JP7692804B2 - Method for producing toner for developing electrostatic images - Google Patents

Description

The present invention relates to a method for producing a toner for developing electrostatic images.

In the field of electrophotography, with the development of electrophotographic systems, there is a demand for the development of electrophotographic toners that can handle higher image quality and faster speeds. To achieve higher image quality, toners are produced using the aggregation and coalescence method (emulsion aggregation method, aggregation and fusion method), in which fine resin particles are aggregated and fused in an aqueous medium to obtain toner, as a method for obtaining small particle size toners with narrow particle size distribution. Among these, toners with a core-shell structure have been proposed to improve thermal properties such as low-temperature fixability and heat-resistant storage stability.

For example, Patent Document 1 describes a method for producing a toner for developing electrostatic images, which includes a step of fusing aggregated particles, which are aggregates of polyester-based resin particles, in an aqueous medium, and in the fusing step, an acidic substance is added at a temperature equal to or higher than the glass transition temperature of the polyester-based resin of the aggregated particles, the pH of the aqueous medium is reduced by 0.1 to 3.0 compared to before the addition of the acidic substance, and the pH after the addition of the acidic substance is set in the range of 4.0 to 7.0, and then a basic substance is added at a temperature equal to or higher than the glass transition temperature of the polyester-based resin of the aggregated particles, and the pH of the aqueous medium is increased by 0.1 to less than 1.0 compared to before the addition of the basic substance.

JP 2019-117239 A

The technology of Patent Document 1 allows fusion to proceed by adjusting the pH in the system during the fusion step, and in particular, after allowing fusion to proceed under acidic conditions, a basic compound is added again, thereby obtaining a toner with excellent cleaning properties.
However, in Patent Document 1, there is a problem that as the solid content concentration of the aggregated particles increases, the circularity of the fused particles decreases.
The present invention relates to a method for producing a toner for developing electrostatic images, which can provide fused particles having excellent circularity and a low rate of coarse particles even when the solid content of aggregated particles is high.

The present inventors have discovered that in a method for producing a toner for developing electrostatic images, the method includes aggregation and fusion steps, by adding specific amphipathic molecules and adding an acidic substance to lower the pH during the fusion step, fused particles with excellent circularity and a low rate of coarse particles can be obtained.

That is, the present invention relates to the following [1].
[1] The method includes the following steps 1 and 3 in this order, or the following steps 1 to 3 in this order:
Step 1: A step of aggregating resin particles X in an aqueous medium to obtain aggregated particles 1;
Step 2: A step of aggregating resin particles Y to the aggregated particles 1 obtained in step 1 to obtain aggregated particles 2;
Step 3: A step of heating the aggregated particles 1 obtained in step 1 or the aggregated particles 2 obtained in step 2 to fuse them to obtain fused particles,
In step 3, an amphiphilic molecule having a naphthalene ring and an acidic substance are added.
A method for producing a toner for developing electrostatic images.

The present invention provides a method for producing a toner for developing electrostatic images, which can produce fused particles with excellent circularity and a low rate of coarse particles, even when the solid content of the aggregated particles is high.

[Method of manufacturing toner for developing electrostatic images]
The method for producing the toner for developing electrostatic images (hereinafter, also simply referred to as "toner") of the present invention includes the following steps 1 and 3 in this order, or the following steps 1 to 3 in this order:
Step 1: A step of aggregating resin particles X in an aqueous medium to obtain aggregated particles 1 (hereinafter, also referred to as "aggregation step 1");
Step 2: A step of aggregating resin particles Y with respect to the aggregated particles 1 obtained in step 1 to obtain aggregated particles 2 (hereinafter, also referred to as "aggregation step 2");
Step 3: A step of heating the aggregated particles 1 obtained in step 1 or the aggregated particles 2 obtained in step 2 to fuse them to obtain fused particles,
In step 3, an amphiphilic molecule having a naphthalene ring and an acidic substance are added.

According to the present invention, fused particles having excellent circularity and low coarse particle ratio can be obtained even if the solid content concentration of the aggregated particles is high. By increasing the solid content concentration of the aggregated particles and decreasing the coarse particle ratio, productivity can be improved. Furthermore, by improving the circularity of the fused particles, a toner excellent in high image quality can be obtained.
The reason why the above effect is obtained is not clear, but is thought to be as follows.
The present invention relates to a method for producing a toner including a step of aggregating resin particles X to obtain aggregated particles 1, and then increasing the temperature of the aggregated particles 1 to fuse them, or a method for producing a toner including a step of aggregating resin particles X to obtain aggregated particles 1 that become cores, and then aggregating resin particles Y that form shells to obtain aggregated particles 2, and further increasing the temperature of the aggregated particles 2 to fuse them, in which a specific amphipathic molecule and an acidic substance are added in the fusing step. If the aggregated particles 1 and/or the aggregated particles 2 are made to have a high concentration in the fusing step in order to improve productivity, aggregation between particles proceeds, making it difficult to achieve a desired circularity.
In the present invention, this has been achieved by the above-mentioned configuration. This is believed to be because, by adding a specific amphipathic molecule in the fusion step, the dispersibility of aggregated particles 1 and 2 in step 3 is improved, and aggregation between aggregated particles 1 and between aggregated particles 2 is suppressed, and by lowering the pH with an acidic substance, repulsion between acid groups possessed by the aggregated particles (for example, when the acid group is a carboxy group) is suppressed, and fusion is promoted.
It should be noted that the above-mentioned mechanism regarding the effect of the present invention is merely a presumption, and the present invention is not limited thereto.

The definitions of various terms used in this specification are given below.
Whether a resin is crystalline or amorphous is determined by the crystallinity index. The crystallinity index is defined as the ratio of the softening point of the resin to the maximum endothermic peak temperature (softening point (°C)/maximum endothermic peak temperature (°C)) in the measurement method described in the examples below. A crystalline resin has a crystallinity index of 0.6 or more and 1.4 or less. A non-crystalline resin has a crystallinity index of less than 0.6 or more than 1.4. The crystallinity index can be appropriately adjusted by the types and ratios of raw material monomers, as well as production conditions such as reaction temperature, reaction time, and cooling rate.
In the specification, the carboxylic acid component of the polyester resin includes not only the compound itself, but also anhydrides that decompose during the reaction to produce an acid, and alkyl esters of each carboxylic acid (alkyl groups having 1 to 3 carbon atoms).
The "volume median particle size (D ₅₀ )" is the particle size at which the cumulative volume frequency calculated as a volume fraction is 50%, calculated from the smallest particle size.
The coefficient of variation of particle size distribution (hereinafter, simply referred to as "CV value") is a value expressed by the following formula: In the following formula, the volume average particle size is a particle size obtained by multiplying the particle size measured on a volume basis by the proportion of particles having that particle size value, and dividing the resulting value by the number of particles.
CV value (%) = [standard deviation of particle size distribution (μm) / volume average particle size (μm)] × 100

<Step 1>
In step 1, resin particles X are aggregated in an aqueous medium to obtain aggregated particles 1. Here, in addition to the resin particles X, it is preferable to aggregate colorant particles and release agent particles, and it is more preferable to mix a resin particle dispersion liquid containing resin particles X, a colorant particle dispersion liquid containing colorant particles, and a release agent particle dispersion liquid containing release agent particles to aggregate these particles.
[Resin particles X]
The resin particle dispersion used in step 1 contains resin particles X. In order to obtain excellent low-temperature fixability, the resin particles X preferably contain an amorphous resin A and a crystalline polyester resin C in the same or different resin particles, and from the viewpoints of further improving the low-temperature fixability of the toner obtained and further widening the non-offset temperature range, preferably, the amorphous resin A and the crystalline polyester resin C are contained in the same resin particles.

<Amorphous resin A>
The amorphous resin A is, for example, an amorphous polyester resin A containing a polycondensate of an alcohol component and a carboxylic acid component.
Examples of the amorphous polyester resin include polyester resin and modified polyester resin. Examples of the modified polyester resin include urethane modified polyester resin, epoxy modified polyester resin, and composite resin containing polyester resin segment and addition polymerization resin segment. Among these, it is preferable to use an amorphous composite resin containing a polyester resin segment which is a polycondensation product of an alcohol component and a carboxylic acid component, and an addition polymerization resin segment which is an addition polymerization product of a raw material monomer containing a styrene-based compound.

Examples of the alcohol component 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 having excellent low-temperature fixing properties.
The alkylene oxide adduct of an aromatic diol is preferably an alkylene oxide adduct of bisphenol A, more preferably represented by 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 each 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 include a propylene oxide adduct of bisphenol A [2,2-bis(4-hydroxyphenyl)propane] and an ethylene oxide adduct of bisphenol A. These may be used alone or in combination. 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 70 mol % or more, more preferably 90 mol % or more, even more preferably 95 mol % or more, and is 100 mol % or less, even more preferably 100 mol %.

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 the alicyclic diol include hydrogenated bisphenol A [2,2-bis(4-hydroxycyclohexyl)propane] and alkylene oxide adducts of hydrogenated bisphenol A having 2 to 4 carbon atoms (average molar number added: 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 include dicarboxylic acids and polycarboxylic acids having three or more carboxylic acids.
Examples of the dicarboxylic acid 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, even more preferably 50 mol% or more, and is preferably 90 mol% or less, more preferably 85 mol% or less, even more preferably 80 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 has 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 acid substituted with an aliphatic hydrocarbon group having 1 to 20 carbon atoms. Examples of succinic acid substituted with an aliphatic hydrocarbon group having 1 to 20 carbon atoms include dodecylsuccinic acid, dodecenylsuccinic acid, and octenylsuccinic acid. Among these, fumaric acid, sebacic acid, and succinic acid substituted with an aliphatic hydrocarbon group having 1 to 20 carbon atoms 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 10 mol % or more, and is preferably 80 mol % or less, more preferably 50 mol % or less, even more preferably 30 mol % or less.

The trivalent or higher polyvalent carboxylic acid is preferably a trivalent carboxylic acid, for example, trimellitic acid, preferably 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 3 mol % or more, more preferably 5 mol % or more, even more preferably 8 mol % or more, and is preferably 30 mol % or less, more preferably 25 mol % or less, even more preferably 20 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 0.8 or more, and is preferably 1.3 or less, more preferably 1.2 or less.

The addition polymerized resin segment is, for example, an addition polymer of raw material monomers including 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 1 to 5 carbon atoms, a halogen atom, an alkoxy group having 1 to 5 carbon atoms, a sulfonic acid group, or a salt thereof.
Examples of styrene-based compounds include styrene, methylstyrene, α-methylstyrene, β-methylstyrene, tert-butylstyrene, chlorostyrene, chloromethylstyrene, methoxystyrene, styrenesulfonic acid, and salts thereof. Among these, styrene is preferred.
In the raw material monomers for the addition polymerization resin segment, the content of the styrene-based compound 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; halovinyls 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 these, 2-ethylhexyl (meth)acrylate or stearyl (meth)acrylate is preferred, stearyl (meth)acrylate is more preferred, and stearyl methacrylate is even more preferred.
In addition, "(iso or tertiary)" and "(iso)" refer to both the presence and absence of these prefixes, and the absence of these prefixes refers to normal. In addition, "(meth)acrylic acid" refers to acrylic acid or methacrylic acid.

In the raw material monomers for the addition polymerization resin segment, the content of the (meth)acrylic acid ester is preferably 5 mass% or more, more preferably 10 mass% or more, even more preferably 15 mass% or more, and is preferably 50 mass% or less, more preferably 35 mass% or less, even more preferably 25 mass% or less.
The total amount of the styrene-based compound and the (meth)acrylic acid ester in the raw material monomers of the addition polymerization resin segment is preferably 80 mass % or more, more preferably 90 mass % or more, even more preferably 95 mass % or more, and still more preferably 100 mass %.

The amorphous polyester resin A preferably has a constitutional unit derived from a bireactive monomer bonded to a polyester resin segment and an addition polymerization resin segment via a covalent bond.
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 the addition polymerizable monomer having a carboxy group include acrylic acid, methacrylic acid, fumaric acid, and maleic acid. Among these, from the viewpoint of reactivity in both the polycondensation reaction and the addition polymerization reaction, 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 units derived from the bireactive monomer is preferably 1 mol part or more, more preferably 5 mol parts or more, even more preferably 8 mol parts or more, and is preferably 30 mol parts or less, more preferably 25 mol parts or less, even more preferably 20 mol parts or less, relative to 100 mol parts of the alcohol component of the polyester resin segment of the amorphous polyester resin A.

The content of the polyester resin segment in the amorphous polyester resin A is preferably 35% by mass or more, more preferably 45% by mass or more, even more preferably 50% by mass or more, and is preferably 90% by mass or less, more preferably 85% by mass or less, even more preferably 75% by mass or less.

The content of the addition polymerization resin segment in the amorphous polyester resin A is preferably 5% by mass or more, more preferably 15% by mass or more, even more preferably 25% by mass or more, and preferably 60% by mass or less, more preferably 55% by mass or less, even more preferably 45% by mass or less.

The amount of structural units derived from bireactive monomers in the amorphous polyester resin A 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, and is preferably 10% by mass or less, more preferably 7% by mass or less, even more preferably 4% by mass or less.

In the amorphous polyester resin A, the total amount of the polyester resin segment, the addition polymerization resin segment, and the structural units derived from the bireactive monomer 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 are based on the mass excluding the amount of dehydration due to polycondensation in the polyester resin segment, etc. When a radical polymerization initiator is used, the mass of the radical polymerization initiator is included in the addition polymerization resin segment in the calculation.

The amorphous polyester resin A may be produced, for example, by a method including a step A of polycondensing an alcohol component and a carboxylic acid component, and a step B of addition polymerizing a raw material monomer for 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.
In the step A, a part of the carboxylic acid component is subjected to a polycondensation reaction, and then the step B is carried out, and thereafter the remainder of the carboxylic acid component is added to the polymerization system to further proceed with the polycondensation reaction of the 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, polycondensation may be performed using an esterification catalyst such as tin(II) di(2-ethylhexanoate), dibutyltin oxide, or titanium diisopropoxybis(triethanolaminate) in an amount of 0.01 part by mass or more and 5 parts by mass or less per 100 parts by mass of the total amount of the alcohol component and the carboxylic acid component; or an esterification promoter such as gallic acid (equivalent to 3,4,5-trihydroxybenzoic acid) in an amount of 0.001 part by mass or more and 0.5 part by mass or less per 100 parts by mass of the total amount of the alcohol component and the carboxylic acid component.
When a monomer having an unsaturated bond such as fumaric acid is used in polycondensation, a radical polymerization inhibitor may be used, if necessary, in an amount of preferably 0.001 part by mass or more and 0.5 part by mass or less per 100 parts by mass of the total amount of the alcohol component and the carboxylic acid component. An example of the radical polymerization inhibitor is 4-tert-butylcatechol.
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 further preferably 210° C. or lower.

(Physical Properties of Amorphous Resin A)
The softening point of the amorphous resin A is preferably 70° C. or higher, more preferably 90° C. or higher, and even more preferably 100° C. or higher, and from the viewpoint of further improving the low-temperature fixability, it is preferably 150° C. or lower, more preferably 140° C. or lower, and even more preferably 125° C. or lower.
The glass transition temperature of the amorphous resin A 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 the low-temperature fixability, is preferably 80° C. or lower, more preferably 70° C. or lower, and even more preferably 60° C. or lower.

The acid value of the amorphous resin A is preferably 5 mgKOH/g or more, more preferably 10 mgKOH/g or more, even more preferably 15 mgKOH/g or more, and is preferably 40 mgKOH/g or less, more preferably 35 mgKOH/g or less, even more preferably 30 mgKOH/g or less.
The hydroxyl value of the amorphous resin A is preferably 1 mgKOH/g or more, more preferably 3 mgKOH/g or more, even more preferably 10 mgKOH/g or more, and is preferably 60 mgKOH/g or less, more preferably 40 mgKOH/g or less, even more preferably 20 mgKOH/g or less.
The softening point, glass transition temperature, and acid value of the amorphous resin A can be appropriately adjusted by the types and amounts of raw material monomers used, as well as production conditions such as reaction temperature, reaction time, and cooling rate, and these values can be determined by the methods described in the examples.
When two or more kinds of amorphous resins A are used in combination, it is preferable that the softening point, glass transition temperature and acid value of the mixture thereof are each within the above-mentioned ranges.

The content of amorphous resin A is preferably 40% by mass or more, more preferably 50% by mass or more, even more preferably 60% by mass or more, even more preferably 65% by mass or more, and is preferably 95% by mass or less, more preferably 90% by mass or less, even more preferably 85% by mass or less, based on the total amount of the resin components of resin particles X.

<Crystalline polyester resin C>
The crystalline polyester resin C is, for example, a crystalline polyester resin which is a polycondensation product of an alcohol component and a carboxylic acid component.
The crystalline polyester resin is a polycondensation product of an alcohol component and a carboxylic acid component.
The alcohol component is preferably an α,ω-aliphatic diol.
The α,ω-aliphatic diol preferably has 2 or more carbon atoms, more preferably 4 or more, and even more preferably 6 or more carbon atoms, and preferably has 16 or less, more preferably 14 or less, 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, even more 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, and even more preferably 10 or more carbon atoms, and preferably has 14 or less, and more preferably 12 or less carbon atoms.
Examples of the aliphatic dicarboxylic acid 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 the aliphatic dicarboxylic acid. Examples of other carboxylic acid components include aromatic dicarboxylic acids such as terephthalic acid and isophthalic acid; and polyvalent carboxylic acids having three or more valences. 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 is preferably 1.3 or less, more preferably 1.2 or less.

The method for producing the crystalline polyester resin can be, for example, the same as step A for producing the amorphous polyester resin A described above.

(Physical Properties of Crystalline Polyester Resin C)
The softening point of the crystalline polyester 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 fixing ability.
The melting point of the crystalline polyester 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 the low-temperature fixing ability.

The acid value of the crystalline polyester 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 the crystalline polyester resin C can be appropriately adjusted by the type and amount of the raw material monomer, 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 crystalline polyester resin C are used in combination, it is preferable that the softening point, melting point and acid value obtained as a mixture thereof are each within the above-mentioned ranges.

The content of the crystalline polyester resin C is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 15% by mass or more, relative to the total amount of the resin components of the resin particles X, and is preferably 60% by mass or less, more preferably 50% by mass or less, even more preferably 40% by mass or less, and even more preferably 35% by mass or less.
The mass ratio of the amorphous resin A to the crystalline polyester resin C [amorphous resin A/crystalline polyester resin C] is preferably 40/60 or more, more preferably 50/50 or more, even more preferably 60/40 or more, even more preferably 65/35 or more, and is preferably 95/5 or less, more preferably 90/10 or less, even more preferably 85/15 or less.

<Preparation of Resin Particle Dispersion>
The preparation of a resin particle dispersion containing resin particles X, preferably a resin particle dispersion containing amorphous resin A and crystalline polyester resin C in the same or different resin particles, can be carried out using a known method, but it is preferable to disperse the resin particles by a phase inversion emulsification method. An example of the phase inversion emulsification method is a method in which an aqueous medium is added to an organic solvent solution of a resin or a molten resin to perform phase inversion emulsification.

The organic solvent used for phase inversion emulsification is not particularly limited as long as it dissolves the resin, but from the viewpoint of facilitating phase inversion, examples include alcohol-based solvents such as ethanol, isopropanol, isobutanol, etc.; ketone-based solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, diethyl ketone, etc.; ether-based solvents such as dibutyl ether, tetrahydrofuran, dioxane, etc.; and acetate-based solvents such as ethyl acetate, isopropyl acetate, etc. Among these, from the viewpoint of easy removal from the mixed solution after addition of the aqueous medium, ketone-based solvents and acetate-based solvents are preferred, and methyl ethyl ketone, ethyl acetate, and isopropyl acetate are more preferred.
It is preferable to add a neutralizing agent to the organic solvent solution. Examples of the neutralizing agent include basic substances. Examples of the basic substance include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, and nitrogen-containing basic substances such as ammonia, trimethylamine, and diethanolamine.
The equivalent amount (mol %) of the neutralizing agent used relative to the acid groups of the resin contained in the resin particles X is, from the viewpoints of obtaining fine resin particles and improving dispersion stability, preferably 10 mol % or more, more preferably 30 mol % or more, even more preferably 40 mol % or more, and is preferably 90 mol % or less, more preferably 70 mol % or less.
The equivalent amount (mol %) of the neutralizing agent used can be calculated by the following formula: When the equivalent amount of the neutralizing agent used is 100 mol % or less, it is synonymous with the degree of neutralization.
Equivalent amount of neutralizing agent used (mol %)=[{weight (g) of neutralizing agent added/equivalent amount of neutralizing agent}/[{weighted average acid value (mg KOH/g) of resin constituting resin particle X×weight (g) of resin constituting resin particle X}/(56×1000)]×100

While stirring the organic solvent solution or the molten resin, the aqueous medium is gradually added to cause phase inversion.
From the viewpoint of improving the dispersion stability of the resin particles X, the temperature of the organic solvent solution when the aqueous medium is added is preferably equal to or higher than the glass transition temperature of the amorphous resin constituting the resin particles X, more preferably equal to or higher than 50° C., even more preferably equal to or higher than 60° C., and is preferably equal to or lower than 85° C., more preferably equal to or lower than 80° C.
The contents of the amorphous resin A and the crystalline polyester resin C are as described above.

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

From the viewpoint of obtaining a toner that can obtain high-quality images, the volume median particle size ( _D50 ) of the resin particles X in the dispersion is preferably 0.05 μm or more, more preferably 0.08 μm or more, even more preferably 0.12 μm or more, and is preferably 0.8 μm or less, more preferably 0.4 μm or less, even more preferably 0.3 μm or less.
From the viewpoint of obtaining a toner that can obtain high-quality images, the CV value of the resin particles X in the dispersion is preferably 10% or more, more preferably 20% 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 (D ₅₀ ) and CV value of the resin particles X are determined by the method described in the Examples section below.

When resin particles Xa containing the amorphous resin A and resin particles Xc containing the crystalline polyester resin C are used in combination, the resin particles Xa and Xc can be obtained by the same method as described above.
The amount of resin particles Xa and resin particles Xc added is preferably an amount that corresponds to the content of the amorphous resin A and the crystalline polyester resin C described above.

[Aqueous medium]
In the present invention, the aqueous medium is a medium containing water as a main component, and the content of water in the aqueous medium is preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more, and 100% by mass or less. As the water, deionized water, ion-exchanged water, or distilled water is preferable.
Examples of components other than water that can form the aqueous medium together with water include organic solvents that dissolve in water, such as alkyl alcohols having 1 to 5 carbon atoms, dialkyl ketones having 3 to 5 carbon atoms, such as acetone and methyl ethyl ketone, and cyclic ethers, such as tetrahydrofuran. Among these, alkyl alcohols having 1 to 5 carbon atoms are preferred, and methanol or ethanol are more preferred.

[Colorant Particles]
The colorant particles are preferably mixed with the above-mentioned resin particle dispersion in the form of a colorant particle dispersion in which colorant particles containing a colorant are dispersed in an aqueous medium.

<Coloring agent>
In step 1, it is preferable to aggregate colorant particles containing a colorant together with the resin particles X. As the colorant, any dye, pigment, or the like that is used as a toner colorant 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.

(Colorant Particle Dispersion)
The colorant is preferably mixed with the resin particles as a dispersion of colorant particles, and then aggregated, so that the colorant is contained in the aggregated particles.
The colorant particle dispersion is preferably obtained by dispersing the colorant and the aqueous medium using a dispersing machine such as a homogenizer or an ultrasonic dispersing machine. From the viewpoint of improving the dispersion stability of the colorant, the dispersion is preferably carried out in the presence of an addition polymer (hereinafter, the addition polymer used to disperse the colorant is also referred to as "addition polymer E") or a surfactant. Examples of the surfactant include nonionic surfactants, anionic surfactants, and cationic surfactants, and from the viewpoint of improving the dispersion stability of the colorant particles, anionic surfactants are preferred. Examples of the anionic surfactant include dodecylbenzenesulfonate, dodecyl sulfate, lauryl ether sulfate, and alkenyl succinate. Among these, dodecylbenzenesulfonate is preferred.
From the viewpoint of improving the dispersion stability of the colorant, the content of the surfactant in the colorant particle dispersion liquid is preferably 1 part by mass or more, more preferably 5 parts by mass or more, and even more preferably 10 parts by mass or more, relative to 100 parts by mass of the colorant, and is preferably 40 parts by mass or less, and more preferably 30 parts by mass or less.

The addition polymer E is preferably an addition polymer of raw material monomers including an addition polymerizable monomer a having an aromatic group (hereinafter, also simply referred to as "monomer a"). The addition polymer E more preferably includes a constitutional unit derived from the addition polymerizable monomer a having an aromatic group in the main chain.
The raw material monomers for the addition polymer E contain, in addition to the addition polymerizable monomer a having an aromatic group, more preferably, an addition polymerizable monomer b having an ionic group (hereinafter, also simply referred to as "monomer b").
Furthermore, the raw material monomers of the addition polymer E preferably further contain, in addition to the monomer b, at least one selected from an addition polymerizable monomer c having a polyalkylene oxide group (hereinafter also simply referred to as "monomer c") or a macromonomer d (hereinafter also simply referred to as "monomer d").

The addition-polymerizable monomer a having an aromatic group is preferably non-ionic.
Examples of the addition polymerizable monomer a having an aromatic group include a styrene-based compound a-1 and an aromatic group-containing (meth)acrylate a-2.
The styrene-based compound a-1 may be, for example, substituted or unsubstituted styrene. Examples of the substituent substituted on 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 molecular weight of the styrene-based compound a-1 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 styrene-based compound a-1 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 further improving hot offset resistance and image quality, the amount of the styrene-based compound a-1 is preferably 1 mass % or more, more preferably 5 mass % or more, even more preferably 10 mass % or more, even more preferably 20 mass % or more, even more preferably 30 mass % or more, even more preferably 35 mass % or more, and is preferably 98 mass % or less, more preferably 80 mass % or less, even more preferably 65 mass % or less, and even more preferably 50 mass % or less, in the raw material monomers of the addition polymer E.

Examples of the aromatic group-containing (meth)acrylate a-2 include benzyl (meth)acrylate and phenoxyethyl (meth)acrylate.
The molecular weight of the aromatic group-containing (meth)acrylate a-2 is preferably 1,000 or less, more preferably 800 or less, even more preferably 500 or less, still more preferably 300 or less, and preferably 160 or more.
When an aromatic group-containing (meth)acrylate a-2 is used, from the viewpoint of further improving hot offset resistance and image quality, the content of the aromatic group-containing (meth)acrylate a-2 in the raw material monomers of the addition polymer E is preferably 1 mass % or more, more preferably 5 mass % or more, even more preferably 10 mass % or more, and is preferably 50 mass % or less, more preferably 40 mass % or less, even more preferably 30 mass % or less.

From the viewpoint of further improving image density, the amount of the addition polymerizable monomer a having an aromatic group in the raw material monomers of the addition polymer E is preferably 1% by mass or more, more preferably 5% by mass or more, even more preferably 10% by mass or more, even more preferably 20% by mass or more, even more preferably 30% by mass or more, even more preferably 35% by mass or more, and is preferably 98% by mass or less, more preferably 95% by mass or less, even more preferably 90% by mass or less, even more preferably 80% by mass or less, even more preferably 65% by mass or less, even more preferably 50% by mass or less.

The ionic group in the monomer b means a group that undergoes ionization 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 from the viewpoint of improving the dispersion stability of the colorant particles. 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 the addition polymerizable monomer 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 b is contained, the amount of monomer b in the raw material monomers of the addition polymer E is preferably 2 mass % or more, more preferably 5 mass % or more, even more preferably 10 mass % or more, and preferably 40 mass % or less, more preferably 30 mass % or less, even more preferably 20 mass % or less.

The average number of moles of alkylene oxide added in the polyalkylene oxide group of monomer c 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 c is preferably non-ionic.
Examples of monomer c include polyalkylene glycol (meth)acrylates such as polyethylene glycol (meth)acrylate and polypropylene glycol (meth)acrylate; alkoxy polyalkylene glycol (meth)acrylates such as methoxy polyethylene glycol (meth)acrylate; and aryloxy polyalkylene glycol (meth)acrylates such as phenoxy (ethylene glycol-propylene glycol copolymer) (meth)acrylate.
When monomer c is contained, the amount of monomer c in the raw material monomers of the addition polymer E is preferably 3 mass% or more, more preferably 10 mass% or more, even more preferably 20 mass% or more, and preferably 50 mass% or less, more preferably 40 mass% or less, even more preferably 30 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 to 10,000. 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 in the raw material monomers of the addition polymer E is 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.

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

From the viewpoint of further improving image density, the weight average molecular weight of addition 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 48,000 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.

The addition 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 monomer.
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.

The mass ratio of the colorant to the addition polymer E in the colorant particles (colorant/addition polymer E) 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, and is preferably 95/5 or less, more preferably 90/10 or less, even more preferably 85/15 or less, from the viewpoint of obtaining a toner having excellent hot offset resistance and image quality.

<<Method for producing colorant particles and colorant particle dispersion>>
The colorant particles are obtained, for example, by mixing a colorant and the addition polymer E.
The method for producing the colorant particle dispersion is not particularly limited as long as it is possible to control the colorant particles to have a desired volume median particle diameter _D50 using a known kneader, disperser, or the like, but it is preferable to obtain the colorant particle dispersion by mixing the colorant and a dispersion of the addition polymer E using a bead mill or homogenizer.

The method for producing colorant particles preferably comprises the steps of:
This method includes: step a: a step of mixing the addition polymer E with an organic solvent, optionally mixing a neutralizing agent, and further mixing with an aqueous medium to obtain a dispersion of the addition polymer E; and step b: a step of dispersing the dispersion obtained in step a and a colorant to obtain a dispersion of colorant particles (colorant particle dispersion 2).
By including an organic solvent, the addition polymer E dissolves in the organic solvent, and the addition polymer E is more easily adsorbed to the colorant, thereby making it possible to further increase the dispersibility of the colorant.
Furthermore, the step b is preferably a step of dispersing the dispersion liquid obtained in the step a and the colorant with a bead mill or a homogenizer.

In the step a, it is preferable to first mix the addition polymer E with an organic solvent to dissolve the addition polymer E.
Examples of the organic solvent used here include alkyl alcohols having 1 to 3 carbon atoms, dialkyl ketones having a total of 3 to 5 carbon atoms, and cyclic ethers. Among these, dialkyl ketones having a total of 3 to 5 carbon atoms are preferred, and methyl ethyl ketone is more preferred. When the addition polymer E is synthesized by a solution polymerization method, the solvent used in the polymerization may be used as it is.

The neutralizing agent may, for example, be a basic substance, such as an alkali metal hydroxide, such as sodium hydroxide, potassium hydroxide, or a nitrogen-containing basic substance, such as ammonia, trimethylamine, or diethanolamine.
The degree of neutralization of the addition polymer E is preferably 15 mol% or more, more preferably 20 mol% or more, more preferably 40 mol% or more, more preferably 60 mol% or more, more preferably 70 mol% or more, and preferably 100 mol% or less, more preferably 95 mol% or less, more preferably 90 mol% or less.
The degree of neutralization of the addition polymer E can be determined by the following formula.
Degree of neutralization (mol %)=[{weight (g) of neutralizing agent added/equivalent weight of neutralizing agent}/{weight ratio of addition polymerizable monomer having acidic group constituting addition polymer E×weight (g) of addition polymer E/molecular weight of addition polymerizable monomer having acidic group}]×100
In step a), the mixing device may be, for example, a mixing/stirring device equipped with an anchor blade, a dispersing blade, or the like.
The temperature during mixing is preferably 0° C. or higher, more preferably 10° C. or higher, and is preferably 40° C. or lower, more preferably 30° C. or lower, and further preferably 25° C. or lower.
The mixing time is preferably 1 minute or more, more preferably 3 minutes or more, even more preferably 5 minutes or more, and is preferably 30 hours or less, more preferably 10 hours or less, even more preferably 5 hours or less, even more preferably 3 hours or less, even more preferably 1 hour or less.

In the step b, the mass ratio of the colorant to the addition polymer E [colorant/addition polymer E] is as described above.
In the step b, it is preferable to mix the dispersion liquid obtained in the step a with a colorant and then perform a dispersion treatment. As an apparatus used for mixing in the step b, the same apparatus as that used for mixing in the step a can be exemplified.
The temperature during mixing in step b is preferably 0° C. or higher, more preferably 10° C. or higher, and preferably 40° C. or lower, more preferably 30° C. or lower, and even more preferably 25° C. or lower.
The mixing time in step b is preferably 1 minute or more, more preferably 10 minutes or more, even more preferably 30 minutes or more, and is preferably 30 hours or less, more preferably 10 hours or less, even more preferably 5 hours or less, even more preferably 3 hours or less.

Examples of the apparatus used in the dispersion treatment in step b include kneaders such as roll mills and kneaders, homogenizers such as Microfluidizer (manufactured by Microfluidics Corp.) and Starburst (manufactured by Sugino Machine Corp.), and media-type dispersers such as paint shakers and bead mills. One or more of these apparatuses may be used. Among these, bead mills and homogenizers are preferred from the viewpoint of reducing the particle size of the pigment.
When a homogenizer is used, the treatment pressure is preferably 60 MPa or more, more preferably 100 MPa or more, even more preferably 130 MPa or more, and preferably 270 MPa or less, more preferably 200 MPa or less, even more preferably 180 MPa or less.
The number of passes is preferably 5 or more, more preferably 8 or more, and even more preferably 12 or more, and is preferably 30 or less, and more preferably 20 or less.

It is preferable to remove the organic solvent from the obtained colorant particle dispersion.
The colorant particle dispersion is preferably filtered through a wire mesh or the like to remove coarse particles, etc. From the viewpoint of improving the productivity and storage stability of the dispersion, the addition polymer E of the colorant particles may be crosslinked.
In addition, various additives such as organic solvents, preservatives, and antifungal agents may be added to the colorant particle dispersion liquid.

In the colorant particle dispersion, the colorant is preferably 5% by mass or more, more preferably 10% by mass or more, and preferably 50% by mass or less, more preferably 40% by mass or less, even more preferably 30% by mass or less, and even more preferably 25% by mass or less.
The solids 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.

The volume median particle diameter _D50 of the colorant particles in the colorant particle dispersion liquid is, from the viewpoint of improving the image density, preferably 0.05 μm or more, more preferably 0.07 μm or more, even more preferably 0.08 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 in the colorant particle dispersion is preferably 10% or more, more preferably 15% 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 method described in the examples.

From the viewpoint of further improving the image density, the amount of the colorant particles is preferably 3 parts by mass or more, more preferably 5 parts by mass or more, even more preferably 10 parts by mass or more, and is preferably 40 parts by mass or less, more preferably 30 parts by mass or less, even more preferably 25 parts by mass or less, relative to 100 parts by mass of the resin particles X.
The content of the colorant in the toner particles is preferably 0.1% by mass or more, more preferably 1% by mass or more, and even more preferably 5% by mass or more, and is preferably 20% by mass or less, and more preferably 15% by mass or less.

[Mixing conditions]
In step 1, it is preferable to mix the resin particles X and the colorant particles in an aqueous medium, and to aggregate the resin particles X and the colorant particles to obtain aggregated particles. The mixing of the resin particles X and the colorant particles is preferably carried out by mixing a resin particle dispersion containing the resin particles X with a colorant particle dispersion containing the colorant particles. It is also preferable that the resin particle dispersion is an aqueous dispersion of resin particles, and the colorant particle dispersion is an aqueous dispersion of colorant particles.
In step 1, it is preferable to aggregate the release agent particles together with the resin particles X and the colorant particles.

<Release agent>
In step 1, it is preferable to aggregate release agent particles containing a release agent together with the resin particles X and the colorant particles.
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 0.1% by mass or more, more preferably 1% by mass or more, and even more preferably 5% by mass or more, and is preferably 20% by mass or less, and more preferably 15% by mass or less.

(Dispersion of Release Agent Particles)
The release agent is preferably mixed with the resin particle dispersion and the colorant particle dispersion as a dispersion of release agent particles, and then aggregated, so that the release agent is contained in the aggregated particles.
The dispersion of release agent particles can be obtained using a surfactant, but is preferably obtained by mixing the release agent with resin particles Z described below. By preparing the release agent particles using the release agent and resin particles Z, the release agent particles are stabilized by the resin particles Z, and it becomes possible to disperse the release agent in an aqueous medium without using a surfactant. It is considered that the dispersion of release agent particles has a structure in which a large number of resin particles Z are attached to the surfaces of the release agent particles.

The resin constituting the resin particles Z in which the release agent is dispersed is preferably a polyester-based resin, and it is more preferable to use a composite resin D having a polyester resin segment and an addition polymerization resin segment.

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.
From the viewpoint of obtaining fine resin particles and from the viewpoint of obtaining a fine release agent particle dispersion, 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, even more preferably 20 mgKOH/g or more, and is preferably 40 mgKOH/g or less, more preferably 35 mgKOH/g or less, even more preferably 30 mgKOH/g or less.
The hydroxyl value of the composite resin D, from the viewpoint of obtaining fine resin particles and from the viewpoint of obtaining a fine release agent particle dispersion, is preferably 5 mgKOH/g or more, more preferably 10 mgKOH/g or more, even more preferably 15 mgKOH/g or more, even more preferably 20 mgKOH/g or more, and is preferably 40 mgKOH/g or less, more preferably 35 mgKOH/g or less, even more preferably 30 mgKOH/g or less.

The suitable ranges of other resin properties of the composite resin D, suitable examples of the raw material monomers constituting the resin, etc. are the same as those shown for the amorphous polyester resin A. The dispersion of the resin particles Z can be obtained, for example, by the above-mentioned phase inversion emulsification method.
From the viewpoint of dispersion stability of the release agent particles, the resin particles Z have a volume median particle size (D ₅₀ ) of 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 Z 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 (D ₅₀ ) and CV value of the resin particles Z 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 Z, and optionally an aqueous medium, at a temperature equal to or higher than the melting point of the release agent, using a dispersing machine such as a homogenizer, a high-pressure dispersing machine, or an ultrasonic dispersing machine.
The heating temperature during dispersion is preferably equal to or higher than the melting point of the release agent and equal to or higher than 80°C, more preferably equal to or higher than 85°C, and even more preferably equal to or higher than 90°C, 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 Z and equal to or lower than 100°C, more preferably equal to or lower than 98°C, and even more preferably equal to or lower than 95°C.

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

From the viewpoint of obtaining uniform aggregated particles by aggregation, the volume median particle size ( _D50 ) of the release agent particles is preferably 0.05 μm or more, more preferably 0.2 μm or more, even more preferably 0.4 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 20% or more, and is preferably 40% or less, more preferably 35% or less, and further preferably 30% or less.
The volume median particle diameter (D ₅₀ ) and CV value of the release agent particles are measured by the method described in the examples.

The aggregated particles 1 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.

<Surfactants>
In step 1, it is preferable to prepare a mixed dispersion by mixing a resin particle dispersion and, if necessary, a colorant particle dispersion and a release agent particle dispersion, and then aggregate the resin particles X, the colorant particles, and the release agent particles.
When preparing the mixed dispersion, the preparation may be carried out in the presence of a surfactant from the viewpoint of improving the dispersion stability of the resin particles X and optional components such as colorant particles and release agent particles added as necessary. Examples of the surfactant include anionic surfactants such as alkylbenzene sulfonates and alkyl ether sulfates; and nonionic surfactants such as polyoxyethylene alkyl ethers and polyoxyethylene alkenyl ethers. In addition, as the surfactant, an amphipathic molecule having a naphthalene ring, which will be described later, may be used in an amount less than that used during fusion. In this case, an amphipathic molecule having a naphthalene ring is added separately in the fusion step, which will be described later. One or more types of surfactants may be used.
When a surfactant is used, the amount of the surfactant used is, relative to 100 parts by mass of the resin particles X, preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and preferably 10 parts by mass or less, more preferably 5 parts by mass or less, in terms of the total amount of the surfactant.

The dispersion of resin particles X and the optional components are mixed by a conventional method. From the viewpoint of efficient aggregation, it is preferable to add a flocculant to the mixed dispersion obtained by the mixing.

<Flocculant>
Examples of the flocculant include organic flocculants such as cationic surfactants of quaternary salts and polyethyleneimine; 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 inorganic flocculants such as divalent or higher metal complexes. From the viewpoint of improving the flocculation property and obtaining uniform flocculated particles, inorganic flocculants having a valence of 1 to 5 are preferred, inorganic metal salts having a valence of 1 to 2 and inorganic ammonium salts having a valence of 1 to 2 are more preferred, and ammonium sulfate is even more preferred. The flocculant may be added as it is, but is preferably dissolved in an aqueous medium and added as an aqueous solution. In addition, when the flocculant is added as an aqueous solution, the pH of the aqueous flocculant solution may be adjusted.

For example, 5 to 60 parts by mass of the aggregating agent is added to 100 parts by mass of resin particles X in a mixed dispersion liquid containing resin particles X at 0°C or higher and 40°C or lower, and, if necessary, colorant particles and release agent particles, and the resin particles X and colorant particles are aggregated in an aqueous medium to obtain aggregated particles 1. Furthermore, from the viewpoint of promoting aggregation, it is preferable to increase the temperature of the dispersion liquid after adding the aggregating agent.

The volume median particle size _D50 of the aggregated particles 1 obtained in step 1 is preferably 3 μm or more, more preferably 4 μm or more, even more preferably 5 μm or more, and is preferably 10 μm or less, more preferably 8 μm or less, even more preferably 7 μm or less.
It is preferred that the agglomeration process be continued until the desired volume median particle size is reached.

<Step 2>
In step 2, resin particles Y are aggregated with respect to the aggregated particles 1 obtained in step 1 to obtain aggregated particles 2.
[Resin Particles Y]
The resin particle dispersion used in step 2 contains resin particles Y, and the resin particles Y preferably contain a polyester resin B having an aromatic ring.
In the present invention, it is preferable to use a polyester-based resin B having an aromatic ring as the resin constituting the shell portion, and to use an amphipathic molecule having a naphthalene ring in step 3 described later, since this has a high affinity with the toner surface and increases the dispersibility of the aggregated particles 2.

<Polyester resin B>
The polyester resin B is preferably, for example, an amorphous polyester resin containing a polycondensate of an alcohol component and a carboxylic acid component.
The polyester resin may be a polyester resin or a modified polyester resin. The modified polyester resin may be, for example, a urethane modified polyester resin, an epoxy modified polyester resin, or a composite resin containing a polyester resin segment and an addition polymerization resin segment. Among these, a polyester resin that is a polycondensation product of an alcohol component and a carboxylic acid component is preferred.

Examples of the alcohol component include alkylene oxide adducts of aromatic diols from the viewpoint of obtaining a polyester resin having an aromatic ring. Among these, alkylene oxide adducts of aromatic diols are preferred from the viewpoint of obtaining a toner having excellent low-temperature fixing properties.
The alkylene oxide adduct of an aromatic diol is preferably an alkylene oxide adduct of bisphenol A, more preferably represented by 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, 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 include a propylene oxide adduct of bisphenol A [2,2-bis(4-hydroxyphenyl)propane] and an ethylene oxide adduct of bisphenol A. These may be used alone or in combination. Among these, the ethylene oxide adduct of bisphenol A is more preferred.
The content of the alkylene oxide adduct of bisphenol A in the alcohol component is preferably 70 mol % or more, more preferably 90 mol % or more, even more preferably 95 mol % or more, and is 100 mol % or less, even more preferably 100 mol %.

In addition to the alkylene oxide adduct of bisphenol A, the amorphous polyester resin A may contain the linear or branched aliphatic diol, alicyclic diol, trihydric or higher polyhydric alcohol, etc., described above for the amorphous polyester resin A.
These alcohol components may be used alone or in combination of two or more.

Examples of the carboxylic acid component include dicarboxylic acids and polycarboxylic acids having three or more carboxylic acids.
Examples of the dicarboxylic acid 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.
From the viewpoint of obtaining a desired aromatic ring concentration in the carboxylic acid component, the amount of aromatic dicarboxylic acid is preferably 40 mol% or more, more preferably 50 mol% or more, even more preferably 60 mol% or more, even more preferably 70 mol% or more, even more preferably 75 mol% or more, and is preferably 90 mol% or less, more preferably 85 mol% or less.

The linear or branched aliphatic dicarboxylic acid preferably has 2 or more, more preferably 3 or more, and preferably has 30 or less, more preferably 20 or less.
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 acid substituted with an aliphatic hydrocarbon group having 1 to 20 carbon atoms. Examples of succinic acid substituted with an aliphatic hydrocarbon group having 1 to 20 carbon atoms include dodecylsuccinic acid, dodecenylsuccinic acid, and octenylsuccinic acid. Among these, adipic acid and succinic acid substituted with an aliphatic hydrocarbon group having 1 to 20 carbon atoms are preferred.
The amount of the linear or branched aliphatic dicarboxylic acid in the carboxylic acid component is preferably 60 mol % or less, more preferably 30 mol % or less, and further preferably 15 mol % or less.

The trivalent or higher polyvalent carboxylic acid is preferably a trivalent carboxylic acid, for example, trimellitic acid, preferably 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 3 mol % or more, more preferably 5 mol % or more, even more preferably 8 mol % or more, and is preferably 30 mol % or less, more preferably 25 mol % or less, even more preferably 20 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 0.8 or more, and is preferably 1.3 or less, more preferably 1.2 or less.

The polyester resin B may be produced, for example, by a step A in which an alcohol component and a carboxylic acid component are polycondensed.
Step A is the same as step A described in the method for producing amorphous polyester resin A, and the preferred ranges are also the same.
In step A, if necessary, polycondensation may be performed using an esterification catalyst such as tin(II) di(2-ethylhexanoate), dibutyltin oxide, or titanium diisopropoxybis(triethanolaminate) in an amount of 0.01 part by mass or more and 5 parts by mass or less per 100 parts by mass of the total amount of the alcohol component and the carboxylic acid component; or an esterification promoter such as gallic acid (equivalent to 3,4,5-trihydroxybenzoic acid) in an amount of 0.001 part by mass or more and 0.5 part by mass or less per 100 parts by mass of the total amount of the alcohol component and the carboxylic acid component.
When a monomer having an unsaturated bond such as fumaric acid is used in polycondensation, a radical polymerization inhibitor may be used, if necessary, in an amount of preferably 0.001 part by mass or more and 0.5 part by mass or less per 100 parts by mass of the total amount of the alcohol component and the carboxylic acid component. An example of the radical polymerization inhibitor is 4-tert-butylcatechol.
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.

(Physical Properties of Polyester Resin B)
The polyester-based resin B is preferably an amorphous polyester resin, and the softening point of the polyester-based resin B is preferably 70° C. or higher, more preferably 90° C. or higher, and even more preferably 100° C. or higher, and from the viewpoint of further improving the low-temperature fixability, is preferably 150° C. or lower, more preferably 140° C. or lower, and even more preferably 125° C. or lower.
The glass transition temperature of the polyester resin B is preferably 30° C. or higher, more preferably 40° C. or higher, and even more preferably 50° C. or higher, and from the viewpoint of further improving the low-temperature fixability, is preferably 90° C. or lower, more preferably 80° C. or lower, and even more preferably 70° C. or lower.

The acid value of the polyester resin B is preferably 5 mgKOH/g or more, more preferably 10 mgKOH/g or more, even more preferably 15 mgKOH/g or more, and is preferably 40 mgKOH/g or less, more preferably 30 mgKOH/g or less, even more preferably 25 mgKOH/g or less.
The hydroxyl value of the polyester resin B is preferably 1 mgKOH/g or more, more preferably 3 mgKOH/g or more, even more preferably 10 mgKOH/g or more, and is preferably 60 mgKOH/g or less, more preferably 50 mgKOH/g or less, even more preferably 45 mgKOH/g or less.
The softening point, glass transition temperature and acid value of the polyester resin B can be appropriately adjusted by the types and amounts of raw material monomers used, as well as production conditions such as reaction temperature, reaction time and cooling rate, and these values can be determined by the methods described in the examples.
When two or more kinds of polyester resins B are used in combination, it is preferable that the softening point, glass transition temperature and acid value of the mixture thereof are each within the above-mentioned ranges.

The content of polyester resin B is preferably 60% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, and is 100% by mass or less, even more preferably 100% by mass, based on the total amount of the resin components of resin particles Y.

(Preparation of Resin Particle Y Dispersion)
The resin particles Y are preferably produced by a method in which a resin component containing the polyester resin B and, if necessary, an optional component such as a surfactant are dispersed in an aqueous medium to obtain a resin particle Y dispersion.
The method for obtaining the resin particle Y dispersion liquid can be exemplified by the same methods as those for the resin particle dispersion liquid of resin particle X. Among these, from the viewpoint of improving the low-temperature fixability of the obtained toner, it is preferable to obtain the resin particle Y dispersion liquid by a phase inversion emulsification method.
As in the case of resin particles X, the phase inversion emulsification method is preferably a method in which an aqueous medium is added to a solution obtained by dissolving a resin and optional components such as a surfactant in an organic solvent, and then phase inversion emulsification is carried out, as in the case of resin particles X. Preferred aspects of the aqueous medium and organic solvent that can be used are the same as those of the aqueous medium and organic solvent used in the production of resin particles X. In addition, in the phase inversion emulsification method, preferred ranges of the mass ratio of polyester resin B to organic solvent, the degree of neutralization of polyester resin B, the amount of aqueous medium added, the mixing temperature, and the like are the same as those in the production of resin particles X.

From the viewpoint of improving the productivity of the toner and the dispersion stability of the resin particles Y, the solid content concentration of the resulting resin particle Y dispersion is preferably 7% by mass or more, more preferably 10% by mass or more, even more preferably 15% by mass or more, and even more preferably 20% by mass or more, and is preferably 50% by mass or less, more preferably 35% by mass or less. The solid content is the total amount of non-volatile components such as the resin and surfactant.

From the viewpoint of obtaining a toner that can obtain high-quality images, the volume median particle diameter ( _D50 ) of the resin particles Y in the resin particle dispersion is preferably 0.04 μm or more, more preferably 0.06 μm or more, even more preferably 0.08 μm or more, and is preferably 0.5 μm or less, more preferably 0.3 μm or less, even more preferably 0.2 μm or less, and even more preferably 0.15 μm or less.

In addition, the coefficient of variation (CV value) (%) of the particle size distribution of the resin particles Y is preferably 5% or more, more preferably 10% or more, and even more preferably 15% or more, from the viewpoint of improving the productivity of the resin particle Y dispersion liquid, and is preferably 50% or less, more preferably 40% or less, even more preferably 30% or less, and even more preferably 25% or less, from the viewpoint of obtaining a toner that can obtain high-quality images.
The volume median particle diameter (D ₅₀ ) and coefficient of variation (CV value) of the resin particles Y are measured by the method described in the examples.

(Production of Aggregated Particles 2)
In step 2, it is preferable to add a dispersion of resin particles Y to the dispersion of aggregated particles 1 described above to cause the resin particles Y to adhere to the aggregated particles 1, thereby obtaining a dispersion of aggregated particles 2.

Before adding the dispersion of resin particles Y to the dispersion of aggregated particles 1, the dispersion of aggregated particles 1 may be diluted by adding an aqueous medium. When the dispersion of resin particles Y is added to the dispersion of aggregated particles 1, the aggregating agent may be used in this step in order to efficiently attach the resin particles Y to the aggregated particles 1.
From the viewpoint of achieving both low-temperature fixability and heat-resistant storage stability of the toner, the temperature when the resin particle Y dispersion is added is preferably 40° C. or higher, more preferably 45° C. or higher, even more preferably 50° C. or higher, and is preferably 80° C. or lower, more preferably 70° C. or lower, even more preferably 60° C. or lower.

The resin particle Y dispersion may be added continuously over a certain period of time, may be added all at once, or may be added in several divided portions, but it is preferable to add it continuously over a certain period of time or in several divided portions. By adding it as described above, the resin particles Y tend to adhere selectively to the aggregated particles 1. In particular, from the viewpoint of promoting selective adhesion and improving the productivity of the toner, it is preferable to add it continuously over a certain period of time. When adding it continuously, the time is preferably 0.5 hours or more, more preferably 0.8 hours or more, and preferably 10 hours or less, more preferably 7 hours or less, and even more preferably 3 hours or less, from the viewpoint of obtaining uniform aggregated particles 2 and improving the productivity of the toner.

From the viewpoint of achieving both low-temperature fixability and heat-resistant storage stability of the toner, the amount of resin particles Y added is an amount such that the mass ratio of resin particles Y to resin particles X (resin particles Y/resin particles X) is preferably 0.05 or more, more preferably 0.1 or more, and is preferably 0.9 or less, more preferably 0.5 or less, even more preferably 0.3 or less, and even more preferably 0.2 or less.

The volume median particle size ( _D50 ) of the resulting aggregated particles 2 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, from the viewpoint of obtaining a toner that can obtain high-quality images and from the viewpoint of achieving both low-temperature fixability and heat-resistant storage stability of the toner.

<Step 3>
Step 3 is a step of heating the aggregated particles 1 obtained in step 1 or the aggregated particles 2 obtained in step 2 to fuse them to obtain fused particles. In step 3, amphiphilic molecules having a naphthalene ring and an acidic substance are added.
The amphiphilic molecule having a naphthalene ring is added for the purpose of improving the dispersion stability of the aggregated particles during fusion, and the acidic substance is added for the purpose of promoting fusion by lowering the pH.
The amphiphilic molecule having a naphthalene ring may be present during aggregation in step 1 or step 2. However, from the viewpoint of maintaining dispersion stability during fusion in step 3, it is preferable to add the amphiphilic molecule having a naphthalene ring and then raise the temperature to fuse the molecules.

[Amphiphilic molecules containing a naphthalene ring]
The amphiphilic molecule having a naphthalene ring is an amphiphilic molecule having a surface active effect, and is preferably an anionic surfactant.
Examples of the amphiphilic molecule having a naphthalene ring include naphthalenesulfonate and naphthalenesulfonic acid-formalin condensate, with naphthalenesulfonic acid-formalin condensate being preferred.
The naphthalenesulfonate is preferably an alkali metal salt of naphthalenesulfonic acid, more preferably sodium naphthalenesulfonate.
The naphthalenesulfonic acid-formaldehyde condensate is preferably a formaldehyde condensate of unsubstituted or substituted naphthalenesulfonic acid, and more preferably a compound represented by the following formula (1).

In formula (1), n represents an integer of preferably 2 or more and 200 or less, more preferably 6 or more and 100 or less, and further preferably 10 or more and 50 or less.
Each M independently represents a cation, and examples thereof include cations of elements selected from Group 1 and Group 2 elements of the Periodic Table of Elements; quaternary ammonium; and ammonium (NH ₄ ⁺ ). Among these, cations of elements of Group 1 of the Periodic Table of Elements are preferred; cations of elements selected from lithium, sodium, and potassium are more preferred, and sodium cations are even more preferred. In addition, it is preferred that multiple M are the same cation.
Each of the multiple R's independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or a hydroxyl group, and from the viewpoint of improving heat-resistant storage stability, each of them is preferably independently a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. It is more preferable that at least a part of the multiple R's is an alkyl group having 1 to 4 carbon atoms.
In addition, as long as the effect as a dispersion stabilizer is not impaired, other structural units may be included in a portion of the dispersion stabilizer, and examples of the other structural units include structural units formed from copolymerizable monomers such as alkyl alcohol naphthalene sulfonic acid, etc. The content of these structural units is preferably 30% by mass or less.
As the naphthalenesulfonic acid formalin condensate, unsubstituted or substituted β-naphthalenesulfonic acid formalin condensate sodium salt is preferred.

From the viewpoint of improving heat-resistant storage stability, the weight-average molecular weight of the naphthalenesulfonic acid-formalin condensate is preferably 500 or more, more preferably 1,500 or more, even more preferably 2,500 or more, and is preferably 40,000 or less, more preferably 20,000 or less, even more preferably 10,000 or less.
The weight average molecular weight of the naphthalenesulfonic acid-formaldehyde condensate is measured by GPC.

The naphthalenesulfonic acid-formalin condensate can be produced by a known method, for example, by polycondensation using β-naphthalenesulfonic acid (salt) and an equivalent amount of formalin, and other components as necessary, such as sulfonic acids (salts) of β-methylnaphthalene, α-methylnaphthalene, acenaphthene, dibenzofuran, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, and the like.
As the naphthalenesulfonic acid-formalin condensate, commercially available products may be used. Examples thereof include DEMOL N, DEMOL NL, DEMOL RN, DEMOL RN-L, DEMOL T, DEMOL T-45, DEMOL MS, DEMOL SN-B, DEMOL SS-L, and DEMOL SC-30 manufactured by Kao Corporation; Labelin AN-40, Labelin F-45, Labelin FC-45, Labelin FC-P, Labelin FD-40, Labelin FP, Labelin FN-P, and Labelin MN-P manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.; and IONET D-2 manufactured by Sanyo Chemical Industries, Ltd.

In order to obtain fused particles having excellent circularity and a low rate of coarse particles, the amount of the amphiphilic molecule having a naphthalene ring added in step 3 is preferably 1.0 part by mass or more, more preferably 1.5 parts by mass or more, even more preferably 3 parts by mass or more, and is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, even more preferably 15 parts by mass or less, and even more preferably 12 parts by mass or less, relative to 100 parts by mass of the aggregated particles 1 or the aggregated particles 2.
In addition, from the viewpoint of obtaining fused particles having excellent circularity and a small rate of coarse particles, the amphiphilic molecules having a naphthalene ring among the amphiphilic molecules added to the aggregated particles in step 3 are preferably 90% by mass or more, more preferably 95% by mass or more, and 100% by mass or less, and even more preferably 100% by mass.

In the present embodiment, it is preferable to add an acidic substance to lower the pH of the aqueous medium by 0.1 or more in step 3. That is, the pH in the aqueous medium means the pH of the aqueous medium containing the aggregated particles, and is, for example, the pH measured using a pH meter by immersing the electrodes of the pH meter in the dispersion liquid to be fused at the time of adding the acidic substance.
The pH of the aqueous medium is preferably reduced by 0.1 or more, more preferably by 0.15 or more. The pH is also preferably reduced by 4.0 or less, more preferably by 3.0 or less, even more preferably by 2.0 or less, and even more preferably by 1.0 or less. When the pH of the aqueous medium is reduced within the above range, the repulsion between the aggregated particles is appropriately weakened and fusion is promoted, which is preferable.
In step 3, when the aggregated particles 1 obtained in step 1 are fused by heating to obtain fused particles, it is preferable to add an acidic substance in an amount of preferably at least the molar equivalent of the acid group (carboxy group) possessed by the resin particles X, more preferably at least two times the molar equivalent, and preferably at most 20 times the molar equivalent, more preferably at most 10 times the molar equivalent.
In addition, when the aggregated particles 2 obtained in step 2 are heated and fused to obtain fused particles, it is preferable to add an acidic substance in an amount of preferably at least the molar equivalent, more preferably at least two times the molar equivalent, and preferably at most 20 times, more preferably at most 10 times the molar equivalent, of the acid groups (carboxy groups) possessed by the resin particles Y constituting the shell structure.

In step 3, the pH of the aqueous medium after the addition of the acidic substance is preferably 5.0 or more, more preferably 6.0 or more, even more preferably 6.5 or more, from the viewpoint of obtaining fused particles with excellent circularity and a low rate of coarse particles, and is preferably 7.0 or less, more preferably 6.9 or less.

The acidic substance to be added includes inorganic acids and organic acids.
The inorganic acids include nitric acid, sulfuric acid, hydrochloric acid, and phosphoric acid.
Examples of organic acids include carboxylic acid compounds such as carboxylic acids, dicarboxylic acids, and tricarboxylic acids, sulfonic acid compounds such as methanesulfonic acid, benzenesulfonic acid, and toluenesulfonic acid, ascorbic acid, phenol, and cresol. Among these, carboxylic acid compounds are preferred.
Examples of the carboxylic acid compound include acetic acid, lactic acid, tartaric acid, propionic acid, benzoic acid, oxalic acid, terephthalic acid, fumaric acid, succinic acid, acrylic acid, and adipic acid.
Among these, from the viewpoint of obtaining fused particles having excellent circularity and a low rate of coarse particles, inorganic acids are preferred, and sulfuric acid is more preferred.

The acidic substance is preferably added to the system in the form of an aqueous solution of the acidic substance, from the viewpoint of obtaining fused particles having excellent circularity and a low rate of coarse particles.
When added as an aqueous solution of an acidic substance, the concentration of the acidic substance in the aqueous solution of the acidic substance is preferably 0.01 mol/L or more, more preferably 0.03 mol/L or more, even more preferably 0.05 mol/L or more, and preferably 3 mol/L or less, more preferably 2 mol/L or less, even more preferably 1.5 mol/L or less, even more preferably 1 mol/L or less, even more preferably 0.5 mol/L or less, even more preferably 0.3 mol/L or less.

The acidic substance may be added all at once, the entire amount may be added in two or more portions, or the acidic substance may be added continuously over a certain period of time.
Furthermore, the acidic substance may be added before or after the addition of the amphipathic molecule having a naphthalene ring, before or after the temperature is increased, and is not particularly limited. However, from the viewpoint of obtaining fused particles having excellent circularity and a low rate of coarse particles, it is preferable to add the acidic substance after the addition of the amphipathic molecule having a naphthalene ring, and it is more preferable to add the amphipathic molecule having a naphthalene ring, increase the temperature, add the acidic substance, and then maintain the mixture at the increased temperature.

In step 3, the particles in the aggregated particles that were primarily physically attached to each other are fused together to form toner particles having a core-shell structure.
In this step, from the viewpoint of improving the fusibility of the aggregated particles and obtaining fused particles having excellent circularity and a small proportion of coarse particles, it is preferable to maintain the temperature at or above the glass transition temperature of the polyester resin B.
From the viewpoint of improving the fusion properties of the aggregated particles and improving the productivity of the toner, the holding temperature in the fusion step is preferably at least 2° C. higher than the glass transition temperature of polyester resin B, more preferably at least 3° C. higher, and even more preferably at least 5° C. higher, and is preferably not higher than 30° C. higher, more preferably not higher than 20° C. higher, and even more preferably not higher than 15° C. higher than the glass transition temperature of polyester resin B.
In this case, the time for which the mixture is maintained at a temperature equal to or higher than the glass transition temperature of the polyester resin B may be appropriately set within a range in which the circularity of the fused particles falls within a desired range. From the viewpoint of productivity, the time is preferably 240 minutes or less, more preferably 180 minutes or less, even more preferably 120 minutes or less, even more preferably 100 minutes or less, and is preferably 1 minute or more, more preferably 10 minutes or more, even more preferably 30 minutes or more.
It is preferable to maintain the temperature at the above temperature until the desired circularity is achieved.

In step 3, it is preferable from the viewpoint of productivity that the solids concentration of agglomerated particles 1 or agglomerated particles 2 is high. The solids concentration of agglomerated particles 1 or agglomerated particles 2 at the time of holding at the temperature after the above-mentioned temperature increase is preferably 7 mass % or more, more preferably 8 mass % or more, and even more preferably 9 mass % or more. From the viewpoint of obtaining fused particles having excellent circularity and a small proportion of coarse particles, the solids concentration is preferably 20 mass % or less, more preferably 15 mass % or less, even more preferably 12 mass % or less, and even more preferably 10 mass % or less.
The solid content concentration of aggregated particles 1 or 2 in step 3 is the mass ratio of the total amount of resin particles X, release agent particles, colorant particles, and resin particles Y to the total amount in the system at the time when the temperature is maintained after the temperature increase in step 3, and does not include solid contents such as the aggregating agent, pH adjuster, amphipathic molecules, etc. in the system. The solid content concentration of aggregated particles 1 or 2 in step 3 can be determined by dividing the solid content of aggregated particles 1 or 2 by the total amount in step 3.

From the viewpoint of achieving both low-temperature fixability and heat-resistant storage stability of the toner, the volume median particle size ( _D50 ) of the fused particles obtained in step 3 is preferably 2 μm or more, more preferably 3 μm or more, even more preferably 4 μm or more, even more preferably 5 μm or more, and is preferably 10 μm or less, more preferably 8 μm or less, even more preferably 7 μm or less.
The volume median particle diameter of the fused particles obtained in step 3 is preferably equal to or smaller than the volume median particle diameter of the aggregated particles 1 or the aggregated particles 2, and more preferably 0.9 to 1.1 times the volume median particle diameter of the aggregated particles 1 or the aggregated particles 2. That is, in step 3, it is preferable that aggregation and fusion of the aggregated particles 1 or the aggregated particles 2 do not occur.

<Post-treatment process>
In the present invention, a post-treatment step may be carried out after step 3, and it is preferable to obtain toner particles by isolation.
It is preferable to cool the dispersion of fused particles obtained in step 3, remove coarse particles, and then carry out solid-liquid separation. For solid-liquid separation, a suction filtration method or the like is preferably used.
For example, coarse particles can be removed by passing the mixture through a 300 mesh sieve (pore size: 45 μm).
It is preferable to wash the solid-liquid separation product. At this time, it is preferable to remove the added surfactant, etc., and therefore, in the case where the surfactant has a cloud point, washing with an aqueous medium at a temperature below the cloud point of the surfactant is preferable. It is preferable to wash the product several times.

The circularity of the fused particles obtained in step 3 after removing the coarse particles is preferably 0.955 or more, more preferably 0.960 or more, and even more preferably 0.965 or more, from the viewpoint of obtaining a toner for developing electrostatic images that can obtain high image quality, and is preferably 0.990 or less, more preferably 0.985 or less, and even more preferably 0.980 or less, from the viewpoint of improving cleaning properties.

The volume median particle size _D50 of the fused particles after removing the coarse particles is, from the viewpoint of improving the productivity of the toner and obtaining high quality images, 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.

The CV value of the fused particles after removing the coarse particles is preferably 10% or more, more preferably 15% or more, even more preferably 20% or more, from the viewpoint of improving the productivity of the toner and obtaining high-quality images, and is preferably 50% or less, more preferably 40% or less, even more preferably 35% or less.

Next, drying is preferably performed. The temperature during drying is preferably set so that the temperature of the core-shell particles themselves is lower than the glass transition temperature of the amorphous resin A, and more preferably 10°C or more lower. As a drying method, it is preferable to use a vacuum low-temperature drying method, a vibration-type fluidized drying method, a spray drying method, a freeze drying method, a flash jet method, etc.

The coarse particle ratio in the obtained fused particles is preferably low, and is preferably 6.0% or less, more preferably 5.0% or less, even more preferably 4.0% or less, and even more preferably 3.5% or less. The lower limit is not particularly limited, but from the viewpoint of ease of production, it is preferably 0.5% or more.
The coarse particle ratio is measured by the method described in the Examples.

(Toner Particles)
The toner particles obtained by separating the fused particles, washing them as necessary, and then drying or the like can be used as they are as a toner for developing electrostatic images. However, it is preferable to use the toner particles after treating the surfaces thereof as described later as a toner for developing electrostatic images.
The volume median particle size ( _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, from the viewpoint of improving the productivity of the toner and from the viewpoint of achieving both low-temperature fixability and heat-resistant storage stability of the toner.
The CV value of the toner particles is preferably 10% or more, more preferably 15% or more, and even more preferably 20% or more, from the viewpoint of improving the productivity of the toner, and is preferably 50% or less, more preferably 40% or less, and even more preferably 35% or less, from the viewpoint of obtaining high-quality images.
From the viewpoint of obtaining a toner for developing electrostatic images that can obtain high image quality, the circularity of the toner particles is preferably 0.955 or more, more preferably 0.960 or more, and even more preferably 0.965 or more, and from the viewpoint of improving cleaning properties, the circularity is preferably 0.990 or less, more preferably 0.985 or less, and even more preferably 0.980 or less.

(External additives)
The toner particles can be used as they are, but 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.
Examples of the external additive include inorganic fine particles such as hydrophobic silica, titanium oxide fine particles, alumina fine particles, cerium oxide fine particles, and carbon black, and polymer fine particles such as polycarbonate, polymethyl methacrylate, and silicone resin. Of these, hydrophobic silica is preferred.
The external additives may be used alone or in combination of two or more. Also, external additives of the same type but different particle diameters may be used in combination.
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, and even more preferably 4 parts by mass or less, relative to 100 parts by mass of the toner particles.

[Toner for developing electrostatic images]
The toner for developing electrostatic images obtained according to the present invention can be used as a one-component developer, or mixed with a carrier to form a two-component developer.

The present invention will be described in more detail below with reference to examples. The properties were measured by the following methods. Various evaluations were performed by the following methods.
[measurement]
[Acid value and hydroxyl value of resin and release agent]
The acid value and hydroxyl value of the resin and the release agent were measured according to the neutralization titration method described in JIS K 0070: 1992. However, the measurement solvent was chloroform.

[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 under a load of 1.96 MPa applied by a plunger while heating the sample at a temperature increase rate of 6°C/min. The plunger descent 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 from room temperature (20°C) to 0°C at a temperature drop rate of 10°C/min. The sample was then stopped for 1 minute, and then heated to 180°C at a temperature increase rate of 10°C/min to measure the amount of heat. 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 amount of heat was measured. Among 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, the peak temperature was taken as the melting point.
In the case of an amorphous resin, when a peak was observed, the temperature of the peak was taken as the glass transition temperature. When no peak was observed but a step was observed, the temperature at the intersection of the tangent showing the maximum slope of the curve at the step and an extension of the baseline on the low temperature side of the step was taken as the glass transition temperature.

[Weight average molecular weight of addition polymer]
The measurement was performed by gel permeation chromatography (GPC apparatus "HLC-8320GPC" (manufactured by Tosoh Corporation), columns "TSKgel SuperAWM-H", "TSKgel SuperAW3000", "TSKgel guardcolumn Super AW-H" (manufactured by Tosoh Corporation), flow rate: 0.5 mL/min) using a solution of phosphoric acid and lithium bromide dissolved in N,N-dimethylformamide to a concentration of 60 mmol/L and 50 mmol/L, respectively, as an eluent, and using a monodisperse polystyrene kit 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 a standard substance.

[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 drop rate of 10° C./min. The sample was then heated at a temperature rise rate of 10° C./min, the amount of heat was measured, and the maximum endothermic peak temperature was taken as the melting point.

[Volume Median Particle Size (D ₅₀ ) and CV Value of Resin Particles, Colorant Particles, and Release Agent Particles]
(1) Measuring device: Laser diffraction type 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 were measured at a concentration that brought the absorbance into an appropriate range. The relative refractive index was 1.10, the circulation pump was ON, and the circulation speed was 5. The CV value was calculated according to the following formula.
CV value (%) = (standard deviation of particle size distribution/volume average particle size) x 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 (mass%) of 5 g of the measurement sample was measured at a drying temperature of 150°C and measurement mode 96 (monitoring time 2.5 minutes, moisture content fluctuation range 0.05%). The solid content concentration was calculated according to the following formula.
Solid content concentration (mass%) = 100-moisture (mass%)

[Volume Median Particle Size (D ₅₀ ) and CV Value of Agglomerated Particles and Fused Particles]
(1) Measuring device: "Coulter Multisizer (registered trademark) III" (manufactured by Beckman Coulter, Inc.)
(2) Analysis software: "Multisizer (registered trademark) III version 3.51" (manufactured by Beckman Coulter, Inc.)
(3) Measurement conditions:
・Electrolyte: "Isoton (registered trademark) III" (Beckman Coulter, Inc.)
Aperture diameter: 50 μm
The sample dispersion was added to 100 mL of the above electrolyte to adjust the concentration to a level where the particle sizes of 30,000 particles could be measured in 20 seconds, and the 30,000 particles were then measured again to determine the volume median particle size (D ₅₀ ) from the particle size distribution.
CV value (%) = (standard deviation of particle size distribution/volume average particle size) x 100

[pH in aqueous medium]
A pH meter "SevenGo pH meter SG2" (manufactured by Mettler Toledo) was used, and an "InLab Expert Go" (manufactured by Mettler Toledo) was connected as an electrode. The pH was measured at each temperature while stirring by immersing the electrode of the pH meter in the aqueous medium.

[Circularity of fused particles]
The circularity of the fused particles was measured under the following conditions.
・Measuring device: Flow type particle image analyzer "FPIA-3000" (manufactured by Sysmex Corporation)
Preparation of dispersion: The dispersion of fused particles was diluted with deionized water so that the solid content concentration was 0.001% by mass or more and 0.05% by mass or less, and then the measurement was performed.
Measurement mode: HPF measurement mode

[Coarse particle rate]
The dispersion of fused particles was passed through a 300 mesh (hole size 45 μm), and the residue on the mesh was washed with deionized water and then vacuum dried at 33° C. for 48 hours to obtain coarse particles. From the mass of the obtained coarse particles, the coarse particle ratio was calculated according to the following formula. The toner particle mass refers to the mass of toner particles obtained by subjecting the dispersion passed through the mesh to suction filtration to separate the solid content, washing with deionized water, and drying.
Coarse particle ratio (%)=mass of coarse particles (g)/(mass of toner particles (g)+mass of coarse particles (g))×100

[Production of resin]
Production Example A1 (Production of Amorphous 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 3,4,5-trihydroxybenzoic acid were placed in the flask, and the mixture was heated to 235° C. under a nitrogen atmosphere with stirring, and then held at 235° C. for 5 hours. The pressure in the flask was then reduced and held at 8 kPa for 1 hour. After that, the flask was returned to atmospheric pressure, cooled to 160° C., and 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 over 1 hour while the mixture was held at 160° C. After that, the mixture was kept at 160°C for 30 minutes, and then heated to 200°C. The pressure in the flask was further reduced and kept at 8 kPa for 1 hour. After that, the mixture was 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, and the mixture was heated to 210°C at 10°C/hr. Then, the mixture was reacted at 4 kPa until the desired softening point was obtained, to obtain amorphous resin A-1. The physical properties are shown in Table 1.

Production Example B1 (Production of Resin B-1)
The inside of a 10L four-neck flask equipped with a nitrogen inlet tube, a dehydration tube, a stirrer, and a thermocouple was replaced with nitrogen, and 3265g of ethylene oxide (2.2) adduct of bisphenol A, 1334g of terephthalic acid, 25g of tin (II) di(2-ethylhexanoate), and 2.5g of 3,4,5-trihydroxybenzoic acid were added, and the mixture was heated to 235°C under a nitrogen atmosphere while stirring. After maintaining the mixture at 235°C for 6 hours, the pressure in the flask was reduced and maintained at 8.3kPa for 1 hour. After that, the mixture was returned to atmospheric pressure, and then cooled to 180°C, and 73g of adipic acid, 135g of dodecenylsuccinic anhydride, and 193g of trimellitic anhydride were added, and the mixture was heated to 220°C at 10°C/hr, and then the pressure in the flask was reduced and the reaction was carried out at 10kPa until the desired softening point, to obtain amorphous resin B-1. Various physical properties of the resin were measured and are shown in Table 1. Various physical properties of the resin were measured and are shown in Table 1.

Production Example D1 (Production of Resin D-1)
Resin D-1 was obtained in the same manner as in Production Example A1, except that the raw material composition was changed as shown in Table 1. The physical properties are shown in Table 1.

Production Example C1 (Production of Crystalline 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, 3416 g of 1,10-decanediol and 4084 g of sebacic acid were added, and the temperature was raised to 135° C. with stirring, and the mixture was maintained at 135° C. for 3 hours, and then the temperature was raised from 135° C. to 200° C. over 10 hours. Then, 23 g of tin(II) di(2-ethylhexanoate) was added, and the mixture was further maintained at 200° C. for 1 hour, after which the pressure in the flask was reduced and the mixture was maintained under a reduced pressure of 8 kPa for 1 hour, to obtain crystalline resin C-1. The physical properties are shown in Table 2.

[Production of Resin Particle Dispersion]
Production Example X1 (Production of Resin Particle Dispersion X-1)
210 g of amorphous resin A-1, 90 g of crystalline resin C-1, and 360 g of methyl ethyl ketone were placed in a 3 L reaction vessel equipped with a stirrer, a reflux condenser, a dropping funnel, a thermometer, and a nitrogen inlet tube, and the resins were dissolved by stirring for 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 with respect to the acid value of the resin was 50 mol%, and the mixture was stirred for 30 minutes.
Next, while maintaining the temperature at 73° C., 600 g of deionized water was added over 60 minutes while stirring at 280 r/min (circumferential speed 88 m/min) to cause phase inversion emulsification. While continuing to maintain the temperature at 73° C., methyl ethyl ketone was distilled off under reduced pressure to obtain an aqueous dispersion. Thereafter, while stirring at 280 r/min (circumferential speed 88 m/min), the aqueous dispersion was cooled to 30° C., and deionized water was added so that the solid content concentration was 30 mass%, and then the mixture was filtered through a 150 mesh wire net to obtain a resin particle dispersion X-1. The volume median particle diameter (D ₅₀ ) and CV value of the obtained resin particles are shown in Table 3.

Manufacturing Example Y1
(Preparation of Resin Particle Dispersion Y-1)
300 g of amorphous resin B-1 and 360 g of methyl ethyl ketone were placed in a 3 L reaction vessel equipped with a stirrer, a reflux condenser, a dropping funnel, a thermometer, and a nitrogen inlet tube, and the resin was dissolved over 2 hours at 40° C. A 5% by mass aqueous solution of sodium hydroxide was added to the resulting solution so that the degree of neutralization with respect to the acid value of amorphous resin B-1 was 60 mol%, and the mixture was stirred for 30 minutes.
Next, while maintaining the temperature at 40°C, 600 g of deionized water was added over 60 minutes while stirring at 280 r/min (circumferential speed 88 m/min), and phase inversion emulsification was performed. The temperature was raised to 73°C, and methyl ethyl ketone was distilled off under reduced pressure to obtain an aqueous dispersion. Thereafter, while stirring at 280 r/min (circumferential speed 88 m/min), the aqueous dispersion was cooled to 30°C, and deionized water was added so that the solid content concentration was 30 mass%, and then the mixture was filtered through a 150 mesh wire net to obtain a resin particle dispersion Y-1. The volume median particle diameter (D ₅₀ ) and CV value of the obtained resin particles are shown in Table 3.

Manufacturing example Z1
(Preparation of Resin Particle Dispersion Z-1)
200 g of Resin D-1 and 200 g of methyl ethyl ketone were placed in a 3 L reaction tank equipped with a stirrer, a reflux condenser, a dropping funnel, a thermometer, and a nitrogen inlet tube, and the resin was dissolved over 2 hours at 73° C. A 5% by mass aqueous solution of sodium hydroxide was added to the resulting solution so that the degree of neutralization with respect to the acid value of the amorphous resin D-1 was 60 mol %, and the mixture was stirred for 30 minutes.
Next, while maintaining the temperature at 73° C., 700 g of deionized water was added over 50 minutes while stirring at 280 r/min (circumferential speed 88 m/min), and phase inversion emulsification was performed. While continuing to maintain the temperature at 73° C., methyl ethyl ketone was distilled off under reduced pressure to obtain an aqueous dispersion. Thereafter, while continuing to stir at 280 r/min (circumferential speed 88 m/min), the aqueous dispersion was cooled to 30° C., and deionized water was added so that the solid content concentration was 20 mass%, and then the mixture was filtered through a 150 mesh wire net to obtain a resin particle dispersion Z-1. The volume median particle diameter (D ₅₀ ) of the obtained resin particles was 0.09 μm, and the CV value was 23%.

[Preparation of release agent particle dispersion]
Production Example W1 (Production of Release Agent Particle Dispersion W-1)
Into a 1 L beaker were added 120 g of deionized water, 86 g of resin particle dispersion Z-1, and 40 g of paraffin wax "HNP-9" (manufactured by Nippon Seiro Co., Ltd., melting point 75°C), and the mixture was melted by maintaining the temperature at 90 to 95°C and stirred to obtain a molten mixture.
The obtained molten mixture was dispersed for 20 minutes using an ultrasonic homogenizer "US-600T" (manufactured by Nippon Seiki Seisakusho Co., Ltd.) while maintaining the temperature at 90 to 95°C, and then cooled to room temperature (20°C). Deionized water was added to adjust the solid content to 20% by mass, thereby obtaining release agent particle dispersion W-1. The volume median particle diameter _D50 and CV value of the release agent particles in the dispersion are shown in Table 4.

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 used was changed to Fischer-Tropsch wax "FNP-0090" (manufactured by Nippon Seiro Co., Ltd., melting point 90°C). The volume median particle diameter _D50 and CV value of the release agent particles in the dispersion are shown in Table 4.

[Production of Addition Polymer]
Production Example E1 (Synthesis of Addition Polymer E-1)
16 g of methacrylic acid (manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd.), 44 g of styrene (manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd.), 30 g (15 g as solids) of styrene macromonomer "AS-6S" (manufactured by Toagosei Co., Ltd., number average molecular weight 6,000, solids content 50%), and 25 g of methoxypolyethylene glycol methacrylate "BLEMMER PME-200" (manufactured by NOF Corporation) were mixed to prepare 115 g of a monomer mixture.
Into a reaction vessel, 18 g of methyl ethyl ketone, 0.03 g of 2-mercaptoethanol as a chain transfer agent, and 10% (11.5 g) of the monomer mixture were placed and mixed, and the inside of the vessel was thoroughly purged with nitrogen gas.
On the other hand, the remaining 90% (103.5 g) of the monomer mixture was mixed with 0.27 g of the chain transfer agent, 42 g of methyl ethyl ketone, and 3 g of the polymerization initiator 2,2'-azobis(2,4-dimethylvaleronitrile) "V-65" (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and placed in a dropping funnel, and the mixed solution in the reaction vessel was heated to 75°C while stirring under a nitrogen atmosphere, and the mixed solution in the dropping funnel was dropped over 3 hours. After 2 hours at 75°C from the end of the dropping, a solution in which 3 g of the polymerization initiator was dissolved in 5 g of methyl ethyl ketone was added, and the mixture was further aged at 75°C for 2 hours and at 80°C for 2 hours. Thereafter, methyl ethyl ketone was distilled off under reduced pressure to obtain an addition polymer E-1. The weight average molecular weight of the obtained addition polymer is shown in Table 5.

[Preparation of Colorant Particle Dispersion]
Production Example F1 (Production of Colorant Particle Dispersion F-1)
In a 5L container equipped with a stirrer equipped with a dispersing blade, a reflux condenser, a dropping funnel, a thermometer and a nitrogen inlet tube, 75 g of the addition polymer E-1 was dissolved in 620 g of methyl ethyl ketone, and then 96 g of a 5% by mass aqueous sodium hydroxide solution and 942 g of deionized water were added as a neutralizing agent, and the mixture was stirred with a dispersing blade at 20 ° C. for 10 minutes. Thereafter, 300 g of copper phthalocyanine pigment "ECB-301" (manufactured by Dainichi Seika Chemicals Co., Ltd.) was added, and the mixture was stirred with a dispersing blade at 6400 r / min at 20 ° C. for 2 hours. Thereafter, the mixture was passed through a 200 mesh filter and treated with a homogenizer "Microfluidizer M-110EH" (manufactured by Microfluidics Co., Ltd.) at a pressure of 150 MPa for 15 passes. The resulting dispersion was stirred at 70 ° C. under reduced pressure to remove methyl ethyl ketone and some water. The mixture was then passed through a 200 mesh filter, and deionized water was added to give a solid content of 20% by mass, to obtain colorant particle dispersion F-1. The colorant particles in the dispersion had a volume median particle size ( _D50 ) of 0.12 μm and a CV value of 21%.

[Production of Resin Particles for Toner]
Example 1
(Preparation of toner resin particles 1)
[Step 1]
In a 10% dish-bottom cylindrical tank (inner diameter 0.16 m) with an internal volume of 3 L equipped with a stirrer, a stirring blade (Supermix blade (MR205 type, blade diameter 0.1 m)), a dropping funnel and a thermocouple, 360 g of resin particle dispersion X-1, 56 g of release agent particle dispersion W-1, 56 g of release agent particle dispersion W-2, 105 g of colorant particle dispersion F-1 and 290 g of deionized water were mixed at a temperature of 25° C. Next, while the mixture was stirred at a stirring speed of 200 r/min, a solution adjusted to pH 8.8 by adding 63 g of a 4.8 mass % potassium hydroxide aqueous solution to an aqueous solution obtained by dissolving 50 g of ammonium sulfate in 586 g of deionized water was dropped at 25° C. over 30 minutes. Thereafter, the temperature was raised to 62° C. over 2 hours, and the temperature was maintained at 62° C. until the volume median particle diameter _D50 of the aggregated particles reached 6.5 μm, thereby preparing a dispersion of aggregated particles (1). The total amount of the dispersion of aggregated particles (1) in step 1 was 1,566 g, and the solids concentration of the aggregated particles (1) was 9.7%.
[Step 2]
The dispersion of aggregated particles (1) was cooled to 56° C., and while maintaining the temperature at 56° C., a mixed solution of 54 g of resin particle dispersion Y-1 and 16 g of deionized water was added dropwise over one hour to prepare a dispersion of aggregated particles (2) in which resin particles Y were aggregated to aggregated particles (1). The volume median particle diameter _D50 of the obtained aggregated particles (2) was 6.7 μm. The total amount of the dispersion of aggregated particles (2) in step 2 was 1636 g, and the solids concentration of the aggregated particles (2) was 10.3%.
[Step 3]
To the dispersion of the aggregated particles (2), an aqueous solution of 6.2 g of a special β-naphthalenesulfonic acid formalin condensate sodium salt "Demol SN-B" (manufactured by Kao Corporation), which is an amphipathic molecule, was added in 34.4 g of deionized water. After that, the temperature was raised to 75°C over 1 hour, and then 90 g of 0.1 mol/L sulfuric acid was added and the temperature was maintained at 75°C until the circularity reached 0.970, to prepare a dispersion of fused particles (3) in which the aggregated particles (2) were fused. The pH before the addition of sulfuric acid was 7.1, and the pH after the addition of sulfuric acid was 6.9. The amount of sulfuric acid added was 2.4 times the molar equivalent of the acid group (carboxy group) possessed by the resin particles Y. Since the total amount of the dispersion in step 3 was 1766.6 g and the solid content of the aggregated particles (2) was 168.4 g, the solid content concentration of the aggregated particles (2) in step 3 was 9.5%.

(cooling process)
4.0 kg of deionized water was placed in a 20-liter container and cooled to 7.7° C. While stirring the cooled deionized water, 1780 g of the dispersion of fused particles (3) fused at 75° C. was added to the cooled deionized water over 10 seconds, and the mixture was stirred to cool the dispersion of fused particles (3) to 27° C. The cooled dispersion of fused particles (3) was passed through a 300-mesh sieve (pore size 45 μm) to obtain a dispersion of fused particles (4). The physical properties of the fused particles (4) are shown in Table 6. The residue on the mesh was washed with deionized water and then vacuum-dried at 33° C. for 48 hours to obtain coarse particles (5).

(filtration drying process)
The mesh-filtered dispersion of fused particles (4) was suction filtered to separate the solid content, and 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 48 hours using a vacuum low-temperature dryer (DRV622DA manufactured by ADVANTEC) to prepare toner particles (6). The coarse particle ratio was calculated from the mass of the coarse particles (5) and the mass of the toner particles (6), and the results are shown in Table 6.

Example 2
(Preparation of toner resin particles 2)
Toner resin particles 2 were prepared in the same manner as in Example 1, except that the amount of the amphiphilic molecule used in step 3 was changed to 15.5 g and the amount of deionized water was changed to 25.1 g. The physical properties and coarse particle ratio of the obtained fused particles are shown in Table 6.

Example 3
(Preparation of Toner Resin Particles 3)
Toner resin particles 3 were prepared in the same manner as in Example 1, except that the amount of the amphiphilic molecule used in step 3 was changed to 3.1 g and the amount of deionized water was changed to 37.5 g. The physical properties and coarse particle ratio of the obtained fused particles are shown in Table 6.

Example 4
(Preparation of Toner Resin Particles 4)
Toner resin particles 4 were prepared in the same manner as in Example 1, except that the amount of amphipathic molecule used in step 3 was changed to 3.1 g, the amount of deionized water to 37.5 g, and the sulfuric acid concentration to 0.2 mol/L. The physical properties and coarse particle ratio of the obtained fused particles are shown in Table 6. The amount of sulfuric acid added was 4.8 molar equivalents of the acid group (carboxy group) possessed by resin particle Y.

Example 5
(Preparation of Toner Resin Particles 5)
Toner resin particles 5 were prepared in the same manner as in Example 2, except that the amphiphilic molecule used in step 3 was changed as shown in Table 6. The physical properties and coarse particle ratio of the obtained fused particles are shown in Table 6.

Comparative Example 1
(Preparation of Toner Resin Particles 6)
The amphiphilic molecule used in step 3 was changed as shown in Table 6. Since the package was an aqueous solution with an effective concentration of 27% by mass, 57.2 g of the aqueous solution was added without dissolving or diluting, but the procedure was the same as in Example 1 to prepare toner resin particles 6. The physical properties and coarse particle ratio of the obtained fused particles are shown in Table 6.

Comparative Example 2
(Preparation of Toner Resin Particles 7)
Toner resin particles 7 were prepared in the same manner as in Example 5, except that sulfuric acid was not added in step 3. Table 6 shows the physical properties of the obtained fused particles and the rate of coarse particles.

From the results of the Examples and Comparative Examples, it was found that according to the present invention, fused particles with excellent circularity and a low rate of coarse particles were obtained, even when the solid content of the aggregated particles in step 3 was high.

Claims (11)

The method includes the following steps 1 and 3 in this order, or the following steps 1 to 3 in this order:
Step 1: A step of aggregating resin particles X in an aqueous medium to obtain aggregated particles 1;
Step 2: A step of aggregating resin particles Y to the aggregated particles 1 obtained in step 1 to obtain aggregated particles 2;
Step 3: A step of heating the aggregated particles 1 obtained in step 1 or the aggregated particles 2 obtained in step 2 to fuse them to obtain fused particles,
In step 3, an amphiphilic molecule having a naphthalene ring and an acidic substance are added.
A method for producing a toner for developing electrostatic images. The method for producing a toner for developing electrostatic images according to claim 1, wherein in step 3, the solid content concentration of aggregated particles 1 or aggregated particles 2 is 7% by mass or more. The method for producing a toner for developing electrostatic images according to claim 1 or 2, wherein the circularity of the fused particles is 0.955 or more. The method for producing a toner for developing electrostatic images according to any one of claims 1 to 3, wherein the amount of the amphiphilic molecule having a naphthalene ring added in step 3 is 1 part by mass or more per 100 parts by mass of aggregated particles 1 or aggregated particles 2. The method for producing a toner for developing electrostatic images according to any one of claims 1 to 4, wherein the amphiphilic molecule having a naphthalene ring is a formaldehyde condensate of an unsubstituted or substituted naphthalene sulfonate. The method for producing a toner for developing electrostatic images according to any one of claims 1 to 5, wherein the resin particles Y contain a polyester resin B having an aromatic ring. The method for producing a toner for developing electrostatic images according to any one of claims 1 to 6, wherein the resin particles X contain an amorphous polyester resin A. The method for producing a toner for developing electrostatic images according to any one of claims 1 to 7, wherein the resin particles X contain a crystalline polyester resin C. The method for producing a toner for developing electrostatic images according to any one of claims 1 to 8, wherein in step 3, the pH of the aqueous medium after the addition of the acidic substance is 5.0 or more and 7.0 or less. The method for producing a toner for developing electrostatic images according to any one of claims 1 to 9, wherein in step 3, an acidic substance is added to lower the pH of the aqueous medium by 0.1 or more and 2.0 or less. The method for producing a toner for developing electrostatic images according to any one of claims 1 to 10, wherein in step 3, an amphiphilic molecule having a naphthalene ring is added, and then the temperature is raised to fuse the mixture.