Manufacturing method of toner for electrostatic charge image development

Abstract

To provide a manufacturing method of a toner for electrostatic charge image development capable of producing a toner for electrostatic charge image development with a narrow charge amount distribution and excellent charge stability.SOLUTION: A manufacturing method of a toner for electrostatic charge image development includes: a step 1 of obtaining an aqueous dispersion liquid of toner particles by agglomerating and fusing resin particles in an aqueous medium; and a step 2 of filtering the aqueous dispersion liquid of toner particles obtained in the step 1 and drying it using a flash dryer. In the step 1, the ester group concentration of the resin constituting the resin particles is 5 mmol / g or more and 15 mmol / g or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for producing a toner for developing electrostatic images. [Background technology]

[0002] In the field of electrophotography, with the development 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.To meet the demands for higher image quality, a method for obtaining toners with a narrow particle size distribution and small particle size has been adopted, in which toners are obtained by aggregating and fusing fine resin particles or the like in an aqueous medium, which is called an aggregation-fusion method (aggregation-coalescence method, emulsion aggregation method).

[0003] For example, Patent Document 1 describes an electrostatic charge developing toner that has excellent low-temperature fixing ability and good charging performance even in a high-humidity environment, a method for producing the electrostatic charge developing toner, and other features, including core-shell toner particles having a core layer containing at least a crystalline resin, a first binder resin, a release agent, and a colorant, and a shell layer containing a second binder resin, wherein the crystalline resin has an endothermic peak temperature of 25 to 50°C, the total content of the crystalline resin in the toner particles is 3 to 15 wt%, and the toner particles have an acid value of 20 mg / KOH or less, and a method for producing the electrostatic charge developing toner. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-139588 Summary of the Invention [Problem to be solved by the invention]

[0005] The inventors have found through their investigations that there is room for further improvement in the charging stability in the method for producing toner for developing electrostatic images by the aggregation and fusion method. The present invention relates to a method for producing a toner for developing electrostatic images, which can provide a toner for developing electrostatic images having a narrow charge distribution and excellent charge stability. [Means for solving the problem]

[0006] The present inventors have discovered that the charging stability of the toner can be improved by drying toner particles obtained by aggregating and fusing resin particles composed of a resin having an ester group concentration within a specific range using an airflow dryer. That is, the present invention relates to the following [1]. [1] A method for producing a toner for developing electrostatic images, comprising the following steps 1 and 2: Step 1: A step of obtaining an aqueous dispersion of toner particles by aggregating and fusing resin particles in an aqueous medium. Step 2: A step of filtering the aqueous dispersion of toner particles obtained in step 1 and drying it using an airflow dryer. In step 1, the ester group concentration of the resin constituting the resin particles is 5 mmol / g or more and 15 mmol / g or less. A method for producing a toner for developing electrostatic images. [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 provide a toner for developing electrostatic images having a narrow charge distribution and excellent charge stability. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is an explanatory diagram showing an outline of an example of an airflow drying system used in the method for producing a toner for developing electrostatic images of the present invention. [Figure 2] FIG. 2 is an explanatory diagram showing an outline of an example of the flash dryer constituting the flash drying system of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0009] [Method of manufacturing electrostatic image developing toner] The method for producing a toner for developing electrostatic images of the present invention (hereinafter also referred to as "toner production method") includes the following steps 1 and 2. Step 1: A step of obtaining an aqueous dispersion of toner particles by aggregating and fusing resin particles in an aqueous medium. Step 2: A step of filtering the aqueous dispersion of toner particles obtained in step 1 and drying it using an airflow dryer. In step 1, the ester group concentration of the resin constituting the resin particles is 5 mmol / g or more and 15 mmol / g or less. According to the toner production method of the present invention, it is possible to obtain a toner for developing electrostatic images (hereinafter, also simply referred to as "toner") that has a narrow charge distribution and excellent charge stability.

[0010] The reason why the toner having a narrow charge distribution and excellent charge stability can be obtained by the toner manufacturing method of the present invention is not clear, but is thought to be as follows. In the method of forming toner particles by agglomerating and fusing toner raw material components such as resin particles in an aqueous medium, a drying process is performed to remove the aqueous medium. Ideally, the layer derived from the resin particles present in the outermost shell of the toner particles should spread to the surface of the resin on the inner shell, covering the entire toner particle (encapsulation). However, because fused particles are stabilized by balancing the interfacial tension with water during fusion, this layer does not easily spread to the toner surface when drying methods are used, in which the water is gradually evaporated after filtering the toner particles. This results in insufficient encapsulation of the toner particles, exposing internal components such as release agents and colorants to the toner surface, and the toner's charge distribution tends to become broad. In the present invention, a relatively hydrophilic resin with an ester group concentration of 5 mmol / g to 15 mmol / g is used, and toner particles prepared in an aqueous medium are dried using an airflow dryer. The layer derived from the resin particles present on the toner particle surface is relatively hydrophilic, increasing stability in an aqueous medium. However, by continuously blowing air onto the toner particles in the airflow dryer during the drying process, the interfacial tension with the hydrophobic air increases. Therefore, the layer derived from the resin particles tends to spread to the toner particle surface to reduce unevenness and further reduce surface area. This results in smoother, more encapsulated toner particles, which is thought to prevent internal components such as release agents and colorants from being exposed to the toner surface, resulting in toner particles with a narrow charge distribution and excellent charge stability.

[0011] The definitions of various terms used in this specification are shown below. 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. The carboxylic acid component of the polyester resin includes not only the compound itself, but also anhydrides that decompose during the reaction to produce an acid, and alkyl esters of each carboxylic acid (the alkyl group has 1 to 3 carbon atoms).

[0012] [Process 1] In step 1, resin particles are aggregated and fused in an aqueous medium to obtain an aqueous dispersion of toner particles. That is, step 1 includes the steps of aggregating and fusing resin particles in an aqueous medium. In step 1, the ester group concentration of the resin constituting the resin particles is 5.0 mmol / g or more and 15.0 mmol / g or less. From the viewpoint of narrowing the charge distribution of the toner, the ester group concentration of the resin constituting the resin particles is preferably 6.0 mmol / g or more, more preferably 6.5 mmol / g or more, even more preferably 7.0 mmol / g or more, even more preferably 7.5 mmol / g or more, and preferably 13.0 mmol / g or less, more preferably 11.0 mmol / g or less, and even more preferably 10.0 mmol / g or less.

[0013] 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] The components contained in the toner particles may be used alone or in combination of two or more. Furthermore, the raw materials for 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.

[0015] <Resin particles> Examples of the resin constituting the resin particles include polyester resin and styrene-acrylic resin, and among these, the resin constituting the resin particles preferably contains polyester resin.

[0016] (polyester resin) The polyester resin has an ester group concentration of 5.0 mmol / g or more and 15.0 mmol / g or less, and contains a polycondensate of an alcohol component and a carboxylic acid component. From the viewpoint of narrowing the charge distribution of the toner, the content of the polycondensate of an alcohol component and a carboxylic acid component in the polyester resin is preferably 60% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, still more preferably 95% by mass or more, and is 100% by mass or less, preferably 100% by mass. The polyester resin may be a modified polyester resin, such as a urethane-modified polyester resin, an epoxy-modified polyester resin, or a composite resin containing a polyester resin segment and an addition polymerization resin segment. The polyester resin may be amorphous or crystalline, but is preferably amorphous from the viewpoint of facilitating control of the various physical properties of the toner. Furthermore, an amorphous polyester resin and a crystalline polyester resin may be used in combination. Hereinafter, the amorphous polyester resin will be referred to as "amorphous polyester resin A" or simply "resin A," and the crystalline polyester resin will be referred to as "crystalline polyester resin C" or simply "resin C." In addition, from the viewpoint of low-temperature fixability, the toner particles may contain crystalline polyester resin C.

[0017] From the viewpoint of narrowing the charge distribution of the toner, the polyester resin has an ester group concentration of 5.0 mmol / g or more, preferably 6.0 mmol / g or more, more preferably 6.5 mmol / g or more, even more preferably 7.0 mmol / g or more, still more preferably 7.5 mmol / g or more, and 15.0 mmol / g or less, preferably 13.0 mmol / g or less, more preferably 11.0 mmol / g or less, still more preferably 10.0 mmol / g or less. The ester group concentration of the polyester resin is calculated by the following formula.

[0018]

number

[0019] Examples of the alcohol component of the polyester resin include aliphatic diols, alkylene oxide adducts of aromatic diols, alicyclic diols, and trihydric or higher polyhydric alcohols. Among these, aliphatic diols and alkylene oxide adducts of aromatic diols are preferred, and aliphatic diols are more preferred.

[0020] 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, 1,9-nonanediol, 1,10-decanediol, 1,12-dodecanediol, and 3-methyl-1,5-pentanediol, with 1,2-propanediol and neopentyl glycol being preferred.

[0021] The content of the aliphatic diol in the alcohol component is preferably 50 mol % or more, more preferably 70 mol % or more, even more preferably 90 mol % or more, and is 100 mol % or less, preferably 100 mol %.

[0022] The alkylene oxide adduct of an aromatic diol is preferably an alkylene oxide adduct of bisphenol A, more preferably an alkylene oxide adduct of formula (I): [ka] (In the formula, OR 1and R 2 O is an oxyalkylene group, and R 1 and R 2 are each independently an ethylene group or a propylene group, x and y are each a positive number that indicates 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.

[0023] Examples of the alkylene oxide adduct of bisphenol A represented by formula (I) include a propylene oxide adduct of bisphenol A and an ethylene oxide adduct of bisphenol A.

[0024] When the alcohol component contains an alkylene oxide adduct of bisphenol A, the content of the alkylene oxide adduct of bisphenol A in the alcohol component is preferably 20 mol% or more, more preferably 30 mol% or more, even more preferably 35 mol% or more, and preferably 60 mol% or less, preferably 50 mol% or less, even more preferably 45 mol% or less.

[0025] 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).

[0026] Examples of trihydric or higher polyhydric alcohols include glycerin, pentaerythritol, trimethylolpropane, and sorbitol.

[0027] Examples of the carboxylic acid component of the polyester resin include dicarboxylic acids and trivalent or higher polycarboxylic acids.

[0028] Examples of dicarboxylic acids include aromatic dicarboxylic acids, aliphatic dicarboxylic acids, and alicyclic dicarboxylic acids, with aromatic dicarboxylic acids and aliphatic dicarboxylic acids being preferred.

[0029] Examples of aromatic dicarboxylic acids include phthalic acid, terephthalic acid, and isophthalic acid. Of these, terephthalic acid and isophthalic acid are preferred. When the polyester resin is amorphous polyester resin A, the amount of aromatic dicarboxylic acid in the carboxylic acid component is preferably 65 mol% or more, more preferably 75 mol% or more, and even more preferably 80 mol% or more, and 100 mol% or less.

[0030] 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. Of these, fumaric acid is preferred. In the amorphous polyester resin A, when the carboxylic acid component contains an aliphatic dicarboxylic acid, the amount of the aliphatic dicarboxylic acid in the carboxylic acid component is preferably 1 mol % or more, more preferably 3 mol % or more, even more preferably 5 mol % or more, and preferably 35 mol % or less, more preferably 25 mol % or less, even more preferably 20 mol % or less.

[0031] An example of the alicyclic dicarboxylic acid is cyclohexanedicarboxylic acid.

[0032] The trivalent or higher polyvalent carboxylic acid is preferably a trivalent carboxylic acid, such as trimellitic acid.

[0033] When the polyester resin is crystalline polyester resin C, the carboxylic acid component is preferably an aliphatic dicarboxylic acid. The carbon number of the aliphatic dicarboxylic acid is preferably 4 or more, more preferably 8 or more, and even more preferably 10 or more, and is preferably 14 or less, more preferably 12 or less. Examples of the aliphatic dicarboxylic acid include sebacic acid, dodecanedioic acid, and tetradecanedioic acid. Among these, sebacic acid is preferred.

[0034] The carboxylic acid component of the crystalline polyester resin C may also contain a monocarboxylic acid having a hydrocarbon group. The number of carbon atoms in the hydrocarbon group of the monocarboxylic acid is preferably 9 or more, more preferably 10 or more, even more preferably 13 or more, and even more preferably 15 or more, and is preferably 24 or less, more preferably 22 or less, and even more preferably 20 or less. Examples of the hydrocarbon group include aliphatic hydrocarbon groups such as alkyl groups, alkynyl groups, and alkenyl groups, and alkyl groups and alkenyl groups are preferred, and alkyl groups are more preferred. The hydrocarbon group may be branched or linear, and linear is preferred. Examples of monocarboxylic acids having a hydrocarbon group include capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, lignoceric acid, etc. Among these, preferred are lauric acid, stearic acid, and behenic acid, and more preferred is stearic acid.

[0035] The carboxylic acid component of the crystalline polyester resin C may contain other carboxylic acid components different from the aliphatic dicarboxylic acid. Examples of other carboxylic acid components include aromatic dicarboxylic acids such as terephthalic acid and isophthalic acid, and trivalent or higher polycarboxylic acids.

[0036] When the polyester resin is crystalline polyester resin C, the amount of aliphatic dicarboxylic acid in the carboxylic acid component is preferably 75 mol % or more, more preferably 80 mol % or more, and even more preferably 85 mol % or more, and 100 mol % or less.

[0037] When the crystalline polyester resin C contains a monocarboxylic acid having a hydrocarbon group, the amount thereof is preferably 1 mol% or more, 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.

[0038] 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.

[0039] <Method for producing polyester resin> The polyester resin can be produced, for example, by polycondensing raw material monomers containing an alcohol component and a carboxylic acid component. The polycondensation of the alcohol component and the carboxylic acid component can be carried out, for example, in an inert gas atmosphere, in the presence of an esterification catalyst, an esterification promoter, a polymerization inhibitor, etc., as necessary, at a temperature of about 120°C or higher and 250°C or lower. Examples of the esterification catalyst include tin compounds such as dibutyltin oxide and tin(II) di(2-ethylhexanoate), and titanium compounds such as titanium diisopropoxybis(triethanolaminate). Examples of the esterification co-catalyst that can be used together with the esterification catalyst include gallic acid (3,4,5-trihydroxybenzoic acid). The amount of the esterification catalyst used is preferably 0.01 parts by mass or more and 10 parts by mass or less relative to 100 parts by mass of the total amount of the alcohol component and the carboxylic acid component, which are raw material monomers for the polyester resin. The amount of the esterification promoter used is preferably 0.001 part by mass or more and 1 part by mass or less relative to 100 parts by mass of the total amount of the alcohol component and the carboxylic acid component. Furthermore, examples of the polymerization inhibitor include radical polymerization inhibitors such as 4-tert-butylcatechol. When a polymerization inhibitor is used, the amount of the polymerization inhibitor used is preferably 0.001 part 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.

[0040] <Physical properties of polyester resin> The softening point of the amorphous polyester resin A is preferably 70°C or higher, more preferably 85°C or higher, and even more preferably 95°C or higher, and is preferably 140°C or lower, more preferably 130°C or lower, and even more preferably 120°C or lower.

[0041] When the polyester resin is crystalline polyester resin C, the softening point of crystalline polyester resin C is preferably 60°C or higher, more preferably 65°C or higher, even more preferably 70°C or higher, and preferably 130°C or lower, more preferably 110°C or lower, even more preferably 90°C or lower.

[0042] The glass transition temperature of the amorphous polyester resin A is preferably 35°C or higher, more preferably 45°C or higher, even more preferably 50°C or higher, and preferably 85°C or lower, more preferably 80°C or lower, even more preferably 75°C or lower.

[0043] The melting point of the crystalline polyester resin C is preferably 60°C or higher, more preferably 65°C or higher, even more preferably 70°C or higher, and preferably 100°C or lower, more preferably 90°C or lower, even more preferably 80°C or lower.

[0044] The acid value of the amorphous polyester 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 is preferably 35 mgKOH / g or less, more preferably 30 mgKOH / g or less, even more preferably 25 mgKOH / g or less.

[0045] The acid value of the crystalline polyester resin C is preferably 2 mgKOH / g or more, more preferably 5 mgKOH / g or more, and preferably 25 mgKOH / g or less, more preferably 20 mgKOH / g or less, and even more preferably 15 mgKOH / g or less.

[0046] The softening point, glass transition temperature, and acid value of the polyester 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, and cooling rate, and these values ​​can be determined by the methods described in the examples. When two or more polyester resins are used in combination, it is preferable that at least one of them has the above-mentioned ranges for each of the physical properties, and it is more preferable that the softening point, glass transition temperature, and acid value of the resulting mixture of these resins each have the above-mentioned ranges.

[0047] <Release agent> The toner particles obtained in step 1 preferably contain a release agent. 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.

[0048] 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, even more preferably 120°C or lower, and even more preferably 100°C or lower.

[0049] The content of the release agent in the toner particles is preferably 0.5% by mass or more, more preferably 1% by mass or more, even more preferably 5% by mass or more, and preferably 25% by mass or less, more preferably 20% by mass or less, even more preferably 15% by mass or less.

[0050] <Coloring agent> The toner particles obtained in step 1 preferably contain a colorant. 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 (e.g., pigment blue 15:3), 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.

[0051] The content of the colorant 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.

[0052] In addition, the toner particles may contain additives such as a charge control agent, a magnetic powder, a flowability improver, a conductivity adjuster, a reinforcing filler such as a fibrous substance, an antioxidant, an antiaging agent, and a cleaning property improver.

[0053] <Step 1: Agglomerating Resin Particles> The aggregated particles obtained in the step of aggregating resin particles include aggregated particles 1 obtained by aggregating resin particles in an aqueous medium, and aggregated particles 2 obtained by using aggregated particles 1 as cores and attaching shell resin particles to these cores in an aqueous medium to cause aggregation. The term "aggregated particles" simply refers to aggregated particles 1 or 2.

[0054] In the step of aggregating the resin particles, the resin particles are aggregated in an aqueous medium to obtain aggregated particles 1. In the step of aggregating the resin particles, it is preferable to further aggregate the colorant and the release agent in addition to the resin particles, and it is preferable to mix a resin particle dispersion, a release agent particle dispersion, and a colorant particle dispersion and aggregate these particles to obtain aggregated particles 1.

[0055] (Method of manufacturing resin particle dispersion) The dispersion of resin particles in an aqueous medium can be carried out using a known method, but when the resin is a polyester resin, it is preferable to disperse the resin 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 the resin or a molten resin to carry out phase inversion emulsification. A preferred method is a method in which an aqueous medium is added to an organic solvent solution of the resin to carry out phase inversion emulsification. 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 of the polyester resin. 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 polyester resin constituting the resin particles is preferably 50 mol % or more, more preferably 60 mol % or more, and even more preferably 70 mol % or more, and is preferably 100 mol % or less, and more preferably 90 mol % or less. The degree of neutralization of the polyester resin constituting the resin particles can be determined by the following formula. Degree of neutralization (mol%) = [{weight of neutralizing agent added (g) / equivalent weight of neutralizing agent} / [{weighted average acid value of resin constituting resin particles (mg KOH / g) × weight of resin constituting resin particles (g)} / (56 × 1000)]] × 100

[0056] While stirring the organic solvent solution of the resin or the molten resin, the aqueous medium is gradually added to cause phase inversion. From the viewpoint of improving the dispersion stability of resin particles containing a resin, the temperature of the organic solvent solution when adding an aqueous medium is preferably equal to or higher than the glass transition temperature of the resin, more preferably equal to or higher than 60°C, even more preferably equal to or higher than 65°C, and is preferably equal to or lower than 100°C, more preferably equal to or lower than 95°C, even more preferably equal to or lower than 90°C.

[0057] 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 an aqueous dispersion of resin particles 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.

[0058] Resin particle volume median diameter D 50 is preferably 0.03 μm or more, more preferably 0.06 μm or more, even more preferably 0.09 μm or more, and is preferably 1 μm or less, more preferably 0.5 μm or less, even more preferably 0.3 μm or less. The CV value of the resin particles is preferably 10% or more, more preferably 20% or more, and is preferably 40% or less, more preferably 35% or less. Resin particle volume median diameter D 50 The CV value is measured by the method described in the Examples.

[0059] From the viewpoint of improving toner productivity and dispersion stability of the resin particle dispersion, 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 is preferably 50% by mass or less, more preferably 40% by mass or less, even more preferably 30% by mass or less.

[0060] (Method of producing release agent particle dispersion) The release agent particle dispersion may be obtained using a surfactant, or may be 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 the composite resin D, see JP 2024-25642 A. Alternatively, the aforementioned amorphous polyester resin A may be used.

[0061] 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 0.15 μm or more, and is preferably 1 μm or less, more preferably 0.7 μm or less, even more preferably 0.4 μm or less. The CV value of the release agent particles is preferably 20% or more, more preferably 30% or more, and is preferably 55% or less, more preferably 50% or less, and even more preferably 45% or less. Volume median particle size D of release agent particles 50 The CV value is measured by the method described in the Examples.

[0062] (Method of manufacturing colorant particle dispersion) The colorant particles are preferably obtained as a 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 structural unit derived from an addition-polymerizable monomer a having an aromatic group, and preferably further contains at least one monomer 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 2024-25642 A.

[0063] From the viewpoint of image density of printed matter, the content of the colorant in the colorant particle dispersion is preferably 1% by mass or more, more preferably 3% by mass or more, even more preferably 5% 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.

[0064] 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.

[0065] 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, 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.

[0066] <Surfactants> In the step of aggregating the resin particles, dispersions of the respective particles are mixed to prepare a mixed dispersion, and 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 even more preferably 0.5 parts by mass or more, per 100 parts by mass of the total amount of resin particles, and is preferably 10 parts by mass or less, more preferably 5 parts by mass or less.

[0067] <Flocculant> In the step of aggregating the resin particles, it is preferable to add an aggregating agent from the viewpoint of efficient aggregation. 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.

[0068] For example, 10 to 50 parts by mass of the aggregating agent is added to 100 parts by mass of the resin particles in a mixed dispersion liquid containing resin particles, release agent particles, and colorant particles at a temperature of 0 to 40°C, and the resin particles, release agent particles, and colorant particles are aggregated in an aqueous medium to obtain aggregated particles 1. From the viewpoint of promoting aggregation, it is preferable to increase the temperature of the dispersion liquid after adding the aggregating agent.

[0069] Methods for stopping aggregation include cooling the dispersion, adding an aggregation terminator, and diluting the dispersion. From the viewpoint of reliably preventing unnecessary aggregation, a method of stopping aggregation by adding an aggregation terminator is preferred. Furthermore, when a step of aggregating shell resin particles is included for the purpose of producing a toner having a core-shell structure, the step of aggregating shell resin particles may be performed when aggregated particles 1 have grown to an appropriate particle size without terminating the aggregation.

[0070] Volume median particle size D of aggregated particles 1 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.

[0071] Step 1 preferably includes a step of attaching and aggregating shell resin particles to the obtained aggregated particles 1 as cores to obtain aggregated particles 2. By including a step of aggregating shell resin particles, toner particles having a core-shell structure can be obtained. The shell resin particles are preferably the above-mentioned polyester resin.

[0072] The ester group concentration of the resin contained in the shell resin particles, i.e., the resin constituting the shell portion of the toner particles, is preferably 5.0 mmol / g or more, more preferably 6.0 mmol / g or more, even more preferably 6.5 mmol / g or more, even more preferably 7.0 mmol / g or more, even more preferably 7.5 mmol / g or more, from the viewpoint of narrowing the charge distribution of the toner, and is preferably 15.0 mmol / g or less, more preferably 13.0 mmol / g or less, even more preferably 11.0 mmol / g or less, even more preferably 10.0 mmol / g or less.

[0073] The ratio of the ester group concentration (shell) of the resin forming the shell portion to the ester group concentration (core) of the resin forming the core portion of the toner particle [ester group concentration (shell) / ester group concentration (core)] is preferably 1.8 or less, more preferably 1.5 or less, even more preferably 1.3 or less, from the viewpoint of narrowing the charge distribution of the toner, and is preferably 0.9 or more, more preferably 1.0 or more.

[0074] The shell resin particle dispersion liquid can be obtained by the same method as the above-mentioned method for producing the resin particle dispersion liquid.

[0075] From the viewpoint of low-temperature fixability of the toner, the mass ratio of the shell resin particles to the mass of the aggregated particles 1 [shell resin particles / aggregated particles 1] is preferably 1 / 99 or more, more preferably 5 / 95 or more, even more preferably 10 / 90 or more, and is preferably 25 / 75 or less, more preferably 20 / 80 or less, even more preferably 15 / 85 or less.

[0076] When step 1 includes a step of aggregating shell resin particles, it is preferable to stop the aggregation in this step when aggregated particles 2 have grown to a particle size appropriate for toner particles, and a method of stopping the aggregation by adding an aggregation terminator is preferred.

[0077] <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 β-naphthalenesulfonic acid-formalin condensates. These may be used alone or in combination of two or more. The aggregation terminator may be added in the form of an aqueous solution. The amount of the aggregation terminator added is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, relative to 100 parts by mass of aggregated particles immediately before the addition of the aggregation terminator, from the viewpoint of reliably preventing unnecessary aggregation, and is preferably 30 parts by mass or less, more preferably 25 parts by mass or less, from the viewpoint of reducing residue in the toner.

[0078] <Step 1: Fusing Resin Particles> In the fusion step, the aggregated particles are fused in an aqueous medium. By fusion, the particles contained in the aggregated particles are fused together to obtain fused particles. In the fusion step, 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 temperature at or above the glass transition temperature of the resin having the highest glass transition temperature among the amorphous resins contained in the aggregated particles. From the viewpoint of improving the fusion properties of the aggregated particles and improving the productivity of the toner, the holding temperature when fusing the aggregated particles is preferably at least 1°C higher, more preferably at least 3°C ​​higher, than the glass transition temperature of the resin having the highest glass transition temperature among the amorphous resins, and is preferably not higher than 25°C higher, more preferably not higher than 15°C higher, and even more preferably not higher than 10°C higher than the glass transition temperature of the resin having the highest glass transition temperature among the amorphous resins. In this case, the time for maintaining the temperature at or above the glass transition temperature of the amorphous resin is preferably 1 minute or more, more preferably 10 minutes or more, even more preferably 30 minutes or more, from the viewpoint of improving toner productivity, and is preferably 240 minutes or less, more preferably 180 minutes or less, even more preferably 120 minutes or less, even more preferably 90 minutes or less. It is preferable to maintain the temperature at the above temperature until the desired circularity is achieved.

[0079] The volume median particle size D of the fused particles obtained by fusion 50is 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.

[0080] 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.

[0081] [Process 2] <Filtration> In step 2, the aqueous dispersion of toner particles obtained in step 1 is filtered and dried to obtain toner particles. As a filtering method, suction filtration method or the like is preferably used. <Cleaning> It is preferable to wash the mixture after filtration. At this time, it is preferable to remove the added surfactant, so washing with an aqueous medium at a temperature below the cloud point of the surfactant is preferable. Washing is preferably performed multiple times. <Drying> The wet toner particles obtained through the above-mentioned filtration and, if necessary, washing are dried using an airflow dryer. Examples of flash dryers include loop-type flash dryers and fluidized-bed type flash dryers (hereinafter also referred to as "fluidized-bed dryers"), with loop-type flash dryers being preferred. Loop-type flash dryers are also called flash jet dryers.

[0082] (Flash jet dryer) FIG. 1 is an explanatory diagram showing an outline of an example of an airflow drying system equipped with a flash jet dryer (flash jet dryer 50 shown in FIG. 2) used in the method for producing a toner for developing electrostatic images of the present invention. The flash drying system 100 comprises a discharge blower 1, an electric heater 2, a raw material supply hopper 3, a collection cyclone 4, a product recovery section 5, a flash jet dryer 50, and temperature indicator / control alarm meters T1 and T2. Note that if the gas is not heated, the flash drying system 100 does not need to be equipped with the electric heater 2. The arrow connecting the discharge blower 1 and the electric heater 2 and the arrow connecting the electric heater 2 and the flash jet dryer 50 indicate the flow path (traveling direction) of the gas, and the arrow connecting the flash jet dryer 50 and the collecting cyclone 4 and the arrow connecting the collecting cyclone 4 and the product recovery section 5 indicate the flow path (traveling direction) of the gas and the dried toner particles. Furthermore, the arrow connecting the raw material supply hopper 3 and the flash jet dryer 50 indicates the flow path (traveling direction) of the wet toner particles. The diameter (equivalent diameter) of each flow path can be appropriately selected depending on the supply amount of wet toner particles, the flow rate of gas, and the like.

[0083] Gas supplied by a discharge blower 1 is heated by an electric heater 2 as needed and supplied to a flash jet dryer 50. On the other hand, wet toner particles are supplied to the flash jet dryer 50 from a raw material supply hopper 3. Examples of the gas include air, compressed air, and nitrogen.

[0084] In the flash jet dryer 50 shown in Fig. 2, gas is supplied from a discharge blower 1 of a pneumatic drying system 100 and heated as needed by an electric heater 2, and is sent from a gas inlet 7 to a gas supply unit 8. The gas sent to the gas supply unit 8 enters a drying tube 10 through a pneumatic nozzle 9 and circulates within the drying tube 10 in the direction of the arrow. On the other hand, wet toner particles pass through the raw material supply section 6 from the raw material supply hopper 3 of the airflow drying system 100, enter the drying tube 10, and circulate within the drying tube 10 in the direction of the arrow. The diameters (equivalent diameters) of the air flow nozzle 9 and the drying tube 10 can be appropriately selected depending on the flow rate of the gas, the supply amount of the wet toner particles, and the like. The flash jet dryer 50 may be a commercially available product, for example, the FJD series flash jet dryer (manufactured by Seishin Enterprise Co., Ltd.).

[0085] The wet toner particles are dispersed into primary particles in the drying tube 10. The dispersed toner particles are dried while receiving a gas. The dried toner particles are preferentially passed through the discharge port 11 due to the inertial force acting on the toner particles caused by the swirling flow in the drying tube 10, and are collected in the product collection section 5. Meanwhile, the undried toner particles circulate in the drying tube 10 until they are dried. The moisture content in the dried toner particles is preferably 1% by mass or less, more preferably 0.7% by mass or less, and even more preferably 0.5% by mass or less, and is 0% by mass or more.

[0086] The amount of gas (air volume) supplied from the gas inlet 7 into the drying tube 10 can be appropriately selected depending on the amount of wet toner particles supplied and the diameter (equivalent diameter) of the drying tube 10. For example, the air volume is 0.5 m 3 / min or more is acceptable, 3m 3 / min or more is acceptable, 7m 3 / min or more is acceptable, 11m 3 / min or more, and 1500m 3 / min or less is acceptable, 1000m 3 / min or less is acceptable, 500m 3 / min or less is acceptable, 100m 3 / min or less is acceptable, 20m 3 / min or less is acceptable, 14m 3 / min or less is also acceptable.

[0087] The inlet air velocity, i.e., the air velocity at the gas inlet 7, is preferably 1.0 m / s or more, more preferably 10 m / s or more, even more preferably 15 m / s or more, from the viewpoint of narrowing the toner charge distribution, and is preferably 50 m / s or less, more preferably 40 m / s or less, even more preferably 35 m / s or less.

[0088] Cross-sectional area of ​​the drying tube 10 (m 2) the amount of gas supplied into the drying tube 10 (air volume, m 3 From the viewpoint of narrowing the distribution of toner charge amount, the ratio (air volume / cross-sectional area) of the air flow rate (m / min), i.e., the air velocity (m / min), is preferably 60 m / min or more, more preferably 600 m / min or more, even more preferably 900 m / min or more, and is preferably 3000 m / min or less, more preferably 2400 m / min or less, even more preferably 2100 m / min or less. The cross-sectional area of ​​the drying tube 10 (m 2 )" means the maximum area among the cross-sectional areas of the drying tube 10.

[0089] The drying temperature (inlet temperature), i.e., the temperature of the gas at the gas inlet 7, is preferably 20°C or higher, more preferably 30°C or higher, even more preferably 40°C or higher, even more preferably 45°C or higher, from the viewpoint of narrowing the toner charge distribution, and is preferably 75°C or lower, more preferably 70°C or lower, even more preferably 65°C or lower, even more preferably 60°C or lower, even more preferably 55°C or lower. The drying temperature (outlet temperature), i.e., the temperature of the gas at the discharge port 11, is preferably 20°C or higher, more preferably 30°C or higher, even more preferably 35°C or higher, from the viewpoint of narrowing the toner charge distribution, and is preferably 75°C or lower, more preferably 70°C or lower, even more preferably 60°C or lower, even more preferably 55°C or lower, even more preferably 50°C or lower. The temperature inside the drying tube 10, i.e., the temperature of the gas circulating inside the drying tube 10, is preferably 20°C or higher and 75°C or lower, and more preferably, is higher than the drying temperature (outlet temperature) and lower than the drying temperature (inlet temperature).

[0090] The supply rate of the wet toner particles from the raw material supply hopper 3 to the flash jet dryer 50 can be appropriately selected depending on the capacity of the flash jet dryer 50, the diameter (equivalent diameter) of the drying tube 10, etc. The supply rate is preferably 1 kg / h or more, more preferably 2 kg / h or more, even more preferably 3 kg / h or more, and is preferably 10 kg / h or less, more preferably 8 kg / h or less, even more preferably 6 kg / h or less.

[0091] (Fluidized bed dryer) In the toner production method of the present invention, by replacing the flash jet dryer 50 in FIG. 1 with a fluidized bed dryer, step 2 can be carried out using the fluidized bed dryer. As the fluidized bed dryer, a commercially available product can be used, for example, "AGM-2PJ" (manufactured by Hosokawa Micron Corporation).

[0092] The amount of gas (air volume) supplied to the fluidized bed can be appropriately selected depending on the amount of wet toner particles, the volume of the fluidized bed, etc. 3 / min or more is acceptable, 0.7m 3 / min or more is acceptable, 1m 3 / min or more, and 1500m 3 / min or less is acceptable, 1000m 3 / min or less is acceptable, 500m 3 / min or less is acceptable, 100m 3 / min or less is acceptable, 20m 3 / min or less is acceptable, 5m 3 / min or less is also acceptable.

[0093] From the viewpoint of narrowing the charge distribution of the toner, the wind speed of the gas supplied to the fluidized bed is preferably 0.5 m / s or more, more preferably 0.7 m / s or more, even more preferably 0.9 m / s or more, and is preferably 3.0 m / s or less, more preferably 2.0 m / s or less, even more preferably 1.7 m / s or less.

[0094] From the viewpoint of narrowing the charge distribution of the toner, the temperature of the gas in the fluidized bed is preferably 20°C or higher, more preferably 30°C or higher, even more preferably 40°C or higher, even more preferably 45°C or higher, and preferably 75°C or lower, more preferably 70°C or lower, even more preferably 65°C or lower, even more preferably 60°C or lower, even more preferably 55°C or lower.

[0095] [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.

[0096] The circularity of the toner particles is preferably 0.955 or more, more preferably 0.960 or more, even more preferably 0.965 or more, and preferably 0.990 or less, more preferably 0.985 or less, even more preferably 0.980 or less.

[0097] 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 45% or less, more preferably 40% or less, and even more preferably 35% or less from the viewpoint of obtaining high-quality images. Volume median particle size D of toner particles 50 can be measured by the method described in the Examples.

[0098] [Electrostatic image developing toner] The toner for developing electrostatic images of the present invention contains toner particles. Although the toner particles can be used as they are, it is preferable to use the toner after adding a fluidizing agent or the like as an external additive to the surface of the toner particles.

[0099] [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, 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, even more preferably 4 parts by mass or less, relative to 100 parts by mass of the toner particles.

[0100] 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. [Example]

[0101] 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.

[0102] [Measurement method] [Ester group concentration of resin] The ester group concentration of the polyester resin was calculated using the above formula. The ester group concentration of the styrene-acrylic resin was calculated by the following formula. Ester group concentration (mmol / g) = 1000 x moles of acrylic ester (raw material monomer) / total mass of raw material monomers (g)

[0103] [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 "Q100" (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 temperature was then held for 1 minute, after which the temperature was raised 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 "Q100" (manufactured by TA Instruments Japan Co., Ltd.), 0.02 g of sample was weighed into an aluminum pan, heated to 200°C, and 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, and the calorific value was measured. The temperature of the peak with the largest peak area among the observed endothermic peaks was taken as the maximum endothermic peak temperature (2). For crystalline resins, this peak temperature was taken as the melting point. In the case of an amorphous resin, when a peak is observed, the temperature of the peak is taken as the glass transition temperature. When a step is observed instead of a peak, 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 is taken as the glass transition temperature.

[0104] [Acid value of resin] Measurement was carried out according to the neutralization titration method described in JIS K 0070: 1992. However, the measurement solvent was a mixed solvent of acetone and toluene (acetone:toluene=1:1 (volume ratio)).

[0105] [Melting point of release agent] Using a differential scanning calorimeter "Q100" (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.

[0106] [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 into 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

[0107] [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 content concentration (mass%) = 100-moisture (mass%)

[0108] [Volume median particle size of agglomerated particles D 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" (Beckman Coulter, Inc.) Electrolyte: "Isoton (registered trademark) II" (manufactured by 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.

[0109] [Circularity of fused particles] 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: Circularity was measured in HPF measurement mode.

[0110] [Volume median particle size D of toner particles 50 and CV value) 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

[0111] [Manufacturing of amorphous resin] [Production of amorphous polyester resin A] Production Example A1 (Production of Resin A-1) A 10-L four-neck flask equipped with a thermometer, stainless steel stirrer, dehydration tube, condenser, and nitrogen inlet tube was charged with neopentyl glycol, terephthalic acid, and tin(II) di(2-ethylhexanoate) (Table 1). The mixture was heated to 180°C in a nitrogen atmosphere in a mantle heater. After 2 hours of reaction, the mixture was heated to 210°C at a rate of 5°C / h. After cooling to 180°C, the isophthalic acid (Table 1) was added. The mixture was heated again to 190°C and reacted for 1 hour. The mixture was then heated to 220°C at a rate of 10°C / h. The reaction was continued at 13.3 kPa until the softening point (Table 1) was reached, yielding Resin A-1 (polyester resin). The physical properties of Resin A-1 are shown in Table 1.

[0112] Production Example A2 (Production of Resin A-2) The raw material monomers for polyester resin other than fumaric acid and the esterification catalyst shown in Table 1 were placed in a 10 L four-neck flask equipped with a nitrogen inlet tube, a dehydration tube equipped with a fractionating column through which hot water at 98°C was passed, a stirrer, and a thermocouple. Under a nitrogen atmosphere, the reaction system was maintained at 180°C for 1 hour, then heated from 180°C to 230°C at a rate of 10°C / h, and then maintained at 230°C for 5 hours to allow polycondensation. After cooling to 180°C, fumaric acid and a radical polymerization inhibitor were added to the reaction system, and the temperature was increased from 180°C to 210°C at a rate of 10°C / h. The reaction was continued for 1 hour at 210°C, and then further continued at 210°C and 10 kPa until the softening point shown in Table 1 was reached, yielding Resin A-2 (polyester resin). The physical properties of Resin A-2 are shown in Table 1.

[0113] Manufacturing Example A3 (Manufacturing of Resin A-3) The raw material monomers, esterification catalyst, and esterification promoter for the polyester resin shown in Table 1 were placed in a 10-L four-neck flask equipped with a nitrogen inlet tube, a dehydration tube fitted with a fractionating column through which hot water at 98°C was passed, a stirrer, and a thermocouple. After holding at 180°C for 1 hour under a nitrogen atmosphere, the temperature was increased from 180°C to 230°C at a rate of 10°C / h, and then polycondensation was carried out at 230°C for 5 hours. The reaction was further carried out at 230°C under a reduced pressure of 10 kPa until the softening point shown in Table 1 was reached, yielding Resin A-3 (polyester resin). The physical properties of Resin A-3 are shown in Table 1.

[0114] Manufacturing Example A51 (Manufacturing of Resin A-51) A 10-L four-neck flask equipped with a nitrogen inlet tube, dehydration tube, stirrer, and thermocouple was charged with the raw material monomers for the polyester resin (except trimellitic anhydride) shown in Table 1, and the esterification catalyst. Under a nitrogen atmosphere, the mixture was heated to 235°C with stirring and maintained at 235°C for 6 hours. The pressure in the flask was then reduced to 8.3 kPa and maintained for 1 hour. The mixture was then cooled to 215°C and returned to atmospheric pressure. The trimellitic anhydride shown in Table 1 was added and maintained at 215°C for 1 hour. The pressure in the flask was then reduced to 8.3 kPa and the reaction continued until the softening point shown in Table 1 was reached, yielding Resin A-51 (polyester resin). The physical properties of Resin A-51 are shown in Table 1.

[0115] [Table 1]

[0116] [Production of styrene acrylic resin] Manufacturing Example A52 (Manufacturing of Resin A-52) A 5 L four-neck flask equipped with a thermometer, stainless steel stirrer, flow condenser, dropping funnel, and nitrogen inlet tube was charged with 2 L of xylene. A mixture of 880 g of styrene, 220 g of n-butyl acrylate, and 100 g of dibutyl peroxide was placed in the dropping funnel. Under a nitrogen atmosphere, the xylene was heated to 135°C with stirring, and the mixture in the dropping funnel was added dropwise over 1 hour. The temperature was then raised to 200°C and held at 200°C for 2 hours. The pressure in the flask was then reduced to 8 kPa and held for 1 hour. The xylene was then removed to yield Resin A-52 (styrene-acrylic resin). The physical properties of the resulting Resin A-52 were an ester group concentration of 0.85 mmol / g, a softening point of 115°C, a glass transition temperature of 54°C, and a crystallinity index of 1.8.

[0117] [Production of crystalline resin] [Production of Crystalline Polyester Resin C] Manufacturing Example C1 (Manufacturing of Resin C-1) A 10-liter four-neck flask equipped with a nitrogen inlet tube, a downflow condenser with a dehydration tube, a stirrer, and a thermocouple was purged with nitrogen, and the raw material monomers for the polyester resin listed in Table 2 were added. The reaction system was heated to 135°C while stirring, held at 135°C for 3 hours, and then heated from 135°C to 200°C over 10 hours. 10 g of esterification catalyst was then added to the reaction system, which was then held at 200°C for another 1 hour. The pressure inside the flask was then reduced, and the reaction was continued under a reduced pressure of 8 kPa until the softening point listed in Table 2 was reached, yielding Resin C-1. Physical properties are listed in Table 2.

[0118] [Table 2]

[0119] [Production of resin particle dispersion] Production Example X1 (Production of Resin Particle Dispersion X-1) 1000 g of Resin A-1 and 1000 g of methyl ethyl ketone were placed in a 5 L vessel equipped with a stirrer, reflux condenser, dropping funnel, thermometer, and nitrogen inlet tube, and the resin was dissolved over 1 hour at 80° 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 80 mol%, and the mixture was stirred for 30 minutes. Next, while maintaining the temperature at 80°C, 2700 g of deionized water was added over 60 minutes while stirring at 280 r / min (circumferential speed 88 m / min) to cause phase inversion emulsification. While continuing to maintain the temperature at 80°C, methyl ethyl ketone and a portion of the water were distilled off under reduced pressure to obtain an aqueous resin dispersion. Thereafter, while continuing to stir at 280 r / min (circumferential speed 88 m / min), the aqueous dispersion was cooled to 30°C, and deionized water was added to adjust the solids concentration to 25% by mass, thereby obtaining resin particle dispersion X-1. The volume median particle diameter D of the resulting resin particles was 50 and CV values ​​are shown in Table 3.

[0120] Production Examples X2, X3, and X51 (Production of Resin Particle Dispersions X-2, X-3, and X-51) Resin particle dispersions X-2, X-3, and X-51 were obtained in the same manner as in Production Example X1, except that Resin A-1 was replaced with Resin A-2, A-3, and A-51. 50 and CV values ​​are shown in Table 3.

[0121] Production Example X4 (Production of Resin Particle Dispersion X-4) 800 g of Resin A-1, 200 g of Resin C-1, and 1000 g of methyl ethyl ketone were placed in a 5 L vessel equipped with a stirrer, reflux condenser, dropping funnel, thermometer, and nitrogen inlet tube, and the resins were dissolved over 1 hour at 80° 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 80 mol%, and the mixture was stirred for 30 minutes. Next, while maintaining the temperature at 80°C, 2700 g of deionized water was added over 60 minutes while stirring at 280 r / min (circumferential speed 88 m / min) to cause phase inversion emulsification. While continuing to maintain the temperature at 80°C, methyl ethyl ketone and a portion of the water were distilled off under reduced pressure to obtain an aqueous dispersion of resin. Thereafter, while continuing to stir at 280 r / min (circumferential speed 88 m / min), the aqueous dispersion was cooled to 30°C, and deionized water was added to obtain a solids concentration of 25% by mass, thereby obtaining resin particle dispersion X-4. The volume median particle diameter D of the resulting resin particles was 50 and CV values ​​are shown in Table 3.

[0122] Production Example X52 (Production of Resin Particle Dispersion X-52) 500 g of resin A-52, 500 g of ethyl acetate, and 100 g of 15% by mass sodium dodecylbenzenesulfonate aqueous solution "Neopelex G-15" (Kao Corporation, anionic surfactant) were placed in a 3 L vessel equipped with a stirrer, reflux condenser, dropping funnel, thermometer, and nitrogen inlet tube, and the resin was dissolved at 70°C for 2 hours. 1400 g of deionized water at 70°C was added to the resulting resin solution, and dispersion was performed for 30 minutes at 350 W using an ultrasonic homogenizer "UP-400S" (Hielscher). Subsequently, while maintaining the temperature at 70°C, ethyl acetate was distilled off under reduced pressure, and deionized water was added to adjust the solids concentration to 25% by mass, yielding resin particle dispersion X-52. The volume median particle diameter D of the resulting resin particles was 1.0 g. 50 and CV values ​​are shown in Table 3.

[0123] [Table 3]

[0124] Production Example W1 (Production of Release Agent Particle Dispersion W-1) In a 1 L beaker, 100 g of deionized water and 67 g of anionic surfactant "Neopelex G15" (manufactured by Kao Corporation, effective concentration 15% by mass) were mixed, and then 50 g of paraffin wax "HNP-9" (manufactured by Nippon Seiro Co., Ltd., melting point 75°C) was added. While maintaining the temperature at 95-98°C, the mixture was dispersed for 20 minutes using an ultrasonic homogenizer "US-600T" (manufactured by Nippon Seiki Seisakusho Co., Ltd.), and then cooled to 25°C. Deionized water was added to adjust the solids concentration to 20% by mass, and release agent particle dispersion W-1 was obtained. The volume median particle diameter D of the release agent particles was 50 The particle size was 0.28 μm and the CV value was 39%.

[0125] Production Example F1 (Production of Colorant Particle Dispersion F-1) In a 1 L beaker, 100 g of Pigment Blue 15:3 (Dainichiseika Color & Chemicals Mfg. Co., Ltd., "ECB301"), 167 g of 15 wt% sodium dodecylbenzenesulfonate aqueous solution "Neopelex G-15" (Kao Corporation, anionic surfactant), and 102 g of deionized water were mixed and dispersed at 20°C for 1 hour using a homomixer "TKAGI HOMOMIXER 2M-03" (Primix Corporation) at a stirring blade rotation speed of 8000 r / min. The mixture was then subjected to 15 passes at 150 MPa using a homogenizer "Microfluidizer M-110EH" (Microfluidics). The mixture was then passed through a 200-mesh filter, and deionized water was added to adjust the solids concentration to 20 wt% to obtain colorant particle dispersion F-1. The volume median particle diameter D of the resulting colorant particles was 1.0 μm. 50 The particle size was 0.12 μm and the CV value was 22%.

[0126] [Toner manufacturing example] Example 1 (Production of Toner 1) [Process 1] In a 3 L four-neck flask equipped with a reflux condenser, a stirrer, and a thermocouple, 800 g of resin particle dispersion X-1, 178 g of release agent particle dispersion W-1, and 101 g of colorant particle dispersion F-1 were placed and mixed at a temperature of 25° C. Next, while stirring the mixture, a solution prepared by dissolving 51 g of ammonium sulfate in 952 g of deionized water and adding a 4.8 mass % potassium hydroxide aqueous solution to adjust the pH to 8.0 was added dropwise over 60 minutes at 25° C., and the temperature was then raised to 55° C. over 1 hour 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 6.0 μm, thereby obtaining a dispersion of aggregated particles 1. To the resulting dispersion of aggregated particles 1, 120 g of resin particle dispersion X-1 was added dropwise at 50° C. over 60 minutes to obtain a dispersion of aggregated particles 2. To the resulting dispersion of aggregated particles 2, 276 g of a 20 mass % aqueous solution of β-naphthalenesulfonic acid formalin condensate sodium salt "Demol N" (manufactured by Kao Corporation), 155 g of deionized water, and 191 g of a 4.8 mass % aqueous potassium hydroxide solution were added. The mixture was then heated to 70°C over 1 hour and maintained at 70°C until the circularity reached 0.970, thereby obtaining a dispersion of fused particles in which aggregated particles 2 were fused together. [Process 2] The resulting 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 subjected to suction filtration at 25°C for 2 hours to obtain a wet cake. The wet cake was then dried in an airflow dryer "Flash Jet Dryer FJD-4" (manufactured by Seishin Enterprise Co., Ltd.) at a feed rate of 4.5 kg / h and an air volume of 13 m3. 3 Drying was carried out at a drying speed of 1 / min, a drying temperature (inlet temperature) of 50°C, and a drying temperature (outlet temperature) of 43°C, to obtain toner particles 1 having a moisture content of 0.5% by mass or less. The physical properties of toner particles 1 are shown in Table 4. The water content of the toner particles was measured in the same manner as in the above-mentioned [Solid content concentrations of resin particle dispersion, colorant particle dispersion, and release agent particle dispersion]. 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 with 100 parts by mass of toner particles 1, and the mixture was stirred and passed through a 150 mesh sieve to obtain toner 1. The obtained toner 1 was evaluated as follows. The evaluation results of toner 1 are shown in Table 4.

[0127] [Toner evaluation method] [Charge amount distribution of toner] Under an environment of 25°C and 50% relative humidity, 0.6g of toner and ferrite carrier (ferrite core, silicone coated, saturation magnetization: 71Am 2 19.4 g of the powder (19.4 g / kg) was placed in a 50 mL polypropylene bottle "PP Sample Bottle Wide Mouth" (manufactured by Sanplatec Co., Ltd.) and stirred for 20 minutes in a ball mill. After that, 5 g was sampled and measured using a charge amount measuring device "q-test" (manufactured by Epping) under the following measurement conditions. Toner Flow (ml / min): 160 Electrode Voltage (V): 4000 Deposition Time(s):2 The median q / d was the toner charge Q / d (fC / 10 μm), where the specific density was 1.2 g / cm 3 and Median Diameter is the volume median particle diameter of the toner D 50 The obtained Q / d range of -0.4 to 0.4 (fC / 10 μm) was connected with a straight line to create a graph of the charge distribution. The charge distribution was evaluated by the half-width of the maximum peak of the obtained graph (the width of the cut when the distribution is cut at half the value of the maximum peak height in the distribution). The smaller the value, the narrower the charge distribution and the better the charge stability.

[0128] [Yield (%) of dry toner after 45 μm mesh processing] The toner extracted after the drying process was passed through a stainless steel mesh with 45 μm openings, and the yield (%) of the dried toner after 45 μm mesh processing was calculated using the following formula based on the amount of toner subjected to mesh processing and the amount of toner that passed through the mesh. Yield (%) of dry toner after 45 μm mesh processing = Amount of toner that passed through the mesh (g) / Amount of toner subjected to mesh processing (g)

[0129] Examples 2 to 6 (Production of Toners 2 to 6) Toner particles 2 to 6 and toners 2 to 6 were produced in the same manner as in Example 1, except that in step 2, the drying conditions of the flash jet dryer were changed as shown in Table 4. The physical property values ​​of the obtained toner particles 2 to 6 and the evaluation results of toners 2 to 6 are shown in Table 4.

[0130] Examples 7 and 8 and Comparative Examples 1 and 2 (Production of Toners 7, 8, 51, and 52) Toners were produced in the same manner as in Example 1, except that in step 1, the resin particle dispersion liquid used was changed as shown in Table 4. The physical property values ​​of the obtained toner particles 7, 8, 51, and 52 and the evaluation results of toners 7, 8, 51, and 52 are shown in Table 4.

[0131] Example 9 (Production of Toner 9) In process 2, the dryer used was changed to a fluidized bed dryer "AGM-2PJ" (manufactured by Hosokawa Micron Corporation), and the drying conditions were changed to an air volume of 1.5 m 3 Toner 9 was produced in the same manner as in Example 1, except that the drying speed was set to / min, the drying temperature was set to 50°C, and drying was carried out until the moisture content in the toner particles was 0.5% by mass or less. The physical property values ​​of the obtained toner particles 9 and the evaluation results of toner 9 are shown in Table 4.

[0132] Example 10 (Production of Toner 10) Toner 10 was produced in the same manner as in Example 1, except that the shell resin particle dispersion liquid added dropwise when preparing aggregated particles 2 in step 1 was changed as shown in Table 4. The physical property values ​​of the obtained toner particles 10 and the evaluation results of Toner 10 are shown in Table 4.

[0133] Example 11 (Production of Toner 11) Toner 11 was produced in the same manner as in Example 10, except that in step 1, the resin particle dispersion liquid used was changed as shown in Table 4. The physical property values ​​of the obtained toner particles 11 and the evaluation results of Toner 11 are shown in Table 4.

[0134] Comparative Example 3 (Production of Toner 53) Toner 53 was produced in the same manner as in Example 1, except that in step 2, the dryer used was changed to a tray-type dryer "DRV622DA" (manufactured by ADVANTEC), the drying temperature in the tank was set to 50°C, and drying was performed until the moisture content in the toner particles was 0.5% by mass or less. Table 4 shows the physical property values ​​of the obtained toner particles 53 and the evaluation results of Toner 53.

[0135] [Table 4]

[0136] Table 4 shows that the toners obtained by the method for producing a toner for developing electrostatic images of the present invention have a narrow charge distribution and excellent chargeability (Examples 1 to 11). In contrast, the toners produced in step 1 using resin particles composed of a resin with an ester group concentration of less than 5 mmol / g (4.3 mmol / g, 0.85 mmol / g) had a broad charge distribution (Comparative Examples 1 and 2). Furthermore, the toner produced in step 2 using a tray dryer instead of an airflow dryer had a broad charge distribution (Comparative Example 3). [Explanation of symbols]

[0137] 100 Airflow Drying System 50 Loop-type airflow dryer (flash jet dryer) 1 Discharge blower 2 electric heaters 3 Raw material supply hopper 4. Collection cyclone 5. Product Collection Department 6 Raw material supply department 7 Gas inlet 8 Gas supply section 9 Airflow Nozzle 10 Drying tube 11 Outlet T1, T2 Temperature indication adjustment alarm meter

Claims

1. A method for producing a toner for developing electrostatic images, comprising the following steps 1 and 2: Step 1: A step of obtaining an aqueous dispersion of toner particles by aggregating and fusing resin particles in an aqueous medium Step 2: A step of filtering the aqueous dispersion of toner particles obtained in step 1 and drying it using an airflow dryer. In step 1, the ester group concentration of the resin constituting the resin particles is 5 mmol / g or more and 15 mmol / g or less. A method for producing a toner for developing electrostatic images.

2. 2. The method for producing a toner for developing electrostatic images according to claim 1, wherein the airflow dryer is a fluidized bed dryer or a flash jet dryer.

3. The drying conditions for step 2 are: air volume: 0.5 m ３ / min or more 1500m ３ 3. The method for producing a toner for developing electrostatic images according to claim 1, wherein the temperature is 20°C or higher and 75°C or lower.

4. 3. The method for producing a toner for developing electrostatic images according to claim 1, wherein the toner particles have a core-shell structure.

5. 5. The method for producing a toner for developing electrostatic images according to claim 4, wherein the ester group concentration of the resin constituting the shell portion of the toner particles is 5 mmol / g or more and 15 mmol / g or less.

6. 5. The method for producing a toner for developing electrostatic images according to claim 4, wherein a ratio of the ester group concentration (shell) of the resin constituting the shell portion to the ester group concentration (core) of the resin constituting the core portion of the toner particles [ester group concentration (shell) / ester group concentration (core)] is 0.9 or more and 1.8 or less.

7. 3. The method for producing a toner for developing electrostatic images according to claim 1, wherein the resin constituting the resin particles includes a polyester resin.

8. 8. The method for producing a toner for developing electrostatic images according to claim 7, wherein the content of the aliphatic diol in the alcohol component of the polyester resin is 50 mol % or more.

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