Resin particle dispersion

Abstract

This invention relates to a resin particle dispersion that exhibits excellent storage stability at low temperatures and is suitable for the manufacture of toner for electrostatic image development, and to a method for manufacturing electrostatic image development toner that can suppress the generation of coarse particles. [Solution] A resin particle dispersion liquid which is a mixed emulsion of crystalline polyester resin C and amorphous resin, wherein the crystalline polyester resin C is a polycondensate of an alcohol component and a carboxylic acid component, the ester group concentration of the crystalline polyester resin C is 6.5 mmol / g or more and 9.0 mmol / g or less, and the acid value is 3.0 mg KOH / g or more and 6.0 mg KOH / g or less.

Description

[Technical Field]

[0001] The present invention relates to a resin particle dispersion suitable for producing electrostatic image developing toner used for developing latent images formed in electrophotography, electrostatic recording, electrostatic printing, etc., a method for producing the resin particle dispersion, and a method for producing electrostatic image developing toner. [Background technology]

[0002] In the field of electrophotography, the development of electrophotographic systems has led to a demand for the development of electrophotographic toners that can handle higher image quality and higher speeds. To meet the demand for higher image quality and obtain a toner with a narrow particle size distribution, small particle size, and fast fixation that can handle high speeds, so-called chemical toners are manufactured using the emulsification agglutination method (aggregation fusion method, agglutination coalescence method), in which fine resin particles are aggregated and fused in an aqueous medium to obtain toner.

[0003] For example, Patent Document 1 provides an electrostatic image developing toner with uniform particle size and even better low-temperature fixability and blocking resistance, comprising toner particles containing a polyester resin (I) and a colorant, wherein the toner particles are formed by a process including dispersing resin particles with a volume average particle size of at least 1 μm or less in water and agglomerating the resin particles, and the polyester resin (I) is composed of a linear polyester (A) and a nonlinear polyester (B), and is a polycondensed polyester resin of a carboxylic acid component and an alcohol component containing 40 mol% or more of one or more selected from aliphatic polycarboxylic acids having 9 to 30 carbon atoms and their ester-forming derivatives, with an SP value of 9.0 to 10.5 (cal / cm²). 3 ) 1 / 2 The invention describes a method for producing a toner for electrostatic image development, characterized by containing 5% by weight or more of a crystalline polyester (A1) in (A), by emulsification and agglutination. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2010-38969 [Overview of the project] [Problems that the invention aims to solve]

[0005] In the emulsification and agglutination method, resin particles in an aqueous dispersion of resin particles (resin particle dispersion) containing amorphous and / or crystalline resins are typically agglutinated in an agglutination step, and the resulting agglutinated particles are fused together in a fusion step to obtain toner containing toner particles. In the manufacturing of toner using the emulsification and agglutination method, a resin particle dispersion is used in which toner components such as binder resins are dispersed in an aqueous medium beforehand. However, due to manufacturing considerations, the resin particle dispersion is often stored. Crystalline polyester resins, in particular, have high hydrophobicity and therefore poor dispersion stability in aqueous mediums, making it especially important to improve their storage stability at low temperatures. The present invention relates to a resin particle dispersion liquid that exhibits excellent storage stability at low temperatures and is suitable for the manufacture of toner for electrostatic image development, and to a method for manufacturing electrostatic image development toner that can suppress the generation of coarse particles. [Means for solving the problem]

[0006] The present inventors have found that by mixing a crystalline polyester resin having a specific ester group concentration and acid value with an amorphous resin and emulsifying the mixture, a resin particle dispersion with excellent storage stability at low temperatures can be obtained. Furthermore, by agglomerating and fusing the resin particles in the resin particle dispersion, the generation of coarse particles can be suppressed, resulting in a toner for electrostatic image development. The present invention relates to the following [1] to [3]. [1] A resin particle dispersion liquid which is a mixed emulsion of crystalline polyester resin C and amorphous resin, The crystalline polyester resin C is a polycondensate of an alcohol component and a carboxylic acid component. A resin particle dispersion in which the ester group concentration of crystalline polyester resin C is 6.5 mmol / g or more and 9.0 mmol / g or less, and the acid value is 3.0 mg KOH / g or more and 6.0 mg KOH / g or less. [2] A method for producing a resin particle dispersion, comprising the step of mixing and emulsifying a crystalline polyester resin C and an amorphous resin in an aqueous medium, The crystalline polyester resin C is a polycondensate of an alcohol component and a carboxylic acid component. A method for producing a resin particle dispersion in which the ester group concentration of crystalline polyester resin C is 6.5 mmol / g or more and 9.0 mmol / g or less, and the acid value is 3.0 mg KOH / g or more and 6.0 mg KOH / g or less. [3] A method for manufacturing electrostatic image developing toner, comprising the following steps 1 and 2, Step 1: A process to obtain a resin particle dispersion by mixing an amorphous resin and a crystalline polyester resin C in an aqueous medium and emulsifying them. Step 2: A process of agglomerating and fusing the resin particles in the resin particle dispersion obtained in Step 1 in an aqueous medium. The crystalline polyester resin C is a polycondensate of an alcohol component and a carboxylic acid component. A method for producing a toner for electrostatic image development, wherein the ester group concentration of the crystalline polyester resin is 6.5 mmol / g or more and 9.0 mmol / g or less, and the acid value is 3.0 mg KOH / g or more and 6.0 mg KOH / g or less. [Effects of the Invention]

[0007] The present invention provides a resin particle dispersion that exhibits excellent storage stability at low temperatures and is suitable for the manufacture of toner for electrostatic image development, and a method for manufacturing toner for electrostatic image development that can suppress the generation of coarse particles. [Modes for carrying out the invention]

[0008] [Resin particle dispersion] The resin particle dispersion of the present invention is a resin particle dispersion which is a mixed emulsion of a crystalline polyester resin C and an amorphous resin. The crystalline polyester resin C is a polycondensate of an alcohol component and a carboxylic acid component. The ester group concentration of the crystalline polyester resin C is 6.5 mmol / g or more and 9.0 mmol / g or less, and the acid value is 3.0 mgKOH / g or more and 6.0 mgKOH / g or less. The resin particle dispersion of the present invention is excellent in storage stability at low temperatures. Further, even when the resin particles in the resin particle dispersion are aggregated and fused after storing the resin particle dispersion of the present invention at low temperature for a certain period, generation of coarse particles can be suppressed, and a toner for electrostatic charge image development can be obtained. The reason for this is not clear, but it is considered as follows.

[0009] In the present invention, by using a crystalline polyester resin C having an ester group concentration of 6.5 mmol / g or more and 9.0 mmol / g or less and an acid value of 3.0 mgKOH / g or more and 6.0 mgKOH / g or less, and mixing and emulsifying the amorphous resin and the crystalline polyester resin C to obtain a resin particle dispersion, it has been found that the storage stability at low temperatures of the resin particle dispersion containing the crystalline polyester resin C is improved. By setting the ester group concentration to 6.5 mmol / g or more and 9.0 mmol / g or less, the hydrophobicity is reduced without impairing the crystallinity of the crystalline polyester C, and the miscibility with the amorphous resin is improved. Further, by controlling the acid value to 3.0 mgKOH / g or more and 6.0 mgKOH / g or less, it was possible to suppress the exposure of the crystalline polyester resin C on the surface of the mixed resin particles while maintaining the emulsifiability in the aqueous medium. Therefore, it is considered that the destabilization due to aggregation or the like between the crystalline polyester resins C, which easily occurs during storage, could be improved. Further, even when a toner is produced using the resin particle dispersion of the present invention after storing it at low temperature for a certain period, the generation of coarse particles in the aggregation step is suppressed, and the proportion of coarse particles in the obtained toner particles is low. Therefore, the production efficiency of the toner can be increased.

[0010] The definitions of various terms in this specification are shown below. In the specification, the carboxylic acid component of the polyester resin includes not only the compound itself, but also anhydrides that decompose during the reaction to produce carboxylic acids, and alkyl esters (alkyl groups having 1 to 3 carbon atoms) of each carboxylic acid. Whether the resin is crystalline or amorphous is determined by the crystallinity index. The crystallinity index is defined as the ratio of the softening point of the resin to the maximum peak temperature of endotherm in the measurement method described in the examples below (softening point (°C) / maximum peak temperature of endotherm (°C)). A crystalline resin has 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, the crystallinity index is less than 0.6 or more than 1.4. The crystallinity index can be appropriately adjusted by the types and ratios of the raw material monomers, and production conditions such as reaction temperature, reaction time, and cooling rate. Regarding the hydrocarbon group, the description with " (iso or tertiary)" and " (iso)" in parentheses means both the case where these prefixes are present and the case where they are not present. When these prefixes are not present, it indicates normal. "(Meth)acrylic acid" means at least one selected from acrylic acid and methacrylic acid. "Styrenic compound" means unsubstituted or substituted styrene.

[0011] The resin particle dispersion of the present invention is a mixed emulsion of a crystalline polyester resin C (hereinafter, also simply referred to as "resin C") and an amorphous resin, that is, an aqueous dispersion containing resin particles containing resin C and an amorphous resin in an aqueous medium. Resin C is a polycondensate of an alcohol component and a carboxylic acid component, the ester group concentration of resin C is 6.5 mmol / g or more and 9.0 mmol / g or less, and the acid value is 3.0 mgKOH / g or more and 6.0 mgKOH / g or less. Note that the resin particle dispersion may contain each component (essential components and optional components) such as the crystalline polyester resin C and the amorphous resin alone, or in combination of two or more. Also, the raw materials of each component contained in the toner particles, such as the alcohol component and the carboxylic acid component, may be used alone or in combination of two or more.

[0012] [Aqueous medium] In the present invention, the aqueous medium is a medium whose main component is water, and the water content in the aqueous medium is preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, and 100% by mass or less. Deionized water or distilled water is preferred as the water. Other components that can form an aqueous medium together with water include alkyl alcohols having 1 to 5 carbon atoms; dialkyl ketones having 3 to 5 carbon atoms such as acetone and methyl ethyl ketone; and organic solvents that dissolve in water, such as cyclic ethers such as tetrahydrofuran.

[0013] [Crystalline polyester resin C] Resin C is a polycondensate of an alcohol component and a carboxylic acid component. From the viewpoint of storage stability of the resin particle dispersion at low temperatures and suppression of the generation of coarse particles, the ester group concentration is 6.5 mmol / g or more and 9.0 mmol / g or less, and the acid value is 3.0 mg KOH / g or more and 6.0 mg KOH / g or less.

[0014] As the alcohol component, α,ω-aliphatic diols are preferred. The number of carbon atoms in the α,ω-aliphatic diol is preferably 2 or more, preferably 16 or less, more preferably 14 or less, even more preferably 12 or less, and still more preferably 10 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 and 1,9-nonanediol are preferred.

[0015] The amount of α,ω-aliphatic diol is preferably 80 mol% or more, more preferably 85 mol% or more, even more preferably 90 mol% or more, even more preferably 95 mol% or more, and 100 mol% or less, preferably 100 mol%, in the alcohol component.

[0016] The alcohol component may contain other alcohol components different from α,ω-aliphatic diols. Other alcohol components include, for example, aliphatic monoalcohols such as stearyl alcohol and behenyl alcohol; alkylene oxide adducts of aromatic diols such as alkylene oxide adducts of bisphenol A; and trivalent or higher alcohols such as glycerin, pentaerythritol, and trimethylolpropane.

[0017] As the carboxylic acid component, aliphatic dicarboxylic acids are preferred from the viewpoint of storage stability of the resin particle dispersion at low temperatures and from the viewpoint of suppressing the generation of coarse particles. The carbon number of the aliphatic dicarboxylic acid is preferably 4 or more, more preferably 16 or less, more preferably 14 or less, even more preferably 12 or less, and even more preferably 10 or less, from the viewpoint of storage stability of the resin particle dispersion at low temperatures and suppression of the generation of coarse particles. The aliphatic dicarboxylic acid is preferably α,ω-dicarboxylic acid. Specific examples of aliphatic dicarboxylic acids include succinic acid, fumaric acid, maleic acid, adipic acid, sebacic acid, 1,11-undecanediic acid, 1,12-dodecanediic acid, and 1,14-tetradecanediic acid. Among these, succinic acid, fumaric acid, maleic acid, and sebacic acid are preferred, fumaric acid, maleic acid, and sebacic acid are more preferred, and fumaric acid and sebacic acid are even more preferred.

[0018] The amount of aliphatic dicarboxylic acid is preferably 70 mol% or more, more preferably 75 mol% or more, even more preferably 80 mol% or more, even more preferably 85 mol% or more, and 100 mol% or less of the carboxylic acid component. If the carboxylic acid component includes a monocarboxylic acid, the amount is preferably 99 mol% or less, more preferably 97 mol% or less, and even more preferably 95 mol% or less.

[0019] From the viewpoint of hydrophobicity and crystallinity, the carboxylic acid component preferably contains a monocarboxylic acid. From the same viewpoint, the number of carbon atoms in the monocarboxylic acid is preferably 6 or more, more preferably 8 or more, even more preferably 12 or more, even more preferably 16 or more, and preferably 24 or less, more preferably 22 or less, and even more preferably 20 or less. Examples of monocarboxylic acids include caprylic acid, pelargonic acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, and lignoceric acid. Among these, stearic acid is preferred. When the carboxylic acid component includes a monocarboxylic acid, the amount of monocarboxylic acid is preferably 1 mol% or more, more preferably 3 mol% or more, even more preferably 5 mol% or more, and preferably 25 mol% or less, more preferably 20 mol% or less, and even more preferably 15 mol% or less, in the carboxylic acid component. The carboxylic acid component may contain other carboxylic acid components other than aliphatic dicarboxylic acids and monocarboxylic acids. Examples of other carboxylic acid components include aromatic dicarboxylic acids such as terephthalic acid and isophthalic acid; and polycarboxylic acids with a valency of three or more, such as trimellitic acid.

[0020] From the viewpoint of storage stability of the resin particle dispersion at low temperatures and the viewpoint of suppressing the generation of coarse particles, it is preferable that resin C satisfies the following conditions 1 and / or 2. Condition 1: The alcohol component contains ethylene glycol. Condition 2: The carboxylic acid component contains an α,ω-dicarboxylic acid with 4 carbon atoms. Specific examples of α,ω-dicarboxylic acids having 4 carbon atoms include succinic acid, fumaric acid, and maleic acid, with fumaric acid being preferred.

[0021] Furthermore, if resin C satisfies condition 1, the carboxylic acid component preferably contains sebacic acid, 1,11-undecanediic acid, 1,12-dodecanediic acid, and 1,14-tetradecanediic acid, and more preferably contains sebacic acid.

[0022] Furthermore, if resin C satisfies condition 2, the alcohol component preferably contains 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,13-tridecanediol, and 1,14-tetradecanediol, and more preferably contains 1,9-nonanediol.

[0023] The equivalent ratio [COOH group / OH group] of the carboxyl group of the carboxylic acid component to the hydroxyl group of the alcohol component is preferably 0.7 or higher, more preferably 0.8 or higher, and preferably 1.3 or lower, more preferably 1.2 or lower.

[0024] <Method for producing crystalline polyester resin C> Resin C can be produced, for example, by polycondensation of raw material monomers containing an alcohol component and a carboxylic acid component.

[0025] The polycondensation of the alcohol component and the carboxylic acid component can be carried out, for example, in an inert gas atmosphere, at a temperature of approximately 120°C to 250°C, in the presence of an esterification catalyst, esterification co-catalyst, polymerization inhibitor, etc., as needed. Examples of esterification catalysts include tin compounds such as dibutyltin oxide and di(2-ethylhexanoate)tin(II), and titanium compounds such as titanium diisopropoxybis(triethanolamine). Examples of esterification co-catalysts that can be used together with the esterification catalyst include gallic acid (3,4,5-trihydroxybenzoic acid). The amount of esterification catalyst used is preferably 0.01 parts by mass or more and 10 parts by mass or less, based on 100 parts by mass of the total amount of the alcohol component and carboxylic acid component, which are raw material monomers of resin C. The amount of esterification co-catalyst used is preferably 0.001 parts by mass or more and 1 part by mass or less, per 100 parts by mass of the total amount of the alcohol component and the carboxylic acid component. Examples of polymerization inhibitors include radical polymerization inhibitors such as 4-tert-butylcatechol. When a polymerization inhibitor is used, the amount of polymerization inhibitor used is preferably 0.01 parts by mass or more and 1 part by mass or less per 100 parts by mass of the total amount of the alcohol component and the carboxylic acid component.

[0026] (Physical properties of crystalline polyester resin C) From the viewpoint of storage stability of the resin particle dispersion at low temperatures and the suppression of the generation of coarse particles, resin C has an ester group concentration of 6.5 mmol / g or more, preferably 6.7 mmol / g or more, more preferably 7.0 mmol / g or more, and 9.0 mmol / g or less, preferably 8.8 mmol / g or less. The ester group concentration of resin C is calculated by the following formula.

[0027]

number

[0028] The acid value of resin C is 3.0 mg KOH / g or higher, preferably 4.0 mg KOH / g or higher, more preferably 5.0 mg KOH / g or higher, and 6.0 mg KOH / g or lower.

[0029] The softening point of resin C is preferably 55°C or higher, more preferably 60°C or higher, and even more preferably 65°C or higher. Furthermore, from the viewpoint of further improving low-temperature fixation, it is preferably 120°C or lower, more preferably 100°C or lower, and even more preferably 80°C or lower.

[0030] 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. Furthermore, from the viewpoint of further improving low-temperature fixability, it is preferably 90°C or lower, more preferably 85°C or lower, and even more preferably 80°C or lower.

[0031] The ester group concentration, acid value, softening point, and melting point of resin C can be appropriately adjusted depending on the type and amount of raw material monomer used, as well as manufacturing conditions such as reaction temperature, reaction time, and cooling rate. The softening point, melting point, and acid value can be determined by the method described in the examples. When two or more types of resin C are used in combination, it is preferable that the ester group concentration, acid value, softening point, and melting point obtained as a mixture thereof are within the aforementioned ranges.

[0032] [Amorphous resin] In the resin particle dispersion of the present invention, the resin particles include an amorphous resin in addition to resin C. The amorphous resin preferably includes, for example, an amorphous polyester resin A (hereinafter also simply referred to as "resin A") which contains a polyester resin segment that is a polycondensate of an alcohol component and a carboxylic acid component. Examples of resin A include polyester resin and modified polyester resin. Examples of modified polyester resins include urethane-modified polyester resin, epoxy-modified polyester resin, and composite resins containing a polyester resin segment and an addition polymerization resin segment. Among these, resin A is preferably a polyester resin and a composite resin, and more preferably a polyester resin.

[0033] Examples of alcohol components in resin A include aliphatic diols, alkylene oxide adducts of aromatic diols, alicyclic diols, and polyhydric alcohols of trivalent or higher. Among these, aliphatic diols and alkylene oxide adducts of aromatic diols are preferred from the viewpoint of storage stability of the resin particle dispersion at low temperatures and from the viewpoint of suppressing the generation of coarse particles, and aliphatic diols are more preferred.

[0034] The number of carbon atoms in the aliphatic diol is preferably 2 or more, more preferably 3 or more, and preferably 14 or less, more preferably 10 or less, and even more preferably 8 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, 2,2-dimethyl-1,3-propanediol (neopentyl glycol), 1,6-hexanediol, 1,8-octanediol, and 3-methyl-1,5-pentanediol, with neopentyl glycol being preferred. If the alcohol component contains an aliphatic diol, the aliphatic diol content is preferably 50 mol% or more, more preferably 80 mol% or more, even more preferably 90 mol% or more, even more preferably 95 mol% or more, and 100 mol% or less, and preferably 100 mol%.

[0035] The alkylene oxide adduct of an aromatic diol is preferably an alkylene oxide adduct of bisphenol A, and more preferably of formula (I):

[0036] [ka] (In the formula, OR 1 and R 2 O is an oxyalkylene group, R 1 and R 2 This is an alkylene oxide adduct of 2,2-bis(4-hydroxyphenyl)propane, where each is independently an ethylene group or a propylene group, x and y represent the average number of moles of alkylene oxide added, each being a positive number, and the sum of x and y is 1 or more, preferably 1.5 or more, 16 or less, preferably 8 or less, and more preferably 4 or less.

[0037] Examples of alkylene oxide adducts of bisphenol A represented by formula (I) include propylene oxide adducts of bisphenol A and ethylene oxide adducts of bisphenol A. When the alcohol component contains an alkylene oxide adduct of bisphenol A, the content of the alkylene oxide adduct of bisphenol A is preferably 50 mol% or more, more preferably 80 mol% or more, even more preferably 90 mol% or more, even more preferably 95 mol% or more, and 100 mol% or less, and preferably 100 mol%.

[0038] Examples of alicyclic diols include hydrogenated bisphenol A [2,2-bis(4-hydroxycyclohexyl)propane] and alkylene oxide adducts of hydrogenated bisphenol A with 2 to 4 carbon atoms (average number of added moles: 2 to 12).

[0039] Examples of polyhydric alcohols with a valency of 3 or higher include glycerin, pentaerythritol, trimethylolpropane, and sorbitol.

[0040] Examples of carboxylic acid components in resin A include dicarboxylic acids and polycarboxylic acids with a valency of three or more. Examples of dicarboxylic acids include aromatic dicarboxylic acids, aliphatic dicarboxylic acids, and alicyclic dicarboxylic acids. Among these, at least one selected from aromatic dicarboxylic acids and aliphatic dicarboxylic acids is preferred, with aromatic dicarboxylic acids being more preferred. Examples of aromatic dicarboxylic acids include phthalic acid, isophthalic acid, and terephthalic acid. Among these, isophthalic acid and terephthalic acid are preferred. The content of aromatic dicarboxylic acid is preferably 45 mol% or more, more preferably 55 mol% or more, even more preferably 70 mol% or more, even more preferably 85 mol% or more, even more preferably 95 mol% or more, and 100 mol% or less, in the carboxylic acid component.

[0041] The number of carbon atoms in the aliphatic dicarboxylic acid is preferably 2 or more, more preferably 3 or more, and preferably 30 or less, more preferably 20 or less. Examples of aliphatic dicarboxylic acids include oxalic acid, malonic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, succinic acid, adipic acid, sebacic acid, dodecanediic acid, azelaic acid, and succinic acid substituted with an aliphatic hydrocarbon group. Examples of succinic acid substituted with an aliphatic hydrocarbon group include dodecyl succinic acid, dodecenyl succinic acid, and octenyl succinic acid. Among these, fumaric acid, succinic acid, sebacic acid, adipic acid, and succinic acid substituted with an aliphatic hydrocarbon group are preferred, with fumaric acid being more preferred. When the carboxylic acid component contains an aliphatic dicarboxylic acid, the content of the aliphatic dicarboxylic acid is preferably 20 mol% or more, more preferably 30 mol% or more, even more preferably 40 mol% or more, and preferably 60 mol% or less, more preferably 55 mol% or less, in the carboxylic acid component.

[0042] Examples of alicyclic dicarboxylic acids include cyclohexanedicarboxylic acid.

[0043] Preferably, the polycarboxylic acid with a valency of 3 or higher is a trivalent carboxylic acid, such as trimellitic acid.

[0044] The equivalent ratio [COOH group / OH group] of the carboxyl group of the carboxylic acid component to the hydroxyl group of the alcohol component is preferably 0.7 or higher, more preferably 0.8 or higher, and preferably 1.3 or lower, more preferably 1.2 or lower.

[0045] When resin A is a composite resin, for example, a composite resin described in Japanese Patent Publication No. 2024-25642 can be used, and examples of addition polymerization resin segments include addition polymers of raw material monomers containing styrene compounds. Styrene compounds are either unsubstituted or substituted styrene. Examples of substituents that can be substituted for styrene include alkyl groups having 1 to 5 carbon atoms, halogen atoms, alkoxy groups having 1 to 5 carbon atoms, sulfonic acid groups, or salts thereof. Examples of styrene-based compounds include styrene, methylstyrene, α-methylstyrene, β-methylstyrene, tert-butylstyrene, chlorostyrene, chloromethylstyrene, methoxystyrene, styrene sulfonic acid, or salts thereof. Among these, styrene is preferred.

[0046] As raw material monomers other than styrene compounds, raw material monomers other than styrene compounds described in Japanese Patent Publication No. 2024-25642 can be used, and alkyl (meth)acrylate is preferred. The number of carbon atoms in the alkyl group of alkyl (meth)acrylate is preferably 1 or more, more preferably 4 or more, even more preferably 6 or more, and preferably 24 or less, more preferably 22 or less, and even more preferably 20 or less. The alkyl (meth)acrylate is preferably 2-ethylhexyl (meth)acrylate or stearyl (meth)acrylate, more preferably 2-ethylhexyl (meth)acrylate, and even more preferably 2-ethylhexyl acrylate.

[0047] The content of styrene compounds in the raw material monomers of the addition polymerization resin segment is preferably 50% by mass or more, more preferably 65% ​​by mass or more, and even more preferably 75% by mass or more. Furthermore, the total amount of styrene compounds and (meth)acrylic acid esters in the raw material monomers of the addition polymerization resin segment is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and 100% by mass or less, and preferably 100% by mass.

[0048] The composite resin, similar to the composite resin described in Japanese Patent Application Publication No. 2024-25642, preferably has constituent units derived from both reactive monomers that are covalently bonded to a polyester resin segment and an addition polymerization resin segment. As the reactive monomers, addition polymerizable monomers having a carboxyl group are preferred. As addition polymerizable monomers having a carboxyl group, acrylic acid and methacrylic acid are preferred, with acrylic acid being more preferred.

[0049] The polyester resin segment content in the composite resin is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more. The total amount of polyester resin segments and addition polymerization resin segments in the composite resin is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and 100% by mass or less, and preferably 100% by mass. The above content is calculated based on the polyester resin segment content of the constituent units derived from both reactive monomers. The above amount is calculated in the same manner as the composite resin described in Japanese Patent Publication No. 2024-25642.

[0050] <Method for producing amorphous polyester resin A> (Method for producing amorphous polyester resin) If resin A is an amorphous polyester resin, resin A can be produced by polycondensation of raw material monomers containing alcohol and carboxylic acid components, similar to the method for producing resin C.

[0051] (Method of manufacturing composite resin) The composite resin can be manufactured, for example, by referring to the method for manufacturing resin A1 described in Japanese Patent Publication No. 2024-25642.

[0052] (Physical properties of amorphous polyester resin A) The acid value of resin A is preferably 5 mg KOH / g or more, more preferably 10 mg KOH / g or more, even more preferably 15 mg KOH / g or more, and preferably 35 mg KOH / g or less, more preferably 30 mg KOH / g or less, and even more preferably 25 mg KOH / g or less, from the viewpoint of storage stability of the resin particle dispersion.

[0053] 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 storage stability of the resin particle dispersion, and 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 of the toner.

[0054] The glass transition temperature of resin A is preferably 40°C or higher, more preferably 45°C or higher, and even more preferably 50°C or higher, from the viewpoint of storage stability of the resin particle dispersion, and preferably 75°C or lower, more preferably 70°C or lower, and even more preferably 65°C or lower, from the viewpoint of low-temperature fixability of the toner.

[0055] The acid value, softening point, glass transition temperature, and weight-average molecular weight of resin A can be appropriately adjusted depending on the type and amount of raw material monomer used, as well as manufacturing conditions such as reaction temperature, reaction time, and cooling rate. These values ​​can be determined by the method described in the examples. Furthermore, when using two or more types of resin A in combination, it is preferable that at least one of them falls within the range of the above physical properties. Moreover, it is even more preferable that the acid value, softening point, crystallinity index, glass transition temperature, and weight-average molecular weight obtained from the mixture thereof are all within the above ranges.

[0056] The solid content concentration of the resin particle dispersion is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 15% by mass or more, and preferably 45% by mass or less, more preferably 35% by mass or less, and even more preferably 25% by mass or less, from the viewpoint of improving toner productivity, ensuring storage stability of the resin particle dispersion at low temperatures, and suppressing the generation of coarse particles. Note that the solid content represents the total amount of non-volatile components.

[0057] The total content of resin C and amorphous resin in the resin particles is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and 100% by mass or less, and preferably 100% by mass, from the viewpoint of storage stability of the resin particle dispersion at low temperatures and from the viewpoint of suppressing the generation of coarse particles.

[0058] The mass ratio of resin C to amorphous resin in the resin particles [resin C / amorphous resin] is preferably 1 / 99 or more, more preferably 3 / 97 or more, even more preferably 5 / 95 or more, even more preferably 10 / 90 or more, even more preferably 15 / 85 or more, and preferably 40 / 60 or less, more preferably 30 / 70 or less, and even more preferably 25 / 75 or less.

[0059] The content of resin A in the amorphous resin is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and 100% by mass or less, and preferably 100% by mass, from the viewpoint of storage stability of the resin particle dispersion at low temperatures and from the viewpoint of suppressing the generation of coarse particles.

[0060] Volume-average particle size D of resin particles immediately after manufacturing of resin particle dispersion V From the viewpoint of storage stability of the resin particle dispersion at low temperatures and from the viewpoint of suppressing the generation of coarse particles, the particle size is preferably 50 nm or more, more preferably 100 nm or more, even more preferably 150 nm or more, and preferably 300 nm or less, more preferably 230 nm or less. The CV value of the resin particles immediately after manufacturing the resin particle dispersion is preferably 10% or more, more preferably 20% or more, from the viewpoint of ease of manufacturing, and preferably 50% or less, from the viewpoint of obtaining good image quality. Volume average particle size D of resin particles V The CV value is determined by the method described in the examples.

[0061] [Method for producing resin particle dispersion] In the method for producing a resin particle dispersion of the present invention, a crystalline polyester resin C and an amorphous resin are mixed in an aqueous medium and emulsified.

[0062] The "crystalline polyester resin C," "amorphous resin," and "aqueous medium" used in the method for producing the resin particle dispersion of the present invention are synonymous with the "crystalline polyester resin C," "amorphous resin," and "aqueous medium" described in the description of the resin particle dispersion of the present invention, respectively.

[0063] The method for emulsifying a crystalline polyester resin C and an amorphous resin in an aqueous medium can be carried out by known methods, and the phase inversion emulsification method is preferred. Examples of the phase inversion emulsification method include adding an aqueous medium to an organic solvent solution of the resin or to a molten resin and then emulsifying it. The method of adding an aqueous medium to an organic solvent solution of the resin and then emulsifying it 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, but an example is methyl ethyl ketone. It is preferable to add a neutralizing agent to the organic solvent solution of the resin. 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. The degree of neutralization of the resin contained in the resin particles is preferably 10 mol% or more, more preferably 30 mol% or more, even more preferably 50 mol% or more, and preferably 100 mol% or less, more preferably 90 mol% or less, and even more preferably 80 mol% or less. The degree of neutralization of the resin contained in the resin particles can be determined by the following formula. Degree of neutralization (mol%) = [{Mass of neutralizing agent added (g) / Equivalent amount of neutralizing agent} / [{Weighted average acid value of resin contained in resin particles (mgKOH / g) × Mass of resin contained in resin particles (g)} / (56 × 1000)]] × 100

[0064] While stirring the organic solvent solution or molten resin, gradually add an aqueous medium to induce phase inversion. When adding an aqueous medium, the temperature of the organic solvent solution is preferably 50°C or higher, more preferably 60°C or higher, even more preferably 70°C or higher, and preferably 100°C or lower, more preferably 90°C or lower, and even more preferably 80°C or lower, from the viewpoint of improving the dispersion stability of the resin particles.

[0065] After phase inversion emulsification, the organic solvent may be removed from the resulting aqueous dispersion by distillation or other means, if necessary. In this case, the amount of residual organic solvent is preferably 1% by mass or less, more preferably 0.5% by mass or less, and even more preferably substantially 0% by mass in the aqueous dispersion.

[0066] [Manufacturing method for toner for electrostatic image development] The present invention provides a method for producing electrostatic image developing toner containing toner particles (hereinafter also referred to as "the toner production method of the present invention"), which comprises the following steps 1 and 2 in this order. Step 1: A process to obtain a resin particle dispersion by mixing amorphous resin and crystalline polyester resin C in an aqueous medium and emulsifying them. Step 2: A process of agglomerating and fusing the resin particles in the resin particle dispersion obtained in Step 1 in an aqueous medium. The crystalline polyester resin C is a polycondensate of an alcohol component and a carboxylic acid component. The crystalline polyester resin has an ester group concentration of 6.5 mmol / g or more and 9.0 mmol / g or less, and an acid value of 3.0 mg KOH / g or more and 6.0 mg KOH / g or less. Furthermore, each component (essential component and optional component) used in the toner manufacturing method of the present invention may be used individually or in combination of two or more.

[0067] [Process 1] In step 1, it is preferable to obtain the resin particle dispersion in the same manner as described in the "Method for Producing Resin Particle Dispersion".

[0068] [Process 2] In step 2, toner particles are obtained by agglomerating and fusing the resin particles in the resin particle dispersion obtained in step 1. That is, agglomerated particles are obtained by agglomerating the resin particles in the resin particle dispersion obtained in step 1, and toner particles are obtained by fusing the agglomerated particles.

[0069] From the viewpoint of manufacturing toner, in step 2, it is preferable to agglomerate at least one of the colorant and the release agent together with the resin, and it is more preferable to mix the resin particle dispersion with the colorant particle dispersion and / or the release agent particle dispersion to agglomerate these particles.

[0070] The total content of resin C and amorphous resin in the toner particles is preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, and preferably 98% by mass or less, more preferably 95% by mass or less, and even more preferably 90% by mass or less. The content of resin C in the toner particles is preferably 1% by mass or more, more preferably 5% by mass or more, even more preferably 7% by mass or more, and preferably 40% by mass or less, more preferably 30% by mass or less, and even more preferably 25% by mass or less. The mass ratio of resin C to amorphous resin in toner particles [resin C / amorphous resin] is preferably 1 / 99 or more, more preferably 3 / 97 or more, even more preferably 5 / 95 or more, even more preferably 10 / 90 or more, even more preferably 15 / 85 or more, and preferably 40 / 60 or less, more preferably 30 / 70 or less, and even more preferably 25 / 75 or less.

[0071] [Coloring agents] As a coloring agent, all dyes, pigments, etc. used as coloring agents for toners can be used. Examples of colorants include carbon black, phthalocyanine blue, permanent brown FG, brilliant first scarlet, pigment green B, rhodamine-B base, solvent red 49, solvent red 146, solvent blue 35, quinacridone, carmine 6B, and disazo yellow. The toner may be either black toner or a color toner other than black. The colorant content in the toner particles is preferably 1% by mass or more, more preferably 4% by mass or more, and preferably 20% by mass or less, more preferably 15% by mass or less, and even more preferably 10% by mass or less.

[0072] <Coloring agent particle dispersion liquid> The colorant particle dispersion is preferably obtained by dispersing the colorant and an aqueous medium using a disperser such as a homomixer, homogenizer, or ultrasonic disperser. From the viewpoint of improving the dispersion stability of the colorant, this dispersion is preferably carried out in the presence of a surfactant. Furthermore, the dispersion of the colorant particles may be carried out in the presence of an addition polymer E, from the viewpoint of improving the dispersion stability of the colorant. The addition polymer E preferably has constituent units derived from an addition polymerizable monomer a having an aromatic group, and more 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 a colorant particle dispersion using the addition polymer E, refer to the addition polymer E described in Japanese Patent Application Publication No. 2024-25642.

[0073] Examples of surfactants for improving the dispersion stability of a colorant include, for example, nonionic surfactants, anionic surfactants, and cationic surfactants. From the perspective of improving the dispersion stability of colorant particles, a nonionic surfactant is preferably used. Examples of nonionic surfactants include polyoxyalkylene alkyl ethers, polyoxyalkylene alkenyl ethers, and polyoxyalkylene aryl ethers. Among these, polyoxyethylene aryl ethers are preferred, and polyoxyethylene distyrylated phenyl ether is more preferred.

[0074] From the perspective of improving the dispersion stability of the colorant, the content of the surfactant in the colorant particle dispersion is preferably 1 part by mass or more, more preferably 5 parts by mass or more, still more preferably 10 parts by mass or more, and preferably 50 parts by mass or less, more preferably 45 parts by mass or less, still more preferably 40 parts by mass or less, based on 100 parts by mass of the colorant.

[0075] In the colorant particle dispersion, the colorant is preferably 5% by mass or more, more preferably 10% by mass or more, and preferably 50% by mass or less, more preferably 30% by mass or less, still more preferably 25% by mass or less. The solid content concentration of the colorant particle dispersion is preferably 5% by mass or more, more preferably 10% by mass or more, still more preferably 15% by mass or more, and preferably 50% by mass or less, more preferably 40% by mass or less, still more preferably 30% by mass or less.

[0076] The volume median diameter D of the colorant particles 50 is preferably 0.05 μm or more, more preferably 0.08 μm or more, and preferably 0.4 μm or less, more preferably 0.3 μm or less, still more preferably 0.2 μm or less, from the perspective of improving the dispersibility in toner particles. The CV value of the colorant particles is preferably 10% or more, more preferably 15% or more, and preferably 40% or less, more preferably 35% or less, still more preferably 30% or less, from the perspective of improving the dispersibility in toner particles. Volume-intermediate particle size D of colorant particles 50 The CV value is measured by the method of the example.

[0077] The amount of coloring agent particles is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and even more preferably 4 parts by mass or more, per 100 parts by mass of resin particles, from the viewpoint of improving dispersibility in toner particles, and preferably 25 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 15 parts by mass or less.

[0078] [Release agent] Examples of release agents include hydrocarbon waxes or oxides thereof such as polypropylene wax, polyethylene wax, ethylene propylene copolymer wax, microcrystalline wax, paraffin wax, and Fischer-Tropsch wax; ester waxes such as carnauba wax, montane wax or their deoxidizing waxes, and fatty acid ester waxes; and fatty acid amides, fatty acids, higher alcohols, and fatty acid metal salts.

[0079] The melting point of the release agent is preferably 60°C or higher, more preferably 70°C or higher, and more preferably 160°C or lower, more preferably 140°C or lower, even more preferably 120°C or lower, and even more preferably 100°C or lower. The release agent content is preferably 0.1% by mass or more, more preferably 1% by mass or more, even more preferably 3% by mass or more, and preferably 25% by mass or less, more preferably 15% by mass or less, and even more preferably 10% by mass or less, in the toner particles.

[0080] <Release agent particle dispersion> While a release agent particle dispersion can be obtained using a surfactant, it is preferable to obtain it by mixing the release agent and resin particles. By preparing release agent particles using the release agent and resin particles, the release agent particles are stabilized by the resin constituting the resin particles, making it possible to disperse the release agent in an aqueous medium without using a surfactant. In the release agent particle dispersion, it is thought that the release agent particles have a structure in which many resin particles are attached to the surface. The resin constituting the resin particles that disperse the mold release agent is preferably a polyester resin, and more preferably a composite resin D having polyester resin segments and addition polymerization resin segments. For details on the mold release agent particle dispersion and composite resin D, please refer to Japanese Patent Application Publication No. 2024-25642. Alternatively, the aforementioned amorphous polyester resin A may be used.

[0081] Release agent particle volume median particle size D 50 From the viewpoint of obtaining uniform aggregated particles through aggregation, the particle size is preferably 0.05 μm or larger, more preferably 0.1 μm or larger, even more preferably 0.15 μm or larger, and preferably 1 μm or smaller, more preferably 0.8 μm or smaller, and even more preferably 0.5 μm or smaller. The CV value of the release agent particles is preferably 10% or more, more preferably 15% or more, and preferably 50% or less. Release agent particle volume median particle size D 50 The CV value is measured by the method described in the examples.

[0082] The amount of release agent particles is preferably 0.3 parts by mass, more preferably 1 part by mass or more, even more preferably 2 parts by mass or more, per 100 parts by mass of resin particles, from the viewpoint of improving dispersibility in toner particles, and preferably 30 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 15 parts by mass or less.

[0083] In step 2, other additives such as charge control agents, magnetic powders, fluidity improvers, conductivity modifiers, reinforcing fillers such as fibrous materials, antioxidants, anti-aging agents, and cleaning properties improvers may also be used.

[0084] <Agglutinant> In the process of agglomerating resin particles, it is preferable to add a flocculant from the viewpoint of efficiently carrying out the agglomeration. Examples of flocculants include cationic surfactants such as quaternary salts, organic flocculants such as polyethyleneimine, and inorganic flocculants. Examples of inorganic flocculants 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 metal complexes with a valency of 2 or higher. From the viewpoint of improving cohesiveness and obtaining uniform aggregated particles, inorganic flocculants with a valency of 1 to 5 are preferred, inorganic metal salts and inorganic ammonium salts with a valency of 1 to 2 are more preferred, inorganic ammonium salts are even more preferred, and ammonium sulfate is even more preferred.

[0085] Using a flocculant, for example, 5 to 50 parts by mass of a flocculant per 100 parts by mass of resin particles is added to a mixed dispersion containing resin particles, release agent particles, and colorant particles at a temperature of 0°C to 40°C, and the resin particles, release agent particles, and colorant particles are flocculated in an aqueous medium to obtain flocculated particles 1. Furthermore, from the viewpoint of promoting flocculation, it is preferable to raise the temperature of the dispersion after adding the flocculant.

[0086] Volume-intermediate particle size D of aggregated particle 1 50 The particle size is preferably 2 μm or more, more preferably 3 μm or more, even more preferably 4 μm or more, and preferably 10 μm or less, more preferably 8 μm or less, and even more preferably 7 μm or less.

[0087] In the present invention, the process may include a step of using the obtained aggregated particle 1 as a core, attaching and agglomerating shell resin particles to it, and obtaining aggregated particle 2. By including a step of agglomerating the shell resin particles, toner particles having a core-shell structure can be obtained. The resin particles for the shell are preferably amorphous resins, and more preferably amorphous polyester resins. The resin particle dispersion for the shell is obtained by the same method as the method for producing the resin particle dispersion described above. The mass ratio of shell resin particles to the mass of aggregated particles 1 [shell resin particles / aggregated particles 1] is preferably 1 / 99 or more, more preferably 3 / 97 or more, even more preferably 5 / 95 or more, and preferably 25 / 75 or less, more preferably 20 / 80 or less, and even more preferably 15 / 85 or less, from the viewpoint of toner's low-temperature fixation properties.

[0088] Methods for stopping aggregation include cooling the dispersion, adding an aggregation inhibitor, and diluting the dispersion. From the viewpoint of reliably preventing unnecessary aggregation, the method of stopping aggregation by adding an aggregation inhibitor is preferred. That is, aggregation should be stopped when the aggregated particles 1 have grown to an appropriate particle size, and if the toner manufacturing method includes a step of agglomerating shell resin particles, aggregation should be stopped in that step when the aggregated particles 2 have grown to an appropriate particle size as toner particles.

[0089] <Agglutination inhibitor> As a flocculation inhibitor, surfactants are preferred, and anionic surfactants are more preferred. Examples of anionic surfactants include alkylbenzene sulfonates, alkyl sulfates, alkyl ether sulfates, polyoxyalkylene alkyl ether sulfates, aryl sulfonates, and aryl sulfonic acid formalin condensates. The flocculation inhibitor may be added in aqueous solution. From the viewpoint of reliably preventing unnecessary aggregation, the amount of aggregation inhibitor added is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, per 100 parts by mass of aggregated particles immediately before adding the aggregation inhibitor, and from the viewpoint of reducing residue in the toner, it is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and even more preferably 10 parts by mass or less.

[0090] The resulting aggregated particles are fused together in an aqueous medium, fusing each individual particle within the aggregated particles to obtain fused particles. In the fusion process, from the viewpoint of improving the fusion properties of the aggregated particles and improving the productivity of the toner, it is preferable to maintain the aggregated particles at a temperature above the glass transition temperature of the amorphous resin with the highest glass transition temperature among those contained in the aggregated particles. The holding temperature for fusing aggregated particles is preferably 5°C or higher, more preferably 10°C or higher, than the glass transition temperature of the resin having the highest glass transition temperature among amorphous resins, and more preferably 30°C or lower, more preferably 25°C or lower, and even more preferably 20°C or lower, than the glass transition temperature of the resin having the highest glass transition temperature among amorphous resins, from the viewpoint of improving the fusion properties of aggregated particles and improving the productivity of toner. In this case, the time for holding the amorphous resin at a temperature above its glass transition temperature is preferably 1 minute or more, more preferably 10 minutes or more, even more preferably 30 minutes or more, and preferably 240 minutes or less, more preferably 180 minutes or less, even more preferably 120 minutes or less, and even more preferably 90 minutes or less, from the viewpoint of improving toner productivity. Furthermore, it is preferable to maintain the temperature mentioned above until the desired degree of circularity is achieved.

[0091] Volume median particle size D of fused particles obtained by fusion bonding 50 The particle size is preferably 2 μm or more, more preferably 3 μm or more, even more preferably 4 μm or more, and preferably 10 μm or less, more preferably 8 μm or less, and even more preferably 7 μm or less.

[0092] The circularity of the fused particles obtained by fusion is preferably 0.955 or higher, more preferably 0.960 or higher, even more preferably 0.965 or higher, and preferably 0.990 or lower, more preferably 0.985 or lower, and even more preferably 0.980 or lower. It is preferable to terminate the fusion process after achieving the desired degree of circularity described above. The roundness is measured by the method described in the examples.

[0093] [Post-processing steps] A post-processing step may be performed after the fusion step, and toner particles can be obtained by isolating the fused particles. Since the fused particles obtained in the fusion step are present in an aqueous medium, it is preferable to first perform solid-liquid separation. Suction filtration or the like is preferably used for solid-liquid separation. It is preferable to perform washing after solid-liquid separation. At this time, it is also preferable to remove the added surfactant, so it is preferable to wash with an aqueous medium at a temperature below the cloud point of the surfactant. It is preferable to perform washing multiple times. Next, drying is preferable. Examples of drying methods include vacuum constant temperature drying, vibratory fluidized bed drying, spray drying, freeze drying, and flash jet drying.

[0094] Volume-intermediate particle size D of toner particles 50 From the viewpoint of further improving the cleaning performance 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 preferably 10 μm or less, more preferably 8 μm or less, and even more preferably 7 μm or less.

[0095] The circularity of the toner particles is preferably 0.955 or higher, more preferably 0.960 or higher, even more preferably 0.965 or higher, and preferably 0.990 or lower, more preferably 0.985 or lower, and even more preferably 0.980 or lower. Volume-intermediate particle size D of toner particles 50 This can be measured by the method described in the examples. The circularity of the toner particles can be measured in the same manner as the circularity of the fused particles.

[0096] [Toner for developing electrostatic images] The electrostatic image developing toner obtained by the toner manufacturing method of the present invention contains toner particles. While toner particles can be used as toner as is, it is preferable to use toner that has been treated by adding fluidizing agents or the like as external additives to the surface of the toner particles.

[0097] [External additives] Examples of external additives include fine particles of inorganic materials such as hydrophobic silica, titanium dioxide, alumina, cerium oxide, and carbon black, as well as polymer fine particles such as polycarbonate, polymethyl methacrylate, and silicone resin. Among these, hydrophobic silica is preferred. External additives may be used individually or in combination of two or more. In addition, two or more types of hydrophobic silica with different particle sizes may be used. When surface treatment of toner particles is performed using an external additive, the amount of external additive added is preferably 1 part by mass or more, more preferably 2 parts by mass or more, even more preferably 3 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, per 100 parts by mass of toner particles.

[0098] The toner obtained by the manufacturing method of the present invention is used in electrophotographic printing for electrostatic image development. The toner obtained by the manufacturing method of the present invention can be used, for example, as a one-component developer, or mixed with a carrier to form a two-component developer. [Examples]

[0099] The present invention will be specifically described below with reference to examples, but the present invention is not limited in any way by these examples. Each property value was measured and evaluated by the following method. In notations such as "alkylene oxide (X)," the number X in parentheses represents the average number of moles of alkylene oxide added.

[0100] [Measurement or calculation method] [Concentration of ester groups in resins] It was calculated using the formula described above.

[0101] [Acid value of resins] (1) Acid value of crystalline resin The measurement was performed according to the method of JIS K0070:1992. However, the measurement solvent was changed from the mixed solvent of ethanol and ether specified in JIS K0070:1992 to tetrahydrofuran. (2) Acid value of amorphous resin The measurements were performed according to the method of JIS K0070:1992. However, the measurement solvent was changed from the mixed solvent of ethanol and ether specified in JIS K0070:1992 to a mixed solvent of acetone and toluene (acetone:toluene = 1:1 (volume ratio)).

[0102] [Softening point, crystallinity index, melting point, and glass transition temperature of resins] (1) Softening point Using a flow tester "CFT-500EX" (manufactured by Shimadzu Corporation), 1 g of sample was heated at a heating rate of 6°C / min while a load of 1.96 MPa was applied by a plunger, and the sample was extruded from a nozzle with a diameter of 1 mm and a length of 1 mm. The amount of plunger descent of the flow tester was plotted against temperature, and the temperature at which half of the sample flowed out was defined as the softening point. (2) Crystallinity index Using a differential scanning calorimeter "Q100" (manufactured by T.A. Instruments Japan Co., Ltd.), 0.02 g of the sample was weighed into an aluminum pan and cooled to 0°C at a cooling rate of 10°C / min. The temperature was then maintained for 1 minute, and then the temperature was increased to 180°C at a heating rate of 10°C / min, and the amount of heat was measured. Among the observed endothermic peaks, the temperature of the peak with the largest peak area was defined as the maximum endothermic peak temperature (1), and the crystallinity index was determined by (softening point (°C)) / (maximum endothermic peak temperature (1) (°C)). (3) Melting point and glass transition temperature Using a differential scanning calorimeter "Q100" (manufactured by T.A. Instruments Japan Co., Ltd.), 0.02 g of the 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 again at a rate of 10°C / min, and the amount of heat was measured. Among the observed endothermic peaks, the temperature of the peak with the largest peak area was defined as the maximum endothermic peak temperature (2). For crystalline resins, this peak temperature was defined as the melting point. Furthermore, in the case of amorphous resins, if a peak was observed, the temperature of that peak was defined as the glass transition temperature. If no peak was observed but a step was observed, the temperature at the intersection of the tangent line showing the maximum slope of the curve in the step portion and the extension of the baseline on the low-temperature side of the step was defined as the glass transition temperature.

[0103] [Melting point of release agent] Using a differential scanning calorimeter "Q100" (manufactured by T.A. Instruments Japan Co., Ltd.), 0.02 g of the 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. Next, the sample was heated again at a rate of 10°C / min, the amount of heat was measured, and the maximum peak temperature of endothermic reaction was defined as the melting point.

[0104] [Volume median particle size D of resin particles, release agent particles, and colorant particles] 50 [Volume-average particle size Dv and / or CV value] (1) Measuring device: Laser diffraction particle size analyzer "LA-920" (manufactured by Horiba, Ltd.) (2) Measurement conditions: Take the sample dispersion into a measuring cell, add distilled water, and adjust the concentration to the appropriate range for absorbance, using a volume-average particle size D. 50 The volume-average particle size Dv was measured. The CV value (coefficient of variation (particle size distribution)) was calculated according to the following formula. CV value (%) = (Standard deviation of particle size distribution / Volume-average particle size Dv) × 100

[0105] [Solid content concentration of resin particle dispersion, colorant particle dispersion, and mold release agent particle dispersion] Using an infrared moisture meter "FD-230" (manufactured by Kett Scientific Research Institute Co., Ltd.), the moisture content (mass%) of a 5g 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%)

[0106] [Volume-intermediate particle size D of aggregated particles] 50 ] • Measuring instrument: "Coulter Multisizer (registered trademark) III" (manufactured by Beckman Coulter, Inc.) • Aperture diameter: 50 μm • Analysis software: "Multisizer (registered trademark) III version 3.51" (manufactured by Beckman Coulter, Inc.) • Electrolyte: "Isoton (registered trademark) II" (manufactured by Beckman Coulter, Inc.) • Measurement conditions: The sample dispersion was added to 100 mL of the electrolyte solution to adjust the concentration so that the particle size of 30,000 particles could be measured in 20 seconds. Then, 30,000 particles were measured again, and the volume median particle size D was determined from the particle size distribution. 50 They sought it.

[0107] [Circularity of fused particles] • Measurement device: Flow-type particle image analyzer "FPIA-3000" (manufactured by Sysmex Corporation) • Preparation of dispersion: The dispersion of fused particles was prepared by diluting it with deionized water to a solid content concentration of 0.001 to 0.05% by mass. • Measurement mode: Circularity was measured using HPF measurement mode.

[0108] [Toner particle volume median particle size D] 50 ] The measuring device, aperture diameter, analysis software, and electrolyte are the volume median particle size D of the aggregated particles as described above. 50 The same equipment used in the measurement was employed. • Dispersion: Polyoxyethylene lauryl ether "Emulgen® 109P" (manufactured by Kao Corporation, HLB (Hydrophile-Lipophile Balance) = 13.6) was dissolved in the electrolyte to obtain a dispersion with a concentration of 5% by mass. • Dispersion conditions: 10 mg of the measurement sample of dried toner particles was added to 5 mL of the dispersion, dispersed for 1 minute using an ultrasonic disperser, then 25 mL of the electrolyte was added, and dispersed for another minute using an ultrasonic disperser to prepare the sample dispersion. • Measurement conditions: The sample dispersion is added to 100 mL of the electrolyte to adjust the concentration to a level that allows for the measurement of 30,000 particle sizes in 20 seconds. Then, 30,000 particles are measured, and the volume median particle size D is determined from the particle size distribution. 50 They sought it.

[0109] [Resin manufacturing] Manufacturing Examples C1-C3, C'5-C'7 (Manufacturing of crystalline polyester resins C-1-C-3, C'-5-C'-7) The polyester resin raw material monomers shown in Table 1 were placed in a 10-liter four-necked flask equipped with a thermometer, stainless steel stirring rod, a drop-flow condenser with a dewatering tube, and a nitrogen inlet tube. Under a nitrogen atmosphere, the mixture was heated to 220°C over 8 hours in a mantle heater while stirring. Subsequently, an esterification catalyst was added, and the mixture was heated to 210°C over 1 hour. The reaction was then carried out at 8.0 kPa until the acid value shown in Table 1 was reached, yielding crystalline polyester resin (resins C-1 to C3, C'-5 to C'-7). The physical properties are shown in Table 1.

[0110] Manufacturing example C4 (crystalline polyester resin C-4) The raw material monomers and polymerization inhibitors for the polyester resin shown in Table 1 were placed in a 10-liter four-necked flask equipped with a thermometer, stainless steel stirring rod, a fall-flow condenser, and a nitrogen inlet tube. The mixture was heated to 200°C over 8 hours in a mantle heater under a nitrogen atmosphere. Subsequently, an esterification catalyst was added, and the reaction was carried out at 8.0 kPa until the acid value shown in Table 1 was reached, yielding a crystalline polyester resin (resin C-4). The physical properties are shown in Table 1.

[0111] [Table 1]

[0112] Manufacturing Example A1 (Manufacturing of Amorphous Polyester Resin A-1) The raw material monomers for polyester resins other than isophthalic acid, and the esterification catalyst shown in Table 2, were placed in a 10-liter four-necked flask equipped with a thermometer, a stainless steel stirring rod, a dehydration tube, a fall-flow condenser with a fractional distillation tube through which 96°C hot water was passed, and a nitrogen inlet tube. The reaction system was heated in a mantle heater under a nitrogen atmosphere with stirring, at 180°C for 1 hour, then the temperature was increased from 180°C to 230°C at 10°C / h, and then held at 230°C for 5 hours. After cooling to 180°C, isophthalic acid was added, the temperature was increased from 180°C to 230°C at 10°C / h, and the reaction was carried out at 230°C for 1 hour. The reaction was then carried out at 230°C and 10 kPa until the softening point shown in Table 2 was reached to obtain amorphous polyester resin (resin A-1). The physical properties are shown in Table 2.

[0113] Manufacturing example A2 (Amorphous polyester resin A-2) The raw material monomers for polyester resins other than fumaric acid, and the esterification catalyst shown in Table 2, were placed in a 10-liter four-necked flask equipped with a thermometer, a stainless steel stirring rod, a drop-flow condenser with a dewatering tube, and a nitrogen inlet tube. The reaction system was heated to 235°C in a mantle heater under a nitrogen atmosphere with stirring, held for 4 hours, and then held at 8.0 kPa for 1 hour. After cooling to 180°C, fumaric acid and a polymerization inhibitor were added, and the temperature was raised from 180°C to 210°C at 10°C / h. The reaction was carried out at 210°C for 1 hour, and then at 210°C and 10 kPa until the softening point shown in Table 2 was reached to obtain amorphous polyester resin (resin A-2). The physical properties are shown in Table 2.

[0114] Manufacturing example A3 (Amorphous polyester resin A-3) The raw material monomers for polyester resins other than fumaric acid, and the esterification catalyst shown in Table 2, were placed in a 10-liter four-necked flask equipped with a thermometer, a stainless steel stirring rod, a drop-flow condenser with a dehydration tube, and a nitrogen inlet tube. The reaction system was heated to 235°C in a mantle heater under a nitrogen atmosphere with stirring, held for 4 hours, and then maintained at 8.0 kPa for 1 hour. After that, the temperature was lowered to 160°C, and a mixture of both reactive monomers, raw material monomers for vinyl resin segments, and polymerization initiators was added dropwise over 1 hour using a dropping funnel. After the dropwise addition, the addition polymerization reaction was allowed to mature for 1 hour while maintaining the temperature at 160°C, then the temperature was raised to 200°C and the pressure was reduced to 10 kPa for 1 hour. After opening the pressure, the mixture was cooled to 180°C, and the fumaric acid and polymerization inhibitor shown in Table 2 were added. The temperature was then raised from 180°C to 210°C at a rate of 10°C / h, and the reaction was carried out at 210°C for 1 hour. Finally, the reaction was continued at 210°C and 10 kPa until the softening point shown in Table 2 was reached to obtain the composite resin (resin A-3). The physical properties are shown in Table 2.

[0115] [Table 2]

[0116] [Resin particle dispersion] Example 1 (Production of resin particle dispersion EM-1) In a 2L container equipped with a stirrer, reflux condenser, dropping funnel, thermometer, and nitrogen inlet tube, 40g of crystalline polyester resin C-1, 160g of amorphous polyester resin A-1, and 200g of methyl ethyl ketone were placed, and the resins were dissolved at 73°C for 2 hours. To the resulting solution, a 5% by mass aqueous sodium hydroxide solution was added to achieve a neutralization degree of 70 mol% relative to the acid value of the resin, and the mixture was stirred for 30 minutes. Next, while maintaining the temperature at 73°C, 800 g of deionized water was added over 60 minutes while stirring at 200 rpm / min to induce phase inversion emulsification. The resulting emulsion was then distilled off under reduced pressure while maintaining the temperature at 73°C to obtain a resin dispersion. Subsequently, the dispersion was cooled to 30°C while continuing to stir, and then deionized water was added to achieve a solid content concentration of 20% by mass to obtain resin particle dispersion EM-1. The volume-average particle size Dv and CV value of the obtained resin particles are shown in Table 3 as "Volume-average particle size Dv(1)" and "CV value(1)", respectively. The volume-average particle size Dv(2) and the rate of change in volume-average particle size before and after storage at 0°C for 14 days, measured by the evaluation method described below, are also shown in Table 3. The rate of change in volume-average particle size before and after storage at 0°C for 14 days is shown in Table 3 as "Rate of change in volume-average particle size before and after low-temperature storage".

[0117] [Evaluation Method] [Percentage change in volume-average particle size of resin particle dispersion after low-temperature storage] The resin particle dispersion was placed in a sealed container and stored in a constant temperature room at 0°C. After 14 days, it was removed, and the volume-average particle size Dv (volume-average particle size Dv(2)) after 14 days of storage at 0°C was measured using the method described above. The rate of change in volume-average particle size before and after 14 days of storage at 0°C was calculated using the following formula (rounded to the first decimal place). A smaller rate of change in volume-average particle size indicates better storage stability at low temperatures. Volume-average particle size change rate (%) = [Volume-average particle size (Dv(2)) / Volume-average particle size volume (Dv(1))] - 1] × 100

[0118] Examples 2-6, Comparative Examples 1-3 (Production of resin particle dispersions EM-2-EM-6, EM'-7-EM'-9) Resin particle dispersions EM-2 to EM-6 and EM'-7 to EM'-9 were obtained in the same manner as in Example 1, except that the crystalline polyester resin or amorphous polyester resin was changed as shown in Table 3. The volume-average particle size Dv(1), CV value(1), volume-average particle size Dv(2), and the rate of change in volume-average particle size before and after low-temperature storage are shown in Table 3.

[0119] Comparative Example 4 (Manufacturing of Resin Particle Dispersion EM'-10) In a 2L container equipped with a stirrer, reflux condenser, dropping funnel, thermometer, and nitrogen inlet tube, 200g of crystalline polyester resin C-1 and 200g of methyl ethyl ketone were placed, and the resin was dissolved at 73°C for 2 hours. To the resulting solution, a 5% by mass aqueous sodium hydroxide solution was added to achieve a degree of neutralization of 70 mol% relative to the acid value of the resin, and the mixture was stirred for 30 minutes. Next, while maintaining the temperature at 73°C, 800 g of deionized water was added over 60 minutes while stirring at 200 rpm / min to induce phase inversion emulsification. The resulting emulsion was then distilled off under reduced pressure while maintaining the temperature at 73°C to obtain a resin dispersion. Subsequently, the dispersion was cooled to 30°C while continuing to stir, and then deionized water was added to achieve a solid content concentration of 20% by mass to obtain resin particle dispersion EM'-10. The volume-average particle size Dv(1), CV value(1), volume-average particle size Dv(2), and the rate of change in volume-average particle size before and after low-temperature storage are shown in Table 3.

[0120] [Table 3]

[0121] Table 3 shows that the resin particle dispersion of the present invention exhibits excellent low-temperature storage stability, with minimal change in the volume-average particle size of the resin particles even after 14 days of storage at 0°C (Examples 1-6). In contrast, resin particle dispersions produced using crystalline polyester resins with an acid value greater than 6.0 mgKOH / g (14.4 mgKOH / g, 7.2 mgKOH / g) (Comparative Examples 1 and 2), or resin particle dispersions produced using crystalline polyester resins with an acid value less than 3.0 mgKOH / g (1.6 mgKOH / g) (Comparative Example 3), exhibit large changes in the volume-average particle size of the resin particles and poor low-temperature storage stability. Furthermore, resin particle dispersions produced without using amorphous resins exhibit very large changes in the volume-average particle size of the resin particles and poor low-temperature storage stability (Comparative Example 4).

[0122] [Manufacturing of mold release agent particle dispersion] Manufacturing Example W1 (Manufacturing of Release Agent Particle Dispersion W-1) In a 3L container equipped with a stirrer, reflux condenser, dropping funnel, thermometer, and nitrogen inlet tube, 200g of resin A-1 and 200g of methyl ethyl ketone were placed, and the resin was dissolved at 80°C for 1 hour. To the resulting solution, a 5% by mass aqueous sodium hydroxide solution was added to achieve a degree of neutralization of 75 mol% relative to the acid value of resin A-1, and the mixture was stirred for 30 minutes. Next, while maintaining the temperature at 80°C, 600g of deionized water was added over 50 minutes while stirring at 280 r / min (peripheral speed 88 m / min) to induce phase inversion emulsification. While continuing to maintain the temperature at 80°C, the methyl ethyl ketone and water were removed by distillation under reduced pressure to obtain an aqueous dispersion of the resin. Subsequently, the aqueous dispersion was cooled to 30°C while stirring at 280 r / min (peripheral speed 88 m / min), and deionized water was added to obtain resin particle dispersion V-1 by achieving a solid content concentration of 25% by mass. In a 1L beaker, 20g of deionized water, 100g of resin particle dispersion V-1, and 50g of paraffin wax "HNP-9" (manufactured by Nippon Seiro Co., Ltd., melting point 75°C) were added. The mixture was melted while maintaining a temperature of 90-95°C and stirred to obtain a molten mixture. The obtained molten mixture was further 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 adjust the solid content concentration to 40% by mass to obtain release agent particle dispersion W-1. The volume-median particle size D of the release agent particles. 50 The particle size was 0.29 μm, and the CV value was 37%.

[0123] [Manufacturing of colorant particle dispersion] Manufacturing Example P1 (Manufacturing of Colorant Particle Dispersion P-1) In a 1L beaker, 100g of copper phthalocyanine pigment "ECB-301" (manufactured by Dainichi Seika Kogyo Co., Ltd.), 35g of polyoxyethylene (13) distyrenate phenyl ether "Emulgen A-60" (manufactured by Kao Corporation, a nonionic surfactant), and 300g of deionized water were mixed. The mixture was then dispersed for 1 hour at room temperature (20°C) at a stirring blade rotation speed of 8000 rpm using a homomixer "TKAGI HOMOMIXER 2M-03" (manufactured by Primix Corporation). After 15 passes at a pressure of 150 MPa using a "Microfluidizer M-110EH" (manufactured by Microfluidics), the mixture was passed through a 200-mesh filter, and deionized water was added to obtain a colorant particle dispersion P-1 with a solid content concentration of 20% by mass. The volume-median particle size D of the colorant particles was determined. 50 The particle size was 0.12 μm, and the CV value was 21%.

[0124] [Manufacturing of toner particles] Example T1 (Manufacturing of toner particles T1) In a 3L four-necked flask equipped with a reflux condenser, stirrer, and thermocouple, 500g of resin particle dispersion EM-1 (stored for 14 days in a 0°C constant temperature room), 17.5g of mold release agent particle dispersion W-1, 54g of coloring agent particle dispersion P-1, and 3.3g of 15% by mass sodium dodecylbenzenesulfonate aqueous solution "Neoperex G-15" (manufactured by Kao Corporation, anionic surfactant) were added and mixed at 25°C. Separately, a solution was prepared by dissolving 43g of ammonium sulfate in 980g of deionized water and adding a 4.8% by mass potassium hydroxide aqueous solution to adjust the pH to 8.2. This solution was added dropwise to the above mixture over 10 minutes at 25°C while mixing, and then the temperature was raised to 58°C over 2 hours to determine the volume-median particle size D of the aggregated particles. 50 The mixture was maintained at 58°C until it reached a size of 6.2 μm, and a dispersion of aggregated particles was obtained. To the resulting dispersion of aggregated particles, 22 g of polyoxyethylene lauryl ether sodium sulfate "Emal E-27C" (manufactured by Kao Corporation, anionic surfactant, effective concentration 27% by mass) and 1100 g of deionized water were added. The mixture was then heated to 75°C over 1 hour and maintained at 75°C until the circularity reached 0.970, thereby obtaining a dispersion of fused particles in which the aggregated particles had fused together. The resulting dispersion of fused particles was cooled to 30°C, passed through a sieve with a mesh opening of 45 μm, and the solid components were separated by suction filtration. The dispersion was then washed with deionized water at 25°C and suction filtration was performed at 25°C for 2 hours. Subsequently, vacuum drying was performed at 33°C for 24 hours using a vacuum constant-temperature dryer "DRV622DA" (manufactured by ADVANTEC) to obtain toner particles T1. The volume-median particle size D of toner particles T1. 50 This is shown in Table 4. Furthermore, the residue remaining on a sieve with a mesh opening of 45 μm was collected separately, washed with deionized water at 25°C, and filtered by suction at 25°C for 2 hours. Then, it was vacuum dried at 33°C for 24 hours using a vacuum constant-temperature dryer "DRV622DA" (manufactured by ADVANTEC) to obtain the residue of toner particles T1. The proportion of coarse particles generated during toner manufacturing was determined using the evaluation method described below. The evaluation results are shown in Table 4.

[0125] [Evaluation Method] [Percentage of residue (percentage of coarse particles)] The resulting dispersion of fused particles was cooled to 30°C and then passed through a sieve with a mesh size of 45 μm. The coarse particles remaining on the sieve were dried, and the residue was determined as follows. (Residue (mass %)) = 100 × (Dried mass of coarse particles remaining on the sieve (g)) ÷ (Mass of toner particles at 100% yield (g)) The "mass of toner particles (g) at 100% yield" is a theoretical value based on the amount of toner used, assuming that 100% of the toner particles are obtained by mass.

[0126] Examples T2-T6 and Comparative Examples T'1-T'3 (Manufacturing of toner particles T2-T6 and T'1-T'3) In Example 1, the resin particle dispersion was modified as shown in Table 4, but otherwise the same procedure was followed to obtain toner particles T2-T6 and T'1-T'3 and a residue of toner particles T2-T6 and T'1-T'3. The volume median particle size D of toner particles T2-T6 and T'1-T'3 50 The proportion of coarse particles is shown in Table 4.

[0127] Comparative Example 4 (Manufacturing of Toner Particle T'4) The resin particles in the resin particle dispersion EM'-10 were too large, making it impossible to manufacture toner particles.

[0128] [Table 4]

[0129] Table 4 shows that the toner obtained by the toner manufacturing method of the present invention has a low proportion of coarse particles (Examples T1 to T6). In contrast, toners manufactured using crystalline polyester resins with an acid value of more than 6.0 mgKOH / g (14.4 mgKOH / g, 7.2 mgKOH / g) (Comparative Examples T'1, T'2), or toners manufactured using crystalline polyester resins with an acid value of less than 3.0 mgKOH / g (1.6 mgKOH / g) (Comparative Example T'3), have a high proportion of coarse particles.

Claims

1. A resin particle dispersion liquid which is a mixed emulsion of crystalline polyester resin C and amorphous resin, The crystalline polyester resin C is a polycondensate of an alcohol component and a carboxylic acid component. A resin particle dispersion in which the ester group concentration of crystalline polyester resin C is 6.5 mmol / g or more and 9.0 mmol / g or less, and the acid value is 3.0 mg KOH / g or more and 6.0 mg KOH / g or less.

2. The resin particle dispersion according to claim 1, wherein the crystalline polyester resin C satisfies the following conditions 1 and / or 2. Condition 1: The alcohol component contains ethylene glycol. Condition 2: The carboxylic acid component contains an α,ω-dicarboxylic acid with 4 carbon atoms.

3. The resin particle dispersion according to claim 1 or 2, wherein the amorphous resin contains amorphous polyester resin A.

4. A method for producing a resin particle dispersion, comprising the step of mixing and emulsifying a crystalline polyester resin C and an amorphous resin in an aqueous medium, The crystalline polyester resin C is a polycondensate of an alcohol component and a carboxylic acid component. A method for producing a resin particle dispersion in which the ester group concentration of crystalline polyester resin C is 6.5 mmol / g or more and 9.0 mmol / g or less, and the acid value is 3.0 mg KOH / g or more and 6.0 mg KOH / g or less.

5. A method for manufacturing toner for electrostatic image development, comprising the following steps 1 and 2, Step 1: A process to obtain a resin particle dispersion by mixing an amorphous resin and a crystalline polyester resin C in an aqueous medium and emulsifying them. Step 2: A process of agglomerating and fusing the resin particles in the resin particle dispersion obtained in Step 1 in an aqueous medium. The crystalline polyester resin C is a polycondensate of an alcohol component and a carboxylic acid component. A method for producing a toner for electrostatic image development, wherein the ester group concentration of the crystalline polyester resin is 6.5 mmol / g or more and 9.0 mmol / g or less, and the acid value is 3.0 mg KOH / g or more and 6.0 mg KOH / g or less.

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