Toner for developing electrostatic images

Abstract

This invention relates to a toner for electrostatic image development, which has a core-shell structure consisting of a core containing a styrene-based resin and a shell containing a polyester resin, and which can produce printed materials with excellent image density. [Solution] A toner for developing electrostatic images containing toner particles having a core-shell structure, wherein the core contains a styrene-based resin S, and the shell contains an amorphous polyester resin A which is a polycondensate of an alcohol component, a carboxylic acid component, and polyethylene terephthalate, and the content of the polyethylene terephthalate-derived structure in the amorphous polyester resin A is 1 part by mass or more and 12 parts by mass or less per 100 parts by mass of the styrene-based resin S, for use as a toner for developing electrostatic images.

Description

[Technical Field]

[0001] The present invention relates to an electrostatic image developing toner used for developing latent images formed in electrophotography, electrostatic recording, electrostatic printing, and the like. [Background technology]

[0002] In recent years, in the field of electrophotography, the demand for higher image quality and energy efficiency has been increasing with the development of electrophotographic systems. In response to the demand for higher image quality, development is underway on so-called chemical toners, which are obtained by agglomerating and fusing fine resin particles in an aqueous medium. This method involves agglomerating and fusing these particles together in an aqueous medium. To further contribute to energy conservation, and to ensure toner fixation on paper with less energy while also guaranteeing storage stability at high temperatures, a core-shell structure toner is used in which a toner core containing a binder resin with a low softening point is covered by a shell layer made of a resin with a high glass transition point. In the toner with the core-shell structure described above, a styrene-based resin is used as the binder resin for the toner core, and a polyester-based resin is used as the binder resin for the toner shell.

[0003] Patent Document 1 describes an electrostatic image developing toner that has excellent low-temperature fixing properties and storage properties, and also excellent image density for printed materials, and contains toner particles with a core-shell structure having a core and a shell, wherein the core is made of a styrene resin (AS), an alcohol component (C-al) containing 95 mol% to 100 mol% of 1,6-hexanediol, and a carboxylic acid component (C-ac) containing 95 mol% to 100 mol% of an aliphatic dicarboxylic acid compound having 12 to 16 carbon atoms. The toner for developing electrostatic images is described, which contains a crystalline resin (C) which is a polycondensate of a bisphenol A, and the shell contains an amorphous composite resin (AH) which includes a polyester segment (AH-1) which is a polycondensate portion of an alcohol component (A-al) containing an alkylene oxide adduct of bisphenol A and a carboxylic acid component (A-ac) containing 7 mol% to 40 mol% of succinic acid, and a vinyl resin segment (AH-2) which is an addition polymerization portion of a monomer component (A-st) containing a styrene compound. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-076890 [Overview of the project] [Problems that the invention aims to solve]

[0005] Styrene resins are difficult to emulsify on their own, so surfactants are used for emulsification. As a result, styrene resins have high stability against flocculants in aqueous dispersions. On the other hand, polyester resins only have hydrophilic functional groups at their terminals, and the concentration of the somewhat hydrophilic ester bond portion is low, resulting in low stability against flocculants when dispersed in aqueous solutions. However, polyester resins tend to reduce the electrostatic properties of toner, and using surfactants during emulsification leads to a further decrease in electrostatic properties, making the use of surfactants difficult. Therefore, when a styrene resin is used as the core of the toner and a polyester resin is used as the shell, there is a difference in the stability of the core resin particles and the shell resin particles with respect to the aggregating agent. As a result, aggregation occurs between the shell particles with low stability, and the particle size distribution becomes broad. Thereby, the image density when printing the toner tends to decrease. The present invention relates to an electrostatic charge image developing toner having a core-shell structure composed of a core containing a styrene resin and a shell containing a polyester resin, and capable of obtaining a printed matter excellent in image density.

Means for Solving the Problems

[0006] The inventors of the present invention have found that the above problems can be solved by using a styrene resin for the core and an amorphous polyester resin, which is a polycondensate of an alcohol component, a carboxylic acid component, and polyethylene terephthalate, for the shell, and setting the content of the structure derived from polyethylene terephthalate in the amorphous polyester resin within a specific range. The present invention relates to the following [1]. [1] An electrostatic charge image developing toner containing toner particles having a core-shell structure, where the core contains a styrene resin S, the shell contains an amorphous polyester resin A, which is a polycondensate of an alcohol component, a carboxylic acid component, and polyethylene terephthalate, and the content of the structure derived from polyethylene terephthalate in the amorphous polyester resin A is 1 part by mass or more and 12 parts by mass or less with respect to 100 parts by mass of the styrene resin S. An electrostatic charge image developing toner.

Effects of the Invention

[0007] According to the present invention, there is provided an electrostatic charge image developing toner having a core-shell structure composed of a core containing a styrene resin and a shell containing a polyester resin, and capable of obtaining a printed matter excellent in image density.

Modes for Carrying Out the Invention

[0008] Toner for electrostatic charge image development The toner for electrostatic charge image development of the present invention (hereinafter also simply referred to as "toner") contains toner particles having a core - shell structure. The core contains a styrene - based resin S, and the shell contains an amorphous polyester resin A which is a polycondensate of an alcohol component, a carboxylic acid component, and polyethylene terephthalate. The content of the structure derived from polyethylene terephthalate in the amorphous polyester resin A with respect to 100 parts by mass of the styrene - based resin S is 1 part by mass or more and 12 parts by mass or less. Although the toner particles can be used as the toner of the present invention as they are, it is preferable to use those obtained by adding a fluidizing agent or the like as an external additive to the surface of the toner particles as the toner.

[0009] The detailed mechanism by which a printed matter with excellent image density can be obtained using the toner of the present invention is not clear, but it is considered as follows. In the toner of the present invention, the core of the toner particles having a core - shell structure contains a styrene - based resin, and the shell part contains an amorphous polyester resin A which is a polycondensate of an alcohol component, a carboxylic acid component, and polyethylene terephthalate. In the amorphous polyester resin A used for forming the shell, a structure derived from relatively hydrophilic polyethylene terephthalate exists in a specific amount as a block structure with a certain molecular weight. Therefore, the structure derived from polyethylene terephthalate is locally present in the amorphous polyester resin A without being averaged, and acts as a dispersion group in water. As a result, the stability of the shell - forming resin particles against the aggregating agent can approach the stability of the core - forming resin particles against the aggregating agent without using a surfactant. As a result, without using a surfactant, excessive aggregation between the shell - forming resin particles can be suppressed, and the particle size distribution of the toner becomes sharp, so that excellent image density can be exhibited.

[0010] The definitions of various terms 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. "(Meth)acrylic acid" means at least one selected from acrylic acid and methacrylic acid. "(iso or tertiary)" and "(iso)" refer to both cases where these prefixes are present and where they are not, and the absence of these prefixes indicates the normal form. "Styrene compounds" refers to unsubstituted or substituted styrene.

[0011] The components contained in the toner particles 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.

[0012] 〔core〕 The core contains styrene resin S.

[0013] <Styrene-based resin S> Examples of styrene-based resin S (hereinafter also simply referred to as "resin S") include polystyrene, polymers of styrene derivatives, and styrene-acrylic copolymers. From the viewpoint of improving the image density of printed materials, one or more selected from polystyrene, polymers of styrene derivatives, and styrene-acrylic copolymers are preferred, with styrene-acrylic copolymers being more preferred.

[0014] As for the raw material monomer of resin S, from the viewpoint of improving the image density of printed materials, it contains at least a styrene-based compound, preferably styrene, and more preferably both styrene and alkyl (meth)acrylate, which will be described later. The styrene derivative is preferably one or more selected from methylstyrene, α-methylstyrene, β-methylstyrene, tert-butylstyrene, chlorostyrene, chloromethylstyrene, methoxystyrene, styrenesulfonic acid, and their salts. From the viewpoint of improving the image density of printed materials, the content of styrene compounds in the raw material monomer is preferably 70% by mass or more, more preferably 75% by mass or more, and preferably 95% by mass or less, more preferably 90% by mass or less, and even more preferably 85% by mass or less.

[0015] Compounds other than styrene compounds that the raw material monomer may contain include alkyl (meth)acrylates; ethylenically unsaturated monoolefins such as ethylene and propylene; diolefins such as butadiene; halovinyls such as vinyl chloride; vinyl esters such as vinyl acetate and vinyl propionate; ethylenically monocarboxylic acid esters such as dimethylaminoethyl (meth)acrylate; vinyl ethers such as vinyl methyl ether; vinylidene halides such as vinylidene chloride; and N-vinyl compounds such as N-vinylpyrrolidone. Among these, alkyl (meth)acrylates are preferred from the viewpoint of improving the image density of printed materials.

[0016] From the viewpoint of improving the image density of printed materials, the number of carbon atoms in the alkyl(meth)acrylate alkyl group that the raw material monomer may contain is preferably 1 or more, more preferably 2 or more, even more preferably 3 or more, and preferably 12 or less, more preferably 10 or less, even more preferably 8 or less, and even more preferably 6 or less. Here, "the number of carbon atoms in the alkyl group of alkyl (meth)acrylate" refers to the number of carbon atoms derived from the alcohol component that makes up the alkyl (meth)acrylate.

[0017] Examples of alkyl (meth)acrylates include methyl (meth)acrylate, ethyl (meth)acrylate, (iso)propyl (meth)acrylate, (iso or tertiary)butyl (meth)acrylate, (iso)amyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, (iso)octyl (meth)acrylate, (iso)decyl (meth)acrylate, (iso)dodecyl (meth)acrylate, (iso)palmityl (meth)acrylate, (iso)stearyl (meth)acrylate, and (iso)behenyl (meth)acrylate. Among these, n-butyl acrylate is preferred. When alkyl (meth)acrylate is used, the content of alkyl (meth)acrylate in the raw material monomer is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 15% by mass or more, and preferably 30% by mass or less, and more preferably 25% by mass or less, from the viewpoint of improving the image density of the printed material.

[0018] (Method for manufacturing styrene resin S) Resin S can be obtained, for example, by addition polymerization in the presence of a radical polymerization initiator, an organic solvent, or in the absence of a solvent. Examples of radical polymerization initiators include peroxides such as dicumyl peroxide and dibutyl peroxide, persulfates such as sodium persulfate, and azo compounds such as 2,2'-azobis(2,4-dimethylvaleronitrile). As organic solvents, xylene, toluene, methyl ethyl ketone, acetone, etc., can be used. The amount of radical polymerization initiator used is preferably 1 to 20 parts by mass per 100 parts by mass of raw material monomer. The addition polymerization temperature is preferably 110°C or higher, more preferably 130°C or higher, and preferably 240°C or lower, more preferably 230°C or lower, and even more preferably 220°C or lower.

[0019] (Physical properties of styrene resin S) The softening point of resin S is preferably 70°C or higher, more preferably 85°C or higher, even more preferably 95°C or higher, and preferably 140°C or lower, more preferably 130°C or lower, and even more preferably 125°C or lower.

[0020] The glass transition temperature of resin S is preferably 35°C or higher, more preferably 40°C or higher, even more preferably 45°C or higher, and preferably 75°C or lower, more preferably 70°C or lower, and even more preferably 65°C or lower.

[0021] The softening point and glass transition temperature of resin S can be appropriately adjusted depending on the type and amount of raw material monomer used, as well as manufacturing conditions such as reaction temperature, reaction time, and cooling rate. These values ​​can be determined by the method described in the examples. Furthermore, when using two or more types of resin S in combination, it is preferable that the softening point and glass transition temperature obtained from the mixture thereof are within the above ranges.

[0022] <Crystalline polyester resin C> From the viewpoint of improving the image density of printed materials, the core preferably contains a crystalline polyester resin C (hereinafter also simply referred to as "resin C"). Resin C is, for example, a crystalline composite resin comprising a crystalline polyester resin which is a polycondensate of an alcohol component and a carboxylic acid component, a polyester resin segment which is a polycondensate of raw material monomers containing an alcohol component and a carboxylic acid component, a styrene-based resin segment, and constituent units derived from both reactive monomers which bond the polyester resin segment and the styrene-based resin segment via covalent bonds, and a crystalline composite resin is preferred.

[0023] (Alcohol content) The alcohol component preferably includes an α,ω-aliphatic diol. The number of carbon atoms in the α,ω-aliphatic diol is preferably 2 or more, preferably 14 or less, more preferably 12 or less, even more preferably 8 or less, and even 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, 1,5-pentanediol, and 1,6-hexanediol are preferred, ethylene glycol, 1,3-propanediol, 1,4-butanediol, and 1,6-hexanediol are more preferred, ethylene glycol, 1,3-propanediol, and 1,4-butanediol are even more preferred, and ethylene glycol and 1,4-butanediol are even more preferred.

[0024] The amount of α,ω-aliphatic diol is preferably 80 mol% or more, more preferably 85 mol% or more, even more preferably 90 mol% or more, even more preferably 95 mol% or more, and 100 mol% or less, and preferably 100 mol%, in the alcohol component.

[0025] The alcohol component may contain other alcohol components other than α,ω-aliphatic diols. Examples of other alcohol components include aliphatic diols other than α,ω-aliphatic diols such as 1,2-propylene glycol and neopentyl glycol; aromatic diols such as alkylene oxide adducts of bisphenol A; and trivalent or higher alcohols such as glycerin, pentaerythritol, and trimethylolpropane.

[0026] (Carboxylic acid component) The carboxylic acid component preferably includes an aliphatic dicarboxylic acid. The number of carbon atoms in the aliphatic dicarboxylic acid is preferably 4 or more, more preferably 6 or more, and preferably 18 or less, and more preferably 16 or less. Examples of aliphatic dicarboxylic acids include fumaric acid, sebacic acid, dodecanediic acid, and tetradecanediic acid. Among these, tetradecanediic acid is preferred.

[0027] The amount of aliphatic dicarboxylic acid is preferably 80 mol% or more, more preferably 85 mol% or more, even more preferably 90 mol% or more, even more preferably 95 mol% or more, and 100 mol% or less, and preferably 100 mol%, in the carboxylic acid component.

[0028] The carboxylic acid component may contain other carboxylic acid components other than aliphatic dicarboxylic 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.

[0029] The equivalent ratio of the carboxyl group of the carboxylic acid component to the hydroxyl group of the alcohol component (COOH group / OH group) is preferably 0.7 or higher, more preferably 0.8 or higher, even more preferably 0.9 or higher, and preferably 1.3 or lower, more preferably 1.2 or lower, and even more preferably 1.1 or lower.

[0030] When resin C is a crystalline composite resin, the styrene-based resin segment is an addition polymer of raw material monomers containing a styrene-based compound. Examples of raw material monomers containing a styrene-based compound include the raw material monomers of resin S. The content of styrene compounds in the raw material monomers of the styrene resin segment is preferably 50% by mass or more, more preferably 65% ​​by mass or more, even more preferably 75% by mass or more, and preferably 95% by mass or less, more preferably 90% by mass or less, and even more preferably 85% by mass or less.

[0031] When the styrene resin segment contains constituent units derived from (meth)acrylic acid esters such as 2-ethylhexyl (meth)acrylate, the content of (meth)acrylic acid esters in the raw material monomer of the styrene resin segment is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 15% by mass or more, and preferably 50% by mass or less, more preferably 35% by mass or less, and even more preferably 25% by mass or less.

[0032] The total amount of styrene compounds and (meth)acrylic acid esters in the raw material monomers of the styrene resin segment is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and 100% by mass or less, and preferably 100% by mass.

[0033] The crystalline composite resin has constituent units derived from both reactive monomers, which are covalently bonded to polyester resin segments and styrene-based resin segments. "Constituent units derived from both reactive monomers" refers to units formed by the reaction of the functional groups and addition polymerizable groups of both reactive monomers. Examples of addition polymerizable groups include carbon-carbon unsaturated bonds (ethylenically unsaturated bonds). Examples of both reactive monomers include addition polymerizable monomers having at least one functional group selected from hydroxyl groups, carboxyl groups, epoxy groups, primary amino groups, and secondary amino groups within the molecule. Among these, addition polymerizable monomers having at least one functional group selected from hydroxyl groups and carboxyl groups are preferred from the viewpoint of reactivity, and addition polymerizable monomers having carboxyl groups are more preferred. Examples of addition polymerizable monomers having a carboxyl group include acrylic acid, methacrylic acid, fumaric acid, and maleic acid. Among these, acrylic acid and methacrylic acid are preferred from the viewpoint of reactivity in both polycondensation and addition polymerization reactions, with acrylic acid being more preferred. When both reactive monomers are addition polymerizable monomers having a carboxyl group, the amount of constituent units derived from both reactive monomers is preferably 0.5 moles or more, more preferably 1 mole or more, and preferably 5 moles or less, more preferably 3 moles or less, per 100 moles of alcohol component of the polyester resin segment of the crystalline composite resin.

[0034] The amount of constituent units derived from both reactive monomers in the crystalline composite resin is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, and preferably 3% by mass or less, and more preferably 1% by mass or less, of the total amount of the polyester resin segment, the styrene-based resin segment, and the constituent units derived from both reactive monomers.

[0035] In the crystalline composite resin, the total amount of polyester resin segments, styrene-based resin segments, and constituent units derived from both reactive monomers 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.

[0036] In a crystalline composite resin, the mass ratio of polyester resin segments to styrene resin segments (polyester resin segments / styrene resin segments) is preferably 80 / 20 or higher, more preferably 90 / 10 or higher, and more preferably 99 / 1 or lower, and more preferably 97 / 3 or lower, from the viewpoint of improving the image density of printed materials.

[0037] The above amounts are calculated based on the ratio of the raw material monomers for the polyester resin segment and the styrene resin segment, the two reactive monomers, and the radical polymerization initiator. The mass of the polyester resin segment, etc., is based on the mass excluding the mass of water produced by polycondensation. When a radical polymerization initiator is used, the mass of the radical polymerization initiator is included in the calculation of the styrene resin segment.

[0038] (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, even more preferably 80°C or higher, and preferably 120°C or lower, more preferably 115°C or lower, and even more preferably 110°C or lower.

[0039] The crystallinity index of resin C is, from the viewpoint of crystallinity, 0.6 or more and 1.4 or less, preferably 0.8 or more, more preferably 1.0 or more, and preferably 1.3 or less, more preferably 1.2 or less.

[0040] The melting point of resin C is preferably 60°C or higher, more preferably 65°C or higher, even more preferably 70°C or higher, and preferably 110°C or lower, more preferably 100°C or lower, and even more preferably 95°C or lower.

[0041] The acid value of resin C is preferably 5 mg KOH / g or more, more preferably 10 mg KOH / g or more, and more preferably 35 mg KOH / g or less, more preferably 30 mg KOH / g or less, and even more preferably 25 mg KOH / g or less.

[0042] The weight-average molecular weight of resin C is preferably 3,000 or more, more preferably 5,000 or more, even more preferably 10,000 or more, and preferably 100,000 or less, more preferably 50,000 or less, and even more preferably 30,000 or less.

[0043] The softening point, crystallinity index, melting point, acid value, and weight-average molecular weight 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, and can be determined by the method described in the examples. Furthermore, when using two or more types of resin C in combination, it is preferable that the softening point, crystallinity index, melting point, acid value, and weight-average molecular weight obtained from the mixture thereof are all within the aforementioned ranges.

[0044] (Method for manufacturing crystalline polyester resin C) ≪Method for producing crystalline polyester resin≫ Crystalline polyester resins can be produced, for example, by polycondensation of raw material monomers containing alcohol and carboxylic acid components. The polycondensation of the alcohol component and the carboxylic acid component can be carried out, for example, in an inert gas atmosphere, at a temperature of approximately 120°C to 250°C, in the presence of an esterification catalyst, esterification co-catalyst, polymerization inhibitor, etc., as needed. Examples of esterification catalysts include tin compounds such as dibutyltin oxide and di(2-ethylhexanoate)tin(II), and titanium compounds such as titanium diisopropoxybis(triethanolamine). Examples of esterification co-catalysts that can be used together with the esterification catalyst include gallic acid (3,4,5-trihydroxybenzoic acid). The amount of esterification catalyst used is preferably 0.01 parts by mass or more and 10 parts by mass or less, based on 100 parts by mass of the total amount of alcohol and carboxylic acid components, which are raw material monomers for the polyester resin. 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 0.001 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.

[0045] ≪Method for manufacturing crystalline composite resins≫ The crystalline composite resin may be produced, for example, by a method comprising step A, which involves polycondensation of an alcohol component and a carboxylic acid component, and step B, which involves addition polymerization of the raw material monomers of the styrene-based resin segment and both reactive monomers. Process A may be performed after process B, or process B may be performed after process A, or process A and process B may be performed simultaneously. In step A, a portion of the carboxylic acid component is subjected to a polycondensation reaction, and then step B is carried out. After that, the remaining carboxylic acid component is added to the polymerization system to further advance the polycondensation reaction in step A and the polycondensation reaction with, for example, the carboxyl group of both reactive monomers or constituent units derived from both reactive monomers.

[0046] In step A, if necessary, the esterification catalyst and esterification co-catalyst described in the above-mentioned method for producing polyester resin may be used in the same amounts for polycondensation. Furthermore, when using monomers having unsaturated bonds, such as fumaric acid, in polycondensation, the polymerization inhibitor described in the above-mentioned method for producing polyester resin may be used in the same amount as necessary. The temperature of the polycondensation reaction is preferably 120°C or higher, more preferably 150°C or higher, even more preferably 180°C or higher, and preferably 250°C or lower, more preferably 240°C or lower. The polycondensation may be carried out in an inert gas atmosphere.

[0047] Examples of radical polymerization initiators for the addition polymerization in step B include peroxides such as tert-butyl peroxaside and dibutyl peroxide, persulfates such as sodium persulfate, and azo compounds such as 2,2'-azobis(2,4-dimethylvaleronitrile). The amount of radical polymerization initiator used is preferably 1 to 20 parts by mass per 100 parts by mass of raw material monomer of the styrene resin segment. The addition polymerization temperature is preferably 110°C or higher, more preferably 130°C or higher, and preferably 240°C or lower, more preferably 230°C or lower, and even more preferably 220°C or lower.

[0048] 〔shell〕 <Amorphous polyester resin A> The shell contains amorphous polyester resin A (hereinafter sometimes referred to as "resin A"), which is a polycondensate of an alcohol component, a carboxylic acid component, and polyethylene terephthalate (hereinafter sometimes referred to as "PET"), from the viewpoint of improving the image density of printed materials. Ethylene glycol and terephthalic acid, produced by the depolymerization of PET or a portion thereof, are used as raw materials and subjected to a polycondensation reaction to be incorporated into the polyester resin. Through transesterification and polycondensation reactions, a portion of the PET is incorporated into the polyester resin. Since PET is an equimolar polycondensate of ethylene glycol and terephthalic acid, the terephthalic acid-ethylene glycol unit (Mw: 192) is considered as 1 mole. Therefore, the number of moles of PET = the number of moles of ethylene glycol units = the number of moles of terephthalic acid units.

[0049] Examples of alcohol components include alkylene oxide adducts of aromatic diols, aliphatic diols, alicyclic diols, and polyhydric alcohols of trihydric or higher hydric value. Among these, alkylene oxide adducts of aromatic diols are preferred from the viewpoint of improving the image density of printed materials. Examples of alkylene oxide adducts of aromatic diols include those of formula (I): [ka] An example of an alkylene oxide adduct of bisphenol A is given by the formula (wherein OR and RO are oxyalkylene groups, R is independently an ethylene or 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). Examples of alkylene oxide adducts of bisphenol A represented by formula (I) include propylene oxide adducts of 2,2-bis(4-hydroxyphenyl)propane and ethylene oxide adducts of 2,2-bis(4-hydroxyphenyl)propane. The content of the bisphenol A alkylene oxide adduct in the alcohol component is preferably 85 mol% or more, more preferably 90 mol% or more, even more preferably 95 mol% or more, and 100 mol% or less, preferably 100 mol%. The content of the bisphenol A alkylene oxide adduct in the alcohol component is equivalent to the amount of constituent units derived from the bisphenol A alkylene oxide adduct in the constituent units derived from the alcohol component of resin A. The same applies to the content of each subsequent component.

[0050] The aliphatic diol has two or more carbon atoms, preferably 16 or fewer, more preferably 12 or fewer, even more preferably 8 or fewer, and still more preferably 4 or fewer. Examples of aliphatic diols include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, neopentyl glycol (2,2-dimethyl-1,3-propanediol), 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, and 1,12-dodecanediol.

[0051] Examples of alicyclic diols include hydrogenated bisphenol A [2,2-bis(4-hydroxycyclohexyl)propane] and alkylene oxide adducts of hydrogenated bisphenol A with 2 to 4 carbon atoms (average number of added moles: 2 to 12). Examples of polyhydric alcohols with a valency of 3 or higher include glycerin, pentaerythritol, trimethylolpropane, and sorbitol.

[0052] Examples of carboxylic acid components include dicarboxylic acids and polycarboxylic acids with a valency of three or more.

[0053] Examples of dicarboxylic acids include aromatic dicarboxylic acids, aliphatic dicarboxylic acids, and alicyclic dicarboxylic acids. Among these, aromatic dicarboxylic acids are preferred.

[0054] Examples of aromatic dicarboxylic acids include phthalic acid, isophthalic acid, and terephthalic acid. Among these, terephthalic acid is preferred. The content of aromatic dicarboxylic acid in the carboxylic acid component is preferably 70 mol% or more, more preferably 85 mol% or more, even more preferably 95 mol% or more, and 100 mol% or less, and preferably 100 mol%.

[0055] The number of carbon atoms in the aliphatic dicarboxylic acid is preferably 2 or more, more preferably 3 or more, and preferably 30 or less, more preferably 20 or less. Examples of aliphatic dicarboxylic acids include oxalic acid, malonic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, succinic acid, adipic acid, sebacic acid, dodecanediic acid, azelaic acid, and succinic acid substituted with an aliphatic hydrocarbon group 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.

[0056] Examples of alicyclic dicarboxylic acids include cyclohexanedicarboxylic acid.

[0057] Preferably, the polycarboxylic acid with a valency of 3 or higher is a trivalent carboxylic acid, such as trimellitic acid. When the carboxylic acid component contains a polycarboxylic acid of trivalent or higher, the content of the polycarboxylic acid of trivalent or higher in the carboxylic acid component is preferably 10 mol% or more, more preferably 15 mol% or more, even more preferably 20 mol% or more, and preferably 40 mol% or less, more preferably 35 mol% or less, and even more preferably 30 mol% or less.

[0058] PET can be either new PET (virgin PET) or recycled PET. Recycled PET refers to material obtained by collecting used PET and using it as raw material. The collected PET is washed, sorted to prevent mixing with other materials or waste, labels are removed, and then it is crushed into flakes or the like. (1) The crushed material can be used as is, but it may also be subjected to the following post-processing after crushing. (2) Mix the crushed material and coarsely grind it. (3) In many cases, foreign matter is attached to or mixed in with the pulverized material. For example, if chemical substances adsorbed on the surface of PET bottles cannot be sufficiently removed by normal washing, alkaline washing is usually used. If a portion of the pulverized material is hydrolyzed by alkaline washing, it is preferable to melt the washed pulverized material and solid-phase polymerize the pelletized material in order to restore the reduced degree of polymerization. The solid-phase polymerization process can be carried out by continuous solid-phase polymerization of the washed flakes, or pelletized flakes obtained by melt-extrusion, in an inert gas such as nitrogen gas or a noble gas at a temperature of preferably 180°C to 245°C, more preferably 200°C to 240°C. (4) The washed pulverized material is decomposed to monomer units by depolymerization and then resynthesized. In this invention, recycled PET is preferably (1) (crushed product) or (2) (kneaded / coarsely crushed product) because it has a low IV value.

[0059] In this invention, it is preferable that the PET has a relatively low IV value, i.e., a low molecular weight, compared to conventionally used PET. By introducing low IV value (low molecular weight) PET into the polyester resin, the depolymerization of PET proceeds more uniformly. The IV value is the intrinsic viscosity and serves as an indicator of molecular weight. The IV value of PET can be adjusted by the polycondensation time, the charging ratio of raw material monomers, etc.

[0060] From the viewpoint of the above, the IV value of PET is preferably 0.40 or higher, more preferably 0.45 or higher, even more preferably 0.50 or higher, and even more preferably 0.55 or higher. Furthermore, from the viewpoint of low-temperature fixability and uniformity of depolymerization, it is preferably 0.85 or lower, more preferably 0.75 or lower, and even more preferably 0.70 or lower.

[0061] The IV value can be measured, for example, by dissolving the sample at a concentration of 0.4 g / dL in a phenol / tetrachloroethane = 60 / 40 (mass ratio) mixed solvent, measuring it with an Ubbelohde viscometer, and calculating it according to the following formula.

number

[0062] Commercially available PET products with an IV value of 0.40 to 0.85 include RAMAPET L1 (manufactured by Indorama Ventures, IV value: 0.60), RAMAPET BF3067 (manufactured by Indorama Ventures, IV value: 0.65), RAMAPET N2G (manufactured by Indorama Ventures, IV value: 0.75), TRN-NTJ (manufactured by Teijin Limited, IV value: 0.53), TRN-RTJC (manufactured by Teijin Limited, IV value: 0.64), RAMAPET S1 (manufactured by Indorama Ventures, IV value: 0.84), and UK-31 (manufactured by Utsumi Recycling Systems Co., Ltd., IV value: 0.67). Among these, UK-31 is preferred.

[0063] 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 1.2 or lower, more preferably 1.1 or lower.

[0064] The "molar equivalent ratio (COOH group / OH group)" shall be calculated assuming that the alcohol component contains the same mole of ethylene glycol as the constituent units derived from ethylene glycol in the PET, and the carboxylic acid component contains the same mole of terephthalic acid as the constituent units derived from terephthalic acid in the PET.

[0065] The PET content is preferably 20 mol% or more, more preferably 25 mol% or more, even more preferably 30 mol% or more, and preferably 60 mol% or less, more preferably 55 mol% or less, and even more preferably 50 mol% or less, out of 100 mol% of the total amount of alcohol component, carboxylic acid component, and PET that are raw materials of resin A, from the viewpoint of improving the image density of the printed material.

[0066] From the viewpoint of improving the image density of printed materials, the content of PET-derived structures in resin A is preferably 15% by mass or more, more preferably 20% by mass or more, even more preferably 25% by mass or more, and preferably 55% by mass or less, more preferably 50% by mass or less, and even more preferably 45% by mass or less.

[0067] Resin A is produced, for example, by polycondensing an alcohol component, a carboxylic acid component, and polyethylene terephthalate in the same manner as the "Method for Producing Polyester Resin" for Resin C.

[0068] (Physical properties of amorphous polyester resin A) The softening point of resin A is preferably 85°C or higher, more preferably 90°C or higher, and even more preferably 95°C or higher, from the viewpoint of heat-resistant storage of the toner, and preferably 125°C or lower, more preferably 115°C or lower, and even more preferably 105°C or lower, from the viewpoint of low-temperature fixing properties.

[0069] The crystallinity index of resin A is less than 0.6 or greater than 1.4, preferably 1.6 or greater, preferably 2.2 or less, more preferably 2.0 or less, even more preferably 1.9 or less, and even more preferably 1.8 or less, from the viewpoint of amorphousness.

[0070] The glass transition temperature of resin A is preferably 45°C or higher, more preferably 50°C or higher, and even more preferably 55°C or higher, from the viewpoint of heat-resistant storage of the toner, and preferably 75°C or lower, more preferably 70°C or lower, and even more preferably 65°C or lower, from the viewpoint of low-temperature fixing properties.

[0071] The acid value of resin A is preferably 5 mg KOH / g or more, more preferably 10 mg KOH / g or more, even more preferably 15 mg KOH / g or more, and preferably 30 mg KOH / g or less, more preferably 20 mg KOH / g or less, and even more preferably 17 mg KOH / g or less, from the viewpoint of improving the image density of printed materials.

[0072] The weight-average molecular weight of resin A is preferably 2,000 or more, more preferably 4,000 or more, even more preferably 6,000 or more, and preferably 100,000 or less, more preferably 50,000 or less, and even more preferably 10,000 or less, from the viewpoint of improving the image density of printed materials.

[0073] The softening point, crystallinity index, glass transition temperature, acid value, and weight-average molecular weight of resin A can be appropriately adjusted depending on the type and amount of raw material monomer used, as well as manufacturing conditions such as reaction temperature, reaction time, and cooling rate, and 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 the softening point, crystallinity index, glass transition temperature, acid value, and weight-average molecular weight obtained from the mixture thereof are all within the aforementioned ranges.

[0074] The shell may contain, in addition to resin A, a composite resin comprising an amorphous polyester resin other than resin A, polyester resin segments, styrene-based resin segments, and constituent units derived from both reactive monomers that covalently bond the polyester resin segments and the styrene-based resin segments.

[0075] (Content, content ratio) From the viewpoint of improving the image density of printed materials, the content of the binder resin in the toner particles is preferably 70% by mass or more, more preferably 75% by mass or more, even more preferably 80% by mass or more, and preferably 95% by mass or less, more preferably 90% by mass or less.

[0076] The resin S content in the core is preferably 55% by mass or more, more preferably 60% by mass or more, even more preferably 65% ​​by mass or more, and preferably 90% by mass or less, more preferably 85% by mass or less, and even more preferably 80% by mass or less, from the viewpoint of improving the image density of the printed material. From the viewpoint of improving the image density of printed materials, the resin S content in the toner particles is preferably 35% by mass or more, more preferably 40% by mass or more, even more preferably 45% by mass or more, and preferably 85% by mass or less, more preferably 80% by mass or less, and even more preferably 75% by mass or less.

[0077] The content of resin C in the core is preferably 1% by mass or more, more preferably 3% by mass or more, even more preferably 5% by mass or more, and 25% by mass or less, more preferably 20% by mass or less, and even more preferably 15% by mass or less, from the viewpoint of improving the image density of the printed material. The resin C content in the toner particles is preferably 1% by mass or more, more preferably 3% by mass or more, even more preferably 5% by mass or more, and 25% by mass or less, more preferably 20% by mass or less, and even more preferably 15% by mass or less, from the viewpoint of improving the image density of printed materials.

[0078] The content of resin A in the shell is preferably 85% by mass or more, more preferably 90% by mass or more, even 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, from the viewpoint of improving the image density of the printed material. The content of resin A in the toner particles is preferably 1% by mass or more, more preferably 3% by mass or more, even more preferably 5% by mass or more, and 40% by mass or less, more preferably 35% by mass or less, and even more preferably 30% by mass or less, from the viewpoint of improving the image density of the printed material.

[0079] In the toner particles, the mass ratio of resin S, resin C, and resin A (resin S / resin C / resin A) is preferably 55-95 / 1-20 / 1-35, more preferably 60-90 / 3-17 / 3-20, and even more preferably 65-85 / 5-15 / 5-15.

[0080] In toner particles, the content of polyethylene terephthalate-derived structures in amorphous polyester resin A relative to 100 parts by mass of resin S is 1 part by mass or more, preferably 2 parts by mass or more, more preferably 3 parts by mass or more, even more preferably 3.5 parts by mass or more, and 12 parts by mass or less, preferably 11.5 parts by mass or less, from the viewpoint of improving the image density of printed materials.

[0081] The toner particles preferably contain at least one of the above-mentioned resins, a colorant, and a release agent, and it is preferable that they contain both a colorant and a release agent. The toner particles may also contain additives such as charge control agents, magnetic powders, flowability improvers, conductivity modifiers, reinforcing fillers such as fibrous materials, antioxidants, anti-aging agents, and cleaning properties improvers. The toner particles may contain the colorant, release agent, and additives in the core or in the shell, and it is preferable that they be contained in the core.

[0082] <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, disazo yellow, and pigment red 269. The toner may be either black toner or a color toner other than black. The colorant content in the toner particles is preferably 0.5% by mass or more, more preferably 1% by mass or more, and even more preferably 2% by mass or more, from the viewpoint of improving the image density of the printed material, and preferably 15% by mass or less, more preferably 8% by mass or less, and even more preferably 4% by mass or less, from the viewpoint of print quality and economic efficiency.

[0083] <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.

[0084] The melting point of the release agent is preferably 60°C or higher, more preferably 70°C or higher, and more preferably 160°C or lower, more preferably 140°C or lower, and even more preferably 120°C or lower.

[0085] The release agent content in the toner particles is preferably 1% by mass or more, more preferably 3% by mass or more, and preferably 10% by mass or less, more preferably 8% by mass or less.

[0086] <Physical properties of toner particles> Volume-intermediate particle size D of toner particles 50 From the viewpoint of obtaining printed materials with good image quality and further improving the cleaning performance of the toner, the thickness 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] The CV value of the toner particles is preferably 5% or more, more preferably 10% or more, and even more preferably 15% or more, from the viewpoint of improving toner productivity, and preferably 40% or less, more preferably 35% or less, and even more preferably 30% or less, from the viewpoint of obtaining high-quality images.

[0088] From the viewpoint of obtaining printed materials with good image quality, the circularity of the toner particles is preferably 0.925 or higher, more preferably 0.930 or higher, and even more preferably 0.935 or higher. From the viewpoint of cleanability, it is preferably 0.975 or lower, more preferably 0.970 or lower, and even more preferably 0.965 or lower.

[0089] 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.

[0090] [Manufacturing method for toner for electrostatic image development] The method for producing electrostatic image developing toner of the present invention (hereinafter also referred to as "toner production method") is preferably an emulsification agglutination method, but may be any known method such as a melt kneading method, an emulsification phase inversion method, or a suspension polymerization method.

[0091] [Emulsification aggregation method] The emulsification and coagulation method includes the steps of coagulating and fusing resin particles, which contain the same or different resins, in an aqueous medium. The aggregated particles obtained in the process of agglomerating resin particles include aggregated particles 1, which are obtained by agglomerating resin particles in an aqueous medium, and aggregated particles 2, which are obtained by using aggregated particles 1 as a core and attaching and agglomerating shell resin particles to this core in an aqueous medium. When simply referred to as "aggregated particles," it means either aggregated particles 1 or 2.

[0092] <Process for agglomerating resin particles> In the process of agglomerating resin particles, resin particles containing the same or different resins are agglomerated in an aqueous medium to obtain agglomerated particles 1. It is preferable to further agglomerate colorants and release agents in addition to resin particles, and it is preferable to mix the resin particle dispersion, the colorant particle dispersion, and the release agent particle dispersion to agglomerate these particles to obtain agglomerated particles 1. Examples of "resin particles containing the same or different resins" include resin particles containing resin S, resin particles containing resin C, and resin particles containing both resin S and resin C.

[0093] In the present invention, the aqueous medium used in the aqueous dispersion is a medium mainly composed of water, and the water content in the aqueous medium is preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, and 100% by mass or less. Deionized water or distilled water is preferred as the water. Other components that can form an aqueous medium together with water include alkyl alcohols having 1 to 5 carbon atoms; dialkyl ketones having 3 to 5 carbon atoms such as acetone and methyl ethyl ketone; and organic solvents that dissolve in water, such as cyclic ethers such as tetrahydrofuran.

[0094] (Method for producing resin particle dispersion) The resin particles may be manufactured as a resin particle dispersion in which the resin is contained in the same or different particles.

[0095] Dispersion can be carried out using known methods, but dispersion by phase inversion emulsification is preferred. Examples of phase inversion emulsification methods include adding an aqueous medium to an organic solvent solution of the resin or to a molten resin and then emulsifying it. Adding an aqueous medium to an organic solvent solution of the resin and then emulsifying it is preferred. The organic solvent used for phase inversion emulsification is not particularly limited as long as it dissolves the resin and is water-soluble, but an example is methyl ethyl ketone. A neutralizing agent may be added to the organic solvent solution of resin C. Examples of neutralizing agents include basic substances. Examples of basic substances include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide; and nitrogen-containing basic substances such as ammonia, trimethylamine, and diethanolamine. Among these, alkali metal hydroxides such as sodium hydroxide and potassium hydroxide are preferred. The degree of neutralization of resin C constituting the resin particles is preferably 40 mol% or more, more preferably 50 mol% or more, even more preferably 60 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 resin C, which constitutes the resin particles, can be determined by the following formula. Degree of neutralization (mol%) = [{Amount of neutralizing agent added (g) / Equivalent amount of neutralizing agent} / [{Weighted average acid value of the resin constituting the resin particles (mgKOH / g) × Mass of the resin constituting the resin particles (g)} / (56 × 1000)]] × 100

[0096] While stirring the organic solvent solution or molten resin, gradually add an aqueous medium to induce phase inversion. When adding an aqueous medium, the temperature of the organic solvent solution is preferably above the glass transition temperature of the resin, more preferably above 60°C, even more preferably above 65°C, and preferably below 100°C, more preferably below 95°C, and even more preferably below 90°C, from the viewpoint of improving the dispersion stability of the resin particles containing the resin.

[0097] After phase inversion emulsification, the organic solvent may be removed from the resulting dispersion by distillation or other means, if necessary. Alternatively, the resin particles may be isolated by filtration or other means. It is preferable to use an aqueous dispersion of resin particles from which the organic solvent has been removed after phase inversion emulsification. In this case, the amount of residual organic solvent in the dispersion is preferably 1% by mass or less, more preferably 0.5% by mass or less, and even more preferably substantially 0% by mass.

[0098] Volume-intermediate particle size D of resin particles 50 The particle size is preferably 0.03 μm or larger, more preferably 0.06 μm or larger, even more preferably 0.08 μm or larger, and preferably 1 μm or smaller, more preferably 0.5 μm or smaller, and even more preferably 0.2 μm or smaller. Volume-intermediate particle size D of resin particles 50 It is measured by the method described in the examples.

[0099] 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 50% by mass or less, more preferably 40% by mass or less, and even more preferably 35% by mass or less, from the viewpoint of improving toner productivity and improving the dispersion stability of the resin particle dispersion. Note that the solid content represents the total amount of non-volatile components.

[0100] (Method for producing a dispersion of coloring agent particles) It is preferable to obtain the colorant particles as a dispersion of colorant particles by dispersing the colorant and an aqueous medium using a disperser such as a homogenizer or an ultrasonic disperser. From the viewpoint of improving the dispersion stability of the colorant, it is preferable to carry out this dispersion in the presence of a surfactant or an addition polymer (hereinafter, the addition polymer used for dispersing the colorant is also referred to as "addition polymer E"). Examples of such surfactants include nonionic surfactants, anionic surfactants, and cationic surfactants. For a dispersion of colorant particles using addition polymer E, please refer to Japanese Patent Publication No. 2024-25642.

[0101] The colorant content in 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 preferably 35% by mass or less, and more preferably 25% by mass or less, from the viewpoint of the image density of the printed material. The solid content concentration of the coloring agent 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 40% by mass or less, more preferably 30% by mass or less.

[0102] Volume-intermediate particle size D of colorant particles 50 From the viewpoint of improving the dispersibility of the colorant in the toner, the particle size is preferably 0.05 μm or more, more preferably 0.08 μm or more, and preferably 0.4 μm or less, more preferably 0.3 μm or less, and even more preferably 0.2 μm or less. Volume-intermediate particle size D of colorant particles 50 It is measured by the method described in the examples.

[0103] (Method for manufacturing a release agent particle dispersion) Release agent particle dispersions can be obtained using surfactants, but they may also be obtained by mixing the release agent with resin particles. By preparing release agent particles using the release agent and resin particles, the release agent particles are stabilized by the resin constituting the resin particles, making it possible to disperse the release agent in an aqueous medium without using surfactants. The resin constituting the resin particles that disperse the mold release agent is preferably a polyester resin, and more preferably an amorphous composite resin D having polyester resin segments and addition polymerization resin segments. For details on the mold release agent particle dispersion and composite resin D, please refer to Japanese Patent Application Publication No. 2024-25642. Alternatively, the aforementioned amorphous polyester resin A may be used.

[0104] Release agent particle volume median particle size D 50 From the viewpoint of obtaining uniform aggregated particles 1 by aggregation, the particle size is preferably 0.1 μm or larger, more preferably 0.2 μm or larger, even more preferably 0.4 μm or larger, and preferably 1 μm or smaller, more preferably 0.8 μm or smaller, and even more preferably 0.7 μm or smaller. Release agent particle volume median particle size D 50 It is measured by the method described in the examples.

[0105] <<Surfactants>> In the process of agglomerating resin particles, when mixing the dispersions of each particle to prepare a mixed dispersion, the process may be carried out in the presence of a surfactant from the viewpoint of improving the dispersion stability of resin particles, release agent particles, colorant particles, etc. Examples of surfactants include anionic surfactants such as alkylbenzene sulfonates and alkyl ether sulfates; and nonionic surfactants such as polyoxyethylene alkyl ethers and polyoxyethylene alkenyl ethers. When a surfactant is used, the total amount used is preferably 0.1 parts by mass or more, more preferably 0.3 parts by mass or more, even more preferably 0.5 parts by mass or more, and preferably 10 parts by mass or less, and more preferably 5 parts by mass or less, based on 100 parts by mass of the total amount of resin particles.

[0106] <<Agglomerants>> 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 the flocculant include cationic surfactants such as quaternary salts, organic flocculants such as polyethyleneimine, and inorganic flocculants. Examples of the 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 valence of 2 or more. From the viewpoint of improving the aggregability and obtaining uniform aggregated particles 1, inorganic flocculants with a valence of 1 or more and 5 or less are preferable, inorganic metal salts with a valence of 1 or more and 2 or less are more preferable, inorganic metal salts with a valence of 2 or less are still more preferable, and calcium chloride is still more preferable.

[0107] Using a flocculant, for example, to a mixed dispersion liquid at 0°C or higher and 40°C or lower containing resin particles, release agent particles, and colorant particles, 10 parts by mass or more and 50 parts by mass or less of the flocculant is added based on 100 parts by mass in total of the resin particles, and the resin particles, release agent particles, and colorant particles are aggregated in an aqueous medium to obtain aggregated particles 1. From the viewpoint of promoting aggregation, it is preferable to raise the temperature of the dispersion liquid after adding the flocculant.

[0108] A step of aggregating the resin particles for the shell may be performed when the aggregated particles 1 have grown to an appropriate particle size. The volume median particle diameter D of the aggregated particles 1 50 is preferably 2 μm or more, more preferably 3 μm or more, still more preferably 4 μm or more, and is preferably 10 μm or less, more preferably 8 μm or less, still more preferably 7 μm or less. The method for producing the toner of the present invention includes a step of attaching and aggregating resin particles for the shell using the obtained aggregated particles 1 as a core to obtain aggregated particles 2. By having a step of aggregating the resin particles for the shell, toner particles having a core-shell structure can be obtained. The resin particles for the shell are resin particles containing the above-described resin A. The dispersion liquid of the resin particles for the shell is obtained by the same method as the above-described method for producing the dispersion liquid of the resin particles. 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 50 / 50 or less, more preferably 40 / 60 or less, and even more preferably 30 / 70 or less, from the viewpoint of toner's low-temperature fixation. In the process of obtaining aggregated particles 2, it is preferable to stop the aggregation of aggregated particles 2 once they have grown to a suitable particle size for toner. Methods for stopping aggregation include cooling the dispersion, adding an aggregation inhibitor, and diluting the dispersion, with the method of stopping aggregation by adding an aggregation inhibitor being preferred.

[0109] <<Agglomerating Agent>> As the flocculation inhibitor, surfactants are preferred, and anionic surfactants are more preferred. Examples of anionic surfactants include alkylbenzene sulfonates, alkyl sulfates, alkyl ether sulfates, polyoxyalkylene alkyl ether sulfates, aryl sulfonates, and aryl sulfonic acid formalin condensates. One or more of these may be used. The flocculation inhibitor may be added in aqueous solution. From the viewpoint of reliably preventing unnecessary aggregation, the amount of aggregation inhibitor added is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, per 100 parts by mass of aggregated particles immediately before adding the aggregation inhibitor, and from the viewpoint of reducing residue in the toner, it is preferably 15 parts by mass or less, more preferably 10 parts by mass or less.

[0110] <Fusing process> In the fusion process, for example, aggregated particles are fused together in an aqueous medium. Fusion bonding fuses the individual particles contained within the aggregated particles, resulting in fused particles. In the fusion process, from the viewpoint of improving the fusion properties of the aggregated particles and improving the low-temperature fixation properties of the toner, the particles are held 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 2°C or higher, more preferably 3°C or higher, and even more preferably 5°C or higher than the glass transition temperature of the resin having the highest glass transition temperature among amorphous resins, and 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 the low-temperature fixability of the toner. Furthermore, it is preferable to maintain the temperature mentioned above until the desired degree of circularity is achieved.

[0111] Volume median particle size D of fused particles obtained by fusion 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.

[0112] The circularity of the fused particles obtained by fusion is preferably 0.955 or higher, more preferably 0.960 or higher, and more 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.

[0113] <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.

[0114] <External additives> As described above, it is preferable to use toner particles treated with an external additive as the toner of the present invention. 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 0.5 parts by mass or more, more preferably 1 part by mass or more, even more preferably 1.5 parts by mass or more, and preferably 4 parts by mass or less, more preferably 3.5 parts by mass or less, and even more preferably 3 parts by mass or less, per 100 parts by mass of toner particles.

[0115] 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]

[0116] 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 physical property 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.

[0117] [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 the sample was extruded from a nozzle with a diameter of 1 mm and a length of 1 mm. The amount of plunger descent of the flow tester was plotted against temperature, and the temperature at which half of the sample flowed out was defined as the softening point. (2) Crystallinity index Using a differential scanning calorimeter "Q-20" (manufactured by T.A. Instruments Japan Co., Ltd.), 0.01 to 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 sample was then left to stand still for 1 minute, and then heated 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 "Q-20" (manufactured by T.A. Instruments Japan Co., Ltd.), 0.01 to 0.02 g of the sample was weighed into an aluminum pan and heated from room temperature (20°C) to 200°C at a heating rate of 10°C / min, and then cooled to 0°C at a cooling rate of 10°C / min. Next, the sample was heated to 180°C at a heating rate of 10°C / min, and the endothermic peak 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), and in the case of crystalline resins, this peak temperature (2) 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.

[0118] [Acid value of resins] The acid value of the resins was measured according to the neutralization titration method described in JIS K 0070:1992. However, the measurement solvent was changed from the ethanol and ether mixed solvent specified in JIS K 0070:1992 to an acetone and toluene mixed solvent (acetone:toluene = 1:1 (volume ratio)) for amorphous resins, and to tetrahydrofuran for crystalline resins.

[0119] [Weight-average molecular weight of resins] The molecular weight distribution was measured by gel permeation chromatography (GPC), obtained using the following method, and the weight-average molecular weight of the resin was determined. (1) Preparation of sample solution The sample was dissolved at 25°C in tetrahydrofuran for amorphous resins and in chloroform for crystalline resins to a concentration of 0.5 g / 100 mL. Then, the solution was filtered to remove undissolved components using a fluoropolymer filter "DISMIC-25JP" (manufactured by ADVANTEC) with a pore size of 0.2 μm for amorphous resins, and a fluoropolymer filter "FP-200" (manufactured by Sumitomo Electric Industries, Ltd.) with a pore size of 2 μm for crystalline resins, to obtain the sample solution. (2) Molecular weight measurement Using the measurement apparatus and analytical column described below, tetrahydrofuran was used as the eluent for amorphous resins, and chloroform for crystalline resins, and the column was stabilized in a 40°C constant temperature bath while flowing at a flow rate of 1 mL / min. 100 μL of the sample solution was then injected and measured. The molecular weight of the sample was calculated based on a pre-prepared calibration curve. Several types of monodisperse polystyrene "A-500" (5.0 × 10) were used in this calibration curve. 2 ), "A-1000" (1.01 x 10 3 ), "A-2500" (2.63 x 10 3), "A-5000" (5.97 x 10 3 ), "F-1" (1.02×10 4 ), "F-2" (1.81×10 4 ), "F-4" (3.97×10 4 ), "F-10" (9.64×10 4 ), "F-20" (1.90×10 5 ), "F-40" (4.27×10 5 ), "F-80" (7.06×10 5 ), "F-128" (1.09×10 6 The following samples were prepared using the following product (manufactured by Tosoh Corporation) as a standard sample. The values ​​in parentheses indicate the molecular weight. Measuring device: "HLC-8420CPC" (manufactured by Tosoh Corporation) (for amorphous resins) or "HLC-8320CPC" (manufactured by Tosoh Corporation) (for crystalline resins) Analysis columns: "GMHXL" + "G3000HXL" (manufactured by Tosoh Corporation)

[0120] [Melting point of release agent] Using a differential scanning calorimeter "Q-20" (manufactured by T.A. Instruments Japan Co., Ltd.), 0.01 to 0.02 g of the sample was weighed into an aluminum pan, heated to 200°C at a heating rate of 10°C / min, and then cooled from 200°C to -10°C at a cooling rate of 5°C / min. Next, the sample was heated to 180°C at a heating rate of 10°C / min. The maximum endothermic peak temperature observed from the melting endothermic curve was defined as the melting point of the release agent.

[0121] [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 content concentration (mass%) = 100-moisture (mass%)

[0122] [Volume median particle size D of resin particles, colorant particles, mold release agent particles, and charge control agent particles]50 ] (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 so that the absorbance is within the appropriate range, using the medium volume particle size D. 50 We measured it.

[0123] [Circularity of fused particles] The circularity of the fused particles was measured under the following conditions. • 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: HPF measurement mode

[0124] <Toner particle volume median particle size D 50 and CV value > Volume-intermediate particle size D of toner particles 50 The following measurements were taken: • 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.) • 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 (US-1, manufactured by SND Corporation, output 80W). Then, 25 mL of the electrolyte was added, and dispersed for another minute using the 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, the 30,000 particles are measured, and the volume median particle size D is determined from the particle size distribution. 50 and volume-average particle size D V They sought it. Furthermore, 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

[0125] [Average particle size of external additives] Using a field emission scanning electron microscope (FE-SEM) (Hitachi High-Tech Corporation, "S-4800"), the particle sizes of 500 external additives (average values ​​of the major and minor axes of each particle of the external additive) were measured, and the number-average value of the particle sizes was used as the average particle size of the external additive.

[0126] [Resin manufacturing] [Manufacturing of styrene resins] Manufacturing Example S1 (Manufacturing of Styrene Resin S-1) Two liters of xylene were placed in a 10-liter four-necked flask equipped with a thermometer, stainless steel stirring rod, fall-flow condenser, dropping funnel, and nitrogen inlet tube. The raw material monomers and radical polymerization initiators for the styrene resin shown in Table 1 were placed in the dropping funnel attached to the four-necked flask. The xylene in the four-necked flask was then heated to 135°C under a nitrogen atmosphere, and the mixture of raw material monomers and radical polymerization initiators was added dropwise to the xylene from the dropping funnel over a period of one hour. The temperature was further raised to 200°C and maintained at 200°C for two hours. After that, the xylene was removed by maintaining the mixture under reduced pressure of 8 kPa for another hour to obtain the styrene resin S-1. The physical properties are shown in Table 1.

[0127] [Table 1]

[0128] [Manufacturing of crystalline polyester resins] Manufacturing Example C1 (Manufacturing of Crystalline Polyester Resin C-1) Of the raw material monomers for the polyester resin segment shown in Table 2, the entire amount of the alcohol component and half of the carboxylic acid component (50% by mass) were placed in a 10-liter four-necked flask equipped with a thermometer, stainless steel stirring rod, dehydration tube, condenser, and nitrogen inlet tube. The flask was kept warm at 140°C for 2 hours in a mantle heater under a nitrogen atmosphere, and then the temperature was increased from 140°C to 160°C at a rate of 5°C / h. After confirming that the reaction rate reached 95% or more, a mixed solution of the raw material monomers for the styrene-based resin segment, both reactive monomers, and a radical polymerization initiator shown in Table 2 was added dropwise over 1 hour. After maintaining the temperature at 160°C for 30 minutes, the remaining carboxylic acid component was added, and the temperature was increased from 130°C to 200°C at a rate of 10°C / h. Subsequently, an esterification catalyst was added, and the reaction was carried out under reduced pressure of 8 kPa until the acid value shown in Table 2 was reached, yielding crystalline polyester resin C-1 (composite resin). The physical properties are shown in Table 2. The "reaction rate" is calculated from the formula: "100 × amount of water produced (moles) / theoretical amount of water produced (moles)". The theoretical amount of water produced (in moles) is the smaller of the following two values: "the sum of the values ​​obtained by calculating (amount in charge (in moles) × number of hydroxyl groups per molecule) for each alcohol component" and "the sum of the values ​​obtained by calculating (amount in charge (in moles) × number of carboxyl groups per molecule) for each carboxylic acid component." PET is not considered because its molecular weight is sufficiently large, and the amount of water produced from PET during the reaction is negligible. The number of carboxyl groups in carboxylic acid anhydrides, such as trimellitic anhydride, is considered to be 1 in the anhydride portion.

[0129] Manufacturing Examples C2 and C3 (Manufacturing of crystalline polyester resins C-2 and C-3) Crystalline polyester resins C-2 (composite resin) and C-3 (composite resin) were obtained in the same manner as in manufacturing example C1, except that the raw material composition was changed as shown in Table 2. The physical properties are shown in Table 2.

[0130] Manufacturing Example C4 (Manufacturing of Crystalline Polyester Resin C-4) The raw material monomers for the polyester resin shown in Table 2 were placed in a 10-liter four-necked flask equipped with a thermometer, stainless steel stirring rod, dehydration tube, condenser, and nitrogen inlet tube. The mixture was heated in a mantle heater under a nitrogen atmosphere from 130°C to 200°C at a rate of 10°C / h, then reacted at 200°C for 2 hours. After adding the esterification catalyst, the reaction was carried out under reduced pressure of 8 kPa until the acid value shown in Table 2 was reached, yielding crystalline polyester resin C-4 (polyester resin). The physical properties are shown in Table 2.

[0131] [Table 2]

[0132] [Manufacturing of amorphous polyester resin] Manufacturing Example A1 (Manufacturing of Amorphous Polyester Resin A-1) The polyester resin raw materials, esterification catalyst, and esterification co-catalyst shown in Table 3 were placed in a 10-liter four-necked flask equipped with a thermometer, stainless steel stirring rod, dehydration tube, condenser, and nitrogen inlet tube. The mixture was heated to 235°C over 2 hours in a mantle heater under a nitrogen atmosphere. After reacting at 235°C for 8 hours, the reaction was carried out under reduced pressure of 8 kPa until the softening point shown in Table 3 was reached, yielding amorphous polyester resin A-1. The physical properties are shown in Table 3.

[0133] Manufacturing Examples A2, A3, and A'6 (Manufacturing of amorphous polyester resins A-2, A-3, and A'-6) Amorphous polyester resins A-2, A-3, and A'-6 were obtained in the same manner as in manufacturing example A1, except that the raw material composition was changed as shown in Table 3. The physical properties are shown in Table 3.

[0134] Manufacturing Example A4 (Manufacturing of Amorphous Polyester Resin A-4) Of the polyester resin raw materials shown in Table 3, all raw materials except trimellitic anhydride, the esterification catalyst, and the esterification co-catalyst were placed in a 10-liter four-necked flask equipped with a thermometer, stainless steel stirring rod, dehydration tube, condenser, and nitrogen inlet tube. The mixture was heated to 235°C over 2 hours in a mantle heater under a nitrogen atmosphere. After confirming that the reaction rate reached over 95% at 235°C, the mixture was cooled to 180°C. Then, trimellitic anhydride was added, and the mixture was heated to 210°C over 2 hours. After reacting at 210°C for 1 hour, the reaction was carried out under reduced pressure of 8 kPa until the softening point shown in Table 3 was reached, yielding amorphous polyester resin A-4. The physical properties are shown in Table 3.

[0135] Manufacturing Example A'5 (Manufacturing of Amorphous Polyester Resin A'-5) Of the polyester resin raw materials shown in Table 3, all raw materials except succinic acid, the esterification catalyst, and the esterification co-catalyst were placed in a 10-liter four-necked flask equipped with a thermometer, stainless steel stirring rod, dehydration tube, condenser, and nitrogen inlet tube. The mixture was heated to 235°C over 2 hours in a mantle heater under a nitrogen atmosphere. After confirming that the reaction rate reached over 95% at 235°C, the mixture was cooled to 180°C. Succinic acid was then added, and the mixture was heated to 210°C over 2 hours. After reacting at 210°C for 1 hour, the reaction was carried out under reduced pressure of 8 kPa until the softening point shown in Table 3 was reached, yielding amorphous polyester resin A'-5. The physical properties are shown in Table 3.

[0136] Manufacturing Example A'7 (Manufacturing of amorphous polyester resin A'-7) The polyester resin raw materials, esterification catalyst, and esterification co-catalyst shown in Table 3 were placed in a 10-liter four-necked flask equipped with a thermometer, stainless steel stirring rod, dehydration tube, condenser, and nitrogen inlet tube. The flask was then heated in a mantle heater under a nitrogen atmosphere at 180°C for 1 hour, after which the temperature was increased from 180°C to 235°C at a rate of 10°C / h. After confirming that the reaction rate reached 95% or more at 235°C, the reaction was carried out under reduced pressure of 8 kPa until the softening point shown in Table 3 was reached, yielding amorphous polyester resin A'-7. The physical properties are shown in Table 3.

[0137] [Table 3]

[0138] [Manufacturing of resin particle dispersions] Manufacturing Example Z1 (Manufacturing of Styrene-based Resin Particle Dispersion Z-1) In a 3-liter container equipped with a stirrer, reflux condenser, dropping funnel, thermometer, and nitrogen inlet tube, 100 g of styrene resin S-1, 100 g of methyl ethyl ketone, and 16.7 g of the anionic surfactant "Emal E27C" (manufactured by Kao Corporation, solid content 27% by mass) (4.5 g per 100 g of resin) were mixed at 25°C, and the styrene resin was dissolved over 2 hours at 73°C. 475 g of deionized water at 73°C was mixed into the resulting solution, and the mixture was dispersed using an ultrasonic homogenizer (manufactured by Dr. Hielscher, product name: "UP-400S") at an output of 350 W for 30 minutes. Then, at 70°C, the methyl ethyl ketone was removed by reduced pressure distillation, and the water was further removed to a solid content concentration of 20% by mass to obtain an aqueous dispersion of styrene resin particles (styrene resin particle dispersion Z-1). The volume-median particle size D of the styrene resin particles... 50 The solid content concentration of the styrene resin particle dispersion Z-1 is shown in Table 4.

[0139] [Table 4]

[0140] Manufacturing Examples Y1-Y4 (Manufacturing of crystalline polyester resin particle dispersions Y-1-Y-4) In a 3-liter container equipped with a stirrer, reflux condenser, dropping funnel, thermometer, and nitrogen inlet tube, 100 g of crystalline polyester resin, 100 g of methyl ethyl ketone, and 16.7 g of the anionic surfactant "Emal E27C" (manufactured by Kao Corporation, 27% solids by mass) (4.5 g per 100 g of resin) were added, and the resin was dissolved at 73°C for 2 hours. To the resulting solution, a 5% by mass aqueous sodium hydroxide solution was added to achieve a degree of neutralization of 70 mol% relative to the acid value of the resin, and the mixture was stirred for 30 minutes. While maintaining the temperature at 73°C, 475 g of deionized water was added over 77 minutes while stirring at 280 r / min (peripheral speed 88 m / min) to induce phase inversion emulsification. While continuing to maintain the temperature at 73°C, methyl ethyl ketone was removed under reduced pressure, and water was further removed until the solid content concentration reached 20% by mass. Subsequently, the aqueous dispersion was cooled to 30°C while stirring at 280 r / min (peripheral speed 88 m / min) to obtain aqueous dispersions (crystalline polyester resin particle dispersions Y-1 to Y-4) in which crystalline polyester resin was dispersed in the aqueous medium. The volume-median particle size D of the crystalline polyester resin particles was determined. 50 The solid content concentrations of the crystalline polyester resin particle dispersions Y-1 to Y-4 are shown in Table 5.

[0141] [Table 5]

[0142] Manufacturing Examples X1-X4, X'5-X'7 (Manufacturing of amorphous polyester resin particle dispersions X-1-X-4, X'-5-X'-7) In a 3-liter container equipped with a stirrer, reflux condenser, dropping funnel, thermometer, and nitrogen inlet tube, 100 g of amorphous polyester resin and 100 g of methyl ethyl ketone, as shown in Table 6, were placed, and the resin was dissolved at 73°C for 2 hours. To the resulting solution, a 5% by mass aqueous sodium hydroxide solution was added to achieve a degree of neutralization of 70 mol% relative to the acid value of the resin, and the mixture was stirred for 30 minutes. While maintaining the temperature at 73°C, 475 g of deionized water was added over 77 minutes while stirring at 280 r / min (peripheral speed 88 m / min) to induce phase inversion emulsification. While continuing to maintain the temperature at 73°C, methyl ethyl ketone was removed under reduced pressure, and water was further removed by distillation until the solid content concentration reached 20% by mass. Subsequently, the aqueous dispersion was cooled to 30°C while stirring at 280 r / min (peripheral speed 88 m / min) to obtain aqueous dispersions (amorphous polyester resin particle dispersions X-1~X-4, X'-5~X'-7) in which amorphous polyester resin was dispersed in the aqueous medium. The median volume particle size D of the amorphous polyester resin particles. 50 The solid content concentrations of amorphous polyester resin particle dispersions X-1 to X-4 and X'-5 to X'-7 are shown in Table 6.

[0143] [Table 6]

[0144] [Manufacturing of colorant particle dispersion] 50g of copper phthalocyanine "ECB-301" (manufactured by Dainichi Seika Kogyo Co., Ltd.), 5g of nonionic surfactant "Emulgen 150" (polyoxyethylene lauryl ether, manufactured by Kao Corporation), and 200g of deionized water were mixed and dispersed for 10 minutes using an ultrasonic homogenizer (Hielscher UP-400S) to obtain a dispersion of colorant particles. Volume-intermediate particle size D of the colorant fine particles. 50 The wavelength was 120 nm, and the solid content concentration of the colorant particle dispersion was 22% by mass.

[0145] [Manufacturing of mold release agent particle dispersion] 50g of paraffin wax "HNP-9" (manufactured by Nippon Seiro Co., Ltd., melting point: 79℃), 5g of cationic surfactant "Sanizol (registered trademark) B50" (manufactured by Kao Corporation, alkylbenzyldimethylammonium chloride, active ingredient 50% by mass), and 200g of deionized water were heated to 95℃ and dispersed using an ultrasonic homogenizer (Hielscher, product name: "UP-400S") at an output of 350W for 30 minutes to obtain a release agent particle dispersion. Volume-median particle size D of the release agent particles 50 The wavelength was 550 nm, and the solid content concentration of the release agent particle dispersion was 22% by mass.

[0146] [Manufacturing of Charge Control Agent Particle Dispersion] 50 g of the salicylic acid compound "Bontron E-84" (manufactured by Orient Chemical Industries, Ltd.) as a charge control agent, 5 g of "Emulgen 150" (polyoxyethylene lauryl ether, manufactured by Kao Corporation) as a nonionic surfactant, and 200 g of deionized water were mixed and dispersed for 10 minutes using glass beads and a sand grinder (IMEX Corporation "4G") to obtain a dispersion of charge control agent particles. The volume-median particle size D of the charge control agent particles 50The wavelength was 400 nm, and the solid content concentration of the charge control agent particle dispersion was 22% by mass.

[0147] [Toner manufacturing] Example 1 For core formation, 240g of styrene-based resin particle dispersion Z-1, 30g of crystalline polyester-based resin particle dispersion Y-1, 8g of coloring agent particle dispersion, 20g of mold release agent particle dispersion, 2g of charge control agent particle dispersion, and 50g of deionized water were placed in a 2-liter container. Under stirring at 100 r / min (peripheral speed 31 m / min) with an anchor-type stirrer, 150g of 0.1% by mass calcium chloride aqueous solution was added dropwise over 30 minutes at 20°C, and the temperature was raised to 50°C while stirring. The temperature was maintained at 50°C, and the volume-median particle size D of aggregated particle 1 was measured. 50 After the particle size reached 5 μm, 30 g of amorphous polyester resin dispersion X-1 containing shell resin was immediately added and stirred to disperse and aggregate. Then, as an anti-aggregation agent, a diluted solution of 4.2 g of the anionic surfactant "Emal E27C" (polyoxyethylene lauryl ether sulfate sodium, manufactured by Kao Corporation, solid content 27% by mass) diluted with 37 g of deionized water was added to obtain aggregated particles 2. Next, the temperature was raised to 80°C, and after reaching 80°C, it was maintained at 80°C until the circularity reached 0.97, after which heating was terminated. This fused the aggregated particles 2 to form fused particles. After slow cooling to 20°C, the mixture was filtered through a 150-mesh (150 μm opening) wire mesh, followed by suction filtration, washing, and drying to obtain toner particles 1 having a core-shell structure. Volume-median particle size D of toner particles 1. 50 The corresponding coefficients (CV) are shown in Table 7. To 100 parts by mass of the obtained toner particles 1, 1 part by mass of hydrophobic silica "NAX-50" (manufactured by Nippon Aerosil Co., Ltd., average particle size 40 nm), 0.6 parts by mass of hydrophobic silica "R972" (manufactured by Nippon Aerosil Co., Ltd., average particle size 16 nm), and 0.5 parts by mass of titanium dioxide "JMT-150IB" (manufactured by Teika Co., Ltd., average particle size 15 nm) were added to a 10-liter Henschel mixer (manufactured by Nippon Coke Industries Co., Ltd.) and stirred at 3000 r / min for 2 minutes to obtain toner 1. The image density of toner 1 was evaluated using the following evaluation method. The results are shown in Table 7.

[0148] [Evaluation Method] [Image density] Using high-quality paper "J Paper A4 size" (manufactured by Fujifilm Business Innovation Co., Ltd.) and a commercially available printer "HL-2040" (manufactured by Brother Industries, Ltd.), the amount of toner adhering to the paper was measured at 0.42-0.48 mg / cm². 2 A solid image was output, and a printed copy was obtained. Next, the fuser temperature was set to 130°C, and the toner was fixed at a speed of 1.5 seconds per sheet in the A4 portrait direction to obtain the printed material. The reflected image density of the fixed image portion of the printed output was measured using a SpectroEye colorimeter (manufactured by X-Rite, light emission conditions: standard light source D50, observation field of view 2°, density reference DINNB, absolute white reference). A higher reflected image density value indicates better image density.

[0149] Example 2 Toner particles 2 and toner 2 were manufactured in the same manner as in Example 1, except that 210 g of styrene-based resin particle dispersion Z-1 was used as the core resin particle dispersion and 60 g of amorphous polyester resin particle dispersion X-2 was used as the shell resin particle dispersion. Volume median particle size D of toner particles 2 50 The evaluation results for the CV value and the image density of toner 2 are shown in Table 7.

[0150] Examples 3-5, 7 and Comparative Examples 1-2, 4 Toner particles 3-5, 7, c1, c2, c4 and toners 3-5, 7, c1, c2, c4 were manufactured in the same manner as in Example 1, except that the resin particle dispersions listed in Table 7 were used as the core resin particle dispersion and the resin particle dispersion for the shell. Volume median particle size D of toner particles 3-5, 7, c1, c2, c4 50 The CV values ​​and the evaluation results of the image density for toners 3-5, 7, c1, c2, and c4 are shown in Table 7.

[0151] Example 6 Toner particles 6 and toner 6 were manufactured in the same manner as in Example 1, except that 180 g of styrene-based resin particle dispersion Z-1 was used as the core resin particle dispersion and 90 g of amorphous polyester resin particle dispersion X-3 was used as the shell resin particle dispersion. Volume median particle size D of toner particles 6 50 The evaluation results for the CV value and the image density of toner 6 are shown in Table 7.

[0152] Comparative Example 3 Toner particles c3 and toner c3 were manufactured in the same manner as in Example 6, except that the resin particle dispersions listed in Table 7 were used as the core resin particle dispersion and the shell resin particle dispersion. Volume median particle size D of toner particles c3 50 The evaluation results for the CV value and the image density of toner c3 are shown in Table 7.

[0153] [Table 7]

[0154] Table 7 shows that printed materials obtained using the toner of the present invention exhibit excellent image density (Examples 1-7). In contrast, printed materials obtained using toner manufactured with amorphous polyester resin that does not contain PET-derived structures exhibited inferior image density (Comparative Examples 1 and 4). Furthermore, printed materials obtained using toner in which the content of polyethylene terephthalate-derived structures in the amorphous polyester resin was less than 1 part by mass (0.6 parts by mass) or more than 12 parts by mass (15.0 parts by mass) relative to 100 parts by mass of styrene-based resin S exhibited inferior image density (Comparative Examples 2 and 3).

Claims

1. A toner for electrostatic image development containing toner particles having a core-shell structure, The core contains styrene resin S, The shell contains amorphous polyester resin A, which is a polycondensate of an alcohol component, a carboxylic acid component, and polyethylene terephthalate. The content of polyethylene terephthalate-derived structures in amorphous polyester resin A is 1 part by mass or more and 12 parts by mass or less per 100 parts by mass of styrene-based resin S. Toner for developing electrostatic images.

2. The electrostatic image developing toner according to claim 1, wherein the core further contains a crystalline polyester resin C.

3. The electrostatic image developing toner according to claim 2, wherein the crystalline polyester resin C is a crystalline composite resin comprising a polyester resin segment which is a polycondensate of raw material monomers containing an alcohol component and a carboxylic acid component, a styrene resin segment, and constituent units derived from both reactive monomers which covalently bond the polyester resin segment and the styrene resin segment.

4. The electrostatic image developing toner according to claim 2 or 3, wherein the number of carbon atoms in the alcohol component of the crystalline polyester resin C is 2 or more and 4 or less.

5. The electrostatic image developing toner according to claim 1 or 2, wherein the content of polyethylene terephthalate-derived structures in amorphous polyester resin A is 10% by mass or more and 50% by mass or less.

6. The electrostatic image developing toner according to claim 1 or 2, wherein the softening point of the amorphous polyester resin A is 90°C or higher and 125°C or lower.

7. The electrostatic image developing toner according to claim 1 or 2, wherein the content of styrene-based resin S in the binder resin contained in the toner particles is 50% by mass or more.

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