermometer, a stainless steel stirring rod, a dehydration tube equipped with a fractionating column through which hot water of 98°C was passed, and a nitrogen inlet tube were placed in a 10 L four-neck flask. The mixture was kept at 180°C in a mantle heater under a nitrogen atmosphere for 1 hour, and then heated from 180°C to 220°C at a rate of 10°C / h. After cooling to 210°C, trimellitic anhydride was added, the temperature was raised to 220°C, and the reaction was continued at 8 kPa until the softening point shown in Table 2 was reached, yielding amorphous polyester resin B-2.

[0123] Manufacturing Example B3 (Manufacturing of Resin B-3) Amorphous polyester resin B-3 was obtained in the same manner as in Production Example B2, except that the raw material monomers and esterification catalyst for the polyester resin shown in Table 2 were used in the amounts shown in Table 2.

[0124] [Table 2]

[0125] [Production of crystalline polyester resin for core] Production Example C1 (Production of Crystalline Polyester Resin C-1) The raw material monomers for the crystalline polyester resin shown in Table 3 were added to a 10-L four-neck flask equipped with a nitrogen inlet tube, a dehydration tube, a stirrer, and a thermocouple, and the inside of the flask was replaced with nitrogen. The contents were heated to 135°C with stirring, maintained at 135°C for 3 hours, and then heated from 135°C to 200°C over 10 hours. An esterification catalyst was then added, and the mixture was maintained at 200°C for another 1 hour. The pressure in the flask was then reduced, and the reaction was continued under a reduced pressure of 8 kPa until the softening point shown in Table 3 was reached, yielding crystalline polyester resin C-1.

[0126] Production Example C2 (Production of Crystalline Polyester Resin C-2) Crystalline polyester resin C-2 was obtained in the same manner as in Production Example C1, except that the raw material monomers and esterification catalyst for the crystalline polyester resin shown in Table 3 were used in the amounts shown in Table 3.

[0127] [Table 3]

[0128] [Production of amorphous polyester resin for release agent particle dispersion] Production Example D1 (Production of amorphous polyester resin D-1) The inside of a 10 L four-neck flask equipped with a nitrogen inlet tube, a dehydration tube, a stirrer, and a thermocouple was replaced with nitrogen, and 4313 g of propylene oxide (2.2) adduct of bisphenol A, 818 g of terephthalic acid, 30 g of tin(II) di(2-ethylhexanoate), and 3 g of gallic acid were added. Under a nitrogen atmosphere, the reaction system was stirred and heated to 235°C. After maintaining this temperature for 5 hours, the pressure inside the flask was reduced and maintained at 8 kPa for 1 hour. After returning to atmospheric pressure, the system was cooled to 160°C. While maintaining this temperature, a mixture of 2756 g of styrene, 689 g of stearyl methacrylate, 142 g of acrylic acid, and 413 g of dibutyl peroxide was added dropwise to the reaction system over 3 hours. The reaction system was then maintained at 160°C for 30 minutes, after which it was heated to 200°C. The pressure inside the flask was further reduced and maintained at 8 kPa for 1 hour. After returning the pressure to atmospheric pressure, the mixture was cooled to 190°C, 727 g of succinic acid was added, and the temperature was increased to 210°C at a rate of 10°C / hr. Thereafter, the reaction was continued at 4 kPa until the softening point shown in Table 4 was reached, thereby obtaining amorphous polyester resin D-1. The physical properties are shown in Table 4.

[0129] [Table 4]

[0130] [Production of styrene-based resin] Production Example F1 (Production of styrene-based resin F-1) The raw material monomers for the acrylic acid-containing styrene resin shown in Table 5 were placed in an autoclave equipped with a stainless steel stirring rod, and polymerization was allowed to proceed for 2 hours under pressurized and heated conditions (0.35 MPaG, 300°C). The pressure and temperature were returned to normal, and the precipitated styrene resin F-1 was collected.

[0131] Production Examples F2 to F4 (Production of styrene-based resins F-2 to F-4) Styrenic resins F-2 to F-4 were obtained in the same manner as in Production Example F1, except that the raw material monomers for the styrene resins shown in Table 5 were used in the amounts shown in Table 5.

[0132] Production Example F5 (Production of styrene-based resin F-5) The raw material monomers for the acrylic acid-containing styrene-based resin and the polymerization initiator shown in Table 5 were placed in a stainless steel reactor equipped with a thermometer, a stainless steel stirring rod, a downflow condenser, and a nitrogen inlet tube, and polymerization was allowed to proceed at 150°C for 2 hours. The temperature was returned to room temperature, and the precipitated styrene-based resin F-5 was collected.

[0133] Production Example F6 (Production of styrene-based resin F-6) A styrene-based resin F-6 was obtained in the same manner as in Production Example F5, except that the raw material monomers and polymerization initiators shown in Table 5 were used in the amounts shown in Table 5.

[0134] [Table 5]

[0135] [Production of aqueous dispersion] [Production of Core Resin Particle Dispersion] Production Example X1 (Production of Resin Particle Dispersion X-1) In a 3 L vessel equipped with a stirrer, reflux condenser, dropping funnel, thermometer, and nitrogen inlet tube, 180 g of Resin A-1, 20 g of Resin C-1, and 200 g of methyl ethyl ketone were placed and dissolved over 2 hours at 73° C. A 5% by mass aqueous solution of sodium hydroxide was added to the resulting solution so that the degree of neutralization relative to the acid value of the resin was 60 mol %, and the mixture was stirred for 30 minutes. Next, while maintaining the temperature at 73°C, 700 g of deionized water was added over 50 minutes while stirring at 280 r / min to cause phase inversion emulsification. While maintaining the temperature at 73°C, the resulting solution was distilled under reduced pressure to remove methyl ethyl ketone, yielding a dispersion. The dispersion was then cooled to 30°C while continuing to stir, and deionized water was added to adjust the solids concentration to 20% by mass, yielding Resin Particle Dispersion X-1. Physical properties are shown in Table 6.

[0136] Production Examples X2 to X4 (Production of Resin Particle Dispersions X-2 to X-4) Resin particle dispersions X-2 to X-4 were obtained in the same manner as in Production Example X1, except that the resins used were changed as shown in Table 6. Table 6 shows the physical property values.

[0137] [Table 6]

[0138] Production Example F'1 (Production of styrene-based resin particle dispersion F'-1) A 2L vessel equipped with a stirrer, reflux condenser, thermometer, and nitrogen inlet tube was charged with 200g of styrene-based resin F-1, 450g of deionized water, and a 5% by weight aqueous solution of sodium hydroxide (to achieve a neutralization degree of 60 mol% relative to the acid value of styrene-based resin F-1). The styrene-based resin was dispersed in water at 80°C for 3 hours while stirring at 280 r / min (circumferential speed 88 m / min). After cooling to 30°C, deionized water was added to achieve a solids concentration of 20% by weight, yielding styrene-based resin particle dispersion F'-1. Physical properties are listed in Table 7.

[0139] Manufacturing example F'2~F'6 (Production of styrene-based resin particle dispersions F'-2 to F'-6) Styrene-based resin particle dispersions F'-2 to F'-6 were obtained in the same manner as in Production Example F'1, except that the styrene-based resin used was changed as shown in Table 7. Physical property values ​​are shown in Table 7.

[0140] [Table 7]

[0141] [Step a: Preparation of an aqueous dispersion of resin particles containing amorphous polyester resin B and a styrene-based resin having an acid value of 60 mgKOH / g or more] Production Example Y1 (Production of Resin Particle Dispersion Y-1) In a 3 L vessel equipped with a stirrer, a reflux condenser, a dropping funnel, a thermometer, and a nitrogen inlet tube, 200 g of amorphous polyester resin B-1 and 200 g of methyl ethyl ketone were placed and dissolved at 73° C. for 2 hours. A 5 mass % aqueous solution of sodium hydroxide was added to the resulting solution so that the degree of neutralization relative to the acid value of amorphous polyester resin B-1 was 60 mol %, and the mixture was stirred for 30 minutes. Next, while maintaining the temperature at 73°C and stirring at 280 rpm, 440 g of deionized water and 200 g of styrene-based resin particle dispersion F'-1 were added over 50 minutes to induce phase inversion emulsification. While maintaining the temperature at 73°C, the methyl ethyl ketone was removed under reduced pressure to obtain a dispersion. The dispersion was then cooled to 30°C with continued stirring, and deionized water was added to obtain a solids concentration of 20% by mass to obtain resin particle dispersion Y-1. Physical properties are shown in Table 8.

[0142] Production Examples Y2 to Y5, Y8, and Y9 (Production of Resin Particle Dispersions Y-2 to Y-5, Y-8, and Y-9) Resin particle dispersions Y-2 to Y-5, Y-8, and Y-9 were obtained in the same manner as in Production Example Y1, except that the amorphous polyester resin and styrene-based resin particle dispersions shown in Table 8 were used. The physical properties of the obtained resin particles are shown in Table 8.

[0143] [Preparation of aqueous dispersion Y (comparative example) of resin particles containing amorphous polyester resin B and surfactant or styrene-based resin] Production Examples Y6 and Y7 (Production of Resin Particle Dispersions Y-6 and Y-7) Resin particle dispersions Y-6 and Y-7 were obtained in the same manner as in Production Example Y1, except that the amorphous polyester resin and styrene-based resin particle dispersion or surfactant shown in Table 8 were used. The physical properties of the obtained resin particles are shown in Table 8.

[0144] [Table 8]

[0145] [Production of Resin Particle Dispersion for Release Agent Particle Dispersion] Production Example S1 (Production of Resin Particle Dispersion S-1) 200 g of amorphous polyester resin D-1 and 200 g of methyl ethyl ketone were placed in a 3 L vessel equipped with a stirrer, reflux condenser, dropping funnel, thermometer, and nitrogen inlet tube, and dissolved at 73° C. for 2 hours. A 5% by mass aqueous solution of sodium hydroxide was added to the resulting solution so that the degree of neutralization relative to the acid value of resin D-1 was 60 mol %, and the mixture was stirred for 30 minutes. Next, while maintaining the temperature at 73°C, 700 g of deionized water was added over 50 minutes while stirring at 280 r / min, resulting in phase inversion emulsification. While maintaining the temperature at 73°C, the methyl ethyl ketone was distilled off under reduced pressure to obtain an aqueous dispersion. Thereafter, while stirring at 280 r / min, the aqueous dispersion was cooled to 30°C, and deionized water was added to obtain a solids concentration of 20 mass%, thereby obtaining resin particle dispersion S-1. Resin particle volume median particle diameter D 50 The particle size was 0.90 μm and the CV value was 23%.

[0146] [Production of Release Agent Particle Dispersion] Production Example W1 (Production of Release Agent Particle Dispersion W-1) In a 1 L beaker, 120 g of deionized water, 86 g of resin particle dispersion S-1, and 40 g of paraffin wax "HNP-9" (manufactured by Nippon Seiro Co., Ltd., melting point 75°C) were added, and the mixture was melted and stirred while maintaining the temperature at 90-95°C to obtain a molten mixture. The obtained molten mixture was dispersed for 20 minutes using an ultrasonic homogenizer "US-600T" (manufactured by Nippon Seiki Seisakusho Co., Ltd.) while maintaining the temperature at 90-95°C, and then cooled to room temperature (20°C). Deionized water was added to the obtained dispersion to adjust the solid concentration to 20 mass%, thereby obtaining release agent particle dispersion W-1. The volume median particle diameter D of the release agent particles was 50 The particle size was 0.47 μm and the CV value was 27%.

[0147] [Preparation of Colorant Particle Dispersion] Production Example Z1 (Production of Colorant Particle Dispersion Z-1) In a 1 L beaker, 116.2 g of copper phthalocyanine pigment "ECB-301" (manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd.), 154.9 g of anionic surfactant "Neopelex (registered trademark) G-15" (manufactured by Kao Corporation, 15% by mass aqueous solution of sodium dodecylbenzenesulfonate), and 340 g of deionized water were mixed and dispersed at room temperature for 3 hours using an ultrasonic homogenizer "US-600T" (manufactured by Nippon Seiki Seisakusho Co., Ltd.), and then deionized water was added to adjust the solids concentration to 20% by mass, thereby obtaining colorant particle dispersion Z-1. The volume median particle diameter D of the colorant particles was 50The particle size was 0.12 μm and the CV value was 22%.

[0148] [Toner manufacturing] Example 1 (Production of Toner 1) [Process 1] A 3 L four-neck flask equipped with a reflux condenser, a stirrer, and a thermocouple was charged with 500 g of resin particle dispersion X-1, 25 g of release agent particle dispersion W-1, 25 g of colorant particle dispersion Z-1, and 3.3 g of a 15 mass % aqueous solution of sodium dodecylbenzenesulfonate "Neopelex G-15" (Kao Corporation, an anionic surfactant), and mixed at a temperature of 25° C. Next, while stirring the mixture, a solution prepared by dissolving 43 g of ammonium sulfate in 980 g of deionized water and adding a 4.8 mass % aqueous solution of potassium hydroxide to adjust the pH to 8.2 was added dropwise over 10 minutes at 25° C., and the temperature was then raised to 55° C. over 2 hours to measure the volume median particle diameter D of the aggregated particles. 50 The temperature was maintained at 55° C. until the particle size reached 6.8 μm, thereby obtaining an aqueous dispersion of aggregated particles 1. [Process 2] The aqueous dispersion of aggregated particles 1 obtained in step 1 was cooled to 50°C, and while maintaining the temperature at 50°C, 75 g of resin particle dispersion Y-1 obtained in step a was added over 90 minutes, and resin particles containing amorphous polyester resin B and a styrene-based resin having an acid value of 60 mgKOH / g or more were aggregated into aggregated particles 1, thereby obtaining a dispersion of aggregated particles 2 having a core-shell structure. To the resulting aggregated particle 2 dispersion, 22 g of an aggregation terminator (polyoxyethylene lauryl ether sodium sulfate "EMAL E-27C" (Kao Corporation, anionic surfactant, solid content 27% by mass)) and 1100 g of deionized water were added. [Step 3] After the addition of the aggregation terminator, the temperature was raised to 75°C over 1 hour and maintained at 75°C until the circularity reached 0.970, thereby obtaining an aqueous dispersion of fused particles in which aggregated particles 2 were fused. [Post-processing process] The obtained aqueous dispersion of fused particles was cooled to 30°C, and the dispersion was subjected to suction filtration to separate the solids. The solids were then washed with deionized water at 25°C and suction filtrated at 25°C for 2 hours. The solids were then vacuum dried at 33°C for 24 hours using a vacuum constant temperature dryer "DRV622DA" (manufactured by ADVANTEC Corporation), yielding toner particles 1 having a core-shell structure. The physical properties of toner particles 1 are shown in Table 9. 100 parts by mass of toner particles 1, 2.5 parts by mass of hydrophobic silica "RY50" (manufactured by Nippon Aerosil Co., Ltd., number average particle size: 0.04 μm), and 1 part by mass of hydrophobic silica "Cabosil (registered trademark) TS720" (manufactured by Cabot Japan Co., Ltd., number average particle size: 0.012 μm) were placed in a Henschel mixer and stirred, and the mixture was passed through a 150 mesh sieve to obtain toner 1.

[0149] [evaluation] [Fog] Toner 1 was loaded into a non-magnetic single-component developing device "OKI MICROLINE 5400" (manufactured by OKI Electric Industry Co., Ltd.) equipped with an organic photoreceptor, and after leaving it for 12 hours in an environment with a temperature of 40°C and a relative humidity of 80%, printing was performed at a print rate of 0%. The remaining Toner 1 on the organic photoreceptor was then transferred with mending tape (manufactured by 3M Japan Ltd.), and the image density difference ΔE from the reference (before printing) was measured using a color difference meter "X-Rite" (manufactured by X-Rite) to evaluate fogging. The results are shown in Table 9. A smaller ΔE value indicates better fogging suppression.

[0150] [Durability] Toner 1 was mounted on a "MICROLINE 3010" (manufactured by Oki Electric Industry Co., Ltd.), fixing: contact fixing type, development: non-magnetic single-component development type, and a diagonal stripe pattern with a blackening rate of 5.5% was continuously printed in an environment of 25°C temperature and 50% humidity. During printing, a black solid image was printed every 500 sheets, and the presence or absence of streaks on the image was checked. Printing was stopped when streaks appeared on the image. The number of sheets on which streaks did not appear due to toner fusing and adhering to the developing roll was determined by subtracting 500 sheets from the number of printed sheets at which streaks were first visually observed on the image. In Example 1, streaks were first observed on the 8000th sheet, so the "durability (number of printed sheets)" was set to 7500. The results are shown in Table 9. The greater the number of printed sheets until streaks are first visually observed on the image, the better the durability of the toner.

[0151] Examples 2 to 12, Comparative Examples 1 and 2 (Production of Toners 2 to 12, c1, and c2) Toner particles 2 to 12, c1, c2 and toners 2 to 12, c1, c2 were produced in the same manner as in Example 1, except that the types of resin particle dispersions used were changed as shown in Table 9. Table 9 shows the physical properties of toner particles 2 to 12, c1, c2 and the evaluation results of toners 2 to 12, c1, c2.

[0152] [Table 9]

[0153] It is clear that, compared with the toners of Comparative Examples 1 and 2, which contain toner particles containing resin particles obtained without going through step 2, the toners of Examples 1 to 12 can suppress the occurrence of fogging.

Claims

1. A method for producing a toner for developing electrostatic images, comprising the following steps 1 to 3 in this order: Step 1: A step of aggregating resin particles containing an amorphous polyester resin A in an aqueous medium to obtain aggregated particles 1 Step 2: A step of aggregating resin particles containing an amorphous polyester resin B and a styrene-based resin having an acid value of 60 mgKOH / g or more to the obtained aggregated particles 1 to obtain aggregated particles 2. Step 3: A step of fusing the obtained aggregated particles 2 to obtain fused particles

2. 2. The method for producing a toner for developing electrostatic images according to claim 1, wherein the resin particles containing the amorphous polyester resin B and the styrene-based resin having an acid value of 60 mgKOH / g or more are obtained by either of the following steps a and b: Step a: adding an aqueous dispersion of styrene-based resin particles having an acid value of 60 mgKOH / g or more to an aqueous organic solvent solution of amorphous polyester resin B, and performing phase inversion emulsification to obtain resin particles containing amorphous polyester resin B and a styrene-based resin having an acid value of 60 mgKOH / g or more. Step b: adding an aqueous medium to an aqueous organic solvent solution of amorphous polyester resin B, carrying out phase inversion emulsification, and then adding and mixing an aqueous dispersion of styrene-based resin particles having an acid value of 60 mgKOH / g or more to obtain resin particles containing amorphous polyester resin B and a styrene-based resin having an acid value of 60 mgKOH / g or more.

3. 3. The method for producing a toner for developing electrostatic images according to claim 2, wherein the resin particles containing the amorphous polyester resin B and the styrene-based resin having an acid value of 60 mgKOH / g or more are obtained by the step a.

4. 3. The method for producing a toner for developing electrostatic images according to claim 1, wherein the styrene resin having an acid value of 60 mgKOH / g or more has a weight average molecular weight of 7,000 or more and 35,000 or less.

5. 4. The method for producing a toner for developing electrostatic images according to claim 2, wherein in step a or b, a mixing mass ratio of the styrene-based resin particles having an acid value of 60 mgKOH / g or more to the amorphous polyester resin B (mass of the styrene-based resin particles having an acid value of 60 mgKOH / g or more / mass of the amorphous polyester resin B) is 1 / 99 or more and 20 / 80 or less.

6. 3. The method for producing a toner for developing electrostatic images according to claim 1, wherein the amorphous polyester resin A and / or the amorphous polyester resin B contains a structural unit derived from polyethylene terephthalate.

Images