JP7734582B2 - Method for producing toner for developing electrostatic images - Google Patents

Description

The present invention relates to a method for producing toner for developing electrostatic images, which is used to develop latent images formed in electrophotography, electrostatic recording, electrostatic printing, etc.

In the field of electrophotography, with the development of electrophotographic systems, there is a demand for the development of electrophotographic toners that can meet the demands for higher image quality and higher speeds.In order to meet the demands for higher image quality, a method for obtaining a toner that has a narrow particle size distribution, a small particle size, and fixing properties that can meet the demands for higher speeds has been carried out, in which a toner is obtained by aggregating and fusing fine resin particles or the like in an aqueous medium using an aggregation and fusion method (emulsion aggregation method, aggregation and coalescence method).
Chemical toners can achieve precise control of toner structure by aggregating fine particles in water, for example, by lowering the glass transition temperature of the resin used in the core and forming a shell with a resin having a high glass transition temperature, thereby making it possible to produce toners with a so-called core-shell structure. However, they have a problem in that charging properties tend to decrease due to the influence of surfactants required during production.

In response to these problems, Patent Document 1 describes a toner containing a binder resin, a colorant, and a nonionic surfactant, wherein the nonionic surfactant has an oxyethylene group and an oxypropylene group, and the ratio (PO/EO) of the number of moles of oxypropylene groups (PO) to the number of moles of oxyethylene groups (EO) is 0.01 or more and 5.00 or less, and wherein the content of the nonionic surfactant on the toner surface extracted from 1 g of the toner with methanol is A (μg/g), and the theoretical specific surface area obtained from the particle size distribution of the toner using a precision particle size distribution measuring device based on a pore electrical resistance method is B ( ^m2 /g), and the ratio (A/B) is 100 μg/ ^m2 or more and 9000 μg/ ^m2 or less.

JP 2011-257750 A

In recent years, with the increase in exports of domestically manufactured toner cartridges and printers, toners are now required to be able to withstand the high-temperature, high-humidity environment of shipping by ship, i.e., a high-temperature, high-humidity environment that far exceeds the normal usage environment. The inventors have conducted research and found that if a surfactant is used in the production of chemical toner, the surfactant is exposed to the surface of the toner particles in a high-temperature, high-humidity environment, such as shipping, resulting in a significant decrease in charge, and printing problems such as fog. Furthermore, they have found that even toners with a reduced content of nonionic surfactant, as described in Patent Document 1, can suppress charge loss in normal usage environments, but when chemical toners are exposed to a high-temperature, high-humidity environment, the surfactant is exposed to the surface of the toner particles, resulting in a significant decrease in charge, and printing problems such as fog. On the other hand, they have found that if a chemical toner is produced without any surfactant at all in order to completely suppress the decrease in charge and the exposure of the surfactant to the toner particle surface in a high-temperature, high-humidity environment, the particle stability in water is insufficient, resulting in problems such as the generation of coarse particles and a broad particle size distribution, significantly degrading print quality.
The present invention relates to a method for producing a toner for developing electrostatic images, which has a narrow particle size distribution, exhibits high chargeability even after storage in a high-temperature, high-humidity environment, produces printed matter with high image density, and suppresses the occurrence of fog when printing images in a high-temperature, high-humidity environment.

The present inventors have discovered a method for producing a toner for developing electrostatic images, which uses a polyester resin and an addition polymer having a specific structure as a binder resin, and which can produce images of good quality even after storage under high-temperature and high-humidity conditions, without generating coarse particles or broadening the particle size distribution, even when the amount of surfactant used is reduced.
The present invention relates to the following [1].
[1] A method for producing a toner for developing electrostatic images, comprising the following steps 1 to 3:
Step 1: A process for mixing a polyester resin A and an addition polymer E to obtain an aqueous dispersion of resin particles X containing the polyester resin A and the addition polymer E. Step 2: A process for aggregating the resin particles X in an aqueous medium to obtain aggregated particles. Step 3: A process for fusing the aggregated particles obtained in step 2 to obtain fused particles. A method for producing a toner for developing electrostatic images, wherein the addition polymer E is an addition polymer of raw material monomers including a styrene-based compound and an addition-polymerizable monomer having a polyalkylene oxide group.

The present invention provides a method for producing a toner for developing electrostatic images that has a narrow toner particle size distribution, exhibits high charging properties even after storage in a high-temperature, high-humidity environment, produces printed matter with high image density, and suppresses the occurrence of fog when printing images in a high-temperature, high-humidity environment.

[Method of manufacturing toner for developing electrostatic images]
The method for producing a toner for developing electrostatic images of the present invention includes step 1 of mixing a polyester resin A and an addition polymer E to obtain an aqueous dispersion of resin particles X containing the polyester resin A and the addition polymer E, step 2 of aggregating the resin particles X in an aqueous medium to obtain aggregated particles, and step 3 of fusing the aggregated particles obtained in step 2 to obtain fused particles.
Addition polymer E is an addition polymer of raw material monomers including a styrene-based compound and an addition-polymerizable monomer having a polyalkylene oxide group.
The above-described manufacturing method provides a toner for developing electrostatic images that has a narrow particle size distribution, exhibits high charging properties even after storage in a high-temperature, high-humidity environment, produces printed matter with high image density, and suppresses the occurrence of fog when printing images in a high-temperature, high-humidity environment.

The reason why the manufacturing method of the present invention can produce a toner for developing electrostatic images (hereinafter also simply referred to as "toner") that has a narrow particle size distribution of toner particles, exhibits high charging properties even after storage in a high-temperature, high-humidity environment, produces printed matter with high image density, and suppresses the occurrence of fog when printing images in a high-temperature, high-humidity environment is not clear, but is thought to be as follows.
Surfactants function to stabilize the dispersion of polyester microparticles in water and are essential compounds for the production of chemical toners using emulsion aggregation. However, surfactants are generally water-soluble and therefore highly electrically conductive. If surfactants remain inside the toner after production, they are thought to migrate to the toner surface under high-temperature, high-humidity conditions, causing charge leakage from the surfactant during charging. Through further investigations, the inventors have found that the surfactants used to stabilize the system during the chemical toner production process, particularly during the aggregation process in which resin microparticles are aggregated, have a significant impact on the chargeability of the resulting toner.

After extensive research into possible solutions, the inventors discovered that addition polymer E, an addition polymer of raw material monomers including a styrene-based compound and an addition-polymerizable monomer having a polyalkylene oxide group, stabilizes the dispersibility of resin particles, thereby significantly reducing the amount of surfactant used in the aggregation process. Resin particles X, which contain addition polymer E and polyester-based resin A, have a composite structure in which the hydrophobic styrene-based compound-derived moieties of addition polymer E are adsorbed to the hydrophobic moieties of polyester-based resin A, and it is believed that in an aqueous dispersion medium, the hydrophilic polyalkylene oxide group-derived moieties of the addition-polymerizable monomer are oriented toward the aqueous layer. Therefore, due to the steric stabilization effect of the polyalkylene oxide group, resin particles X are believed to be able to exist stably in water without the addition of a surfactant. Furthermore, aggregated particles with a relatively narrow particle size distribution are obtained without coarsening during the process of obtaining aggregated particles, resulting in a narrow particle size distribution for the final toner particles. Furthermore, toner containing toner particles obtained by aggregating and fusing resin particles X does not contain any surfactant, or if it does contain any, it contains only a small amount. Therefore, even when stored in a high-temperature, high-humidity environment, the surfactant does not migrate to the toner surface, causing no decrease in the toner's charge, resulting in printed materials with high image density and stable printing performance with reduced fogging when printing images in a high-temperature, high-humidity environment.

The definitions of various terms used in this specification are shown below.
Whether a resin is crystalline or amorphous is determined by its crystallinity index. The crystallinity index is defined as the ratio of the softening point of the resin to the endothermic maximum peak temperature (softening point (°C)/endothermic maximum peak temperature (°C)) in the measurement method described in the Examples below. A crystalline resin is one whose crystallinity index is 0.6 or more and 1.4 or less. An amorphous resin is one in which no endothermic peak is observed, or, if an endothermic peak is observed, whose crystallinity index is less than 0.6 or more than 1.4. The crystallinity index can be appropriately adjusted by adjusting the types and ratios of raw material monomers, as well as production conditions such as reaction temperature, reaction time, and cooling rate.
With respect to hydrocarbon groups, the parenthetical expressions "(iso or tertiary)" and "(iso)" refer to both the presence and absence of these prefixes; the absence of these prefixes indicates normal.
"(Meth)acrylic acid" means at least one selected from acrylic acid and methacrylic acid.
The term "(meth)acrylate" refers to at least one selected from acrylate and methacrylate.
The term "(meth)acryloyl group" refers to at least one group selected from an acryloyl group and a methacryloyl group.
The term "styrenic compound" means unsubstituted or substituted styrene.
"Main chain" means the relatively longest connecting chain in an addition polymer.

[Step 1]
In step 1, polyester resin A and addition polymer E are mixed to obtain an aqueous dispersion of resin particles X containing polyester resin A and addition polymer E.

[Polyester Resin A]
The polyester resin A (hereinafter also simply referred to as "resin A") is, for example, a polyester resin containing a polycondensate of an alcohol component and a carboxylic acid component, and is preferably an amorphous polyester resin.
Examples of resin A include polyester resins and modified polyester resins. Examples of modified polyester resins include urethane-modified polyester resins, epoxy-modified polyester resins, and composite resins containing polyester resin segments and addition-polymerized resin segments. Among these, resin A is preferably a polyester resin or a composite resin.

Examples of the alcohol component of Resin A include alkylene oxide adducts of aromatic diols, linear or branched aliphatic diols, alicyclic diols, and trihydric or higher polyhydric alcohols. Among these, alkylene oxide adducts of aromatic diols are preferred from the viewpoint of obtaining a toner with excellent low-temperature fixing properties and from the viewpoint of strengthening the hydrophobic interaction with Addition Polymer E.
The alkylene oxide adduct of an aromatic diol is preferably an alkylene oxide adduct of bisphenol A, more preferably an alkylene oxide adduct of formula (I):

(wherein ^OR1 and ^R2O are oxyalkylene groups, ^R1 and ^R2 each independently represent an ethylene group or a propylene group, x and y each represent the average number of moles of alkylene oxide added and are positive numbers, and the sum of x and y is 1 or more, preferably 1.5 or more, and more preferably 1.8 or more, and is 16 or less, preferably 8 or less, more preferably 4 or less, even more preferably 3 or less, and even more preferably 2.5 or less).

Examples of the alkylene oxide adduct of bisphenol A represented by formula (I) include a propylene oxide adduct of 2,2-bis(4-hydroxyphenyl)propane, an ethylene oxide adduct of 2,2-bis(4-hydroxyphenyl)propane, etc. Among these, the propylene oxide adduct of bisphenol A is preferred.
The content of the alkylene oxide adduct of bisphenol A in the alcohol component is preferably 80 mol% or more, more preferably 90 mol% or more, and is 100 mol% or less, preferably 100 mol%, from the viewpoint of strengthening the hydrophobic interaction with the addition polymer E.

Examples of linear or branched aliphatic diols include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 2,2-dimethyl-1,3-propanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, and 1,12-dodecanediol.
Examples of alicyclic diols include hydrogenated bisphenol A [2,2-bis(4-hydroxycyclohexyl)propane] and adducts of hydrogenated bisphenol A with alkylene oxides having 2 to 4 carbon atoms (average number of added moles: 2 to 12).
Examples of trihydric or higher polyhydric alcohols include glycerin, pentaerythritol, trimethylolpropane, and sorbitol.
These alcohol components may be used alone or in combination of two or more.

Examples of the carboxylic acid component of the resin A include dicarboxylic acids and trivalent or higher polycarboxylic acids.
Examples of dicarboxylic acids include aromatic dicarboxylic acids, linear or branched aliphatic dicarboxylic acids, and alicyclic dicarboxylic acids. Among these, at least one selected from aromatic dicarboxylic acids and linear or branched aliphatic dicarboxylic acids is preferred.
Examples of aromatic dicarboxylic acids include phthalic acid, isophthalic acid, and terephthalic acid. Among these, isophthalic acid and terephthalic acid are preferred, and terephthalic acid is more preferred.
The amount of aromatic dicarboxylic acid in the carboxylic acid component is preferably 20 mol% or more, more preferably 30 mol% or more, even more preferably 40 mol% or more, and is preferably 99 mol% or less, more preferably 95 mol% or less, even more preferably 93 mol% or less.

The linear or branched aliphatic dicarboxylic acid preferably has 2 or more carbon atoms, more preferably 3 or more carbon atoms, and preferably 30 or less, more preferably 20 or less carbon atoms.
Examples of linear or branched aliphatic dicarboxylic acids include oxalic acid, malonic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, succinic acid, adipic acid, sebacic acid, dodecanedioic acid, azelaic acid, and succinic acids substituted with an aliphatic hydrocarbon group having from 1 to 20 carbon atoms. Examples of succinic acids substituted with an aliphatic hydrocarbon group having from 1 to 20 carbon atoms include dodecylsuccinic acid, dodecenylsuccinic acid, and octenylsuccinic acid. Of these, fumaric acid, sebacic acid, and adipic acid are preferred.
The amount of the linear or branched aliphatic dicarboxylic acid in the carboxylic acid component is preferably 1 mol % or more, more preferably 3 mol % or more, even more preferably 5 mol % or more, and is preferably 50 mol % or less, more preferably 30 mol % or less, even more preferably 20 mol % or less.

The trivalent or higher polyvalent carboxylic acid is preferably a trivalent carboxylic acid, such as trimellitic acid or its anhydride.
When a trivalent or higher polycarboxylic acid is contained, the amount of the trivalent or higher polycarboxylic acid in the carboxylic acid component is preferably 1 mol% or more, more preferably 1.5 mol% or more, even more preferably 2 mol% or more, and is preferably 30 mol% or less, more preferably 20 mol% or less, even more preferably 15 mol% or less.
These carboxylic acid components may be used alone or in combination of two or more.

The equivalent ratio of the carboxyl groups of the carboxylic acid component to the hydroxyl groups of the alcohol component [COOH groups/OH groups] is preferably 0.7 or more, more preferably 0.75 or more, and preferably 1.3 or less, more preferably 1.2 or less.

When the resin A is a composite resin, the addition polymerized resin segment may be, for example, an addition polymer of raw material monomers containing a styrene-based compound.
Examples of the styrene-based compound include unsubstituted or substituted styrene. Examples of the substituent substituted on the styrene include an alkyl group having from 1 to 5 carbon atoms, a halogen atom, an alkoxy group having from 1 to 5 carbon atoms, a sulfonic acid group, or a salt thereof.
Examples of styrene compounds include styrene, methylstyrene, α-methylstyrene, β-methylstyrene, tert-butylstyrene, chlorostyrene, chloromethylstyrene, methoxystyrene, styrenesulfonic acid, and salts thereof. Among these, styrene is preferred.
The content of the styrene-based compound in the raw material monomers of the addition polymerization resin segment is preferably 50% by mass or more, more preferably 65% by mass or more, even more preferably 75% by mass or more, and is 100% by mass or less, preferably 95% by mass or less, more preferably 90% by mass or less, even more preferably 85% by mass or less.

Examples of raw material monomers other than styrene-based compounds include (meth)acrylic acid esters such as alkyl (meth)acrylate, benzyl (meth)acrylate, and dimethylaminoethyl (meth)acrylate; olefins such as ethylene, propylene, and butadiene; halovinyl compounds such as vinyl chloride; vinyl esters such as vinyl acetate and vinyl propionate; vinyl ethers such as methyl vinyl ether; vinylidene halides such as vinylidene chloride; and N-vinyl compounds such as N-vinylpyrrolidone. Among these, (meth)acrylic acid esters are preferred, and alkyl (meth)acrylates are more preferred.
The number of carbon atoms in the alkyl group in the alkyl (meth)acrylate is preferably 1 or more, more preferably 4 or more, even more preferably 6 or more, and is preferably 24 or less, more preferably 22 or less, even more preferably 20 or less.
Examples of the alkyl (meth)acrylate 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, of which 2-ethylhexyl (meth)acrylate or stearyl (meth)acrylate is preferred, stearyl (meth)acrylate is more preferred, and stearyl methacrylate is even more preferred.

The content of (meth)acrylic acid ester in the raw material monomers for the addition polymerization 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, even more preferably 25% by mass or less.

The total amount of styrene-based compounds and (meth)acrylic acid esters in the raw material monomers for the addition polymerization resin segment is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and even more preferably 100% by mass.

The composite resin preferably has a constitutional unit derived from a bireactive monomer bonded via a covalent bond to a polyester resin segment and an addition polymerized resin segment.
The term "structural unit derived from a bireactive monomer" refers to a unit formed by reaction of a functional group and an addition polymerizable group of a bireactive monomer.
An example of the addition polymerizable group is a carbon-carbon unsaturated bond (ethylenically unsaturated bond).
Examples of the bireactive monomer include addition-polymerizable monomers having at least one functional group selected from a hydroxyl group, a carboxyl group, an epoxy group, a primary amino group, and a secondary amino group in the molecule. Among these, from the viewpoint of reactivity, addition-polymerizable monomers having at least one functional group selected from a hydroxyl group and a carboxyl group are preferred, and addition-polymerizable monomers having a carboxyl group are more preferred.
Examples of addition-polymerizable monomers having a carboxy group include acrylic acid, methacrylic acid, fumaric acid, and maleic acid. Among these, from the viewpoint of reactivity in both polycondensation reactions and addition polymerization reactions, acrylic acid and methacrylic acid are preferred, and acrylic acid is more preferred.
When the bireactive monomer is an addition-polymerizable monomer having a carboxy group, the amount of the constitutional unit derived from the bireactive monomer is preferably 1 part by mol or more, more preferably 5 parts by mol or more, even more preferably 8 parts by mol or more, and preferably 30 parts by mol or less, more preferably 25 parts by mol or less, even more preferably 20 parts by mol or less, relative to 100 parts by mol of the alcohol component of the polyester resin segment of the composite resin.

The content of polyester resin segments in the composite resin is preferably 40% by mass or more, more preferably 45% by mass or more, and even more preferably 55% by mass or more, based on the total amount of polyester resin segments and addition polymerization resin segments, and is preferably 95% by mass or less, more preferably 85% by mass or less, and even more preferably 75% by mass or less. The structural units derived from bireactive monomers are referred to as polyester resin segments.

The content of addition polymerization resin segments in the composite resin is preferably 5% by mass or more, more preferably 15% by mass or more, and even more preferably 25% by mass or more, relative to the total amount of polyester resin segments and addition polymerization resin segments, and is preferably 60% by mass or less, more preferably 55% by mass or less, and even more preferably 45% by mass or less.

The amount of bireactive monomer-derived structural units in the composite resin is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, even more preferably 0.8% by mass or more, relative to the total amount of polyester resin segments and addition polymerization resin segments, and is preferably 10% by mass or less, more preferably 7% by mass or less, even more preferably 4% by mass or less.

The total amount of polyester resin segments and addition polymerization resin segments in the composite resin is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and is 100% by mass or less, and even more preferably 100% by mass.

The above amounts are calculated based on the ratio of the amounts of the polyester resin segment, raw material monomer for the addition polymerization resin segment, bireactive monomer, and radical polymerization initiator, and 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 addition polymerization resin segment.

(Method for producing polyester resin A)
<Method of producing polyester resin>
When the resin A is a polyester resin, the resin A may be produced, for example, by polycondensing raw material monomers containing an alcohol component and a carboxylic acid component.

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

<Method of manufacturing composite resin>
When resin A is a composite resin containing a polyester resin segment and an addition polymerization resin segment, it may be produced, for example, by a method including step A of polycondensing an alcohol component and a carboxylic acid component, and step B of addition polymerizing raw material monomers of the addition polymerization resin segment and a bireactive monomer.
Step B may be carried out after step A, step A may be carried out after step B, or step A and step B may be carried out simultaneously.
A preferred method is to subject a part of the carboxylic acid component to a polycondensation reaction in step A, then carry out step B, and then add the remainder of the carboxylic acid component to the polymerization system to further promote the polycondensation reaction of step A and the polycondensation reaction with the carboxy group of the bireactive monomer or the constituent moiety derived from the bireactive monomer.

In step A, if necessary, the esterification catalyst and esterification promoter described in the above method for producing a polyester resin may be used in the same amounts to carry out polycondensation.
When a monomer having an unsaturated bond such as fumaric acid is used in polycondensation, the polymerization inhibitor described in the above method for producing the polyester resin may be used in the same amount as above, if necessary.
The temperature of the polycondensation reaction is preferably 120° C. or higher, more preferably 160° C. or higher, and even more preferably 180° C. or higher, and is preferably 250° C. or lower, and more preferably 240° C. or lower. The polycondensation may be carried out in an inert gas atmosphere.

Examples of the radical polymerization initiator for the addition polymerization in step B include peroxides such as dibutyl peroxide, persulfates such as sodium persulfate, and azo compounds such as 2,2'-azobis(2,4-dimethylvaleronitrile).
The amount of the radical polymerization initiator used is preferably 1 part by mass or more and 20 parts by mass or less based on 100 parts by mass of the raw material monomer of the addition polymerization resin segment.
The temperature of the addition polymerization is preferably 110°C or higher, more preferably 130°C or higher, and preferably 230°C or lower, more preferably 220°C or lower, and even more preferably 210°C or lower.

(Physical Properties of Polyester Resin A)
The softening point of Resin A is preferably 70°C or higher, more preferably 90°C or higher, even more preferably 100°C or higher, and preferably 140°C or lower, more preferably 130°C or lower, even more preferably 125°C or lower.
The glass transition temperature of Resin A is preferably 30°C or higher, more preferably 35°C or higher, even more preferably 40°C or higher, and preferably 80°C or lower, more preferably 75°C or lower, even more preferably 70°C or lower.

The acid value of Resin A is preferably 3 mgKOH/g or more, more preferably 5 mgKOH/g or more, even more preferably 8 mgKOH/g or more, and preferably 40 mgKOH/g or less, more preferably 35 mgKOH/g or less, even more preferably 30 mgKOH/g or less.

The softening point, glass transition temperature, and acid value of Resin A can be appropriately adjusted by the type and amount of raw material monomers used, as well as production conditions such as reaction temperature, reaction time, and cooling rate, and these values can be determined by the methods described in the examples.
When two or more resins A are used in combination, it is preferable that the softening point, glass transition temperature and acid value of the resulting mixture are within the above-mentioned ranges.

[Addition polymer E]
Addition polymer E (hereinafter also simply referred to as "polymer E") is an addition polymer of raw material monomers including a styrene-based compound a (hereinafter also simply referred to as "monomer a") and an addition-polymerizable monomer b having a polyalkylene oxide group (hereinafter also simply referred to as "monomer b").

The raw material monomers for polymer E include monomer a and monomer b, as well as preferably at least one selected from addition-polymerizable monomer c (hereinafter simply referred to as "monomer c") having an ionic group and macromonomer d (hereinafter simply referred to as "monomer d"), and more preferably both monomer c and monomer d.

Examples of the monomer a include substituted or unsubstituted styrene. Examples of the substituent substituted on the styrene include an alkyl group having 1 to 5 carbon atoms, a halogen atom, an alkoxy group having 1 to 5 carbon atoms, a sulfo group, or a salt thereof. The monomer a is preferably nonionic.
The molecular weight of monomer a is preferably 1,000 or less, more preferably 800 or less, even more preferably 500 or less, even more preferably 300 or less, and preferably 80 or more, more preferably 90 or more, even more preferably 100 or more.
Examples of the monomer a include styrene, methylstyrene, α-methylstyrene, β-methylstyrene, tert-butylstyrene, chlorostyrene, chloromethylstyrene, methoxystyrene, styrenesulfonic acid, and salts thereof. Among these, styrene is preferred.
From the viewpoint of strengthening the hydrophobic interaction with resin A, the amount of monomer a in the raw material monomers of polymer E is preferably 20% by mass or more, more preferably 30% by mass or more, even more preferably 35% by mass or more, and is preferably 70% by mass or less, more preferably 60% by mass or less, even more preferably 55% by mass or less.

The average number of moles of alkylene oxide added in the polyalkylene oxide group of monomer b is preferably 1 or more, more preferably 2 or more, even more preferably 3 or more, and is preferably 30 or less, more preferably 20 or less, even more preferably 10 or less.
Monomer b is preferably nonionic.
Examples of the monomer b include polyalkylene glycol (meth)acrylates such as polyethylene glycol (meth)acrylate and polypropylene glycol (meth)acrylate; alkoxypolyalkylene glycol (meth)acrylates such as methoxypolyethylene glycol (meth)acrylate; and aryloxypolyalkylene glycol (meth)acrylates such as phenoxy (ethylene glycol-propylene glycol copolymer) (meth)acrylate. From the viewpoint of obtaining a steric stabilization effect of the resin particles X in an aqueous medium, alkoxypolyalkylene glycol (meth)acrylate is preferred.
From the viewpoint of improving the dispersion stability of the resin particles X, the amount of the monomer b in the raw material monomers of the polymer E is preferably 5% by mass or more, more preferably 8% by mass or more, even more preferably 10% by mass or more, and is preferably 45% by mass or less, more preferably 40% by mass or less, even more preferably 35% by mass or less.

The ionic group in the monomer c means a group that undergoes ion dissociation in water.
Examples of the ionic group include a carboxy group, a sulfo group, a phosphate group, an amino group, or salts thereof.
The ionic group is preferably an anionic group. The anionic group is preferably an acidic group or a salt thereof, more preferably a carboxy group, a sulfo group, or a salt thereof, and even more preferably a carboxy group or a salt thereof.
Examples of addition polymerizable monomers having a carboxy group include (meth)acrylic acid, itaconic acid, maleic acid, fumaric acid, and 2-methacryloyloxymethylsuccinic acid.
Among these, addition polymerizable monomers having an anionic group are preferred, (meth)acrylic acid is more preferred, and methacrylic acid is even more preferred.
When monomer c is contained, the amount of monomer c in the raw material monomers of polymer E is, from the viewpoint of improving the dispersion stability of resin particles X, preferably 2% by mass or more, more preferably 5% by mass or more, even more preferably 7% by mass or more, and preferably 40% by mass or less, more preferably 35% by mass or less, even more preferably 30% by mass or less.

Examples of the monomer d include a styrene-based compound polymer having an addition-polymerizable functional group at one end (hereinafter also referred to as a "styrene-based macromonomer"). Examples of the addition-polymerizable functional group include a vinyl group, an allyl group, and a (meth)acryloyl group. Among these, a (meth)acryloyl group is preferred.
In the monomer d, the styrene-based compound is preferably styrene.
The number average molecular weight of the monomer d is preferably 1,000 or more and 10,000 or less. The number average molecular weight is measured by gel permeation chromatography using chloroform containing 1 mmol/L dodecyldimethylamine as a solvent and polystyrene as a standard substance.
Commercially available styrene macromonomers include, for example, "AS-6", "AS-6S", "AN-6", "AN-6S", "HS-6", and "HS-6S" (all manufactured by Toagosei Co., Ltd.).

When monomer d is contained, the amount of monomer d is, from the viewpoint of strengthening the hydrophobic interaction with resin A, preferably 3 mass% or more, more preferably 6 mass% or more, even more preferably 10 mass% or more, and preferably 30 mass% or less, more preferably 25 mass% or less, even more preferably 20 mass% or less, of the raw material monomers of polymer E.
From the viewpoint of strengthening the hydrophobic interaction with resin A, the total amount of monomer a and monomer d among the raw material monomers of polymer E is preferably 40% by mass or more, more preferably 45% by mass or more, even more preferably 50% by mass or more, and is preferably 75% by mass or less, more preferably 70% by mass or less, even more preferably 65% by mass or less.

Furthermore, the raw material monomers of polymer E may contain addition polymerizable monomers (other monomers) other than monomers a to d.
Examples of other monomers include alkyl (meth)acrylates having an alkyl group with 1 to 22 carbon atoms (preferably 6 to 18 carbon atoms), and aromatic group-containing (meth)acrylates such as benzyl (meth)acrylate and phenoxyethyl (meth)acrylate.
When other monomers are contained, the amount of the other monomers in the raw material monomers of polymer E is preferably 40% by mass or less, more preferably 30% by mass or less, even more preferably 20% by mass or less, even more preferably 10% by mass or less, and even more preferably 5% by mass or less.
(Method for producing addition polymer E)

Polymer E can be produced, for example, by copolymerizing raw material monomers by a known polymerization method, preferably a solution polymerization method in which raw material monomers are polymerized by heating in a solvent together with a polymerization initiator, a polymerization chain transfer agent, and the like.
Examples of the polymerization initiator include peroxides such as dibutyl peroxide, persulfates such as sodium persulfate, and azo compounds such as 2,2'-azobis(2,4-dimethylvaleronitrile).
The amount of the polymerization initiator added is preferably 0.5 parts by mass or more and preferably 30 parts by mass or less based on 100 parts by mass of the raw material monomer.
Examples of the polymerization chain transfer agent (also simply referred to as "chain transfer agent") include mercaptans such as 2-mercaptoethanol and 3-mercaptopropionic acid.
The amount of the polymerization chain transfer agent added is preferably 0.01 parts by mass or more and preferably 10 parts by mass or less based on 100 parts by mass of the raw material monomers.
After the polymerization reaction is completed, the produced polymer may be isolated and purified by a known method such as reprecipitation from the reaction solution or distillation of the solvent.

(Physical Properties of Addition Polymer E)
From the viewpoint of further improving image density, the weight-average molecular weight of Polymer E is preferably 3,000 or more, more preferably 5,000 or more, even more preferably 20,000 or more, even more preferably 40,000 or more, even more preferably 50,000 or more, and is preferably 200,000 or less, more preferably 90,000 or less, even more preferably 60,000 or less, even more preferably 53,000 or less. The weight-average molecular weight can be measured by the method described in the examples.

[Method for producing aqueous dispersion of resin particles X]
The aqueous dispersion of resin particles X can be obtained by mixing and dispersing resin A and polymer E in an aqueous medium, followed by coalescence.
The aqueous medium is preferably one containing water as a main component. From the viewpoint of improving the dispersion stability of the aqueous dispersion of resin particles X and from the viewpoint of environmental friendliness, the water content in the aqueous medium 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 even more preferably 100% by mass or less. Deionized water or distilled water is preferred as the water. Examples of components other than water that may be contained in the aqueous medium include water-soluble organic solvents such as alkyl alcohols having 1 to 5 carbon atoms; dialkyl ketones having a total carbon number of 3 to 5, such as acetone and methyl ethyl ketone; and cyclic ethers such as tetrahydrofuran. Among these, methyl ethyl ketone is preferred.

Dispersion can be carried out using known methods, but it is preferable to disperse by phase inversion emulsification. Examples of phase inversion emulsification methods include adding an aqueous medium to an organic solvent solution of the resin or to a molten resin, resulting in phase inversion emulsification.

The organic solvent used for phase inversion emulsification is not particularly limited as long as it dissolves the resin, and examples thereof include methyl ethyl ketone.
It is preferable to add a neutralizing agent to the organic solvent solution of the resin. Examples of the neutralizing agent include basic substances. Examples of basic substances include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide; and nitrogen-containing basic substances such as ammonia, trimethylamine, and diethanolamine.
The degree of neutralization of the resin contained in the resin particles X is preferably 10 mol% or more, more preferably 20 mol% or more, even more preferably 30 mol% or more, and even more preferably 40 mol% or more, and is preferably 100 mol% or less, more preferably 80 mol% or less, and even more preferably 70 mol% or less.
The degree of neutralization of the resin contained in the resin particles X can be determined by the following formula.
Degree of neutralization (mol %)=[{weight (g) of neutralizing agent added/equivalent weight of neutralizing agent}/[{weighted average acid value (mg KOH/g) of resin contained in resin particles X×weight (g) of resin contained in resin particles X}/(56×1000)]]×100

While stirring the organic solvent solution of the resin or the molten resin, the aqueous medium is gradually added to cause phase inversion.
From the viewpoint of improving the dispersion stability of resin particles X, the temperature of the organic solvent solution of the resin when the aqueous medium is added is preferably equal to or higher than the glass transition temperature of the resin having the highest glass transition temperature among the resins, more preferably equal to or higher than 50°C, even more preferably equal to or higher than 60°C, and still more preferably equal to or higher than 70°C, and is preferably equal to or lower than 100°C, more preferably equal to or lower than 90°C, and even more preferably equal to or lower than 80°C.

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

From the viewpoint of stability of resin particles X in an aqueous dispersion, the content of polymer E in resin particles X is preferably 1% by mass or more, more preferably 1.5% by mass or more, even more preferably 2% by mass or more, and preferably 10% by mass or less, more preferably 8% by mass or less, even more preferably 5% by mass or less.

The mass ratio of polymer E to resin A in resin particles X [polymer E/resin A] is preferably 0.01 or more, more preferably 0.02 or more, even more preferably 0.025 or more, from the viewpoint of strengthening the hydrophobic interaction between resin A and polymer E and from the viewpoint of the stability of resin particles X in the aqueous dispersion, and is preferably 0.1 or less, more preferably 0.08 or less, even more preferably 0.07 or less.

From the viewpoint of obtaining a toner that can produce high-quality images, the volume median particle diameter _D50 of the resin particles X in the aqueous dispersion is preferably 0.05 μm or more, more preferably 0.08 μm or more, even more preferably 0.1 μm or more, and is preferably 0.5 μm or less, more preferably 0.25 μm or less, even more preferably 0.18 μm or less.
From the viewpoint of obtaining a toner that can produce high-quality images, the CV value of the resin particles X in the aqueous dispersion is preferably 10% or more, more preferably 20% or more, and is preferably 40% or less, more preferably 30% or less.
The volume median particle diameter _D50 and CV value can be determined by the method described in the Examples below.

When the polyester resin A is amorphous, the resin particles X may further contain a crystalline polyester resin C. The resin particles X further containing the crystalline polyester resin C can be produced in accordance with the above-described method. The preferred ranges of the volume median particle diameter _D50 and CV value of the resin particles X further containing the crystalline polyester resin C are the same as those described above.
Furthermore, it is preferable that the resin particles X do not contain a colorant.

[Crystalline Polyester Resin C]
The crystalline polyester resin C (hereinafter also simply referred to as "resin C") is a polycondensate of an alcohol component and a carboxylic acid component.
The alcohol component is preferably an α,ω-aliphatic diol.
The α,ω-aliphatic diol preferably has 2 or more carbon atoms, more preferably 4 or more carbon atoms, and even more preferably 6 or more carbon atoms, and preferably has 16 or less carbon atoms, more preferably 14 or less carbon atoms, and even more preferably 12 or less carbon atoms.
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, 1,6-hexanediol, 1,10-decanediol, and 1,12-dodecanediol are preferred, and 1,10-decanediol is more preferred.

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

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

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

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

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

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

Resin C can be produced, for example, by the same method as that used for Resin A, the polyester resin described above.

(Physical Properties of Crystalline Polyester Resin C)
The softening point of Resin C is preferably 60°C or higher, more preferably 70°C or higher, and even more preferably 80°C or higher, from the viewpoint of the storage stability of the toner, and is preferably 150°C or lower, more preferably 120°C or lower, and even more preferably 100°C or lower, from the viewpoint of further improving the low-temperature fixability.
The melting point of resin C is preferably 50°C or higher, more preferably 60°C or higher, and even more preferably 70°C or higher, from the viewpoint of the storage stability of the toner, and is preferably 100°C or lower, more preferably 90°C or lower, and even more preferably 80°C or lower, from the viewpoint of further improving low-temperature fixability.

The acid value of Resin C is preferably 5 mgKOH/g or more, more preferably 10 mgKOH/g or more, and preferably 35 mgKOH/g or less, more preferably 25 mgKOH/g or less, and even more preferably 20 mgKOH/g or less.
The softening point, melting point, and acid value of Resin C can be appropriately adjusted by the types and amounts of raw material monomers used, as well as production conditions such as reaction temperature, reaction time, and cooling rate, and are determined by the method described in the Examples below. When two or more types of Resin C are used in combination, it is preferable that the softening point, melting point, and acid value obtained as a mixture thereof each fall within the above-mentioned ranges.

From the viewpoint of the thermal responsiveness of the toner, the content of resin C is preferably 3% by mass or more, more preferably 5% by mass or more, even more preferably 7% by mass or more, and is preferably 50% by mass or less, more preferably 40% by mass or less, even more preferably 30% by mass or less, even more preferably 25% by mass or less, relative to the total amount of the resin components of resin particles X.
The mass ratio of resin C to resin A in resin particles X [resin C/resin A] is, from the viewpoint of the thermal responsiveness of the toner, preferably 0.03 or more, more preferably 0.05 or more, even more preferably 0.07 or more, and is preferably 0.50 or less, more preferably 0.40 or less, even more preferably 0.30 or less.

[Step 2]
In step 2, the resin particles X are aggregated in an aqueous medium to obtain aggregated particles 1. Here, it is preferable to further aggregate at least one of a colorant and a release agent in addition to the resin particles X, and it is more preferable to mix a dispersion containing the resin particles X with a colorant particle dispersion containing colorant particles containing a colorant and/or a release agent particle dispersion containing release agent particles containing a release agent to aggregate these particles.

[Coloring Agent]
As the colorant, any dye, pigment, etc. that is used as a colorant for toner can be used.
Examples of colorants include carbon black, phthalocyanine blue, permanent brown FG, brilliant fast scarlet, pigment green B, rhodamine-B base, solvent red 49, solvent red 146, solvent blue 35, quinacridone, carmine 6B, and disazo yellow. The toner may be either a black toner or a color toner other than black.
The content of the colorant in the toner particles is preferably 3% by mass or more, more preferably 5% by mass or more, and preferably 25% by mass or less, more preferably 20% by mass or less, and even more preferably 15% by mass or less.

(Colorant particle dispersion)
The colorant particle dispersion is preferably obtained by dispersing the colorant and an aqueous medium using a disperser such as a homogenizer, an ultrasonic disperser, etc. From the viewpoint of improving the dispersion stability of the colorant, the dispersion is preferably carried out in the presence of a surfactant or an addition polymer.

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

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

As the addition polymer for improving the dispersion stability of the colorant, the same addition polymer as the above-mentioned addition polymer E can be used.
In the colorant particle dispersion, the mass ratio of the colorant to the addition polymer (colorant/addition polymer) is preferably 50/50 or more, more preferably 60/40 or more, even more preferably 70/30 or more, even more preferably 75/25 or more, from the viewpoint of improving the dispersion stability of the colorant, and is preferably 95/5 or less, more preferably 90/10 or less, even more preferably 85/15 or less.
When producing a dispersion of colorant particles from a colorant and an addition polymer, it can be produced, for example, by the production method described in paragraphs [0067] to [0076] of WO 2019/156231.

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

From the viewpoint of improving image density, the volume median particle diameter _D50 of the colorant particles is preferably 0.05 μm or more, more preferably 0.08 μm or more, even more preferably 0.1 μm or more, and is preferably 0.4 μm or less, more preferably 0.3 μm or less, even more preferably 0.2 μm or less.
From the viewpoint of improving image density, the CV value of the colorant particles is preferably 10% or more, more preferably 20% or more, and is preferably 45% or less, more preferably 40% or less, and even more preferably 35% or less.
The volume median particle diameter _D50 and CV value of the colorant particles are measured by the methods in the Examples.

From the viewpoint of further improving image density, the amount of colorant particles is preferably 3 parts by mass or more, more preferably 6 parts by mass or more, even more preferably 10 parts by mass or more, and preferably 40 parts by mass or less, more preferably 30 parts by mass or less, even more preferably 20 parts by mass or less, per 100 parts by mass of resin particles X.

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

The melting point of the release agent is preferably 60°C or higher, more preferably 70°C or higher, and preferably 160°C or lower, more preferably 140°C or lower, even more preferably 120°C or lower, and even more preferably 100°C or lower.
The content of the release agent in the toner particles is preferably 1% by mass or more, more preferably 3% by mass or more, even more preferably 5% by mass or more, and is preferably 20% by mass or less, more preferably 15% by mass or less, even more preferably 12% by mass or less.

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

The resin that constitutes the resin particles S in which the release agent is dispersed is preferably a polyester resin, and it is more preferable to use a composite resin D having a polyester resin segment and an addition polymerization resin segment. The composite resin D can be the same as the composite resin shown above as resin A.

The softening point of composite resin D is preferably 70°C or higher, more preferably 80°C or higher, even more preferably 85°C or higher, and preferably 140°C or lower, more preferably 120°C or lower, even more preferably 100°C or lower.
The glass transition temperature of composite resin D is preferably 30°C or higher, more preferably 35°C or higher, and even more preferably 40°C or higher, and from the viewpoint of further improving low-temperature fixability, is preferably 80°C or lower, more preferably 70°C or lower, and even more preferably 60°C or lower.
From the viewpoint of obtaining fine resin particles and fine release agent particle dispersions, the acid value of the composite resin D is preferably 5 mgKOH/g or more, more preferably 10 mgKOH/g or more, even more preferably 15 mgKOH/g or more, and even more preferably 20 mgKOH/g or more, and is preferably 40 mgKOH/g or less, more preferably 35 mgKOH/g or less, and even more preferably 30 mgKOH/g or less.
The softening point, glass transition temperature, and acid value of the composite resin D can be appropriately adjusted by adjusting the type and amount of the raw material monomer, as well as the production conditions such as the reaction temperature, reaction time, and cooling rate, and these values can be determined by the methods described in the examples.
When two or more types of composite resin D are used in combination, it is preferable that the softening point, glass transition temperature and acid value of the resulting mixture are each within the above ranges.

The dispersion of resin particles S can be obtained, for example, by the phase inversion emulsification method shown in the method for producing the aqueous dispersion of resin particles X above.
From the viewpoint of dispersion stability of the release agent particles, the volume median particle diameter _D50 of the resin particles S is preferably 0.01 μm or more, more preferably 0.03 μm or more, and preferably 0.3 μm or less, more preferably 0.2 μm or less.
From the viewpoint of dispersion stability of the release agent particles, the CV value of the resin particles S is preferably 10% or more, more preferably 15% or more, and is preferably 40% or less, more preferably 35% or less, and even more preferably 30% or less.
The volume median particle diameter _D50 and CV value of the resin particles S are measured by the method described in the examples.

The release agent particle dispersion liquid can be obtained, for example, by dispersing a dispersion liquid of the release agent and the resin particles S, and optionally an aqueous medium, at a temperature equal to or higher than the melting point of the release agent using a disperser such as a homogenizer, a high-pressure disperser, or an ultrasonic disperser.
The heating temperature during dispersion is preferably equal to or higher than the melting point of the release agent and 80°C or higher, more preferably 85°C or higher, and even more preferably 90°C or higher, and is preferably equal to or lower than a temperature 10°C higher than the softening point of the resin contained in the resin particles S and 100°C or lower, more preferably 98°C or lower, and even more preferably 95°C or lower.

The amount of resin particles S is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and even more preferably 20 parts by mass or more, per 100 parts by mass of the release agent, and is preferably 100 parts by mass or less, more preferably 70 parts by mass or less, and even more preferably 50 parts by mass or less.

From the viewpoint of obtaining uniform aggregated particles 1 by aggregation, the volume median particle diameter _D50 of the release agent particles is preferably 0.05 μm or more, more preferably 0.1 μm or more, even more preferably 0.2 μm or more, and is preferably 1 μm or less, more preferably 0.8 μm or less, even more preferably 0.6 μm or less.
The CV value of the release agent particles is preferably 10% or more, more preferably 15% or more, even more preferably 20% or more, and is preferably 40% or less, more preferably 35% or less, even more preferably 30% or less.
The volume median particle diameter _D50 and CV value of the release agent particles are measured by the method described in the examples.

The agglomerated particles may also contain additives such as charge control agents, magnetic powders, flowability improvers, conductivity adjusters, reinforcing fillers such as fibrous substances, antioxidants, anti-aging agents, and cleaning improvers.

[Flocculant]
In the step of aggregating the resin particles, it is preferable to add an aggregating agent from the viewpoint of efficient aggregation.
Examples of the flocculant include cationic surfactants such as quaternary salts, organic flocculants such as polyethyleneimine, and inorganic flocculants. Examples of the inorganic flocculant include inorganic metal salts such as sodium sulfate, sodium nitrate, sodium chloride, calcium chloride, and calcium nitrate; inorganic ammonium salts such as ammonium sulfate, ammonium chloride, and ammonium nitrate; and divalent or higher metal complexes.
From the viewpoint of improving the aggregability and obtaining uniform aggregated particles 1, inorganic aggregating agents having a valence of 1 to 5 are preferred, inorganic metal salts having a valence of 1 to 2 and inorganic ammonium salts are more preferred, inorganic ammonium salts are even more preferred, and ammonium sulfate is even more preferred.

For example, a flocculant is added to a mixed dispersion containing resin particles, release agent particles, and colorant particles at a temperature of 0°C to 40°C in an amount of 5 to 50 parts by weight per 100 parts by weight of resin in the resin particles, and the resin particles, release agent particles, and colorant particles are aggregated in an aqueous medium to obtain aggregated particles 1. Furthermore, from the perspective of promoting aggregation, it is preferable to increase the temperature of the dispersion after adding the flocculant.

Methods for stopping aggregation include cooling the dispersion, adding an aggregation terminator, or diluting the dispersion.

The volume median particle size _D50 of the aggregated particles 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, even more preferably 7 μm or less.

In step 2, after the step of aggregating resin particles X and before the step of fusing, a step of adhering resin particles Y containing polyester-based resin B (hereinafter also simply referred to as "resin B") to the obtained aggregated particles 1 may be included to obtain aggregated particles 2. By including the step of aggregating resin particles Y, toner particles having a core-shell structure can be obtained.
Here, the resin B is preferably amorphous, and is exemplified by the above-mentioned resin A. The resin particles Y are obtained as an aqueous dispersion by the same method as the method for producing the aqueous dispersion of the resin particles X.
Furthermore, when step 2 includes a step of obtaining aggregated particles 2, it is preferable to terminate the aggregation of aggregated particles 2 in this step when the aggregated particles 2 have grown to a particle size appropriate for toner particles, and a method of terminating the aggregation by adding the above-mentioned aggregation terminator is preferred.
From the viewpoint of low-temperature fixability of the toner, the mass ratio of resin particles Y to aggregated particles 1 [resin particles Y/aggregated particles 1] is preferably 0.01 or more, more preferably 0.03 or more, even more preferably 0.05 or more, and is preferably 0.3 or less, more preferably 0.25 or less, even more preferably 0.20 or less.

From the perspective of reducing the surfactant content in the toner, the amount of surfactant used in step 2 is preferably less than 5 parts by mass, more preferably less than 4 parts by mass, and even more preferably less than 3.5 parts by mass per 100 parts by mass of resin particles X.

[Aggregation Stopper]
After the aggregated particles are obtained in step 2, an aggregation terminator may be added before the aggregated particles are fused in step 3 in order to reliably prevent unnecessary aggregation.
The aggregation terminator is preferably a surfactant, more preferably an anionic surfactant. Examples of the anionic surfactant include alkylbenzene sulfonate, alkyl sulfate, alkyl ether sulfate, polyoxyalkylene alkyl ether sulfate, aryl sulfonate, and aryl sulfonic acid formalin condensate, and preferably an alkali metal salt of aryl sulfonic acid formalin condensate, and more preferably a sodium salt of naphthalene sulfonic acid formalin condensate. These may be used alone or in combination of two or more. The aggregation terminator may be added in the form of an aqueous solution.
The amount of the aggregation terminator added is preferably 1 part by mass or more, more preferably 5 parts by mass or more, per 100 parts by mass of the resin in the resin particles, from the viewpoint of reliably preventing unnecessary aggregation, and is preferably 60 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 20 parts by mass or less, from the viewpoint of reducing residue in the toner.

[Step 3]
In step 3, for example, the aggregated particles 1 or aggregated particles 2 obtained in step 2 are fused in an aqueous medium to obtain fused particles.
In step 3, from the viewpoint of improving the fusion property of aggregated particles 1 or aggregated particles 2 and achieving both low-temperature fixability and heat-resistant storage stability of the toner, the aggregated particles are maintained at a temperature equal to or higher than the glass transition temperature of the resin having the highest glass transition temperature.
From the viewpoint of improving the fusion properties of the aggregated particles and improving the productivity of the toner, the holding temperature when fusing the aggregated particles is preferably at least 2°C higher, more preferably at least 3°C higher, and even more preferably at least 5°C higher than the glass transition temperature of the resin having the highest glass transition temperature of the aggregated particles, and is preferably not higher than 30°C higher, more preferably not higher than 25°C higher, and even more preferably not higher than 20°C higher.
In this case, the time for which the aggregated particles are maintained at a temperature equal to or higher than the glass transition temperature of the resin having the highest glass transition temperature is, from the viewpoint of achieving both low-temperature fixability and heat-resistant storage stability of the toner, preferably 1 minute or more, more preferably 10 minutes or more, even more preferably 30 minutes or more, and is preferably 240 minutes or less, more preferably 180 minutes or less, even more preferably 120 minutes or less, even more preferably 90 minutes or less.
It is preferable to maintain the temperature at the above temperature until the desired circularity is achieved.

The volume median particle size _D50 of the fused particles obtained by fusion is preferably 2 μm or more, more preferably 3 μm or more, even more preferably 4 μm or more, and is preferably 10 μm or less, more preferably 8 μm or less, even more preferably 7 μm or less.

The circularity of the fused particles obtained by fusion is preferably 0.955 or more, more preferably 0.960 or more, even more preferably 0.965 or more, and is preferably 0.990 or less, more preferably 0.985 or less, even more preferably 0.980 or less.
The fusion is preferably terminated after the desired circularity is reached.
The circularity is measured by the method described in the Examples.

[Post-processing process]
A post-treatment step may be carried out after the fusion step, and the fused particles are isolated to obtain toner particles. Since the fused particles obtained in the fusion step are present in an aqueous medium, it is preferable to first carry out solid-liquid separation. For solid-liquid separation, a suction filtration method or the like is preferably used.
It is preferable to wash the solid-liquid separation product. At this time, it is preferable to remove the added surfactant, so washing with an aqueous medium at a temperature below the cloud point of the surfactant is preferable. Washing is preferably performed multiple times.
Next, it is preferable to carry out drying. Examples of drying methods include vacuum low-temperature drying, vibration fluidized bed drying, spray drying, freeze drying, and flash jet drying.

[Toner particles]
From the viewpoint of further improving the cleaning properties of the toner, the volume median particle diameter _D50 of the toner particles is preferably 2 μm or more, more preferably 3 μm or more, even more preferably 4 μm or more, and is preferably 10 μm or less, more preferably 8 μm or less, even more preferably 7 μm or less.

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

The CV value of the toner particles is preferably 10% or more, more preferably 15% or more, and even more preferably 18% or more from the viewpoint of improving toner productivity, and is preferably 40% or less, more preferably 35% or less, and even more preferably 32% or less from the viewpoint of obtaining high-quality images.
The volume median particle diameter D ₅₀ of the toner particles can be measured by the method described in the examples.

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

[External additives]
Examples of external additives include fine particles of inorganic materials such as hydrophobic silica, titanium oxide, alumina, cerium oxide, and carbon black, and fine particles of polymers such as polycarbonate, polymethyl methacrylate, and silicone resin. Among these, hydrophobic silica is preferred. One type of external additive may be used alone, or two or more types may be used. Two or more types of hydrophobic silica having different particle sizes may also be used.
When the surface treatment of the toner particles is performed using an external additive, the amount of the external additive added is preferably 1 part by mass or more, more preferably 2 parts by mass or more, even more preferably 3 parts by mass or more, and is preferably 5 parts by mass or less, more preferably 4.5 parts by mass or less, even more preferably 4 parts by mass or less, relative to 100 parts by mass of the toner particles.

Toner is used to develop electrostatic images in electrophotographic printing. Toner can be used, for example, as a one-component developer or mixed with a carrier to form a two-component developer.

The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. Each property value was measured and evaluated by the following methods.
In the notation "alkylene oxide (X)", the number X in parentheses means the average number of moles of alkylene oxide added.

[Measurement method]
The properties of the polyester resin, resin particles, toner, etc. were measured and evaluated by the following methods.
[Softening point, crystallinity index, melting point and glass transition temperature of resin]
(1) Softening Point Using a flow tester "CFT-500D" (manufactured by Shimadzu Corporation), 1 g of a sample was extruded from a nozzle having a diameter of 1 mm and a length of 1 mm while applying a load of 1.96 MPa with a plunger while heating at a temperature increase rate of 6°C/min. The plunger depression amount of the flow tester was plotted against the temperature, and the temperature at which half of the sample flowed out was taken as the softening point.
(2) Crystallinity Index Using a differential scanning calorimeter "Q100" (manufactured by TA Instruments Japan Co., Ltd.), 0.02 g of a sample was weighed into an aluminum pan and cooled to 0°C at a temperature drop rate of 10°C/min. The sample was then left to stand for 1 minute, and then heated to 180°C at a temperature increase rate of 10°C/min, and the calorific value was measured. The temperature of the peak with the largest peak area among the observed endothermic peaks was defined as the endothermic maximum peak temperature (1), and the crystallinity index was calculated by (softening point (°C))/(endothermic maximum peak temperature (1) (°C)).
(3) Melting point and glass transition temperature Using a differential scanning calorimeter "Q100" (manufactured by TA Instruments Japan Co., Ltd.), 0.02 g of a sample was weighed into an aluminum pan, heated to 200°C, and cooled from that temperature to 0°C at a rate of 10°C/min. The sample was then heated at a rate of 10°C/min, and the calorific value was measured. Of the endothermic peaks observed, the temperature of the peak with the largest peak area was taken as the maximum endothermic peak temperature (2). In the case of a crystalline resin, this peak temperature was taken as the melting point.
In the case of an amorphous resin, when a peak is observed, the temperature of the peak is taken as the glass transition temperature. When a step is observed instead of a peak, the temperature at the intersection of the tangent line showing the maximum slope of the curve at the step and an extension of the baseline on the low-temperature side of the step is taken as the glass transition temperature.

[Acid value of resin]
The acid value of the resin was measured according to the neutralization titration method described in JIS K 0070: 1992. The measurement solvent was a mixed solvent of acetone and toluene (acetone:toluene=1:1 (volume ratio)).

[Melting point of release agent]
Using a differential scanning calorimeter "Q100" (manufactured by TA Instruments Japan Co., Ltd.), 0.02 g of a sample was weighed into an aluminum pan, heated to 200°C, and then cooled from 200°C to 0°C at a temperature decrease rate of 10°C/min. The sample was then heated at a temperature increase rate of 10°C/min, the calorific value was measured, and the maximum endothermic peak temperature was taken as the melting point.

[Volume Median Particle Size _D50 and CV Value of Resin Particles, Colorant Particles, and Release Agent Particles]
(1) Measuring device: Laser diffraction particle size measuring instrument "LA-920" (manufactured by Horiba, Ltd.)
(2) Measurement conditions: A sample dispersion was placed in a measurement cell, distilled water was added, and the volume median particle size _D50 and volume average particle size Dv were measured at a concentration that brought the absorbance into an appropriate range. The CV value was calculated according to the following formula:
CV value (%) = (standard deviation of particle size distribution / volume average particle size Dv) × 100

[Solid Content Concentration of Resin Particle Dispersion, Colorant Particle Dispersion, and Release Agent Particle Dispersion]
Using an infrared moisture meter "FD-230" (Kett Electric Laboratory Co., Ltd.), the moisture content (% by mass) of 5 g of the measurement sample was measured at a drying temperature of 150°C and measurement mode 96 (monitoring time 2.5 minutes, moisture content fluctuation range 0.05%). The solid content concentration was calculated according to the following formula.
Solid content concentration (mass%) = 100 - water (mass%)

[Volume Median Particle Diameter D ₅₀ of Aggregated Particles]
The volume median particle diameter _D50 of the agglomerated particles was measured as follows.
- Measuring instrument: "Coulter Multisizer (registered trademark) III" (manufactured by Beckman Coulter, Inc.)
Aperture diameter: 50 μm
Analysis software: "Multisizer (registered trademark) III version 3.51" (Beckman Coulter, Inc.)
・Electrolyte: "Isoton (registered trademark) II" (Beckman Coulter, Inc.)
Measurement conditions: The sample dispersion was added to 100 mL of the electrolyte solution to adjust the concentration to a level that would allow the particle sizes of 30,000 particles to be measured in 20 seconds, and then the 30,000 particles were measured again, and the volume median particle size _D50 was determined from the particle size distribution.

[Circularity of fused particles]
The circularity of the fused particles was measured under the following conditions.
Measurement equipment: Flow particle image analyzer "FPIA-3000" (Sysmex Corporation)
Preparation of dispersion: The dispersion of fused particles was diluted with deionized water to a solids concentration of 0.001 to 0.05% by mass.
Measurement mode: HPF measurement mode

[Volume Median Particle Size _D50 and CV Value of Toner Particles]
The volume median particle diameter _D50 of the toner particles was measured as follows.
The measuring device, aperture diameter, analysis software, and electrolyte used were the same as those used in the measurement of the volume median particle diameter D ₅₀ of the agglomerated particles described above.
Dispersion: Polyoxyethylene lauryl ether "EMULGEN (registered trademark) 109P" (manufactured by Kao Corporation, HLB (Hydrophile-Lipophile Balance) = 13.6) was dissolved in the electrolyte solution to obtain a dispersion with a concentration of 5 mass %.
Dispersion conditions: 10 mg of a measurement sample of dried toner particles was added to 5 mL of the dispersion liquid, and the mixture was dispersed for 1 minute using an ultrasonic disperser. Thereafter, 25 mL of the electrolyte solution was added, and the mixture was further dispersed for 1 minute using the ultrasonic disperser to prepare a sample dispersion liquid.
Measurement conditions: The sample dispersion was added to 100 mL of the electrolyte to adjust the concentration to a level that would allow the particle sizes of 30,000 particles to be measured in 20 seconds, and then the 30,000 particles were measured, and the volume median particle size _D50 and the volume average particle size _DV were determined from the particle size distribution.
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

[Weight average molecular weight of addition polymer]
The measurement was carried out by gel permeation chromatography (GPC apparatus "HLC-8320GPC" (manufactured by Tosoh Corporation), columns "TSKgel SuperAWM-H", "TSKgel SuperAW3000", and "TSKgel guardcolumn Super AW-H" (manufactured by Tosoh Corporation), flow rate: 0.5 mL/min) using a solution prepared by dissolving phosphoric acid and lithium bromide in N,N-dimethylformamide to concentrations of 60 mmol/L and 50 mmol/L, respectively, as an eluent, and using monodisperse polystyrene kits with known molecular weights (PStQuick B (F-550, F-80, F-10, F-1, A-1000), PStQuick C (F-288, F-40, F-4, A-5000, A-500), manufactured by Tosoh Corporation) as standards.

[Charge amount at normal temperature and humidity]
At a temperature of 25°C and a relative humidity of 50%, 2.1 g of toner and 27.9 g of silicone ferrite carrier (manufactured by Kanto Denka Kogyo Co., Ltd., average particle size: 40 μm) were placed in a 50 mL cylindrical polypropylene bottle (manufactured by Nikko Hansen Co., Ltd.) and mixed for 10 minutes at 250 r/min using a ball mill. Thereafter, the charge amount was measured under the following conditions using a "q/m-meter" (manufactured by Epping).
-Mesh size: 635 mesh (opening: 24 μm, stainless steel)
・Soft blow: blow pressure (1000V)
Suction time: 90 seconds The amount of charge was calculated using the following formula, and the larger the absolute value of the value, the better the chargeability.
Charge amount (μC/g)=Total amount of electricity (μC) after 90 seconds/Amount of toner absorbed (g)
[Charge amount under high temperature and humidity conditions]
The measurement was carried out in the same manner as in the measurement of the charge amount under normal temperature and humidity, except that the measurement environment was a temperature of 45° C. and a relative humidity of 70%.

[Production of resin]
[Production of Polyester Resin A]
Production Example A1 (Production of Resin A-1)
The inside of a 10 L four-neck flask equipped with a nitrogen inlet tube, a dehydration tube, a stirrer, and a thermocouple was replaced with nitrogen, and 3253 g of a propylene oxide (2.2) adduct of bisphenol A, 1003 g of terephthalic acid, 24 g of tin (II) di(2-ethylhexanoate), and 2.4 g of gallic acid were placed in the flask. Under a nitrogen atmosphere, the reaction system was stirred and heated to 235 ° C., and maintained at 235 ° C. for 5 hours. The pressure in the flask was then reduced and maintained at 8 kPa for 1 hour. After that, the pressure was returned to atmospheric pressure, and the mixture was cooled to 160 ° C. While maintaining the temperature at 160 ° C., a mixture of 2139 g of styrene, 535 g of stearyl methacrylate, 107 g of acrylic acid, and 321 g of dibutyl peroxide was added dropwise to the reaction system over 3 hours. The reaction system was then maintained at 160°C for 30 minutes, then heated to 200°C, and the pressure in the flask was further reduced and maintained at 8 kPa for 1 hour. The pressure was then returned to atmospheric pressure, cooled to 190°C, and 129 g of fumaric acid, 94 g of sebacic acid, 214 g of trimellitic anhydride, and 2.4 g of 4-tert-butylcatechol were added. The temperature was raised to 210°C at 10°C/hr, and then the reaction was continued at 4 kPa until the desired softening point was reached, yielding Resin A-1. The physical properties are shown in Table 1.

Production Example A2 (Production of Resin A-2)
The raw material monomers for polyester resin, excluding trimellitic anhydride, shown in Table 1 were placed in a 20 L stainless steel kettle equipped with a nitrogen inlet tube, a dehydration tube, a stirrer, and a thermocouple. The mixture was reacted at 230°C for 8 hours under a nitrogen atmosphere, and then reacted under a reduced pressure of 1.3 kPa to 2.0 kPa for 4 hours. Trimellitic anhydride was further added, and the mixture was reacted at 180°C for 3 hours to obtain amorphous polyester resin A-2. The physical properties are shown in Table 1.

[Production of Polyester Resin B]
Production Example B1 (Production of Resin B-1)
Resin B-1 was obtained in the same manner as in Production Example A2, except that the raw material monomers for the polyester resin were changed as shown in Table 1. The physical properties are shown in Table 1.

[Production of Composite Resin D]
Production Example D1 (Production of Resin D-1)
The inside of a 10 L four-neck flask equipped with a nitrogen inlet tube, a dehydration tube, a stirrer, and a thermocouple was replaced with nitrogen, and 4313 g of a propylene oxide (2.2) adduct of bisphenol A, 818 g of terephthalic acid, 30 g of tin (II) di(2-ethylhexanoate), and 3.0 g of gallic acid were placed in the flask. Under a nitrogen atmosphere, the reaction system was stirred and heated to 235 ° C., and maintained at 235 ° C. for 5 hours. The pressure in the flask was then reduced and maintained at 8 kPa for 1 hour. After that, the pressure was returned to atmospheric pressure, and the mixture was cooled to 160 ° C. While maintaining the temperature at 160 ° C., a mixture of 2756 g of styrene, 689 g of stearyl methacrylate, 142 g of acrylic acid, and 413 g of dibutyl peroxide was added dropwise to the reaction system over 3 hours. The reaction system was then maintained at 160°C for 30 minutes, then heated to 200°C, and the pressure in the flask was further reduced and maintained at 8 kPa for 1 hour. The pressure was then returned to atmospheric pressure, cooled to 190°C, 727 g of succinic acid was added, and the temperature was increased to 210°C at 10°C/hr. Resin D-1 was then obtained by reacting at 4 kPa until the desired softening point was reached. The physical properties are shown in Table 1.

[Production of Addition Polymer E]
Production Example E1 (Synthesis of Addition Polymer E-1)
The types and amounts of raw material monomers shown in Table 2 were mixed to prepare a monomer mixture having a total monomer amount of 100 g.
The inside of a four-neck flask equipped with a nitrogen inlet tube, a dropping funnel, a stirrer, and a thermocouple was replaced with nitrogen, and 18 g of methyl ethyl ketone, 0.03 g of 2-mercaptoethanol, and 10% by mass of the monomer mixture were added and heated to 75°C with stirring. While the reaction system was maintained at 75°C, a mixture of the remaining 90% by mass of the monomer mixture, 0.27 g of 2-mercaptoethanol, 42 g of methyl ethyl ketone, and 3 g of 2,2'-azobis(2,4-dimethylvaleronitrile) "V-65" (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added dropwise to the reaction system over 3 hours from the dropping funnel. After completion of the addition, the reaction system was maintained at 75°C for 2 hours, and then a solution of 3 g of V-65 dissolved in 5 g of methyl ethyl ketone was added, followed by further maintaining at 75°C for 2 hours and then at 80°C for 2 hours. The methyl ethyl ketone was then distilled off under reduced pressure to obtain addition polymer E-1. The weight average molecular weight of the resulting addition polymer is shown in Table 2.

Production Examples E2 to E6 (Synthesis of Addition Polymers E-2 to E-6)
Addition polymers E-2 to E-6 were obtained in the same manner as in Production Example E1, except that the raw material monomers were changed as shown in Table 2. The weight average molecular weights are shown in Table 2.

[Production of Crystalline Polyester Resin (C)]
Production Example C1 (Production of Resin C-1)
The inside of a 10 L four-neck flask equipped with a nitrogen inlet tube, a dehydration tube, a stirrer, and a thermocouple was replaced with nitrogen, and the raw material monomers for the polyester resin shown in Table 3 were added. The reaction system was stirred while the temperature was raised to 135°C and maintained at 135°C for 3 hours, and then the temperature was raised from 135°C to 200°C over 10 hours. 23 g of tin(II) di(2-ethylhexanoate) was then added to the reaction system, and the system was further maintained at 200°C for 1 hour. The pressure inside the flask was then reduced, and the system was maintained under a reduced pressure of 8 kPa for 1 hour, yielding Resin C-1, a crystalline polyester resin. The physical properties are shown in Table 3.

[Preparation of Aqueous Dispersion of Resin Particles X]
Production Example X1 (Production of aqueous dispersion of resin particles X-1)
Resin A, Resin C, Addition Polymer E shown in Table 4, and 100 g of methyl ethyl ketone were placed in a 2 L vessel equipped with a stirrer, a reflux condenser, a dropping funnel, a thermometer, and a nitrogen inlet tube, and dissolved over 2 hours at 73° C. A 5% by mass aqueous solution of sodium hydroxide was added to the resulting solution so that the degree of neutralization relative to the acid value of the resin was 60 mol %, and the mixture was stirred for 30 minutes.
Next, while maintaining the temperature at 73°C, 100 g of deionized water was added over 50 minutes while stirring at 200 r/min to cause phase inversion emulsification. While maintaining the temperature at 73°C, the methyl ethyl ketone was distilled off under reduced pressure to obtain a dispersion. Thereafter, while continuing to stir, the dispersion was cooled to 30°C, and deionized water was added so that the solids concentration was 20% by mass, thereby obtaining an aqueous dispersion of resin particles X-1 containing resin A, resin C, and addition polymer E in the same particle. The physical properties are shown in Table 4.

Production Examples X2 to X8 (Production of aqueous dispersions of resin particles X-2 to X-8)
Resin particle dispersions X-2 to X-8 were obtained in the same manner as in Production Example X1, except that the resin was changed as shown in Table 4. The physical property values are shown in Table 4.

Production Example X9 (Production of aqueous dispersion of resin particles X-9)
Resin particle dispersion X-9 was obtained in the same manner as in Production Example X1, except that addition polymer E was not used. The physical properties are shown in Table 4.

Production Example Y1 (Production of Resin Particle Dispersion Y-1)
250 g of Resin B-1 and 250 g of methyl ethyl ketone were placed in a 3 L vessel equipped with a stirrer, a reflux condenser, a dropping funnel, a thermometer, and a nitrogen inlet tube, and dissolved over 2 hours at 73° C. A 5% by mass aqueous solution of sodium hydroxide was added to the resulting solution so that the degree of neutralization relative to the acid value of the resin was 60 mol %, and the mixture was stirred for 30 minutes.
Next, while maintaining the temperature at 73°C, 500 g of deionized water was added over 50 minutes while stirring at 200 rpm to cause phase inversion emulsification. While maintaining the temperature at 73°C, the methyl ethyl ketone was distilled off under reduced pressure to obtain a dispersion. Thereafter, while continuing to stir, the dispersion was cooled to 30°C, and deionized water was added to adjust the solids concentration to 20% by mass, thereby obtaining resin particle dispersion Y-1. The volume median particle diameter _D50 of the resin particles in resin particle dispersion Y-1 was 0.04 μm, and the CV value was 29%.

Production Example S1 (Production of Resin Particle Dispersion S-1)
Resin particle dispersion S-1 was obtained in the same manner as in Production Example Y1, except that Resin B-1 was changed to Resin D-1. The volume median particle diameter _D50 of the resin particles in Resin particle dispersion S-1 was 0.11 μm and the CV value was 21%.

[Production of Release Agent Particle Dispersion]
Production Example W1 (Production of Release Agent Particle Dispersion W-1)
To a 1 L beaker were added 120 g of deionized water, 86 g of resin particle dispersion S-1, and 40 g of paraffin wax "HNP-9" (manufactured by Nippon Seiro Co., Ltd., melting point 75°C), and the mixture was melted while maintaining the temperature at 90 to 95°C and stirred to obtain a molten mixture.
The obtained molten mixture was subjected to a dispersion treatment for 20 minutes using an ultrasonic homogenizer "US-600T" (manufactured by Nippon Seiki Seisakusho Co., Ltd.) while maintaining the temperature at 90 to 95°C, and then cooled to room temperature (20°C). Deionized water was added to the obtained dispersion to adjust the solid content to 20% by mass, thereby obtaining release agent particle dispersion W-1. The volume median particle diameter _D50 of the release agent particles in release agent particle dispersion W-1 was 0.47 μm, and the CV value was 27%.

Production Example W2 (Production of Release Agent Particle Dispersion W-2)
A release agent particle dispersion W-2 was obtained in the same manner as in Production Example W1, except that the type of release agent was changed to Fischer-Tropsch wax "FNP-0090" (manufactured by Nippon Seiro Co., Ltd., melting point 90°C). The volume median particle diameter _D50 of the release agent particles in the release agent particle dispersion W-2 was 0.45 μm, and the CV value was 28%.

[Preparation of Colorant Particle Dispersion]
Production Example Z1 (Production of Colorant Particle Dispersion Z-1)
In a 1 L beaker, 100 g of copper phthalocyanine pigment "ECB-301" (manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd.), 35 g of polyoxyethylene (13) distyrenated phenyl ether "EMULGEN A-60" (manufactured by Kao Corporation, nonionic surfactant), and 300 g of deionized water were mixed and dispersed using a homomixer "T.K.AGI HOMOMIXER 2M-03" (manufactured by Tokushu Kika Kogyo Co., Ltd.) at room temperature (20°C) with a stirring blade rotation speed of 8000 rpm for 1 hour. The mixture was then subjected to 15 passes at a pressure of 150 MPa using a "Microfluidizer M-110EH" (manufactured by Microfluidics), and the mixture was passed through a 200 mesh filter, and deionized water was added so that the solids concentration was 20% by mass, thereby obtaining colorant particle dispersion Z-1. The resulting colorant particles had a volume median particle size _D50 of 0.12 μm and a CV value of 21%.

[Toner production]
Example 1 (Production of Toner 1)
500 g of the aqueous dispersion of resin particles X-1, 49 g of release agent particle dispersion W-1, 49 g of release agent particle dispersion W-2, and 63 g of colorant particle dispersion Z-1 were added to a 3 L four-neck flask equipped with a dehydration tube, a stirrer, and a thermocouple, and mixed at a temperature of 25° C. Next, while stirring the mixture, a solution prepared by dissolving 40 g of ammonium sulfate in 570 g of deionized water and adding a 4.8 mass % potassium hydroxide aqueous solution to adjust the pH to 8.2 was added dropwise at 25° C. over 10 minutes, and the temperature was then raised to 58° C. over 2 hours and maintained at 58° C. until the volume median particle diameter D ₅₀ of the aggregated particles reached 6.2 μm, thereby obtaining a dispersion of aggregated particles 1. The obtained dispersion of aggregated particles 1 was cooled to 55°C, and while maintaining the temperature at 55°C, 48 g of resin particle dispersion Y-1 was added to the dispersion of aggregated particles 1 over 90 minutes to obtain a dispersion of aggregated particles 2 in which resin particles were aggregated into aggregated particles 1.
To the obtained dispersion of aggregated particles 2, 50 g of sodium salt of naphthalenesulfonic acid formalin condensate "Demol MS" (manufactured by Kao Corporation, effective concentration 20% by mass) and 1,500 g of deionized water were added. Thereafter, the temperature was raised to 75°C over 1 hour and maintained at 75°C until the circularity reached 0.970, thereby obtaining a dispersion of fused particles in which the aggregated particles were fused together.
The obtained dispersion of fused particles was cooled to 30°C, and the dispersion was suction filtered to separate the solid content, which was then washed with deionized water at 25°C and suction filtered for 2 hours at 25°C. Thereafter, the solid content was vacuum dried at 33°C for 24 hours using a vacuum constant temperature dryer "DRV622DA" (manufactured by ADVANTEC Corporation), to obtain toner particles having a core-shell structure. The physical properties of the toner particles are shown in Table 5.
100 parts by mass of the toner particles, 2.5 parts by mass of hydrophobic silica "RY50" (manufactured by Nippon Aerosil Co., Ltd., number average particle size: 0.04 μm), and 1.0 part by mass of hydrophobic silica "Cabosil (registered trademark) TS720" (manufactured by Cabot Japan Co., Ltd., number average particle size: 0.012 μm) were placed in a Henschel mixer, stirred, and passed through a 150 mesh sieve to obtain toner 1. The physical properties of the obtained toner 1 are shown in Table 5.

[Toner Evaluation]
The obtained toner 1 was evaluated as follows.
[Evaluation of Image Density]
Using a printer "Microline (registered trademark) 5400" (manufactured by Oki Electric Industry Co., Ltd.) modified to have a temperature-variable fixing unit, the temperature of the fixing unit was set to 130°C, and the toner was fixed onto high-quality paper "J paper A4 size" (manufactured by Fuji Xerox Co., Ltd.) in an A4 portrait direction at a speed of 1.5 seconds per sheet, and a printed matter was obtained in an environment of a temperature of 25°C and a humidity of 50%.
Thirty sheets of high-quality paper "Excellent White Paper A4 size" (manufactured by Oki Electric Industry Co., Ltd.) were placed under the print, and the reflected image density of the solid image portion of the output print was measured using a colorimeter "SpectroEye" (manufactured by GretagMacbeth, light irradiation conditions: standard light source D50, observation field of view 2°, density standard DINNB, absolute white standard), and the values measured at any 10 points on the image were averaged to determine the image density. The larger the value, the better the image density. The evaluation results are shown in Table 5.

[Evaluation of Fog]
The toner was loaded into a commercially available printer, "Microline (registered trademark) 5400" (manufactured by Oki Electric Industry Co., Ltd.), and an image with a print density of 1% was printed on high-quality paper, "J paper A4 size" (manufactured by Fuji Xerox Co., Ltd.), in an environment of 40°C temperature and 70% humidity. This was repeated until a total of 1,000 sheets were printed, after which a blank sheet was printed, and the printer was stopped midway through the blank sheet printing. The development unit was removed from the printer, and "Scotch (registered trademark) Mending Tape 810" (manufactured by 3M Japan Ltd., width: 18 mm) was attached to the photoreceptor, and the toner on the photoreceptor was removed with the tape.
The tape peeled off from the photoreceptor and unused tape were attached to high-quality paper "J paper A4 size" (manufactured by Fuji Xerox Co., Ltd.), and the color of the tape peeled off from the photoreceptor and unused tape was measured using a colorimeter "SpectroEye" (manufactured by GretagMacbeth, light irradiation conditions: standard light source D50, observation field 2°, density standard DINNB, absolute white standard). The color difference (ΔE) between the tape peeled off from the photoreceptor and unused tape was defined as fog. The smaller the fog value, the better the image without fog. The evaluation results are shown in Table 5.

Examples 2 to 8, Comparative Example 1 (Production of Toners 2 to 9)
Toners 2 to 9 were obtained in the same manner as in Example 1, except that the aqueous dispersion of resin particles X-1 was changed to the aqueous dispersion of resin particles X shown in Table 5. Toners 2 to 9 were also evaluated in the same manner as in Example 1. The evaluation results of Toners 2 to 9 are shown in Table 5.

Comparative Example 2 (Production of Toner 10)
To a 3 L four-neck flask equipped with a stirrer and a thermocouple, 500 g of the aqueous dispersion of resin particles X-9, 49 g of release agent particle dispersion W-1, 49 g of release agent particle dispersion W-2, 63 g of colorant particle dispersion Z-1, and 25 g of a 10 mass % aqueous solution of polyoxyethylene (50) lauryl ether "EMULGEN 150" (manufactured by Kao Corporation, nonionic surfactant) were added and mixed at a temperature of 25°C. The subsequent operations were carried out in the same manner as in Example 1 to obtain toner 10. Toner 10 was also evaluated in the same manner as in Example 1. The evaluation results of toner 10 are shown in Table 5.

From the results of the Examples and Comparative Examples, it is clear that the manufacturing method of the present invention can produce toner particles with a narrow particle size distribution. On the other hand, in the manufacturing method of Comparative Example 1, the addition polymer E is not contained in the fine particles aggregated in the aggregation step, which is thought to have resulted in coarse aggregated particles and a broad particle size distribution of the toner particles contained in the toner. Furthermore, the toner obtained by the manufacturing method of Comparative Example 1 had low charging properties and caused fogging when printing images under a high-temperature, high-humidity environment.
Furthermore, the toner obtained by the manufacturing method of the present invention showed high chargeability, similar to that at room temperature and humidity, even after storage in a high-temperature, high-humidity environment, without the surfactant being exposed to the surface of the toner particles. On the other hand, as shown in Comparative Example 2, it is believed that the toner obtained by the manufacturing method using a surfactant in step 2 had low chargeability due to the surfactant being exposed to the surface of the toner particles when stored in a high-temperature, high-humidity environment. Because the toner obtained by the manufacturing method of the present invention showed high chargeability in a high-temperature, high-humidity environment, good images with low fog values could be obtained even when printed in a high-temperature, high-humidity environment.
Furthermore, the toner obtained by the production method of the present invention was able to give printed matter with high image density.

Claims (2)

A method for producing a toner for developing electrostatic images, comprising the following steps 1 to 3:
Step 1: Mixing polyester resin A and addition polymer E to obtain an aqueous dispersion of resin particles X containing the polyester resin A and the addition polymer E; Step 2: Mixing the aqueous dispersion of resin particles X with a colorant particle dispersion containing colorant particles containing a colorant to aggregate the resin particles X and the colorant particles in the aqueous medium to obtain aggregated particles; Step 3: Fusing the aggregated particles obtained in step 2 to obtain fused particles; and the addition polymer E is an addition polymer of raw material monomers including a styrene compound , an addition- polymerizable monomer having a polyalkylene oxide group, and a styrene compound polymer having an addition-polymerizable functional group at one end ,
the content of the addition polymer E in the resin particles X is 1% by mass or more and 10% by mass or less,
the volume median particle diameter _D50 of the resin particles X is 0.05 μm or more and 0.5 μm or less;
Step 2 includes adhering resin particles Y containing a polyester-based resin B to the aggregated particles,
The method for producing a toner for developing electrostatic images , wherein in step 2, the amount of surfactant used is less than 5 parts by mass per 100 parts by mass of resin particles X. 2. The method for producing a toner for developing electrostatic images according to claim 1 , wherein the resin particles X do not contain a colorant.