Method for producing a resin particle dispersion

Abstract

The present invention relates to a method for producing 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 producing toner for electrostatic image development that can suppress the occurrence of fogging in image printing even when the resin particles in the resin particle dispersion are aggregated and fused together after being stored at low temperatures for a certain period of time. [Solution] A method for producing a resin particle dispersion liquid comprising the following steps 1 and 2 in this order, Step 1: A process to neutralize the resin containing acid groups. Step 2: A step to obtain a resin particle dispersion by adding an aqueous medium to the neutralized resin obtained in Step 1. The resin having acid groups includes a crystalline polyester resin C which is a polycondensate of an alcohol component and a carboxylic acid component, and the alcohol component of the crystalline polyester resin C contains 60 mol% or more of ethylene glycol. A method for producing a resin particle dispersion, wherein the amount of organic solvent used in steps 1 and 2 is 10 parts by mass or less per 100 parts by mass of resin.

Description

[Technical Field]

[0001] The present invention relates to a method for producing a resin particle dispersion suitable for manufacturing electrostatic image developing toner used for developing latent images formed in electrophotography, electrostatic recording, electrostatic printing, and the like, and a method for manufacturing 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 describes a method for manufacturing a toner for electrostatic image development that has excellent low-temperature fixing properties and a narrow charge distribution, comprising the steps of agglomerating and fusing resin particles containing amorphous resin and crystalline resin in the same or different particles in an aqueous medium, wherein the amorphous resin contains amorphous polyester resin (A), which is a polycondensate of an alcohol component (a) containing an aliphatic diol having 2 to 5 carbon atoms and a carboxylic acid component (b), and the crystalline resin contains crystalline polyester resin (C), which is a polycondensate of an alcohol component (c) containing ethylene glycol and a carboxylic acid component (d). [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2023-98716 [Overview of the project] [Problems that the invention aims to solve]

[0005] In the production of toner for electrostatic image development using the emulsification and agglutination method, after obtaining a resin particle dispersion, the dispersion may be stored for a certain period before the agglutination process, depending on the conditions of the manufacturing site. At this time, it is desirable to store it at a low temperature to suppress the agglutination of the resin particles. Therefore, it is desirable for the resin particle dispersion to have properties that make it less prone to agglutination even when stored at low temperatures, that is, to have improved storage stability at low temperatures. However, Patent Document 1 does not examine the storage stability of the resin particle dispersion. The present invention relates to a method for producing a resin particle dispersion liquid that exhibits excellent storage stability at low temperatures and is suitable for the production of toner for electrostatic image development, and to a method for producing electrostatic image development toner that can suppress the occurrence of fogging in image printing. [Means for solving the problem]

[0006] The present inventors have found that a resin particle dispersion can be obtained by a method for producing a resin particle dispersion, comprising the steps of neutralizing a resin having an acid group, and adding an aqueous medium to the neutralized resin obtained in the first step to obtain a resin particle dispersion, wherein the resin having an acid group is a polycondensate of an alcohol component containing a specific amount of ethylene glycol and a carboxylic acid component, and the amount of organic solvent used in the two steps is specified, thereby obtaining a resin particle dispersion with excellent storage stability at low temperatures. Furthermore, they have found that by agglomerating and fusing the resin particles in the resin particle dispersion, an electrostatic image developing toner can be obtained that can suppress the occurrence of fogging in image printing. The present invention relates to the following [1] and [2]. [1] A method for producing a resin particle dispersion, comprising the following steps 1 and 2 in this order: Step 1: A process to neutralize the resin containing acid groups. Step 2: A step to obtain a resin particle dispersion by adding an aqueous medium to the neutralized resin obtained in Step 1. The resin having acid groups includes a crystalline polyester resin C which is a polycondensate of an alcohol component and a carboxylic acid component, and the alcohol component of the crystalline polyester resin C contains 60 mol% or more of ethylene glycol. A method for producing a resin particle dispersion liquid, wherein the amount of the organic solvent used in Processes 1 and 2 is 10 parts by mass or less with respect to 100 parts by mass of the resin having an acid group. [2] A method for producing an electrostatic charge image developing toner having the following Processes 1 to 3 in this order, Process 1: A process of neutralizing a resin having an acid group Process 2: A process of adding an aqueous medium to the neutralized resin obtained in Process 1 to obtain a resin particle dispersion liquid Process 3: A process of aggregating and fusing resin particles in an aqueous medium The resin having an acid group contains a crystalline polyester resin C which is a polycondensate of an alcohol component and a carboxylic acid component, and the alcohol component of the crystalline polyester resin C contains 60 mol% or more of ethylene glycol, A method for producing an electrostatic charge image developing toner, wherein the amount of the organic solvent used in Processes 1 and 2 is 10 parts by mass or less with respect to 100 parts by mass of the resin having an acid group. [Advantages of the Invention]

[0007] According to the present invention, there are provided a method for producing a resin particle dispersion liquid which is excellent in storage stability at low temperatures and suitable for producing an electrostatic charge image developing toner, and a method for producing an electrostatic charge image developing toner which can suppress the occurrence of fogging in image printing. [Embodiments for Carrying Out the Invention]

[0008] [Method for Producing Resin Particle Dispersion Liquid] The method for producing a resin particle dispersion liquid of the present invention has the following Processes 1 and 2 in this order. Process 1: A process of neutralizing a resin having an acid group Process 2: A process of adding an aqueous medium to the neutralized resin obtained in Process 1 to obtain a resin particle dispersion liquid The resin having an acid group contains a crystalline polyester resin C which is a polycondensate of an alcohol component and a carboxylic acid component, and the alcohol component of the crystalline polyester resin C contains 60 mol% or more of ethylene glycol, and the amount of the organic solvent used in Processes 1 and 2 is 10 parts by mass or less with respect to 100 parts by mass of the resin having an acid group.

[0009] The resin particle dispersion obtained by the method for producing the resin particle dispersion of the present invention exhibits excellent storage stability at low temperatures. Furthermore, by agglomerating and fusing the resin particles in the resin particle dispersion obtained by the method for producing the resin particle dispersion of the present invention, an electrostatic image developing toner can be obtained that can suppress the occurrence of fogging in image printing. The reason for this is not entirely clear, but it is thought to be as follows.

[0010] In the manufacturing of toner using the emulsification and agglutination method, a dispersion of toner components, such as binder resins, is used, which is pre-dispersed in an aqueous medium. However, for manufacturing convenience, the dispersion is often stored in this state. Crystalline polyester resins, in particular, are relatively hydrophobic and therefore have poor dispersion stability in aqueous mediums, making it especially important to improve their storage stability at low temperatures. In this invention, a crystalline polyester resin containing 60 mol% or more of ethylene glycol in the alcohol component is used as the crystalline polyester resin. Because the alcohol component contains a large amount of hydrophilic ethylene glycol, the hydrophobicity is reduced without impairing the crystallinity of the resin, and the affinity with water is increased. When producing the resin particle dispersion, emulsification is performed without dissolving the resin in an organic solvent, so that the constituent units derived from ethylene glycol in the crystalline polyester resin spontaneously adopt a stable orientation form with respect to water, which is the dispersion medium, and particle formation is promoted while increasing the hydrophilicity of the particle surface. As a result, the stability of the obtained resin particle dispersion is improved, and it is believed that instability due to aggregation between crystalline polyester resins, which tends to occur during storage at low temperatures, has been improved. Furthermore, by using the resin particle dispersion obtained by the present invention to produce toner by emulsification and agglutination, the generation of coarse particles in the agglutination process is suppressed, which improves the homogeneity between toner particles, resulting in stable electrostatic properties and suppression of fogging in the resulting image.

[0011] The definitions of various terms used in this specification are shown below. In this specification, the carboxylic acid component of the polyester resin includes not only the compound itself, but also anhydrides that decompose during the reaction to produce carboxylic acids, and alkyl esters of each carboxylic acid (alkyl group having 1 to 3 carbon atoms). Whether a resin is crystalline or amorphous is determined by its crystallinity index. The crystallinity index is defined as the ratio of the softening point of the resin to the maximum endothermic peak temperature (softening point (°C) / maximum endothermic peak temperature (°C)) in the measurement method described in the examples below. A crystalline resin is one in which the crystallinity index is 0.6 or higher and 1.4 or lower. An amorphous resin is one in which no endothermic peak is observed, or if observed, the crystallinity index is less than 0.6 or greater than 1.4. The crystallinity index can be appropriately adjusted depending on the type and ratio of raw material monomers, as well as manufacturing conditions such as reaction temperature, reaction time, and cooling rate.

[0012] In the method for producing the resin particle dispersion of the present invention, each component (essential component and optional component), such as crystalline polyester resin C, may be used individually or in combination of two or more. Furthermore, the raw materials for each component contained in the toner particles, such as alcohol components and carboxylic acid components, may be used individually or in combination of two or more.

[0013] [Process 1] Step 1 is a step of neutralizing the resin that has acid groups. <Resin containing acidic groups> The resin having acidic groups in this invention is a resin that serves as a binder for toner, and from the viewpoint of improving the storage stability of the resin particle dispersion at low temperatures and obtaining a toner that can suppress the occurrence of fogging in image printing, it includes crystalline polyester resin C (hereinafter sometimes simply referred to as "resin C"). Resin C is a polycondensate of an alcohol component and a carboxylic acid component, and the alcohol component contains 60 mol% or more of ethylene glycol. In addition, the resin having acidic groups may also include amorphous polyester resin A (hereinafter sometimes simply referred to as "resin A").

[0014] (Crystalline polyester resin C) The ethylene glycol content in the alcohol component is 60 mol% or more, preferably 70 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, preferably 100 mol%, from the viewpoint of improving the storage stability of the resin particle dispersion at low temperatures and obtaining a toner that can suppress the occurrence of fogging in image printing.

[0015] The alcohol component may contain aliphatic diols other than ethylene glycol. As aliphatic diols other than ethylene glycol, α,ω-alkanediols are preferred from the viewpoint of obtaining a crystalline resin, and the number of carbon atoms is preferably 3 or more, more preferably 16 or less, more preferably 10 or less, even more preferably 6 or less, and even more preferably 4 or less, from the viewpoint of improving the storage stability of the resin particle dispersion at low temperatures. Examples of aliphatic diols other than ethylene glycol include 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.

[0016] The alcohol component may contain other alcohol components different from 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 improving the storage stability of the resin particle dispersion at low temperatures and from the viewpoint of obtaining a toner that can suppress the occurrence of fogging in image printing. From the viewpoint of obtaining a crystalline resin, the aliphatic dicarboxylic acid is preferably an α,ω-dicarboxylic acid, and from the viewpoint of improving the storage stability of the resin particle dispersion at low temperatures and obtaining a toner that can suppress the occurrence of fogging in image printing, the number of carbon atoms is preferably 4 or more, more preferably 8 or more, even more preferably 10 or more, and preferably 16 or less, more preferably 14 or less, and even more preferably 12 or less. Specific examples of aliphatic dicarboxylic acids include succinic acid, fumaric acid, maleic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, 1,11-undecanediic acid, 1,12-dodecanediic acid, and 1,14-tetradecanediic acid. Among these, sebacic acid, 1,12-dodecanediic acid, and 1,14-tetradecanediic acid are preferred, with sebacic acid being more preferred, from the viewpoint of improving the storage stability of the resin particle dispersion at low temperatures and obtaining a toner that can suppress the occurrence of fogging in image printing.

[0018] The amount of aliphatic dicarboxylic acid in the carboxylic acid component is preferably 60 mol% or more, more preferably 70 mol% or more, even more preferably 80 mol% or more, even more preferably 85 mol% or more, and 100 mol% or less, from the viewpoint of improving the storage stability of the resin particle dispersion at low temperatures and obtaining a toner that can suppress the occurrence of fogging in image printing. If a carboxylic acid component other than aliphatic dicarboxylic acid is included, it is preferably 98 mol% or less, 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, from the viewpoint of hydrophobicity and crystallinity, include caproic acid, caprylic acid, pelargonic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, and lignoceric acid. Among these, stearic acid is preferred. The amount of monocarboxylic 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 25 mol% or less, more preferably 20 mol% or less, and even more preferably 15 mol% or less, from the viewpoint of hydrophobicity and crystallinity. 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] 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.

[0021] ≪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.

[0022] 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 to 10 parts by mass, more preferably 0.05 parts by mass to 1 part by mass, 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.

[0023] ≪Physical properties of crystalline polyester resin C≫ 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, from the viewpoint of toner storage stability, and preferably 120°C or lower, more preferably 100°C or lower, and even more preferably 80°C or lower, from the viewpoint of further improving the low-temperature fixability of the toner.

[0024] 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, from the viewpoint of toner storage stability, and preferably 90°C or lower, more preferably 85°C or lower, and even more preferably 80°C or lower, from the viewpoint of further improving the low-temperature fixability of the toner.

[0025] Resin C has an acid group. From the viewpoint of improving the storage stability of the resin particle dispersion at low temperatures, the acid value of resin C is preferably 5 mg KOH / g or more, more preferably 10 mg KOH / g or more, and preferably 25 mg KOH / g or less, more preferably 20 mg KOH / g or less.

[0026] The softening point, melting point, and acid value 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 softening point, melting point, and acid value obtained from the mixture thereof are within the aforementioned ranges.

[0027] (Amorphous polyester resin A) Resin A is, for example, a polycondensate of an alcohol component and a carboxylic acid component.

[0028] Examples of alcohol components include aliphatic diols, alkylene oxide adducts of aromatic diols, alicyclic diols, and polyhydric alcohols of three or higher valencies. Among these, aliphatic diols are preferred from the viewpoint of the storage stability of the resin particle dispersion at low temperatures. The number of carbon atoms in the aliphatic diol is preferably 2 or more, more preferably 3 or more, and preferably 16 or less, more preferably 12 or less, even more preferably 8 or less, and even more preferably 5 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, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, and 1,8-octanediol. Among these, neopentyl glycol is preferred from the viewpoint of improving the storage stability of the resin particle dispersion at low temperatures.

[0029] The amount of aliphatic diol is preferably 50 mol% or more, 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, and preferably 100 mol%, in the alcohol component.

[0030] The alcohol component may contain other alcohol components besides aliphatic diols. Examples of other alcohol components include alkylene oxide adducts of aromatic diols and trivalent or higher alcohols.

[0031] The alkylene oxide adduct of an aromatic diol is preferably an alkylene oxide adduct of bisphenol A, and more preferably of formula (I): [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.

[0032] 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.

[0033] Examples of alcohols with a hydride of 3 or higher include glycerin, pentaerythritol, and trimethylolpropane.

[0034] Examples of carboxylic acid components include dicarboxylic acids and polycarboxylic acids with a valency of three or more.

[0035] Examples of dicarboxylic acids include aromatic dicarboxylic acids, aliphatic dicarboxylic acids, and alicyclic dicarboxylic acids. Among these, aromatic dicarboxylic acids are preferred.

[0036] Examples of aromatic dicarboxylic acids include phthalic acid, isophthalic acid, and terephthalic acid. Among these, isophthalic acid and terephthalic acid are preferred. The amount of aromatic dicarboxylic acid is preferably 70 mol% or more, more preferably 80 mol% or more, even more preferably 90 mol% or more, and preferably 100 mol% or less, and preferably 100 mol%, in the carboxylic acid component.

[0037] 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, glutaric acid, adipic acid, azelaic acid, sebacic acid, dodecanediic acid, azelaic acid, and succinic acid substituted with an aliphatic hydrocarbon group having 1 to 20 carbon atoms. Examples of succinic acid substituted with an aliphatic hydrocarbon group having 1 to 20 carbon atoms include dodecyl succinic acid, dodecenyl succinic acid, and octenyl succinic acid.

[0038] Examples of alicyclic dicarboxylic acids include cyclohexanedicarboxylic acid.

[0039] Preferably, the polycarboxylic acid with a valency of 3 or higher is a trivalent carboxylic acid, such as trimellitic acid.

[0040] 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.

[0041] Resin A can be manufactured, for example, in the same manner as resin C.

[0042] ≪Physical properties of amorphous polyester resin A≫ The softening point of resin A is preferably 70°C or higher, more preferably 80°C or higher, and even more preferably 90°C or higher, from the viewpoint of toner's storage properties, and preferably 140°C or lower, more preferably 130°C or lower, and even more preferably 120°C or lower, from the viewpoint of toner's low-temperature fixing properties.

[0043] The glass transition temperature of resin A is preferably 30°C or higher, more preferably 40°C or higher, and even more preferably 50°C or higher, from the viewpoint of toner storage properties, and preferably 80°C or lower, more preferably 75°C or lower, and even more preferably 70°C or lower, from the viewpoint of toner low-temperature fixing properties.

[0044] The acid value of resin A is preferably 2 mg KOH / g or more, more preferably 5 mg KOH / g or more, even more preferably 10 mg KOH / g or more, and preferably 40 mg KOH / g or less, more preferably 35 mg KOH / g or less, and even more preferably 30 mg KOH / g or less, from the viewpoint of the dispersion stability of the resin particle dispersion.

[0045] The softening point, glass transition temperature, and acid value 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. Furthermore, the softening point, glass transition temperature, and acid value of resin A 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-mentioned physical properties. Moreover, it is even more preferable that the softening point, glass transition temperature, and acid value obtained as a mixture thereof are each within the aforementioned ranges.

[0046] <Neutralization> In step 1, the resin having acidic groups is neutralized. Neutralization is preferably carried out using a neutralizing agent, and 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 neutralizing agent can be used as an aqueous solution. From the viewpoint of efficiently neutralizing resins having acidic groups, the concentration of the aqueous solution of the neutralizing agent is preferably 1% by mass or more, more preferably 3% by mass or more, and preferably 15% by mass or less, more preferably 10% by mass or less.

[0047] From the viewpoint of efficiently neutralizing the resin having acidic groups, the degree of neutralization 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 a resin containing an acidic group 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 with acidic groups (mgKOH / g) × Mass of resin with acidic groups (g)} / (56 × 1000)] × 100

[0048] In step 1, from the viewpoint of efficiently neutralizing the resin having acidic groups, it is preferable to add an aqueous solution of a neutralizing agent to the resin having acidic groups, and then heat and stir the resin to melt it. From the same viewpoint, the heating temperature is preferably above the melting point of resin C, preferably 80°C or higher, more preferably 85°C or higher, even more preferably 90°C or higher, and preferably 120°C or lower, more preferably 110°C or lower, and even more preferably 105°C or lower.

[0049] [Process 2] In step 2, an aqueous medium is added to the neutralized resin containing acid groups obtained in step 1 to obtain a resin particle dispersion. From the viewpoint of dispersion stability of the resin particle dispersion, it is preferable to obtain the resin particle dispersion by gradually adding the aqueous medium while stirring the molten resin containing acid groups to emulsify the resin containing acid groups. An aqueous medium is a medium whose main component is water. From the viewpoint of improving the storage stability of the resin particle dispersion at low temperatures, the water content in the aqueous medium is preferably 90% by mass or more, more preferably 95% by mass or more, even more preferably 98% by mass or more, and 100% by mass or less, and preferably 100% by mass. 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.

[0050] From the viewpoint of efficiently emulsifying the resin having acid groups, the rate at which the aqueous medium is added is preferably 30 parts by mass / min or less, more preferably 20 parts by mass / min or less, even more preferably 10 parts by mass / min or less, and preferably 1 part by mass / min or more, and more preferably 3 parts by mass / min or more, per 100 parts by mass of the resin having acid groups.

[0051] When adding the aqueous medium, the temperature of the resin solution containing acidic groups is the same as the heating temperature in step 1 described above, from the viewpoint of improving the dispersion stability of the resin particles.

[0052] In steps 1 and 2, organic solvents may be used, but from the viewpoint of improving the storage stability of the resin particle dispersion at low temperatures, it is preferable to use a small amount. Specific examples of organic solvents include those that dissolve resins having acidic groups and are water-soluble, although they are not particularly limited; for example, methyl ethyl ketone can be used. The total amount of organic solvent used in steps 1 and 2 is 10 parts by mass or less, preferably 5 parts by mass or less, more preferably 1 part by mass or less, and even more preferably 0 parts by mass, per 100 parts by mass of the resin having an acid group, from the viewpoint of improving the storage stability of the resin particle dispersion at low temperatures.

[0053] In steps 1 and 2, surfactants may be used to improve the dispersibility of the resin having acid groups, but from the viewpoint of improving the storage stability of the resin particle dispersion at low temperatures, it is preferable to use a small amount. The total amount of surfactant used in steps 1 and 2 is preferably 1 part by mass or less, more preferably 0.5 parts by mass or less, and even more preferably 0 parts by mass, per 100 parts by mass of the resin having acid groups.

[0054] From the viewpoint of improving toner productivity, 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 35% by mass or less, more preferably 30% by mass or less, and even more preferably 25% by mass or less. Note that the solid content represents the total amount of non-volatile components.

[0055] The total content of resin C and resin A 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 improving the storage stability of the resin particle dispersion at low temperatures.

[0056] When the resin particles contain resin A, the mass ratio of resin C to resin A [resin C / resin A] 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, and even more preferably 15 / 85 or more, from the viewpoint of the low-temperature fixability of the toner, and preferably 40 / 60 or less, more preferably 30 / 70 or less, and even more preferably 25 / 75 or less, from the viewpoint of the storage stability of the toner.

[0057] Volume-average particle size D of resin particles immediately after manufacturing of resin particle dispersion V From the viewpoint of obtaining a toner that can suppress the occurrence of fogging in image printing, the toner is preferably 0.02 μm or more, more preferably 0.05 μm or more, even more preferably 0.07 μm or more, and preferably 0.35 μm or less, more preferably 0.3 μm or less, and even more preferably 0.25 μm or less. Volume average particle size D of resin particles V This can be obtained by the method described in the examples.

[0058] [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 to 3 in this order. Step 1: A process to neutralize the resin containing acid groups. Step 2: A step to obtain a resin particle dispersion by adding an aqueous medium to the neutralized resin obtained in Step 1. Step 3: A process of agglomerating and fusing resin particles in an aqueous medium. The aforementioned resin having acid groups includes a crystalline polyester resin C which is a polycondensate of an alcohol component and a carboxylic acid component, wherein the alcohol component of the crystalline polyester resin C contains 60 mol% or more of ethylene glycol. The amount of organic solvent used in steps 1 and 2 is 10 parts by mass or less per 100 parts by mass of the resin having an acidic group. 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.

[0059] [Steps 1 and 2] In steps 1 and 2, it is preferable to obtain the resin particle dispersion in the same manner as in steps 1 and 2 of the "Method for Producing Resin Particle Dispersion" described above. Hereinafter, the resin particle dispersion obtained in step 2 will also be referred to as "Resin Particle Dispersion EM".

[0060] [Step 3] In step 3, the resin particles in the resin particle dispersion EM obtained in step 2 are aggregated and fused in an aqueous medium to obtain toner particles. That is, the resin particles in the resin particle dispersion EM obtained in step 2 are aggregated to obtain aggregated particles, and the obtained aggregated particles are fused to obtain toner particles.

[0061] In step 3, toner particles may be obtained by agglomerating and fusing together with resin particles in an aqueous medium dispersion of resin particles containing resin A, which was manufactured separately from steps 1 and 2 (hereinafter also referred to as "resin particle dispersion V"). Furthermore, in step 3, it is preferable to agglomerate the resin particles in the resin particle dispersion EM together with at least one of the colorant and the mold release agent, and optionally the resin particles in the resin particle dispersion V. More preferably, the resin particle dispersion EM, the colorant particle dispersion and the mold release agent particle dispersion, and optionally the resin particle dispersion V are mixed to agglomerate these particles.

[0062] The total content of resin C and resin A is preferably 60% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass or more, in the toner particles from the viewpoint of improving toner fixation, and preferably less than 100% by mass, preferably 98% by mass or less, more preferably 95% by mass or less, and even more preferably 90% by mass or less, from the viewpoint of improving toner image density.

[0063] The content of resin C in the toner particles is preferably 0.5% by mass or more, more preferably 3% by mass or more, even more preferably 7% by mass or more, and even more preferably 10% by mass or more, from the viewpoint of the toner's low-temperature fixability, and preferably 40% by mass or less, more preferably 30% by mass or less, and even more preferably 25% by mass or less, from the viewpoint of the toner's storage stability.

[0064] The content of resin A in the toner particles is preferably 50% by mass or more, more preferably 55% by mass or more, and even more preferably 60% by mass or more, from the viewpoint of the storage stability of the toner, and preferably 99% by mass or less, more preferably 85% by mass or less, and even more preferably 75% by mass or less, from the viewpoint of the low-temperature fixability of the toner.

[0065] The mass ratio of resin C to resin A in toner particles [resin C / resin A] 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, and even more preferably 15 / 85 or more, from the viewpoint of the toner's low-temperature fixability, and from the viewpoint of the toner's storage stability, it is preferably 40 / 60 or less, more preferably 30 / 70 or less, and even more preferably 25 / 75 or less.

[0066] (Method for producing resin particle dispersion V) The resin particle dispersion V can be manufactured using known methods, but 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 resin A or to molten resin A and then emulsifying it. From the viewpoint of productivity of the resin particle dispersion V, the method of adding an aqueous medium to an organic solvent solution of resin A and then emulsifying it is preferred. The organic solvent used for phase inversion emulsification is not particularly limited as long as it dissolves resin A and is water-soluble, but an example is methyl ethyl ketone. From the viewpoint of the dispersibility stability of the resin particle dispersion, it is preferable to add a neutralizing agent to the organic solvent solution of resin A. 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. From the viewpoint of efficiently neutralizing resin A, the degree of neutralization of resin A 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. Furthermore, the degree of neutralization of resin A contained in the resin particles can be determined in the same way as the degree of neutralization of resins containing acidic groups.

[0067] While stirring the organic solvent solution or molten resin, gradually add an aqueous medium to induce phase inversion. When adding the 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 85°C or lower, from the viewpoint of efficiently neutralizing resin A.

[0068] 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.

[0069] <Coloring agent> As a coloring agent, all dyes, pigments, etc. used as coloring agents for toners can be used. Examples of colorants include carbon black, phthalocyanine blue, permanent brown FG, brilliant first scarlet, pigment green B, rhodamine-B base, solvent red 49, solvent red 146, solvent blue 35, quinacridone, carmine 6B, 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, from the viewpoint of toner image density, and preferably 20% by mass or less, more preferably 15% by mass or less, and even more preferably 10% by mass or less, from the viewpoint of toner fixation.

[0070] (Method for producing a dispersion of coloring agent particles) 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 particles. The addition polymer E preferably has structural 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.

[0071] Examples of surfactants that improve the dispersion stability of colorant particles include nonionic surfactants, anionic surfactants, and cationic surfactants, with nonionic surfactants being preferred from the viewpoint of improving the dispersion stability of colorant particles. Examples of nonionic surfactants include polyoxyalkylene alkyl ethers, polyoxyalkylene alkenyl ethers, and polyoxyalkylene aryl ethers. Among these, polyoxyethylene aryl ethers are preferred, and polyoxyethylene distyleninated phenyl ethers are more preferred.

[0072] From the viewpoint of improving the dispersion stability of the colorant particles, the surfactant content in the colorant particle dispersion is preferably 1 part by mass or more, more preferably 10 parts by mass or more, even more preferably 20 parts by mass or more, and even more preferably 30 parts by mass or more, and preferably 50 parts by mass or less, more preferably 45 parts by mass or less, and even more preferably 40 parts by mass or less, per 100 parts by mass of colorant.

[0073] From the viewpoint of improving toner productivity, the colorant content in the colorant particle dispersion is preferably 5% by mass or more, more preferably 10% by mass or more, and from the viewpoint of improving the dispersion stability of the colorant particles, it is preferably 50% by mass or less, more preferably 30% by mass or less, and even more preferably 25% by mass or less. From the viewpoint of improving toner productivity, the solid content concentration 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. From the viewpoint of improving the dispersion stability of the colorant particles, it is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less.

[0074] Volume-intermediate particle size D of colorant particles 50 From the viewpoint of the dispersibility of the colorant in the toner particles, the particle size is preferably 0.05 μm or larger, more preferably 0.08 μm or larger, even more preferably 0.1 μm or larger, and preferably 0.4 μm or smaller, more preferably 0.3 μm or smaller, and even more preferably 0.2 μm or smaller. From the viewpoint of productivity of the coloring agent particles, the CV value is preferably 10% or more, more preferably 15% or more, and preferably 40% or less, more preferably 30% or less, and even more preferably 25% or less. Volume-intermediate particle size D of colorant particles 50 The CV value is measured by the method of the example.

[0075] The amount of coloring agent particles used 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 the image quality of the toner, and preferably 30 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 10 parts by mass or less, from the viewpoint of the low-temperature fixation of the toner.

[0076] <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.

[0077] From the perspective of the storage stability of the toner, the melting point of the release agent is preferably 60°C or higher, more preferably 70°C or higher, and from the perspective of the low-temperature fixing property of the toner, it is preferably 160°C or lower, more preferably 120°C or lower, and still more preferably 90°C or lower.

[0078] From the perspective of the release property of the toner, the content of the release agent in the toner particles is preferably 1% by mass or more, more preferably 3% by mass or more, and from the perspective of the charging stability of the toner, it is preferably 20% by mass or less, more preferably 15% by mass or less, and still more preferably 10% by mass or less.

[0079] (Method for producing the release agent particle dispersion liquid) The release agent particle dispersion liquid can be obtained using a surfactant, but can also 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 constituting the resin particles, and it becomes possible to disperse the release agent in an aqueous medium without using a surfactant. In the release agent particle dispersion liquid, it is considered to have a structure in which a large number of resin particles adhere to the surface of the release agent particles. The resin constituting the resin particles for dispersing the release agent is preferably a polyester-based resin, and it is more preferable to use a composite resin D having a polyester resin segment and an addition polymerization resin segment. For the release agent particle dispersion liquid and the composite resin D, reference is made to Japanese Patent Application Laid-Open No. 2024-25642. Also, the aforementioned resin A may be used.

[0080] The volume median diameter D of the release agent particles 50 is preferably 0.05 μm or more, more preferably 0.1 μm or more, still more preferably 0.2 μm or more from the perspective of obtaining uniform toner particles by aggregation, and is preferably 0.5 μm or less, more preferably 0.4 μm or less, still more preferably 0.35 μm or less. From the perspective of the productivity of the release agent particles, 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, still more preferably 45% or less. Release agent particle volume median particle size D 50 The CV value is measured by the method described in the examples.

[0081] The amount of release agent particles used is preferably 1 part by mass or more, more preferably 3 parts by mass or more, per 100 parts by mass of resin particles, from the viewpoint of toner release properties, and preferably 30 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 10 parts by mass or less, from the viewpoint of toner charge stability.

[0082] In step 3, 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.

[0083] <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 metal salts with a valency of 1 to 5 and inorganic ammonium salts are preferred, inorganic metal salts with a valency 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.

[0084] 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.

[0085] Methods for stopping aggregation include cooling the dispersion, adding an aggregation inhibitor, and diluting the dispersion. Furthermore, if the process involves agglomerating shell resin particles for the purpose of manufacturing toner having a core-shell structure, the aggregation process may be carried out without stopping the aggregation, once the aggregated particles 1 have grown to an appropriate particle size.

[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] If the toner manufacturing method includes a step of agglomerating resin particles for the shell, it is preferable to stop the agglomeration in this step when the agglomerated particles 2 have grown to a suitable particle size for toner, and it is preferable to stop the agglomeration by adding an agglomeration inhibitor.

[0089] <Agglutination inhibitor> As a flocculation inhibitor, surfactants are preferred, and anionic surfactants are more preferred, from the viewpoint of reliably preventing unnecessary flocculation. Examples of anionic surfactants include carboxylates, sulfonates, sulfate esters, phosphate esters, and amino acid salts, and sulfate esters are preferred from the viewpoint of reliably preventing unnecessary flocculation. Examples of sulfate esters include alkyl sulfates, polyoxyethylene alkyl ether sulfates, sulfated oils, sulfated fatty acid esters, and sulfated olefins, and polyoxyethylene alkyl ether sulfates are preferred from the viewpoint of reliably preventing unnecessary flocculation. The flocculant 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 obtained aggregated particles are fused together in an aqueous medium, fusing each particle contained 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] From the viewpoint of improving image quality, the circularity of the fused particles obtained by fusion is preferably 0.955 or higher, more preferably 0.960 or higher, and even more preferably 0.965 or higher. From the viewpoint of toner productivity, it is 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 obtaining images with good image quality, 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] From the viewpoint of improving image quality, the circularity of the toner particles is preferably 0.955 or higher, more preferably 0.960 or higher, and even more preferably 0.965 or higher. From the viewpoint of toner productivity, it is 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, from the viewpoint of improving the fluidity of the toner.

[0098] Toner is used in electrophotographic printing for electrostatic image development. Toner can be used, for example, as a one-component developer, or mixed with a carrier to form a two-component developer. [Examples]

[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 method] [Softening point, crystallinity index, melting point, and glass transition temperature of resins] (1) Softening point Using a flow tester "CFT-500EX" (manufactured by Shimadzu Corporation), 1 g of sample was heated at a heating rate of 6°C / min while a load of 1.96 MPa was applied by a plunger and 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.

[0101] [Acid value of crystalline polyester resin] The measurement was performed according to the method of JIS K 0070:1992. However, the measurement solvent was changed from the mixed solvent of ethanol and ether specified in JIS K 0070:1992 to tetrahydrofuran. [Acid value of amorphous polyester 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] [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.

[0103] [Volume-intermediate particle size D of resin particles, colorant particles, and mold release agent 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 was calculated according to the following formula. CV value (%) = (Standard deviation of particle size distribution / Volume average particle size D) v ) × 100

[0104] [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%)

[0105] [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.

[0106] [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.

[0107] [Toner particle volume medium 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 and 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.

[0108] [Resin manufacturing] [Manufacturing of crystalline polyester resin] Manufacturing Example C1 (Manufacturing of Crystalline Polyester Resin C-1) The raw material monomers for the polyester resin shown in Table 1 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. Under a nitrogen atmosphere, the mixture was heated to 200°C over 8 hours in a mantle heater while stirring. Then, tin(II) di(2-ethylhexanoate) was added as an esterification catalyst, and the mixture was heated to 210°C over 1 hour. The reaction was then carried out at 8 kPa until the softening point shown in Table 1 was reached, yielding crystalline polyester resin C-1. The physical properties are shown in Table 1.

[0109] Manufacturing Example C'2 (Manufacturing of Crystalline Polyester Resin C'-2) The alcohol components, carboxylic acid components, and polymerization inhibitor 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 kPa until the softening point reached the temperature shown in Table 1, yielding crystalline polyester resin C'-2. The physical properties are shown in Table 1.

[0110] [Table 1]

[0111] [Manufacturing of amorphous polyester resin] Manufacturing example (Manufacturing of amorphous polyester resin A-1) The raw material monomers for polyester resins other than isophthalic acid, and the esterification catalyst, as shown in Table 2, were placed in a 10 L four-necked flask equipped with a nitrogen inlet tube, a dehydration tube fitted with a fractionation tube through which 98°C hot water was passed, a stirrer, and a thermocouple. Under a nitrogen atmosphere, the reaction system was held 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 to allow polycondensation. After cooling to 180°C, isophthalic acid was added to the reaction system, 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 A-1. The physical properties are shown in Table 2.

[0112] [Table 2]

[0113] [Manufacturing of resin particle dispersions] Example 1-1 (Production of resin particle dispersion EM-1) In a 2L container equipped with a stirrer, reflux condenser, dropping funnel, thermometer, and nitrogen inlet tube, 200g of crystalline polyester resin C-1 and a 5% by mass sodium hydroxide aqueous solution were added to achieve a neutralization degree of 70 mol% relative to the acid value of the resin. The mixture was then melted and stirred at 98°C until the system was homogenized. Next, while maintaining the temperature at 98°C, 750 g of deionized water was added over 60 minutes while stirring at 200 r / min (peripheral speed 64 m / min) to obtain a resin dispersion. Subsequently, the dispersion was cooled to 30°C while continuing to stir, and deionized water was added to obtain resin particle dispersion EM-1 by reducing the solid content concentration to 20% by mass. The volume-average particle size Dv of the resin particles is shown in Table 3 as "Volume-average particle size Dv(1)". Furthermore, the volume-average particle size Dv(2) measured by the evaluation method described below, and the volume-average particle size change rate before and after storage at 5°C for 14 days are shown in Table 3 as "Volume-average particle size change rate before and after low-temperature storage".

[0114] [Evaluation method for resin particle dispersions] [Percentage change in volume-average particle size of resin particle dispersion before and after low-temperature storage] The resin particle dispersion was placed in a sealed container and stored in a constant temperature room at 5°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 5°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 5°C was calculated using the following formula (rounded down to the second 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 (Dv(1))] - 1] × 100

[0115] Example 1-2 (Production of resin particle dispersion EM-2) Resin particle dispersion EM-2 was obtained in the same manner as in Example 1-1, except that 40 g of crystalline polyester resin C-1 and 160 g of amorphous polyester resin A-1 were used instead of 200 g of crystalline polyester resin C-1. The evaluation results are shown in Table 3.

[0116] Comparative Example 1-1 (Production of Resin Particle Dispersion EM'-3) 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 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 r / min (peripheral speed 64 m / 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 stirring at 200 r / min (peripheral speed 64 m / min), and then deionized water was added to achieve a solid content concentration of 20% by mass to obtain resin particle aqueous dispersion EM'-3. The evaluation results are shown in Table 3.

[0117] Comparative Example 1-2 (Production of Resin Particle Dispersion EM'-4) Resin particle dispersion EM'-4 was obtained in the same manner as in Example 1-1, except that the crystalline polyester resin was changed as shown in Table 3.

[0118] [Table 3]

[0119] Table 3 shows that the resin particle dispersion obtained by the method for producing the resin particle dispersion of the present invention shows little change in the volume-average particle size of the resin particles even when stored at 5°C for 14 days, demonstrating excellent low-temperature storage stability (Examples 1-1 and 1-2). In contrast, the resin particle dispersion produced using an organic solvent (Comparative Example 1-1) showed a large change in the volume-average particle size of the resin particles and poor low-temperature storage stability. Furthermore, the resin particle dispersion obtained using crystalline polyester resin C'-2 produced with 1,9-nonanediol as the alcohol component showed a very large change in the volume-average particle size of the resin particles and poor low-temperature storage stability (Comparative Example 1-2).

[0120] Manufacturing Example V1 (Manufacturing of Resin Particle Dispersion V-1) In a 3L container equipped with a stirrer, reflux condenser, dropping funnel, thermometer, and nitrogen inlet tube, 200g of amorphous polyester resin A-1 and 200g of methyl ethyl ketone were placed, and amorphous polyester resin A-1 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 amorphous polyester resin A-1, and the mixture was stirred for 30 minutes. Next, while maintaining the temperature at 80°C, 600 g of deionized water was added over 60 minutes while stirring at 280 r / min (peripheral speed 88 m / min) to induce phase inversion emulsification. The resulting emulsion was then distilled off under reduced pressure while maintaining the temperature at 80°C to obtain a resin dispersion. Subsequently, the dispersion was cooled to 30°C while stirring at 280 r / min (peripheral speed 88 m / min), and then deionized water was added to achieve a solid content concentration of 20% by mass to obtain resin particle dispersion V-1. The median volume particle size of the resin particles was 0.25 μm, and the CV value was 33%.

[0121] [Manufacturing of mold release agent particle dispersion] Manufacturing Example W1 (Manufacturing of Release Agent Particle Dispersion W-1) In a 1L beaker, 5g of deionized water, 125g 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 a temperature of 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%.

[0122] [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 and dispersed for 1 hour at room temperature (20°C) using a homomixer "TKAGI HOMOMIXER 2M-03" (manufactured by Primix Corporation) at a stirring blade rotation speed of 8000 rpm. After that, the mixture was subjected to 15 passes at a pressure of 150 MPa using a "Microfluidizer M-110EH" (manufactured by Microfluidics Inc.), then 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. Medium volume particle size D of the colorant particles 50 The particle size was 0.12 μm, and the CV value was 21%.

[0123] [Toner manufacturing] Example 2-1 (Manufacturing of Toner 1) In a 3L four-necked flask equipped with a reflux condenser, stirrer, and thermocouple, 100g of resin particle dispersion EM-1 (stored for 14 days in a constant temperature room at 5°C), 400g of resin particle dispersion V-1, 17.5g of mold release agent particle dispersion W-1, 54g of coloring agent particle dispersion P-1, and 3.3g of 16% by mass sodium dodecylbenzenesulfonate aqueous solution "Neoperex G-15" (manufactured by Kao Corporation, anionic surfactant) were added and mixed at 25°C to obtain a mixture. Separately, a solution was obtained 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 stirring, and then the temperature was raised to 58°C over 2 hours to obtain the volume-median particle size D of the aggregated particles. 50 The mixture was kept at 58°C until it reached a size of approximately 6 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 1. The volume-median particle size D of toner particles 1. 50 This is shown in Table 4. To 100 parts by mass of toner particles 1, 2.5 parts by mass of hydrophobic silica "RY50" (manufactured by Nippon Aerosil Co., Ltd., average particle size: 0.04 μm) and 1 part by mass of hydrophobic silica "Cabosil® TS720" (manufactured by Cabot Japan Co., Ltd., average particle size: 0.012 μm) were mixed in a Henschel mixer and stirred, and the mixture was passed through a 150-mesh sieve to obtain toner 1. Toner 1 was evaluated as follows. The evaluation results of toner 1 are shown in Table 4.

[0124] Example 2-2 and Comparative Examples 2-1, 2-2 (Manufacturing of Toner 2, c1, c2) In Example 2-1, toner particles 2, c1, c2 were obtained in the same manner as shown in Table 4, except that the resin particle dispersion was modified. The volume median particle size D of the toner particles was obtained. 50 The toner evaluation results are shown in Table 4.

[0125] [Toner Evaluation Method] [Printed material overlay] A commercially available printer, "Microline® 5400" (manufactured by OKI Electric Industry Co., Ltd.), was loaded with toner, and blank pages were printed on high-quality paper, "Excellent White Paper A4 size" (manufactured by OKI Electric Industry Co., Ltd.), under conditions of 23°C and 50% humidity (NN environment). The printer was stopped midway through the blank page printing process. The developing unit was removed from the printer, and "Scotch® Mending Tape 810" (manufactured by 3M Japan Limited, width: 18mm) was attached to its photoconductor, and the toner on the photoconductor was peeled off the tape. The tape peeled from the photoconductor and the unused tape were attached to high-quality paper "Excellent White Paper A4 size" (manufactured by OKI Electric Industry Co., Ltd.), and the peeled tape and the unused tape were each measured using a colorimeter "SpectroEye" (manufactured by X-Rite, lighting conditions: standard light source D50, observation field of view 2°, density standard DINNB, absolute white standard) L * a * b * The following was measured: the color difference (ΔE([(ΔL) between the tape peeled off the photoreceptor and the unused tape). * ) 2 +(Δa * ) 2 +(Δb * ) 2 ] 1 / 2 )) was defined as the haze. The smaller the haze value, the better the image with less haze.

[0126] [Table 4]

[0127] The toner obtained by the toner manufacturing method of the present invention showed a sufficient reduction in fogging (Examples 2-1 and 2-2). In contrast, the toner produced using an organic solvent (Comparative Example 2-1) and the toner produced using crystalline polyester resin C'-2 with 1,9-nonanediol as the alcohol component (Comparative Example 2-2) did not sufficiently suppress the occurrence of fogging.

Claims

1. A method for producing a resin particle dispersion, comprising the following steps 1 and 2 in this order, Step 1: A step to neutralize the resin containing acid groups. Step 2: A step to obtain a resin particle dispersion by adding an aqueous medium to the neutralized resin obtained in Step 1. The resin having acid groups includes a crystalline polyester resin C which is a polycondensate of an alcohol component and a carboxylic acid component, and the alcohol component of the crystalline polyester resin C contains 60 mol% or more of ethylene glycol. A method for producing a resin particle dispersion, wherein the amount of organic solvent used in steps 1 and 2 is 10 parts by mass or less per 100 parts by mass of the resin having an acid group.

2. A method for producing a resin particle dispersion according to claim 1, wherein in steps 1 and 2, the amount of surfactant used is 1 part by mass or less per 100 parts by mass of the resin having an acid group.

3. A method for producing a resin particle dispersion according to claim 1 or 2, wherein in step 2, the rate of adding the aqueous medium is 30 parts by mass / min or less per 100 parts by mass of the resin having an acid group.

4. A method for manufacturing electrostatic image developing toner, comprising the following steps 1 to 3 in this order, Step 1: A step to neutralize the resin containing acid groups. Step 2: A step to obtain a resin particle dispersion by adding an aqueous medium to the neutralized resin obtained in Step 1. Step 3: A process of agglomerating and fusing resin particles in an aqueous medium. The resin having acid groups includes a crystalline polyester resin C which is a polycondensate of an alcohol component and a carboxylic acid component, and the alcohol component of the crystalline polyester resin C contains 60 mol% or more of ethylene glycol. A method for manufacturing toner for electrostatic image developing, wherein the amount of organic solvent used in steps 1 and 2 is 10 parts by mass or less per 100 parts by mass of resin having an acid group.

Images