Resin particle dispersion liquid, and method for manufacturing toner for electrostatic charge image development

Abstract

To provide a resin particle dispersion liquid which is excellent in storage stability at low temperature, and is suitable for manufacturing a toner for electrostatic charge image development, and a method for manufacturing a toner for electrostatic charge image development which suppresses occurrence of fogging in printing of an image under a high temperature and high humidity environment, after storage under a high temperature and high humidity environment.SOLUTION: A resin particle dispersion liquid contains an aqueous medium, resin particles containing a crystalline polyester resin C, and a block copolymer of polyethylene glycol and polypropylene glycol, wherein a volume median particle diameter D50 of the resin particles is 0.05 μm or more and 0.50 μm or less.SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] In the field of electrophotography, with the advancement of electrophotographic systems, there is a demand for the development of electrophotographic toners that can accommodate higher image quality and higher speeds. To meet this demand for higher image quality, so-called chemical toners are being produced by aggregating and fusing fine resin particles or the like in an aqueous medium using an emulsion aggregation method (aggregation fusion method, aggregation coalescence method), in order to obtain toners with small particle sizes and a fixing property that can accommodate higher speeds. In recent years, with the increase in exports of domestically manufactured toner cartridges and printers, toners are sometimes stored and used in high-temperature, high-humidity environments that exceed the normal usage environment, and toners are now being required to have the performance to withstand such environments.

[0003] For example, Patent Document 1 describes a method for producing a toner for developing electrostatic images, which has a narrow particle size distribution, exhibits high chargeability even after storage in a high-temperature, high-humidity environment, produces printed matter with high image density, and suppresses the occurrence of fog when printing images in a high-temperature, high-humidity environment. The method includes the following steps 1 to 3: step 1: mixing a polyester resin A and an addition polymer E to obtain an aqueous dispersion of resin particles X containing the polyester resin A and the addition polymer E; step 2: aggregating the resin particles X in an aqueous medium to obtain aggregated particles; and step 3: fusing the aggregated particles obtained in step 2 to obtain fused particles, wherein the addition polymer E is an addition polymer of raw material monomers including a styrene compound and an addition-polymerizable monomer having a polyalkylene oxide group. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2023-98415 Summary of the Invention [Problem to be solved by the invention]

[0005] In the emulsion aggregation method, resin particles in an aqueous dispersion (resin particle dispersion) of resin particles containing an amorphous resin and / or a crystalline resin are typically aggregated in an aggregation step, and the resulting aggregated particles are fused in a fusion step to obtain a toner containing toner particles. In the production of toner for developing electrostatic images, after a resin particle dispersion is obtained, the resin particle dispersion may be stored at low temperatures for a certain period of time before the aggregation step, depending on the conditions at the manufacturing site. Therefore, from the perspective of improving the image quality of images obtained using toner for developing electrostatic images, the resin particle dispersion is required to have properties that make it difficult for the resin particles to aggregate even during storage at low temperatures, i.e., excellent storage stability at low temperatures. In particular, resin particle dispersions containing highly hydrophobic crystalline polyester resins are prone to resin aggregation even during storage at low temperatures, so improved storage stability is required. However, the technology described in Patent Document 1 does not address improving the storage stability of resin particle dispersions at low temperatures. The present invention relates to a resin particle dispersion liquid that has excellent storage stability at low temperatures and is suitable for producing a toner for developing electrostatic images, and a method for producing a toner for developing electrostatic images that can suppress the occurrence of fog when printing images in a high-temperature, high-humidity environment after storage in a high-temperature, high-humidity environment. [Means for solving the problem]

[0006] The present inventors have found that by causing a crystalline polyester resin to coexist with a polymer compound having a specific structure in an aqueous medium to form resin particles of a specific particle size, a resin particle dispersion liquid having excellent storage stability at low temperatures can be obtained, and that by aggregating and fusing the resin particles in the resin particle dispersion liquid, a toner for developing electrostatic images can be obtained that can suppress the occurrence of fog when printing images in a high-temperature, high-humidity environment. The present invention relates to the following [1]. [1] A water-based medium, resin particles containing a crystalline polyester resin C, and a block copolymer of polyethylene glycol and polypropylene glycol, wherein the volume median particle size of the resin particles is D 50 The resin particle dispersion has a particle size of 0.05 μm or more and 0.50 μm or less. [2] A method for producing a toner for developing electrostatic images, comprising the following steps 1 and 2 in this order: Step 1: A water-based medium, resin particles containing a crystalline polyester resin C, and a block copolymer of polyethylene glycol and polypropylene glycol, the volume median particle size of the resin particles being D 50 A step of obtaining a resin particle dispersion liquid having a particle size of 0.05 μm or more and 0.50 μm or less Step 2: A step of aggregating and fusing resin particles to obtain toner particles [Effects of the Invention]

[0007] According to the present invention, there are provided a resin particle dispersion liquid that has excellent storage stability at low temperatures and is suitable for producing a toner for developing electrostatic images, and a method for producing a toner for developing electrostatic images that can suppress the occurrence of fog when printing images in a high-temperature, high-humidity environment after storage in a high-temperature, high-humidity environment. DETAILED DESCRIPTION OF THE INVENTION

[0008] [Resin particle dispersion] The resin particle dispersion of the present invention contains an aqueous medium, resin particles containing a crystalline polyester resin C, and a block copolymer of polyethylene glycol and polypropylene glycol, and the resin particles have a volume median particle diameter D 50 is 0.05 μm or more and 0.50 μm or less. The resin particle dispersion of the present invention has excellent storage stability at low temperatures. Furthermore, the toner for developing electrostatic images obtained by aggregating and fusing the resin particles in the resin particle dispersion of the present invention can suppress the occurrence of fog when printing images under high-temperature and high-humidity environments after storage under high-temperature and high-humidity environments. The reason for this is unclear, but is thought to be as follows.

[0009] In the present invention, a block copolymer of polyethylene glycol and polypropylene glycol is used in an aqueous dispersion containing resin particles including crystalline polyester resin C. The hydrophobic polypropylene glycol chains in the block copolymer are easily adsorbed to the highly hydrophobic crystalline polyester resin C, and it is believed that the hydrophilic polyethylene glycol chains act as dispersing groups in the aqueous dispersion, thereby improving the storage stability of the resin particle dispersion at low temperatures. When a toner for developing electrostatic images is produced by aggregating and fusing the resin particles in the resin particle dispersion of the present invention, the hydrophobic polypropylene glycol chains in the block copolymer are adsorbed to domains derived from the highly hydrophobic crystalline polyester resin, and the hydrophilic polyethylene glycol chains gather together in the toner, improving the dispersibility of the crystalline polyester resin C. Furthermore, because the block copolymer is a polymer compound rather than a low-molecular-weight surfactant, migration of the crystalline polyester resin C and the surfactant to the toner surface is suppressed even when stored in a high-temperature, high-humidity environment. This is thought to suppress a decrease in the charge amount of the toner for developing electrostatic images and to suppress the occurrence of fog when printing images in a high-temperature, high-humidity environment.

[0010] 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).

[0011] The resin particle dispersion of the present invention contains an aqueous medium, resin particles containing a crystalline polyester resin C (hereinafter also referred to as "resin C"), and a block copolymer of polyethylene glycol and polypropylene glycol (hereinafter also referred to as "block copolymer"). The resin particles may contain an amorphous polyester resin A (hereinafter also simply referred to as "resin A") in addition to resin C. When the resin particles contain resin A, the resin particles may contain resin C and resin A in the same or different particles.

[0012] [Aqueous medium] In the present invention, the aqueous medium is a medium containing water as a main component, and the water content in the aqueous medium is preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more, and 100% by mass or less. The water is preferably deionized water or distilled water. Examples of components other than water that can constitute the aqueous medium together with water include water-soluble organic solvents such as alkyl alcohols having 1 to 5 carbon atoms; dialkyl ketones having 3 to 5 carbon atoms, such as acetone and methyl ethyl ketone; and cyclic ethers, such as tetrahydrofuran.

[0013] [Crystalline polyester resin C] The crystalline polyester resin C is a polycondensation product of an alcohol component and a carboxylic acid component. The alcohol component is preferably an α,ω-aliphatic diol. The α,ω-aliphatic diol preferably has 2 or more carbon atoms, and preferably 16 or less, more preferably 12 or less, even more preferably 8 or less, and still more preferably 4 or less. Examples of α,ω-aliphatic diols include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,13-tridecanediol, and 1,14-tetradecanediol. Among these, ethylene glycol, 1,3-propanediol, 1,4-butanediol, and 1,5-pentanediol are preferred, ethylene glycol and 1,3-propanediol are more preferred, and ethylene glycol is even more preferred.

[0014] The amount of the α,ω-aliphatic diol in the alcohol component is preferably 80 mol% or more, more preferably 85 mol% or more, even more preferably 90 mol% or more, even more preferably 95 mol% or more, and is 100 mol% or less, even more preferably 100 mol%.

[0015] The alcohol component may contain an alcohol component other than the α,ω-aliphatic diol. Examples of the other alcohol component include aliphatic diols other than α,ω-aliphatic diols, such as 1,2-propanediol and neopentyl glycol; alkylene oxide adducts of aromatic diols, such as alkylene oxide adducts of bisphenol A; and trihydric or higher alcohols, such as glycerin, pentaerythritol, and trimethylolpropane. These alcohol components may be used alone or in combination.

[0016] The carboxylic acid component is preferably an aliphatic dicarboxylic acid, more preferably a straight-chain aliphatic dicarboxylic acid. The aliphatic dicarboxylic acid preferably has 4 or more carbon atoms, more preferably 8 or more carbon atoms, and even more preferably 10 or more carbon atoms, and preferably 14 or less carbon atoms. Examples of aliphatic dicarboxylic acids include fumaric acid, sebacic acid, 1,12-dodecanedioic acid, and 1,14-tetradecanedioic acid. Among these, 1,14-tetradecanedioic acid is preferred. These carboxylic acid components may be used alone or in combination of two or more.

[0017] The amount of the aliphatic dicarboxylic acid in the carboxylic acid component is preferably 70 mol % or more, more preferably 80 mol % or more, and even more preferably 85 mol % or more, and is 100 mol % or less. From the viewpoint of improving hydrophobicity, the carboxylic acid component preferably further contains a monocarboxylic acid. From the same viewpoint, the number of carbon atoms of 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 is preferably 24 or less, more preferably 22 or less, even more preferably 20 or less. The monocarboxylic acid is preferably an aliphatic monocarboxylic acid, such as caprylic acid, pelargonic acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, lignoceric acid, etc. Among these, caprylic acid, lauric acid, stearic acid, and behenic acid are preferred, and from the viewpoint of improving hydrophobicity, stearic acid and behenic acid are more preferred, and stearic acid is even more preferred. When the carboxylic acid component contains a monocarboxylic acid, the amount of the monocarboxylic acid in the carboxylic acid component is preferably 1 mol% or more, more preferably 5 mol% or more, even more preferably 7 mol% or more, and preferably 35 mol% or less, more preferably 25 mol% or less, even more preferably 15 mol% or less.

[0018] The carboxylic acid component may contain other carboxylic acid components different from aliphatic dicarboxylic acids and monocarboxylic acids. Examples of other carboxylic acid components include aromatic dicarboxylic acids such as terephthalic acid and isophthalic acid, and trivalent or higher polycarboxylic acids. These carboxylic acid components may be used alone or in combination.

[0019] 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.

[0020] The resin C may be produced, for example, by polycondensing raw material monomers containing an alcohol component and a carboxylic acid component.

[0021] 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 Resin C. 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 0.01 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.

[0022] (Physical properties of crystalline polyester resin C) The softening point of Resin C is preferably 60°C or higher, more preferably 70°C or higher, and even more preferably 80°C or higher, and from the viewpoint of low-temperature fixability, is preferably 150°C or lower, more preferably 120°C or lower, and even more preferably 100°C or lower. The melting point of Resin C is preferably 50°C or higher, more preferably 70°C or higher, and even more preferably 80°C or higher, and from the viewpoint of low-temperature fixability, is preferably 110°C or lower, more preferably 100°C or lower, and even more preferably 90°C or lower.

[0023] The acid value of Resin C is preferably 3 mgKOH / g or more, more preferably 7 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. The softening point, melting point, and acid value of Resin C can be appropriately adjusted by the types and amounts of raw material monomers used, as well as production conditions such as reaction temperature, reaction time, and cooling rate, and are determined by the method described in the Examples. When two or more types of Resin C are used in combination, the softening point, melting point, and acid value of the mixture thereof are preferably within the above-mentioned ranges.

[0024] [Amorphous polyester resin A] The amorphous polyester resin A is, for example, a polycondensate of an alcohol component and a carboxylic acid component. Resin A may be a modified amorphous polyester resin. Examples of modified amorphous polyester resins include urethane-modified amorphous polyester resins, epoxy-modified amorphous polyester resins, and composite resins containing an amorphous polyester resin segment and an addition polymerization resin segment.

[0025] Examples of the alcohol component include alkylene oxide adducts of aromatic diols, aliphatic diols, alicyclic diols, and trihydric or higher polyhydric alcohols. Among these, alkylene oxide adducts of aromatic diols are preferred. The amount of the alkylene oxide adduct of the aromatic diol in the alcohol component is preferably 70 mol% or more, more preferably 90 mol% or more, even more preferably 95 mol% or more, and is 100 mol% or less, even more preferably 100 mol%. 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):

[0026] [ka] (In the formula, OR 1 and 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. As the alkylene oxide adduct of bisphenol A, a propylene oxide adduct of bisphenol A [2,2-bis(4-hydroxyphenyl)propane] and an ethylene oxide adduct of bisphenol A are preferred. These may be used alone or in combination of two or more. Among these, the propylene oxide adduct of bisphenol A is preferred, and the propylene oxide adduct of bisphenol A and the ethylene oxide adduct of bisphenol A are more preferred. The amount of the alkylene oxide adduct of bisphenol A in the alcohol component is preferably 70 mol% or more, more preferably 90 mol% or more, even more preferably 95 mol% or more, and is 100 mol% or less, even more preferably 100 mol%.

[0027] 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, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, and 1,12-dodecanediol. Examples of alicyclic diols include hydrogenated bisphenol A [2,2-bis(4-hydroxycyclohexyl)propane] and adducts of hydrogenated bisphenol A with alkylene oxides having 2 to 4 carbon atoms (average number of added moles: 2 to 12). Examples of trihydric or higher polyhydric alcohols include glycerin, pentaerythritol, trimethylolpropane, and sorbitol. These alcohol components may be used alone or in combination of two or more.

[0028] Examples of the carboxylic acid component include dicarboxylic acids and trivalent or higher polycarboxylic acids. Examples of dicarboxylic acids include aromatic dicarboxylic acids, aliphatic dicarboxylic acids, and alicyclic dicarboxylic acids. Among these, aromatic dicarboxylic acids and aliphatic dicarboxylic acids are preferred. Examples of aromatic dicarboxylic acids include phthalic acid, isophthalic acid, and terephthalic acid. Among these, isophthalic acid and terephthalic acid are preferred, and terephthalic acid is more preferred. The amount of aromatic dicarboxylic acid in the carboxylic acid component is preferably 20 mol% or more, more preferably 40 mol% or more, even more preferably 45 mol% or more, and preferably 85 mol% or less, more preferably 70 mol% or less, even more preferably 60 mol% or less.

[0029] 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 a hydrocarbon group having from 1 to 20 carbon atoms. Examples of succinic acids substituted with a hydrocarbon group having from 1 to 20 carbon atoms include octenylsuccinic acid, decenylsuccinic acid, undecenylsuccinic acid, dodecylsuccinic acid, and dodecenylsuccinic acid. Among these, dodecenylsuccinic acid is preferred. The amount of the aliphatic dicarboxylic acid in the carboxylic acid component is preferably 1 mol% or more, more preferably 10 mol% or more, even more preferably 30 mol% or more, and preferably 60 mol% or less, more preferably 50 mol% or less, even more preferably 45 mol% or less.

[0030] The trivalent or higher polyvalent carboxylic acid is preferably a trivalent carboxylic acid, such as trimellitic acid. When a trivalent or higher polycarboxylic acid is contained, the amount of the trivalent or higher polycarboxylic 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 is preferably 25 mol% or less, more preferably 20 mol% or less, even more preferably 15 mol% or less. These carboxylic acid components may be used alone or in combination of two or more.

[0031] 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.

[0032] Resin A can be produced, for example, in the same manner as Resin C.

[0033] (Physical properties of amorphous polyester resin A) The softening point of Resin A is preferably 70°C or higher, more preferably 90°C or higher, even more preferably 100°C or higher, and preferably 140°C or lower, more preferably 130°C or lower, even more preferably 125°C or lower. The glass transition temperature of Resin A is preferably 30°C or higher, more preferably 40°C or higher, even more preferably 50°C or higher, and preferably 80°C or lower, more preferably 70°C or lower, even more preferably 60°C or lower.

[0034] The acid value of Resin A is preferably 5 mgKOH / g or more, more preferably 10 mgKOH / g or more, and preferably 30 mgKOH / g or less, more preferably 25 mgKOH / g or less, and even more preferably 20 mgKOH / g or less. The softening point, glass transition temperature, and acid value of Resin A can be appropriately adjusted by the types and amounts of raw material monomers used, as well as production conditions such as reaction temperature, reaction time, and cooling rate, and these values ​​can be determined by the methods described in the Examples. When two or more types of Resin A are used in combination, it is preferable that the softening point, glass transition temperature, and acid value of the mixture thereof each fall within the above-mentioned ranges.

[0035] [Block copolymer of polyethylene glycol and polypropylene glycol] The block copolymer of polyethylene glycol and polypropylene glycol may be a block copolymer having at least one polyethylene glycol segment and at least one polypropylene glycol segment, but is preferably a polyethylene glycol-polypropylene glycol-polyethylene glycol triblock copolymer, more preferably a triblock copolymer represented by the following formula (1), and even more preferably a triblock copolymer represented by the following formula (2).

[0036] [ka]

[0037] In formula (1), R 1 and R 2 are each independently a hydrogen atom or a hydrocarbon group having from 1 to 24 carbon atoms. The hydrocarbon group may be linear or branched. R 1 and R 2 is preferably a hydrogen atom or a linear or branched alkyl group having 1 to 5 carbon atoms, more preferably a hydrogen atom. R 1 and R 2 Examples of the alkyl group having 1 to 5 carbon atoms that can be used in a preferred embodiment include a methyl group, an ethyl group, various propyl groups, various butyl groups, and various pentyl groups. In formula (1), x and z represent the average number of moles of ethylene oxide added, and y represents the average number of moles of propylene oxide added. x, y, and z are each independently 1 or more and 500 or less, preferably 20 or more and 300 or less. In addition, the ratio of the sum of x and z to y [(x+z) / y] is preferably 0.1 or more and 7.0 or less.

[0038] [ka]

[0039] In formula (2), m represents the average number of moles of propylene oxide added, and n represents the average number of moles of ethylene oxide added. m is 10 or more, preferably 20 or more, more preferably 30 or more, and 80 or less, preferably 65 or less, more preferably 50 or less. n is 1 or more, preferably 10 or more, more preferably 20 or more, and is 200 or less, preferably 170 or less, more preferably 140 or less. The ratio of 2n to m (2n / m) is preferably 0.1 or more, more preferably 0.5 or more, even more preferably 1.0 or more, and is preferably 7.0 or less, more preferably 6.0 or less.

[0040] From the viewpoint of the storage stability of the resin particle dispersion and the viewpoint of obtaining an image with suppressed fogging under high temperature and high humidity conditions, the content of polyethylene glycol segments in the block copolymer of polyethylene glycol and polypropylene glycol is preferably 5% by mass or more, more preferably 30% by mass or more, even more preferably 45% by mass or more, and is preferably 90% by mass or less, more preferably 85% by mass or less.

[0041] As the block copolymer, commercially available products can also be used, and preferred examples include "ADEKA (registered trademark) Pluronic F108," "ADEKA (registered trademark) Pluronic F88," "ADEKA (registered trademark) Pluronic F68," "ADEKA (registered trademark) Pluronic F87," "ADEKA (registered trademark) Pluronic P85," "ADEKA (registered trademark) Pluronic P84," and "ADEKA (registered trademark) Pluronic L81" (all manufactured by ADEKA Corporation).

[0042] From the viewpoint of improving the productivity of the toner and the storage 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 35% by mass or less, more preferably 30% by mass or less, even more preferably 25% by mass or less. The solid content is the total amount of non-volatile components.

[0043] From the viewpoint of storage stability of the resin particle dispersion, the content of resin particles in the solid content of the resin particle dispersion is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 93% by mass or more, and is 99.99% by mass or less.

[0044] From the viewpoint of the storage stability of the resin particle dispersion and of obtaining an image with suppressed fogging under high temperature and high humidity conditions, the content of the block copolymer in the resin particle dispersion is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, even more preferably 0.1% by mass or more, and even more preferably 0.15% by mass or more, and is preferably 2% by mass or less, more preferably 1.5% by mass or less, even more preferably 0.8% by mass or less, and even more preferably 0.4% by mass or less. From the viewpoint of the storage stability of the resin particle dispersion and of obtaining an image with suppressed fogging under high temperature and high humidity conditions, the content of the block copolymer in the resin particle dispersion is preferably 0.05 parts by mass or more, more preferably 0.2 parts by mass or more, even more preferably 0.5 parts by mass or more, and even more preferably 0.7 parts by mass or more, relative to 100 parts by mass of Resin C, and is preferably 10 parts by mass or less, more preferably 7 parts by mass or less. From the viewpoint of the storage stability of the resin particle dispersion and of obtaining an image with suppressed fogging under high temperature and high humidity conditions, the content of the block copolymer in the resin particle dispersion is preferably 0.05 parts by mass or more, more preferably 0.2 parts by mass or more, even more preferably 0.5 parts by mass or more, and even more preferably 0.7 parts by mass or more, relative to 100 parts by mass of the total amount of Resin C and Resin A, and is preferably 10 parts by mass or less, more preferably 7 parts by mass or less, even more preferably 4 parts by mass or less, and even more preferably 2 parts by mass or less.

[0045] From the viewpoint of storage stability of the resin particle dispersion, 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, and even more preferably 95% by mass or more, and 100% by mass or less.

[0046] When the resin particles contain resin A, the mass ratio of resin C to resin A in the resin particles [resin C / resin A] is, from the viewpoint of low-temperature fixability, preferably 1 / 99 or more, more preferably 5 / 95 or more, even more preferably 10 / 90 or more, even more preferably 15 / 85 or more, and is preferably 40 / 60 or less, more preferably 30 / 70 or less, even more preferably 25 / 75 or less.

[0047] Resin particle volume median diameter D 50 is 0.05 μm or more, preferably 0.08 μm or more, more preferably 0.10 μm or more, and is 0.5 μm or less, preferably 0.35 μm or less, more preferably 0.20 μm or less, from the viewpoint of the storage stability of the resin particle dispersion and from the viewpoint of obtaining an image with suppressed fogging under high temperature and high humidity conditions. Resin particle volume median diameter D 50 is determined by the method described in the Examples.

[0048] [Method of manufacturing resin particle dispersion] In the method for producing a resin particle dispersion of the present invention, an aqueous medium, crystalline polyester resin C, and a block copolymer of polyethylene glycol and polypropylene glycol are mixed together, and the crystalline polyester resin C is dispersed in the aqueous medium.

[0049] The terms "aqueous medium," "resin particles containing crystalline polyester resin C," and "block copolymer of polyethylene glycol and polypropylene glycol" used in the method for producing a resin particle dispersion of the present invention are synonymous with the terms "aqueous medium," "resin particles containing crystalline polyester resin C," and "block copolymer of polyethylene glycol and polypropylene glycol" described in the resin particle dispersion of the present invention, respectively.

[0050] The mixing of the aqueous medium, the crystalline polyester resin C, and the block copolymer of polyethylene glycol and polypropylene glycol, as well as the dissolution and dispersion of the crystalline polyester resin C and the block copolymer of polyethylene glycol and polypropylene glycol in the aqueous medium can be carried out using known methods.

[0051] The method for producing a resin particle dispersion of the present invention includes any one of the following steps 1a to 1c. Step 1a: A step of adding an aqueous solution of a block copolymer of polyethylene glycol and polypropylene glycol to an organic solvent solution of crystalline polyester resin C, and performing phase inversion emulsification. Step 1b: A step of adding an aqueous medium to an organic solvent solution obtained by mixing a crystalline polyester resin C, a block copolymer of polyethylene glycol and polypropylene glycol, and an organic solvent to perform phase inversion emulsification. Step 1c: A step of adding an aqueous medium to an organic solvent solution of crystalline polyester resin C to effect phase inversion emulsification, and then adding a block copolymer of polyethylene glycol and polypropylene glycol. However, the volume median particle size D of the resin particles 50 is 0.05 μm or more and 0.50 μm or less. The method for producing a resin particle dispersion of the present invention preferably includes step 1a from the viewpoint of improving the storage stability of the resin particle dispersion. The organic solvent solutions in steps 1a and 1c may contain amorphous polyester resin A. In step 1b, the organic solvent solution may be obtained by mixing crystalline polyester resin C, amorphous polyester resin A, a block copolymer of polyethylene glycol and polypropylene glycol, and an organic solvent.

[0052] The organic solvent is not particularly limited as long as it dissolves the resin, and examples thereof include methyl ethyl ketone. It is preferable to add a neutralizing agent to the organic solvent solution of the 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. The degree of neutralization of the resin contained in the resin particles is preferably 10 mol% or more, more preferably 30 mol% or more, even more preferably 40 mol% or more, and preferably 100 mol% or less, more preferably 80 mol% or less, even more preferably 70 mol% or less. The degree of neutralization of the resin contained in the resin particles can be determined by the following formula. Degree of neutralization (mol %) = [{weight of neutralizing agent added (g) / equivalent weight of neutralizing agent} / [{weighted average acid value of resin contained in resin particles (mg KOH / g) × weight of resin contained in resin particles (g)} / (56 × 1000)]] × 100

[0053] In steps 1a to 1c, the aqueous solution of the block copolymer or the aqueous medium is gradually added to the organic solvent solution while stirring to cause phase inversion. The temperature of the organic solvent solution when adding the block copolymer aqueous solution or aqueous medium is preferably 50°C or higher, more preferably 60°C or higher, and even more preferably 70°C or higher, from the viewpoint of improving the dispersion stability of the resin particles, and is preferably 100°C or lower, more preferably 90°C or lower, and even more preferably 80°C or lower.

[0054] After the phase inversion emulsification, if necessary, the organic solvent may be removed from the obtained aqueous dispersion by distillation, etc. In this case, the amount of the remaining organic solvent in the aqueous dispersion is preferably 1% by mass or less, more preferably 0.5% by mass or less, and even more preferably substantially 0% by mass.

[0055] [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 "the method for producing a toner of the present invention") comprises the following steps 1 and 2 in this order. Step 1: A water-based medium, resin particles containing a crystalline polyester resin C, and a block copolymer of polyethylene glycol and polypropylene glycol, the volume median particle size of the resin particles being D 50 A step of obtaining a resin particle dispersion liquid having a particle size of 0.05 μm or more and 0.50 μm or less Step 2: A step of aggregating and fusing resin particles to obtain toner particles

[0056] <Process 1> Step 1 is the same as the "Method for producing a resin particle dispersion liquid" described above.

[0057] <Process 2> In step 2, the resin particles in the resin particle dispersion obtained in step 1 are aggregated and fused to obtain toner particles. In other words, the resin particles in the resin particle dispersion obtained in step 1 are aggregated to obtain aggregated particles, and the aggregated particles are fused to obtain toner particles.

[0058] From the viewpoint of producing a toner, in step 2, it is preferable to aggregate at least one of a colorant and a release agent together with the resin, and it is more preferable to mix a resin particle dispersion with a colorant particle dispersion and / or a release agent particle dispersion to aggregate these particles.

[0059] The total content of Resin C and Resin A in the toner particles is preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, and is preferably 98% by mass or less, more preferably 95% by mass or less, even more preferably 90% by mass or less. The content of resin C in the toner particles is preferably 1% by mass or more, more preferably 5% by mass or more, even more preferably 7% by mass or more, and preferably 40% by mass or less, more preferably 30% by mass or less, even more preferably 25% by mass or less.

[0060] [Coloring Agent] As the colorant, any dye, pigment, etc. that is used as a colorant for toner can be used. Examples of colorants include carbon black, phthalocyanine blue, permanent brown FG, brilliant fast scarlet, pigment green B, rhodamine-B base, solvent red 49, solvent red 146, solvent blue 35, quinacridone, carmine 6B, disazo yellow, and pigment red 269. The toner may be either black toner or a color toner other than black. The content of the colorant in the toner particles is preferably 2% by mass or more, more preferably 5% by mass or more, and preferably 25% by mass or less, more preferably 20% by mass or less, and even more preferably 15% by mass or less.

[0061] (Colorant particle dispersion) The colorant particle dispersion is preferably obtained by dispersing the colorant and an aqueous medium using a disperser such as a homomixer, a homogenizer, an ultrasonic disperser, etc. The dispersion is preferably carried out in the presence of a surfactant, from the viewpoint of improving the dispersion stability of the colorant. In addition, from the viewpoint of improving the dispersion stability of the colorant, it is also preferable to disperse the colorant particles in the presence of addition polymer E. The addition polymer E preferably has a structural unit derived from addition polymerizable monomer a having an aromatic group, and preferably further contains at least one selected from the group consisting of addition polymerizable monomer b having an ionic group, addition polymerizable monomer c having a polyalkylene oxide group, and macromonomer d. For colorant particle dispersions using addition polymer E, reference is made to the addition polymer E described in JP 2021-26129 A.

[0062] Examples of surfactants that improve the dispersion stability of colorants include nonionic surfactants, anionic surfactants, and cationic surfactants. From the viewpoint of improving the dispersion stability of colorant particles, nonionic surfactants are preferred. Examples of nonionic surfactants include polyoxyalkylene alkyl ethers, polyoxyalkylene alkenyl ethers, and polyoxyalkylene aryl ethers. Among these, polyoxyethylene aryl ethers are preferred, and polyoxyethylene distyrenated phenyl ether is more preferred.

[0063] From the viewpoint of improving the dispersion stability of the colorant, the content of the surfactant in the colorant particle dispersion liquid is preferably 1 part by mass or more, more preferably 5 parts by mass or more, even more preferably 10 parts by mass or more, and is preferably 50 parts by mass or less, more preferably 45 parts by mass or less, even more preferably 40 parts by mass or less, relative to 100 parts by mass of the colorant.

[0064] In the colorant particle dispersion, the colorant is preferably 5% by mass or more, more preferably 10% by mass or more, and preferably 50% by mass or less, more preferably 30% by mass or less, and even more preferably 25% by mass or less. The solid content concentration of the colorant particle dispersion is preferably 5% by mass or more, more preferably 10% by mass or more, 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.

[0065] Volume median particle size D of colorant particles 50 From the viewpoint of improving dispersibility in toner particles, the average particle size is preferably 0.05 μm or more, more preferably 0.08 μm or more, even more preferably 0.1 μm or more, and is preferably 0.4 μm or less, more preferably 0.3 μm or less, even more preferably 0.2 μm or less. Volume median particle size D of colorant particles 50 is measured by the method of the examples.

[0066] The amount of colorant particles is preferably 2 parts by mass or more, more preferably 4 parts by mass or more, 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, relative to 100 parts by mass of resin particles, from the viewpoint of improving dispersibility in toner particles.

[0067] [Release agent] Examples of release agents include polypropylene wax, polyethylene wax, ethylene-propylene copolymer wax; hydrocarbon waxes such as microcrystalline wax, paraffin wax, and Fischer-Tropsch wax, or oxides thereof; ester waxes such as carnauba wax, montan wax, or deacidified waxes thereof, and fatty acid ester wax; fatty acid amides, fatty acids, higher alcohols, and fatty acid metal salts. These may be used alone or in combination.

[0068] 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. The content of the release agent in the toner particles is preferably 0.1% by mass or more, more preferably 1% by mass or more, even more preferably 3% by mass or more, and preferably 25% by mass or less, more preferably 20% by mass or less, even more preferably 15% by mass or less.

[0069] (Release agent particle dispersion) Although the release agent particle dispersion can be obtained using a surfactant, it is preferable to obtain it by mixing the release agent with resin particles S from the viewpoint of reducing the content of surfactant contained in the toner. By preparing the release agent particles using the release agent and resin particles S, the release agent particles are stabilized by the resin particles S, and it becomes possible to disperse the release agent in an aqueous medium without using a surfactant. It is thought that the release agent particle dispersion has a structure in which a large number of resin particles S adhere to the surfaces of the release agent particles.

[0070] The resin constituting the resin particles S 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 or the above-mentioned resin A. For details about the release agent particle dispersion and the composite resin D, see JP 2021-26129 A.

[0071] The amount of the release agent particles is preferably 2 parts by mass or more, more preferably 4 parts by mass or more, and is 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, relative to 100 parts by mass of the resin particles, from the viewpoint of improving dispersibility in the toner particles.

[0072] In step 2, other additives may be added, 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.

[0073] [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 coagulation properties and obtaining uniformly coagulated particles, inorganic coagulants 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.

[0074] For example, a flocculant is added to a mixed dispersion containing resin particles, release agent particles, and colorant particles at a temperature of 0° C. to 40° C. in an amount of 5 parts by mass to 50 parts by mass of the flocculant relative to 100 parts by mass of the resin in the resin particles, and the resin particles, release agent particles, and colorant particles are aggregated in an aqueous medium to obtain aggregated particles. Furthermore, from the viewpoint of promoting aggregation, it is preferable to increase the temperature of the dispersion after adding the flocculant.

[0075] Examples of methods for stopping the aggregation include cooling the dispersion, adding an aggregation terminator, and diluting the dispersion.

[0076] Volume median particle size of agglomerated particles D 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.

[0077] In step 2, after the step of aggregating the resin particles and before the step of fusing, a step may be included in which shell resin particles containing an amorphous resin are further attached to the obtained aggregated particles (referred to as aggregated particles 1) and aggregated to obtain aggregated particles 2. By including the step of aggregating the shell resin particles, toner particles having a core-shell structure can be obtained. The shell resin particles are preferably made of an amorphous resin, more preferably an amorphous polyester resin. 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. 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 3 / 97 or more, even more preferably 5 / 95 or more, and is preferably 25 / 75 or less, more preferably 20 / 80 or less, even more preferably 15 / 85 or less.

[0078] [Aggregation Stopper] In order to reliably prevent unnecessary aggregation, an aggregation terminator may be added to the aggregated particles obtained in step 2 before the aggregated particles are fused in step 2. The aggregation terminator is preferably a surfactant, more preferably an anionic surfactant. Examples of anionic surfactants include alkylbenzene sulfonates, alkyl sulfates, alkyl ether sulfates, polyoxyalkylene alkyl ether sulfates, aryl sulfonates, and aryl sulfonic acid formalin condensates. These may be used alone or in combination. The aggregation terminator may be added in the form of an aqueous solution. The amount of the aggregation terminator added is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, relative to 100 parts by mass of aggregated particles, from the viewpoint of reliably preventing unnecessary aggregation, and is preferably 20 parts by mass or less, more preferably 10 parts by mass or less, and even more preferably 5 parts by mass or less, from the viewpoint of reducing residue in the toner.

[0079] The resulting aggregated particles are fused in an aqueous medium to fuse the individual particles contained in the aggregated particles, thereby obtaining fused particles. In the fusion step, from the viewpoint of improving the fusion properties of the aggregated particles, the aggregated particles are maintained at a temperature equal to or higher than the glass transition temperature of the resin having the highest glass transition temperature among the resins contained in the aggregated particles. The holding temperature when fusing the agglomerated particles is, from the viewpoint of improving the fusibility of the agglomerated particles, preferably at least 20°C lower than the melting point of resin C, more preferably at least 15°C lower, and even more preferably at least 10°C lower, and is preferably not higher than 1°C lower, more preferably not higher than 2°C lower than the melting point of resin C. In this case, the retention time is preferably 1 minute or more, more preferably 10 minutes or more, even more preferably 30 minutes or more, from the viewpoint of improving the low-temperature fixability of the toner, 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.

[0080] Volume median particle size D of fused particles obtained by fusion 50 is preferably 2 μm or more, more preferably 3 μm or more, even more preferably 4 μm or more, and is preferably 10 μm or less, more preferably 8 μm or less, even more preferably 7 μm or less.

[0081] The circularity of the fused particles obtained by fusion 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. The fusion is preferably terminated after the desired circularity is reached. The circularity is measured by the method described in the Examples.

[0082] <Post-processing process> A post-treatment step may be carried out after the fusion step, and the fused particles are isolated to obtain toner particles. Since the fused particles obtained in the fusion step are present in an aqueous medium, it is preferable to first carry out solid-liquid separation. For solid-liquid separation, a suction filtration method or the like is preferably used. It is preferable to wash the solid-liquid separation product. 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. Next, it is preferable to carry out drying. Examples of the drying method include vacuum constant temperature drying, vibration fluidized bed drying, spray drying, freeze drying, and flash jet drying.

[0083] 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.

[0084] 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. Circularity and volume median particle size D of toner particles 50 can be measured by the method described in the Examples.

[0085] [Electrostatic image developing toner] The toner for developing electrostatic images obtained by the toner production method 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.

[0086] [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.

[0087] 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]

[0088] 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.

[0089] [Measurement method] [Softening point, crystallinity index, melting point and glass transition temperature of resin] (1) Softening point Using a flow tester "CFT-500D" (Shimadzu Corporation), 1 g of sample was heated at a temperature increase rate of 6°C / min, while a load of 1.96 MPa was applied by the plunger, and the sample was extruded from a nozzle 1 mm in diameter and 1 mm in length. The plunger depression distance of the flow tester was plotted against the temperature, and the temperature at which half of the sample flowed out was taken as the softening point. (2) Crystallinity index Using a differential scanning calorimeter "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 then cooled to 0°C at a rate of 10°C / min. The sample was then heated at a rate of 10°C / min, and the calorific value was measured. The temperature of the endothermic peak with the largest peak area was taken as the maximum endothermic peak temperature (2). For crystalline resins, this peak temperature was taken as the melting point. For amorphous resins, if a peak was observed, the peak temperature was used; if no peak was observed but a step was observed, the glass transition temperature was taken as the temperature at the intersection of the tangent line showing the maximum slope of the curve at the step and an extension of the baseline on the low-temperature side of the step.

[0090] [Acid value of resin] The acid value of the resin was measured according to the neutralization titration method described in JIS K 0070:1992, except that the measurement solvent was chloroform.

[0091] [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 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.

[0092] [Volume median particle diameter D of resin particles, release agent particles, and colorant particles 50 〕 (1) Measuring device: Laser diffraction particle size measuring instrument "LA-920" (manufactured by Horiba Ltd.) (2) Measurement conditions: Put the sample dispersion into the 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 was measured.

[0093] [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 min / fluctuation range 0.05%). The solid content concentration was calculated according to the following formula. Solid concentration (mass%) = 100-moisture (mass%)

[0094] [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" (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, and the volume median particle size D is calculated from the particle size distribution. 50 asked for.

[0095] [Circularity of Fused Particles and Toner 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: HPF measurement mode

[0096] [Volume median particle size D of toner particles50 〕 The measuring instrument, aperture diameter, analysis software, and electrolyte are all set to 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 to obtain a dispersion with a concentration of 5% by mass. Dispersion conditions: 10 mg of a measurement sample of 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 asked for.

[0097] [Resin manufacturing] [Production of Crystalline Polyester Resin C] Manufacturing Example C1 (Manufacturing of Resin C-1) The alcohol and carboxylic acid components shown in Table 1 were placed in a 10-L four-neck flask equipped with a nitrogen inlet tube, a dehydration tube, a stirrer, and a thermocouple, and the temperature was raised to 200°C over 8 hours while stirring the reaction system in a nitrogen atmosphere. An esterification catalyst was then added, and the reaction was continued at 8 kPa until the softening point shown in Table 1 was reached, yielding Resin C-1. The physical properties are shown in Table 1.

[0098] Manufacturing Example C2 (Manufacturing of Resin C-2) Resin C-2 was obtained in the same manner as in Production Example C1, except that the raw material monomers for the polyester resin were changed as shown in Table 1. Table 1 shows the physical property values.

[0099] [Table 1]

[0100] [Production of amorphous polyester resin A] Production Example A1 (Production of Resin A-1) A four-neck flask equipped with a nitrogen inlet, dehydration tube, stirrer, and thermocouple was purged with nitrogen. 3,558 g of propylene oxide (2.2) adduct of bisphenol A, 1,416 g of ethylene oxide (2.2) adduct of bisphenol A, 1,229 g of terephthalic acid, 1,518 g of dodecenylsuccinic anhydride, and 40 g of tin(II) di(2-ethylhexanoate) were added. The mixture was heated to 230°C under nitrogen atmosphere with stirring. After 6 hours at 230°C, the pressure in the flask was further reduced to 8.3 kPa and maintained at this temperature for 1 hour. The mixture was then cooled to 215°C and returned to atmospheric pressure. 279 g of trimellitic anhydride was added. The mixture was then maintained at 215°C for 1 hour. The pressure in the flask was further reduced to 8.3 kPa and the reaction proceeded until the softening point shown in Table 2 was reached, yielding Resin A-1. The physical properties are shown in Table 2.

[0101] [Table 2]

[0102] [Block copolymer] Table 3 shows the block copolymers of polyethylene glycol and polypropylene glycol (polyethylene glycol-polypropylene glycol-polyethylene glycol triblock copolymers) P-1 to P-4 used in the examples.

[0103] [Table 3]

[0104] [Production of resin particle dispersion] Example X1 (Production of Resin Particle Dispersion X-1) 200 g of Resin C-1 and 200 g of methyl ethyl ketone were placed in a 3 L vessel equipped with a stirrer, reflux condenser, dropping funnel, thermometer, and nitrogen inlet tube, and Resin C-1 was dissolved over 2 hours at 73° C. A 5% by mass aqueous solution of sodium hydroxide was added to the resulting solution so that the degree of neutralization relative to the acid value of the resin was 60 mol %, and the mixture was stirred for 30 minutes. Next, while maintaining the temperature at 73°C, an aqueous solution prepared by dissolving 2 g of block copolymer P-1 in 700 g of deionized water was added over 50 minutes while stirring at 200 r / min to the resulting solution, resulting in phase inversion emulsification. While continuing to maintain the temperature at 73°C, methyl ethyl ketone was distilled off under reduced pressure to obtain a resin dispersion. Thereafter, while continuing to stir, the dispersion was cooled to 30°C, and deionized water was added to obtain a solids concentration of 20% by mass, thereby obtaining resin particle dispersion X-1.

[0105] [Evaluation of resin particle dispersion] Resin particle dispersion X-1: Volume median particle diameter D of resin particles immediately after production 50-0 , the volume median particle diameter D of the resin particles after storing the resin particle dispersion X-1 at 15°C for 2 weeks after production 50-T , particle size change rate (volume median particle size D after storage at 15°C for 2 weeks) 50-T / Volume median particle diameter D of resin particles immediately after production of resin particle dispersion X-1 50-0 ) are shown in Table 4.

[0106] Examples X2, X8 to X10 (Production of Resin Particle Dispersions X-2, X-8 to X-10) Resin particle dispersions X-2, X-8 to X-10 were obtained in the same manner as in Example X1, except that the type of crystalline polyester resin or block copolymer used was changed as shown in Table 4. Resin particle dispersions X-2, X-8 to X-10 were evaluated in the same manner as in Example 1. The results are shown in Table 4.

[0107] Example X3 (Production of Resin Particle Dispersion X-3) Resin particle dispersion X-3 was obtained in the same manner as in Example X1, except that an aqueous solution prepared by dissolving 10 g of block copolymer P-1 in 700 g of deionized water was used. Resin particle dispersion X-3 was evaluated in the same manner as in Example 1. The results are shown in Table 4.

[0108] Example X4 (Production of Resin Particle Dispersion X-4) Resin particle dispersion X-4 was obtained in the same manner as in Example X1, except that an aqueous solution prepared by dissolving 0.6 g of block copolymer P-1 in 700 g of deionized water was used. Resin particle dispersion X-4 was evaluated in the same manner as in Example 1. The results are shown in Table 4.

[0109] Example X5 (Production of Resin Particle Dispersion X-5) Resin particle dispersion X-5 was obtained in the same manner as in Example X1, except that an aqueous solution prepared by dissolving 0.2 g of block copolymer P-1 in 700 g of deionized water was used. Resin particle dispersion X-5 was evaluated in the same manner as in Example 1. The results are shown in Table 4.

[0110] Example X6 (Production of Resin Particle Dispersion X-6) 200 g of resin C-1, 2 g of block copolymer P-1, and 200 g of methyl ethyl ketone were placed in a 3 L vessel equipped with a stirrer, reflux condenser, dropping funnel, thermometer, and nitrogen inlet tube, and resin C-1 and block copolymer P-1 were dissolved over 2 hours at 73° C. A 5% by mass aqueous solution of sodium hydroxide was added to the resulting solution so that the degree of neutralization relative to the acid value of the resin was 60 mol %, and the mixture was stirred for 30 minutes. Next, while maintaining the temperature at 73°C, 700 g of deionized water was added to the resulting solution over 50 minutes while stirring at 200 r / min, resulting in phase inversion emulsification. While continuing to maintain the temperature at 73°C, methyl ethyl ketone was distilled off under reduced pressure to obtain a resin dispersion. Thereafter, while continuing to stir, the dispersion was cooled to 30°C, and deionized water was added to adjust the solids concentration to 20% by mass, thereby obtaining resin particle dispersion X-6. Resin particle dispersion X-6 was evaluated in the same manner as in Example 1. The results are shown in Table 4.

[0111] Example X7 (Production of Resin Particle Dispersion X-7) 200 g of Resin C-1 and 200 g of methyl ethyl ketone were placed in a 3 L vessel equipped with a stirrer, reflux condenser, dropping funnel, thermometer, and nitrogen inlet tube, and Resin C-1 was dissolved over 2 hours at 73° C. A 5% by mass aqueous solution of sodium hydroxide was added to the resulting solution so that the degree of neutralization relative to the acid value of the resin was 60 mol %, and the mixture was stirred for 30 minutes. Next, while maintaining the temperature at 73°C, 700 g of deionized water was added over 50 minutes while stirring at 200 r / min to induce phase inversion emulsification. While continuing to maintain the temperature at 73°C, methyl ethyl ketone was distilled off under reduced pressure to obtain a resin dispersion. Thereafter, 2 g of block copolymer P-1 was added, and the dispersion was cooled to 30°C with continued stirring. Deionized water was then added to obtain a solids concentration of 20% by mass to obtain resin particle dispersion X-7. Resin particle dispersion X-7 was evaluated in the same manner as in Example 1. The results are shown in Table 4.

[0112] Example X11 (Production of Resin Particle Dispersion X-11) Resin particle dispersion X-11 was obtained in the same manner as in Example X1, except that the resins used were changed from 200 g of Resin C-1 to 160 g of Resin A-1 and 40 g of Resin C-1. Resin particle dispersion X-11 was evaluated in the same manner as in Example 1. The results are shown in Table 4.

[0113] Comparative Example X51 (Production of Resin Particle Dispersion X-51) 200 g of Resin C-1 and 200 g of methyl ethyl ketone were placed in a 3 L vessel equipped with a stirrer, reflux condenser, dropping funnel, thermometer, and nitrogen inlet tube, and Resin C-1 was dissolved over 2 hours at 73° C. A 5% by mass aqueous solution of sodium hydroxide was added to the resulting solution so that the degree of neutralization relative to the acid value of the resin was 60 mol %, and the mixture was stirred for 30 minutes. Next, while maintaining the temperature at 73°C, 700 g of deionized water was added to the resulting solution over 50 minutes while stirring at 200 r / min, resulting in phase inversion emulsification. While continuing to maintain the temperature at 73°C, methyl ethyl ketone was distilled off under reduced pressure to obtain a resin dispersion. Thereafter, while continuing to stir, the dispersion was cooled to 30°C, and deionized water was added to adjust the solids concentration to 20% by mass, thereby obtaining resin particle dispersion X-51. Resin particle dispersion X-51 was evaluated in the same manner as in Example 1. The results are shown in Table 4.

[0114] Comparative Example X52 (Production of Resin Particle Dispersion X-52) 200 g of Resin C-1 and 200 g of methyl ethyl ketone were placed in a 3 L vessel equipped with a stirrer, reflux condenser, dropping funnel, thermometer, and nitrogen inlet tube, and Resin C-1 was dissolved over 2 hours at 73° C. A 5% by mass aqueous solution of sodium hydroxide was added to the resulting solution so that the degree of neutralization relative to the acid value of the resin was 60 mol %, and the mixture was stirred for 30 minutes. Next, while the resulting solution was maintained at 73°C and stirred at 200 r / min, an aqueous solution prepared by dissolving 13.3 g (1 part by mass of solids) of 15% by mass sodium dodecylbenzenesulfonate aqueous solution (aqueous surfactant solution, manufactured by Kao Corporation) in 700 g of deionized water was added over 50 minutes to induce phase inversion emulsification. While continuing to maintain the temperature at 73°C, the methyl ethyl ketone was distilled off under reduced pressure to obtain a resin dispersion. Thereafter, while continuing to stir, the dispersion was cooled to 30°C, and deionized water was added to obtain a solids concentration of 20% by mass, thereby obtaining Resin Particle Dispersion X-52. Resin Particle Dispersion X-52 was evaluated in the same manner as in Example 1. The results are shown in Table 4.

[0115] [Table 4]

[0116] From Table 4, it can be seen that the resin particles containing the aqueous medium, the crystalline polyester resin C, and the block copolymer of polyethylene glycol and polypropylene glycol have a volume median particle size D 50It can be seen that the resin particle dispersions (Examples X1 to X11) having a particle size of 0.05 μm or more and 0.50 μm or less have excellent storage stability at low temperatures. Furthermore, it can be seen from Examples X1, X6, and X7 that in the production of the resin particle dispersion, by including Step 1a among Steps 1a to 1c in Step 1, the storage stability at low temperatures can be further improved. In contrast, the resin particle dispersion liquid produced without using a block copolymer of polyethylene glycol and polypropylene glycol (Comparative Example X51) and the resin particle dispersion liquid produced using a low molecular weight anionic surfactant (Comparative Example X52) are found to have poor storage stability at low temperatures.

[0117] Production Example Y1 (Production of Resin Particle Dispersion Y-1) 200 g of Resin A-1 and 200 g of methyl ethyl ketone were placed in a 3 L vessel equipped with a stirrer, reflux condenser, dropping funnel, thermometer, and nitrogen inlet tube, and Resin A-1 was dissolved over 2 hours at 73° C. A 5% by mass aqueous solution of sodium hydroxide was added to the resulting solution so that the degree of neutralization relative to the acid value of the resin was 60 mol %, and the mixture was stirred for 30 minutes. Next, while the obtained solution was maintained at 73°C and stirred at 200 r / min, 700 g of deionized water was added over 50 minutes to cause phase inversion emulsification. While continuing to maintain the temperature at 73°C, methyl ethyl ketone was distilled off under reduced pressure to obtain a resin dispersion. Thereafter, while continuing to stir, the dispersion was cooled to 30°C, and deionized water was added to adjust the solids concentration to 20 mass%, thereby obtaining resin particle dispersion Y-1. The resin particle dispersion was evaluated in the same manner as in Example 1, and D 50-0 and D 50-T are both 0.11 μm, D 50-T / D 50-0 was 1.0.

[0118] [Production of Release Agent Particle Dispersion] Production Example W1 (Production of Release Agent Particle Dispersion W-1) 120 g of deionized water, 86 g of resin particle dispersion Y-1, and 40 g of paraffin wax "HNP-9" (manufactured by Nippon Seiro Co., Ltd., melting point 75°C) were added to a 1 L beaker, and the mixture was melted by maintaining the temperature at 90 to 95°C and stirred to obtain a molten mixture. The obtained molten mixture was further dispersed for 20 minutes using an ultrasonic homogenizer "US-600T" (manufactured by Nippon Seiki Seisakusho Co., Ltd.) while maintaining the temperature at 90 to 95°C, and then cooled to room temperature (20°C). Deionized water was added to the obtained dispersion to adjust the solid content to 20% by mass, thereby obtaining release agent particle dispersion W-1. The volume median particle diameter D of the release agent particles 50 was 0.47 μm.

[0119] [Preparation of Colorant Particle Dispersion] Production Example E1 (Production of Colorant Particle Dispersion E-1) A 2-L container was charged with 150 g of CI Pigment Red 269 (Permanent Carmine 3810, manufactured by Sanyo Pigment Co., Ltd.), 50 g of polyoxyethylene distyrenated phenyl ether "Emulgen A-60" (manufactured by Kao Corporation, nonionic surfactant), and 750 g of deionized water. The mixture was stirred at 6400 rpm / min at 20°C for 1 hour using a "Labo-Lution" mixer (manufactured by Primix Corporation) equipped with a dispersing blade. The mixture was then passed through a 200-mesh filter and subjected to 15 passes at 150 MPa using a "Microfluidizer M-110EH" homogenizer (manufactured by Microfluidics). The mixture was then passed through a 200-mesh filter and deionized water was added to adjust the solids concentration to 20% by mass, yielding colorant particle dispersion E-1. The volume median particle diameter D of the resulting colorant particles was 1.0 μm. 50 was 0.18 μm.

[0120] [Toner manufacturing] Example T1 (Production of Toner 1) Into a 3 L four-neck flask equipped with a reflux condenser, a stirrer, and a thermocouple, 100 g of resin particle dispersion X-1 that had been stored at 15° C. for two weeks, 400 g of resin particle dispersion Y-1, 40 g of release agent particle dispersion W-1, and 47 g of colorant particle dispersion E-1 were placed and mixed at a temperature of 25° C. Next, while stirring the resulting mixture, a solution prepared by dissolving 38 g of ammonium sulfate in 550 g of deionized water and adding a 4.8 mass % potassium hydroxide aqueous solution to adjust the pH to 8.5 was added dropwise over 10 minutes at 25° C., and the temperature was then raised to 61° C. over 2 hours to measure the volume median particle diameter D of the aggregated particles. 50 The temperature was maintained at 61°C until the particle size reached 6.3 µm, yielding a dispersion of aggregated particles. To the resulting dispersion of aggregated particles was added an aqueous solution prepared by mixing 8 g of sodium polyoxyethylene lauryl ether sulfate "EMAL E-27C" (manufactured by Kao Corporation, anionic surfactant, effective concentration 27% by mass), 220 g of deionized water, and 35 g of a 0.1 mol / L aqueous sulfuric acid solution. Thereafter, the temperature was raised to 85°C over one and a half hours, and the temperature was maintained at 85°C until the circularity reached 0.970, thereby obtaining a dispersion of fused particles in which aggregated particles were fused together. The obtained dispersion of fused particles was cooled to 30°C, and the dispersion was subjected to suction filtration to separate the solid content, which was then washed with deionized water at 25°C and suction filtrated at 25°C for 2 hours. Thereafter, the solid content was vacuum dried at 33°C for 24 hours using a vacuum constant temperature dryer "DRV622DA" (manufactured by ADVANTEC Corporation) to obtain toner particles 1. The volume median particle diameter D of the obtained toner particles was 50 The diameter was 6.0 μm and the circularity was 0.970. 100 parts by mass of toner particles 1, 2.5 parts by mass of hydrophobic silica "RY50" (manufactured by Nippon Aerosil Co., Ltd., number average particle size: 0.04 μm), and 1.0 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, 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 5.

[0121] [Evaluation of fogging under HH (high temperature and humidity) environment] The toner was stored for 24 hours in an environment of a temperature of 30° C. and a relative humidity of 80%. The stored toner was loaded into a commercially available printer, "Microline® 5400" (manufactured by Oki Electric Industry Co., Ltd.), and an image with a print density of 1% was printed on high-quality paper, "J Paper A4 Size" (manufactured by Fujifilm Business Innovation Co., Ltd.), in an environment of 30°C temperature and 80% relative humidity. This process was repeated for a total of 1,000 prints, after which a blank print was performed, during which the printer was stopped midway through the blank print. The development unit was removed from the printer, and "Scotch® Mending Tape 810" (manufactured by 3M Japan Ltd., width: 18 mm) was attached to the photoreceptor, after which the tape was peeled off from the photoreceptor. The tape removed from the photoconductor and unused tape were attached to high-quality paper "J paper A4 size" (manufactured by Fujifilm Business Innovation Co., Ltd.), and the tape removed from the photoconductor and the tape before being attached to the photoconductor were measured using a colorimeter "SpectroEye" (manufactured by GretagMacbeth, lighting conditions: standard light source D50, observation field 2°, density standard DINNB, absolute white standard). * a * b * The color difference (ΔE) between the tape peeled from the photoreceptor and the tape before being attached to the photoreceptor was calculated. The smaller the ΔE, the better the image with less fog. The evaluation results are shown in Table 5.

[0122] Examples T2 to T10, Comparative Examples T51 and T52 (Production of Toners 2 to 10, 51, and 52) Toners 2 to 10, 51, and 52 were obtained in the same manner as in Example 1, except that the resin particle dispersion X-1 used was changed as shown in Table 5. The evaluation results of toners 2 to 10, 51, and 52 are shown in Table 5.

[0123] Example T11 (Production of Toner 11) Toner 11 was obtained in the same manner as in Example 1, except that the resin particle dispersion used was changed to 500 g of X-11. The evaluation results of Toner 11 are shown in Table 5.

[0124] [Table 5]

[0125] From Table 5, it can be seen that the toner obtained by the toner manufacturing method of the present invention can sufficiently reduce fog in the resulting images (Examples T1 to T11). In contrast, it can be seen that the toner produced without using a block copolymer of polyethylene glycol and polypropylene glycol in step 1, and the toner produced using a low molecular weight anionic surfactant in step 1, did not sufficiently reduce fog in the resulting images (Comparative Examples T51 and T52).

Claims

1. The present invention relates to a coating composition comprising an aqueous medium, resin particles containing a crystalline polyester resin C, and a block copolymer of polyethylene glycol and polypropylene glycol, and the resin particles have a volume median particle size D ５０ The resin particle dispersion liquid has a particle size of 0.05 μm or more and 0.50 μm or less.

2. 2. The resin particle dispersion according to claim 1, wherein the block copolymer of polyethylene glycol and polypropylene glycol is a polyethylene glycol-polypropylene glycol-polyethylene glycol triblock copolymer.

3. 3. The resin particle dispersion according to claim 1, wherein the content of the polyethylene glycol segment in the block copolymer of polyethylene glycol and polypropylene glycol is 5% by mass or more and 90% by mass or less.

4. A method for producing a resin particle dispersion, comprising any one of the following steps 1a to 1c: Step 1a: A step of adding an aqueous solution of a block copolymer of polyethylene glycol and polypropylene glycol to an organic solvent solution of a crystalline polyester resin C, and performing phase inversion emulsification. Step 1b: A step of adding an aqueous medium to an organic solvent solution obtained by mixing a crystalline polyester resin C, a block copolymer of polyethylene glycol and polypropylene glycol, and an organic solvent, thereby causing phase inversion emulsification. Step 1c: A step of adding an aqueous medium to an organic solvent solution of crystalline polyester resin C to effect phase inversion emulsification, and then adding a block copolymer of polyethylene glycol and polypropylene glycol. However, the volume median particle diameter D of the resin particles ５０ is 0.05 μm or more and 0.50 μm or less.

5. The method for producing a resin particle dispersion according to claim 4 , comprising step 1a.

6. A method for producing a toner for developing electrostatic images, comprising the following steps 1 and 2 in this order: Step 1: A water-based medium, resin particles containing a crystalline polyester resin C, and a block copolymer of polyethylene glycol and polypropylene glycol, the volume median particle size of the resin particles being D ５０ a step of obtaining a resin particle dispersion liquid having a particle size of 0.05 μm or more and 0.50 μm or less Step 2: A step of aggregating and fusing resin particles to obtain toner particles

7. 7. The method for producing a toner for developing electrostatic images according to claim 6, wherein step 1 comprises adding an aqueous solution of a block copolymer of polyethylene glycol and polypropylene glycol to an organic solvent solution of the crystalline polyester resin C, and performing phase inversion emulsification.

Images