JP2024073394A - Toner for developing electrostatic images - Google Patents

Abstract

[Problem] Toner for developing electrostatic images with excellent charging stability. [Solution] Toner for developing electrostatic images containing a crystalline polyester resin, an amorphous resin A, and a quaternary ammonium salt compound X, the crystalline polyester resin being a polycondensate of an alcohol component containing 80 mol % or more of ethylene glycol and a carboxylic acid component containing an aliphatic dicarboxylic acid compound, and containing a crystalline polyester resin C having an ester group concentration of 6.0 mmol/g or more and 9.0 mmol/g or less and/or a composite resin containing the crystalline polyester resin C. [Selected Figure] None

Description

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

As a binder resin for toner, crystalline polyester resin is known to be effective in improving the low-temperature fixing properties of toner, and its use in combination with amorphous resin is also being considered.

Patent Document 1 discloses an image forming apparatus including an image carrier, a developing device that contains toner and is configured to develop an electrostatic latent image formed on the image carrier with the toner to form a toner image on the image carrier, a transfer section that transfers the toner image on the image carrier to a recording medium, and a fixing device that fixes the toner image transferred to the recording medium to the recording medium, the fixing device including a first roller and a second roller, and is configured to fix the toner image to the recording medium by sandwiching the recording medium such that the first roller contacts the toner image transferred to the front side of the recording medium and the second roller contacts the rear side of the recording medium, the first roller having a coating layer containing a fluororesin and having a surface resistivity of 1.0×10 ¹⁰ Ω or more on a surface layer portion, and the toner substantially contained in the developing device in an initial state includes a plurality of toner particles containing a crystalline polyester resin having a volume resistivity of 7×10 ⁹ Ω·cm or less and a non-crystalline resin.

Patent document 2 discloses a toner containing toner particles, the toner particles comprising toner base particles having a sea-like domain containing a non-crystalline polyester resin and an island-like domain distributed in an island shape relative to the sea-like domain, the island-like domain containing a crystalline polyester resin and a cellulose nanofiber.

Patent Document 3 discloses a toner for developing electrostatic latent images, which contains a plurality of toner particles containing a crystalline polyester resin and a non-crystalline polyester resin, and in the storage elastic modulus temperature dependence curve of the toner, a shoulder exists in the range of a temperature of 69° C. or more and 93° C. or less and a storage elastic modulus of 1.00×10 ⁶ Pa or more and 1.00×10 ⁷ Pa or less, the storage elastic modulus at a temperature of 180° C. is 1.00×10 ³ Pa or more and 1.00×10 ⁴ Pa or less, and the softening point of the toner measured with a flow tester is 115° C. or more and 125° C. or less.

JP 2017-198835 A JP 2020-16689 A JP 2017-151253 A

On the other hand, quaternary ammonium salt compounds have high positive charging properties, but have issues with charging stability.

The present invention relates to a toner for developing electrostatic images that has excellent charging stability.

The present invention relates to a toner for developing electrostatic images, which contains a crystalline polyester resin, an amorphous resin A, and a quaternary ammonium salt compound X, in which the crystalline polyester resin is a polycondensate of an alcohol component containing 80 mol % or more of ethylene glycol and a carboxylic acid component containing an aliphatic dicarboxylic acid compound, and which contains a crystalline polyester resin C having an ester group concentration of 6.0 mmol/g or more and 9.0 mmol/g or less and/or a composite resin containing the crystalline polyester resin C.

The toner for developing electrostatic images of the present invention exhibits excellent effects in terms of charge stability.

The present invention is a toner for developing electrostatic images that contains a crystalline polyester resin, an amorphous resin A, and a quaternary ammonium salt compound X, and is characterized in that the crystalline polyester resin is a polycondensate obtained using ethylene glycol as the alcohol component, and contains a crystalline polyester resin C having an ester group concentration of 6.0 mmol/g or more and 9.0 mmol/g or less and/or a composite resin containing the crystalline polyester resin C. The reason why the toner for developing electrostatic images of the present invention has excellent charge stability is unclear, but is presumed to be as follows.

Quaternary ammonium salt compounds are in a cationic state, and therefore are incompatible with amorphous resins, making them difficult to disperse in the amorphous resin, and thus posing a problem in terms of charging stability. In response to this, the present invention has found that the dispersibility of quaternary ammonium salt compounds is improved by using a crystalline polyester resin C that contains ethylene glycol as an alcohol component and has a predetermined ester group concentration. This is because the ester groups sandwiching the ethylene glycol portion in the crystalline polyester resin C are likely to interact with the quaternary ammonium salt, which is the cationic site, and the ester group concentration of the crystalline polyester resin C is within a specific range, which allows sufficient interaction with the quaternary ammonium salt compound while suppressing aggregation between the crystalline polyester resins C themselves. As a result, the dispersibility of the quaternary ammonium salt compound in the amorphous resin is improved, and the conductive path is reduced, improving charging stability.

In the present invention, the crystalline polyester resin is a crystalline polyester resin C, which is a polycondensation product of an alcohol component containing ethylene glycol and a carboxylic acid component containing an aliphatic dicarboxylic acid compound, and/or a composite resin containing the crystalline polyester resin C. In the present invention, the composite resin is more preferable from the viewpoint of improving the charging stability.

The crystallinity of a resin is represented by a crystallinity index defined as the ratio of the softening point to the maximum endothermic peak temperature measured by a differential scanning calorimeter, i.e., the value of [softening point/maximum endothermic peak temperature]. A crystalline resin is a resin having a crystallinity index of 0.6 or more, preferably 0.7 or more, more preferably 0.9 or more, and 1.4 or less, preferably 1.2 or less, more preferably 1.1 or less.
On the other hand, an amorphous resin is a resin in which no endothermic peak is observed, or if an endothermic peak is observed, the crystallinity index is greater than 1.4, preferably greater than 1.5, more preferably 1.6 or more, or less than 0.6, preferably 0.5 or less.
The crystallinity of the resin can be adjusted by the type and ratio of the raw material monomers, and the production conditions (e.g., reaction temperature, reaction time, cooling rate), etc. The maximum endothermic peak temperature refers to the temperature of the peak with the largest peak area among the observed endothermic peaks. In the case of a crystalline resin, the maximum endothermic peak temperature is the melting point.

The content of ethylene glycol in the alcohol component is 80 mol% or more, preferably 90 mol% or more, more preferably 95 mol% or more, and 100 mol% or less, from the viewpoints of low-temperature fixability and smear resistance, and when the alcohol component contains a monoalcohol, it is preferably 98 mol% or less, more preferably 95 mol% or less.

Examples of alcohol components other than ethylene glycol include aliphatic diols other than ethylene glycol, such as 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, neopentyl glycol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, and 1,12-dodecanediol; aromatic diols such as alkylene oxide adducts of bisphenol A; bisphenol A, hydrogenated bisphenol A, sorbitol, pentaerythritol, glycerin, and trimethylolpropane or higher alcohols.

Examples of aliphatic dicarboxylic acid compounds include succinic acid (carbon number: 4), fumaric acid (carbon number: 4), adipic acid (carbon number: 6), suberic acid (carbon number: 8), azelaic acid (carbon number: 9), sebacic acid (carbon number: 10), dodecanedioic acid (carbon number: 12), tetradecanedioic acid (carbon number: 14), succinic acid having an alkyl or alkenyl group on the side chain, anhydrides of these acids, and alkyl esters of these acids having 1 to 3 carbon atoms. Here, when the aliphatic dicarboxylic acid compound is an alkyl ester, the number of carbon atoms of the alkyl group is not included in the above carbon number.

From the viewpoint of hydrophobicity, the carbon number of the aliphatic dicarboxylic acid compound is preferably 4 or more, more preferably 10 or more, and even more preferably 12 or more, and from the viewpoint of low-temperature fixability, it is preferably 16 or less, and more preferably 14 or less.

The content of the aliphatic dicarboxylic acid compound in the carboxylic acid component is, from the viewpoint of hydrophobicity, preferably 50 mol% or more, more preferably 60 mol% or more, even more preferably 70 mol% or more, even more preferably 80 mol% or more, and 100 mol% or less. When the carboxylic acid component contains a monocarboxylic acid compound, it is preferably 98 mol% or less, more preferably 95 mol% or less.

Other carboxylic acid components include aromatic dicarboxylic acid compounds such as phthalic acid, isophthalic acid, and terephthalic acid, and trivalent or higher carboxylic acid compounds such as trimellitic acid and pyromellitic acid.

Furthermore, it is preferable that the alcohol component and/or the carboxylic acid component of the crystalline polyester resin C contain a monofunctional monomer.

Examples of monofunctional monomers contained in the alcohol component include aliphatic monoalcohols such as capryl alcohol, lauryl alcohol, myristyl alcohol, palmityl alcohol, stearyl alcohol, and behenyl alcohol.

Examples of monofunctional monomers contained in the carboxylic acid component include aliphatic monocarboxylic acids such as capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, and behenic acid, and aliphatic monocarboxylic acid compounds such as alkyl esters of these acids in which the alkyl group has 1 to 3 carbon atoms.

From the viewpoint of improving hydrophobicity, it is preferable that the monofunctional monomer contains an aliphatic monocarboxylic acid compound and/or an aliphatic monoalcohol.

From the viewpoint of hydrophobicity, the carbon number of the aliphatic monoalcohol is preferably 10 or more, more preferably 12 or more, and even more preferably 14 or more, and from the viewpoint of low-temperature fixability, it is preferably 22 or less, more preferably 20 or less, and even more preferably 18 or less.

The carbon number of the aliphatic monocarboxylic acid compound is preferably 10 or more, more preferably 12 or more, and even more preferably 14 or more, from the viewpoint of hydrophobicity, and is preferably 22 or less, more preferably 20 or less, and even more preferably 18 or less, from the viewpoint of low-temperature fixability. Here, when the aliphatic monocarboxylic acid compound is an alkyl ester, the carbon number of the alkyl group is not included in the above carbon number.

The content of monofunctional monomers in the raw material monomers (the total amount of alcohol components and carboxylic acid components) is preferably 1 mol% or more, more preferably 3 mol% or more, and even more preferably 5 mol% or more, and from the viewpoint of low-temperature fixability, is preferably 30 mol% or less, more preferably 20 mol% or less, and even more preferably 15 mol% or less.

In this specification, macromonomers and hydroxycarboxylic acids are not included in the alcohol component and carboxylic acid component.

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 0.8 or more, more preferably 0.9 or more, from the viewpoint of charging stability, and is preferably 1.2 or less, more preferably 1.1 or less, from the viewpoint of low-temperature fixability.

Crystalline polyester resin C can be produced, for example, by polycondensing an alcohol component and a carboxylic acid component in an inert gas atmosphere, preferably in the presence of an esterification catalyst, and, if necessary, in the presence of an esterification promoter, a polymerization inhibitor, etc., at a temperature preferably between 120°C and 230°C.

Examples of the esterification catalyst include tin compounds such as dibutyltin oxide and tin(II) 2-ethylhexanoate, and titanium compounds such as titanium diisopropylate bistriethanolamine. The amount of the esterification catalyst used is preferably 0.01 parts by mass or more, more preferably 0.1 parts by mass or more, and preferably 1.5 parts by mass or less, and more preferably 1 part by mass or less, relative to 100 parts by mass of the total amount of the alcohol component and the carboxylic acid component. Examples of the esterification promoter include gallic acid. The amount of the esterification promoter used is preferably 0.001 parts by mass or more, more preferably 0.01 parts by mass or more, and preferably 0.5 parts by mass or less, and more preferably 0.1 parts by mass or less, relative to 100 parts by mass of the total amount of the alcohol component and the carboxylic acid component. Examples of the polymerization inhibitor include tert-butylcatechol. The amount of the polymerization inhibitor used is preferably 0.001 parts by mass or more, more preferably 0.01 parts by mass or more, and preferably 0.5 parts by mass or less, more preferably 0.1 parts by mass or less, per 100 parts by mass of the total amount of the alcohol component and the carboxylic acid component.

In the present invention, the polyester resin may be modified to such an extent that its properties are not substantially impaired. Examples of modified polyester resins include polyester resins grafted or blocked with phenol, urethane, epoxy, or the like, by the methods described in JP-A-11-133668, JP-A-10-239903, JP-A-8-20636, and the like. Among the modified polyester resins, urethane-modified polyester resins in which polyester resins are urethane-extended with a polyisocyanate compound are preferred.

When the ester group concentration of the crystalline polyester resin C is 6.0 mmol/g or more, there are sufficient interaction points with the quaternary ammonium salt compound X, and the dispersibility of the quaternary ammonium salt compound X is improved. On the other hand, when the ester group concentration of the crystalline polyester resin C is 9.0 mmol/g or less, the dispersibility of the quaternary ammonium salt compound X is improved, possibly because the aggregation between the crystalline polyester resins C is suppressed, and the interaction with the quaternary ammonium salt compound X is maintained. Therefore, from these viewpoints, the ester group concentration of the crystalline polyester resin C is 6.0 mmol/g or more, preferably 6.2 mmol/g or more, more preferably 6.5 mmol/g or more, and 9.0 mmol/g or less, preferably 8.0 mmol/g or less, more preferably 7.8 mmol/g or less.

The ester group concentration of crystalline polyester resin C is calculated using the following formula:

[In the formula, A is the total amount (mol) of ester bonds produced when all of the raw material monomers (E) of the polyester resin are reacted, and B is the total mass (g) of the raw material monomers (E) that make up the polyester resin. The numbers in parentheses in the formula indicate the units of each value.]

From the viewpoint of improving charging stability, a composite resin in which crystalline polyester resin C is combined with a styrene-based resin is preferred as the composite resin.

In the composite resin containing the crystalline polyester resin C and the styrene-based resin, the styrene-based resin is an addition polymer of raw material monomers containing at least styrene or a styrene derivative such as α-methylstyrene or vinyltoluene (hereinafter, styrene and styrene derivatives are collectively referred to as "styrene compounds").

The content of the styrene compound, preferably styrene, in the raw material monomer of the styrene-based resin is preferably 50% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, and 100% by mass or less, from the viewpoint of charging stability.

The raw material monomers for styrene-based resins may include raw material monomers other than styrene compounds, such as (meth)acrylic acid alkyl esters; ethylenically unsaturated monoolefins such as ethylene and propylene; diolefins such as butadiene; halovinyls such as vinyl chloride; vinyl esters such as vinyl acetate and vinyl propionate; ethylenically monocarboxylic acid esters such as dimethylaminoethyl (meth)acrylate; vinyl ethers such as methyl vinyl ether; vinylidene halides such as vinylidene chloride; and N-vinyl compounds such as N-vinylpyrrolidone.

The addition polymerization reaction of the raw material monomers for styrene-based resins can be carried out in the presence of a polymerization initiator such as dibutyl peroxide or dicumyl peroxide, a polymerization inhibitor, a crosslinking agent, etc., in the presence of an organic solvent or without a solvent, by a conventional method, and the temperature conditions are preferably 110°C or higher, more preferably 140°C or higher, and preferably 200°C or lower, more preferably 170°C or lower.

When an organic solvent is used in the addition polymerization reaction, xylene, toluene, methyl ethyl ketone, acetone, etc. can be used. The amount of the organic solvent used is preferably 10 parts by mass or more and 50 parts by mass or less per 100 parts by mass of the raw material monomer of the styrene-based resin.

The composite resin is preferably a resin in which a polyester resin (crystalline polyester resin C in the case of crystalline polyester resin) is bonded to a styrene resin, and more preferably a resin in which the polyester resin and the styrene resin are chemically bonded to each other via a bireactive monomer that can react with both the raw monomers of the polyester resin and the raw monomers of the styrene resin.

The bireactive monomer is preferably a compound having at least one functional group selected from the group consisting of hydroxyl, carboxyl, epoxy, primary amino, and secondary amino groups, preferably a hydroxyl and/or carboxyl group, more preferably a carboxyl group, and an ethylenically unsaturated bond in the molecule, more preferably at least one selected from the group consisting of acrylic acid, methacrylic acid, fumaric acid, maleic acid, and maleic anhydride, and from the viewpoint of the reactivity of the polycondensation reaction and the addition polymerization reaction, still more preferably at least one selected from the group consisting of acrylic acid, methacrylic acid, and fumaric acid. However, when used together with a polymerization inhibitor, a polyvalent carboxylic acid compound having an ethylenically unsaturated bond such as fumaric acid functions as a raw material monomer for polyester resin. In this case, fumaric acid, etc. is not a bireactive monomer, but a raw material monomer for polyester resin.

The amount of the bireactive monomer used is preferably 1 mol or more, more preferably 2 mol or more, relative to 100 mol of the total of the alcohol components of the polyester resin, from the viewpoint of increasing the dispersibility of the styrene resin and the polyester resin and improving the charging stability of the toner, and is preferably 30 mol or less, more preferably 20 mol or less, from the viewpoint of low-temperature fixing property.
The amount of the bireactive monomer used is preferably 1 part by mass or more, more preferably 2 parts by mass or more, relative to 100 parts by mass of the raw material monomers of the styrene resin, from the viewpoint of increasing the dispersibility of the styrene resin and the polyester resin and improving the charging stability of the toner, and is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 10 parts by mass or less, from the viewpoint of low-temperature fixability. Here, the polymerization initiator is included in the total amount of the raw material monomers of the styrene resin.

Specifically, the composite resin is preferably produced by the following method. When a bireactive monomer is used, it is preferable to use the bireactive monomer in an addition polymerization reaction together with the raw material monomer of the styrene-based resin from the viewpoint of improving the charge stability and low-temperature fixing property of the toner.

(i) A method of carrying out step (A) of polycondensation reaction with raw material monomers of polyester resin, followed by step (B) of addition polymerization reaction with raw material monomers of styrene resin and bireactive monomers. In this method, step (A) is carried out under reaction temperature conditions suitable for polycondensation reaction, the reaction temperature is lowered, and step (B) is carried out under temperature conditions suitable for addition polymerization reaction. The raw material monomers of styrene resin and bireactive monomers are preferably added to the reaction system at a temperature suitable for addition polymerization reaction. The bireactive monomers carry out addition polymerization reaction and also react with polyester resin.
After step (B), the reaction temperature is increased again, and if necessary, a raw material monomer of a polyester resin having a valence of 3 or more and serving as a crosslinking agent is added to the polymerization system, so that the polycondensation reaction of step (A) and the reaction with the bireactive monomer can be further promoted.

(ii) A method in which step (B) of an addition polymerization reaction of raw material monomers of a styrene-based resin and a bireactive monomer is followed by step (A) of a polycondensation reaction of raw material monomers of a polyester resin. In this method, step (B) is carried out under reaction temperature conditions suitable for an addition polymerization reaction, and the reaction temperature is raised to carry out the polycondensation reaction of step (A) under temperature conditions suitable for a polycondensation reaction. The bireactive monomer is involved in both the polycondensation reaction as well as the addition polymerization reaction.
The raw material monomers of the polyester resin may be present in the reaction system during the addition polymerization reaction, or may be added to the reaction system under temperature conditions suitable for the polycondensation reaction. In the former case, the progress of the polycondensation reaction can be controlled by adding an esterification catalyst at a temperature suitable for the polycondensation reaction.

(iii) A method of carrying out the reaction under conditions in which the step (A) of the polycondensation reaction of the raw material monomer of the polyester resin and the step (B) of the addition polymerization reaction of the raw material monomer of the styrene resin and the bireactive monomer proceed in parallel. In this method, it is preferable to carry out the steps (A) and (B) in parallel under reaction temperature conditions suitable for the addition polymerization reaction, raise the reaction temperature, add a raw material monomer of the polyester resin having a valence of 3 or more as a crosslinking agent to the polymerization system as necessary under temperature conditions suitable for the polycondensation reaction, and further carry out the polycondensation reaction of step (A). At that time, under temperature conditions suitable for the polycondensation reaction, it is also possible to add a polymerization inhibitor to proceed with only the polycondensation reaction. The bireactive monomer is involved in the polycondensation reaction as well as the addition polymerization reaction.

In the above method (i), a prepolymerized polycondensation resin may be used instead of step (A) in which a polycondensation reaction is carried out. In the above method (iii), when the reaction is carried out under conditions in which steps (A) and (B) proceed in parallel, a mixture containing raw material monomers for a styrene resin may be dripped into a mixture containing raw material monomers for a polyester resin to cause the reaction.

The above methods (i) to (iii) are preferably carried out in the same container.

The mass ratio of the polyester resin to the styrene resin in the composite resin (polyester resin/styrene resin) is preferably 98/2 or less, more preferably 95/5 or less, and even more preferably 90/10 or less from the viewpoint of charging stability, and is preferably 60/40 or more, more preferably 70/30 or more, more preferably 75/25 or more, and even more preferably 85/15 or more from the viewpoint of low-temperature fixability. In the above calculation, the mass of the polyester resin is the mass of the raw material monomer of the polyester resin used minus the amount of reaction water dehydrated by the polycondensation reaction (calculated value), and the amount of the bireactive monomer is included in the amount of raw material monomer of the polyester resin. The amount of the styrene resin is the total amount of the raw material monomer of the styrene resin and the polymerization initiator.

The softening point of the crystalline polyester resin is preferably 50°C or higher, more preferably 65°C or higher, and even more preferably 70°C or higher, from the viewpoint of charging stability, and is preferably 120°C or lower, and more preferably 110°C or lower, from the viewpoint of low-temperature fixability.

The melting point of the crystalline polyester resin is preferably 60°C or higher, more preferably 70°C or higher, from the viewpoint of charge stability, and is preferably 130°C or lower, more preferably 120°C or lower, from the viewpoint of low-temperature fixability.

The acid value of the crystalline polyester resin is preferably 1 mgKOH/g or more, more preferably 3 mgKOH/g or more, from the viewpoint of low-temperature fixability, and is preferably 40 mgKOH/g or less, more preferably 30 mgKOH/g or less, and even more preferably 20 mgKOH/g or less, from the viewpoint of charge stability.

The content of the crystalline polyester resin in the total amount of the crystalline polyester resin and the amorphous resin A is preferably 3% by mass or more, more preferably 4% by mass or more, and even more preferably 5% by mass or more, from the viewpoint of low-temperature fixing property, and is preferably 30% by mass or less, more preferably 25% by mass or less, and even more preferably 20% by mass or less, from the viewpoint of charging stability.

Examples of the amorphous resin A include amorphous polyester resin, composite resin in which polyester resin is bonded to a styrene-based resin, polyamide resin, vinyl resin such as styrene-acrylic resin, epoxy resin, polycarbonate resin, polyurethane resin, etc., but in the present invention, from the viewpoint of improving the charging stability, amorphous polyester resin or composite resin is preferred, and amorphous polyester resin is more preferred.

As the amorphous polyester resin, a polycondensation product of an alcohol component and a carboxylic acid component, including an alkylene oxide adduct of bisphenol A, is preferred.

The alkylene oxide adduct of bisphenol A is represented by the formula (I):

(wherein ^OR1 and ^R1O are oxyalkylene groups, ^R1 is an ethylene group and/or a propylene group, x and y are the average number of moles of alkylene oxide added, each of which is a positive number, and the sum of x and y is 1 or more, preferably 1.5 or more, and 16 or less, preferably 8 or less, more preferably 6 or less, and even more preferably 4 or less.)
Preferred is a compound represented by the following formula:

From the viewpoint of low-temperature fixability, the content of the alkylene oxide adduct of bisphenol A in the alcohol component is preferably 70 mol% or more, more preferably 80 mol% or more, even more preferably 90 mol% or more, even more preferably 95 mol% or more, and even more preferably 100 mol%.

Other alcohol components include aliphatic diols, bisphenol A, hydrogenated bisphenol A, sorbitol, pentaerythritol, glycerin, trimethylolpropane, and other trihydric or higher alcohols.

Carboxylic acid components include aliphatic dicarboxylic acid compounds, aromatic dicarboxylic acid compounds, trivalent or higher carboxylic acid compounds, etc.

Aliphatic dicarboxylic acid compounds include fumaric acid, maleic acid, succinic acid, succinic acid derivatives substituted with hydrocarbon groups, glutaric acid, adipic acid, sebacic acid, anhydrides of these acids, and alkyl esters of these acids having 1 to 3 carbon atoms.

Specific examples of succinic acid derivatives substituted with a hydrocarbon group include dodecylsuccinic acid, dodecenylsuccinic acid, tetrapropenylsuccinic acid, decenylsuccinic acid, their acid anhydrides, and their alkyl esters having 1 to 3 carbon atoms. Among these, from the viewpoint of low-temperature fixability, dodecenylsuccinic acid, tetrapropenylsuccinic acid, or their acid anhydrides are preferred, and dodecenylsuccinic anhydride is more preferred.

From the viewpoint of hydrophobicity, the number of carbon atoms in the hydrocarbon group in the succinic acid derivative is preferably 8 or more, more preferably 10 or more, even more preferably 12 or more, and is preferably 20 or less, more preferably 18 or less, even more preferably 16 or less.

The content of the succinic acid derivative in the carboxylic acid component is preferably 1 mol% or more, more preferably 5 mol% or more, and even more preferably 7 mol% or more from the viewpoint of hydrophobicity, and is preferably 40 mol% or less, more preferably 35 mol% or less, and even more preferably 30 mol% or less from the viewpoint of charge stability.

Examples of aromatic dicarboxylic acid compounds include phthalic acid, isophthalic acid, terephthalic acid, anhydrides of these acids, and alkyl esters of these acids having 1 to 3 carbon atoms.

Examples of trivalent or higher carboxylic acid compounds include trimellitic acid, pyromellitic acid, anhydrides of these acids, and alkyl esters of these acids having 1 to 3 carbon atoms.

In addition to the alcohol component and the carboxylic acid component, polyethylene terephthalate (PET) may be used. PET, or ethylene glycol and terephthalic acid produced by depolymerizing a portion of it, are used as raw material monomers in a polycondensation reaction and are incorporated into the polyester resin. PET is an equimolar polycondensation product of ethylene glycol and terephthalic acid, and the ethylene glycol and terephthalic acid that make up PET are regarded as the alcohol component and the carboxylic acid component, respectively.

In addition, the alcohol component may contain a monohydric alcohol, and the carboxylic acid component may contain a monovalent carboxylic acid compound, as appropriate.

From the viewpoint of adjusting the softening point of the polyester resin, 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 0.6 or more, more preferably 0.7 or more, even more preferably 0.75 or more, and is preferably 1.2 or less, more preferably 1.15 or less.

The polycondensation reaction conditions of the alcohol component and the carboxylic acid component of the amorphous polyester resin are the same as those of the crystalline polyester resin C, except that the suitable reaction temperature is preferably 130°C or higher, more preferably 170°C or higher, and preferably 250°C or lower, more preferably 240°C or lower.

In the composite resin containing the polyester resin and the styrene-based resin, the polyester resin is the same as the amorphous polyester resin, and other than the preferred form of the raw material monomer of the styrene-based resin being different (bireactive monomer, manufacturing method, etc.), it is the same as the composite resin as the crystalline polyester-based resin.

Styrenic resins, like the composite resins for the crystalline polyester resins, are addition polymers of raw material monomers that contain styrene compounds.

The content of the styrene compound, preferably styrene, in the raw material monomer of the styrene-based resin is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass or more, from the viewpoint of charging stability, and is preferably 95% by mass or less, more preferably 93% by mass or less, and even more preferably 90% by mass or less, from the viewpoint of low-temperature fixing property.

The styrene-based resin may also contain, as a raw material monomer, an alkyl (meth)acrylate ester having an alkyl group with 7 or more carbon atoms. Examples of alkyl (meth)acrylate esters include 2-ethylhexyl (meth)acrylate, (iso)octyl (meth)acrylate, (iso)decyl (meth)acrylate, and (iso)stearyl (meth)acrylate. It is preferable to use one or more of these. In this specification, "(iso)" means that both the case where this group is present and the case where it is not present are included, and when these groups are not present, it indicates that it is normal. Furthermore, "(meth)acrylic acid" refers to acrylic acid, methacrylic acid, or both.

The number of carbon atoms in the alkyl group in the (meth)acrylic acid alkyl ester used as a raw material monomer for the styrene-based resin is preferably 7 or more, more preferably 8 or more, and preferably 12 or less, more preferably 10 or less, from the viewpoint of improving the low-temperature fixing property of the toner. The number of carbon atoms in the alkyl ester refers to the number of carbon atoms derived from the alcohol component that constitutes the ester.

The content of the (meth)acrylic acid alkyl ester in the raw material monomer of the styrene-based resin is preferably 5% by mass or more, more preferably 7% by mass or more, and even more preferably 10% by mass or more, from the viewpoint of low-temperature fixability, and is preferably 50% by mass or less, more preferably 30% by mass or less, and even more preferably 20% by mass or less, from the viewpoint of charging stability.

The softening point of the amorphous resin A is preferably 90°C or higher, more preferably 100°C or higher, from the viewpoint of charging stability, and is preferably 150°C or lower, more preferably 140°C or lower, from the viewpoint of low-temperature fixing ability.

From the viewpoint of low-temperature fixing property and fixing width, the amorphous resin A may be made of resins with different softening points. The difference in the softening points of the two types of resins is preferably 10°C or more, more preferably 12°C or more, and is preferably 60°C or less, more preferably 40°C or less.

The softening point of the amorphous resin with the higher softening point (resin AH) is preferably 100°C or higher, more preferably 110°C or higher, and even more preferably 120°C or higher, from the viewpoint of fixing width, and is preferably 180°C or lower, more preferably 170°C or lower, and even more preferably 160°C or lower, from the viewpoint of low-temperature fixing ability.

The softening point of the amorphous resin with the lower softening point (resin AL) is preferably 70°C or higher, more preferably 90°C or higher, and even more preferably 100°C or higher, from the viewpoint of charging stability, and is preferably 130°C or lower, more preferably 125°C or lower, and even more preferably 120°C or lower, from the viewpoint of low-temperature fixing ability.

The mass ratio of resin AH to resin AL (resin AH/resin AL) is preferably 10/90 or more, more preferably 20/80 or more, even more preferably 30/70 or more, and preferably 90/10 or less, more preferably 80/20 or less, even more preferably 70/30 or less.

The glass transition temperature of the amorphous resin A is preferably 40°C or higher, more preferably 50°C or higher, from the viewpoint of charge stability, and is preferably 80°C or lower, more preferably 70°C or lower, from the viewpoint of low-temperature fixability.

From the viewpoint of low-temperature fixing ability, the acid value of the amorphous resin A is preferably 1 mgKOH/g or more, more preferably 3 mgKOH/g or more, and from the viewpoint of charging stability, it is preferably 20 mgKOH/g or less, more preferably 15 mgKOH/g or less.

The content of amorphous resin A in the total amount of crystalline polyester resin and amorphous resin A is preferably 70% by mass or more, more preferably 75% by mass or more, and even more preferably 80% by mass or more, from the viewpoint of low-temperature fixability, and is preferably 97% by mass or less, more preferably 96% by mass or less, and even more preferably 95% by mass or less, from the viewpoint of charging stability.

The mass ratio of the crystalline polyester resin to the amorphous resin A (crystalline polyester resin/amorphous resin A) is preferably 3/97 or more, more preferably 4/96 or more, and even more preferably 5/95 or more, from the viewpoint of low-temperature fixability, and is preferably 30/70 or less, more preferably 25/75 or less, and even more preferably 20/80 or less, from the viewpoint of charging stability.

In the toner, crystalline polyester resin and amorphous resin A are contained as binder resins.

The total content of the crystalline polyester resin and the amorphous resin A in the binder resin is preferably 70% 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 even more preferably 100% by mass.

The content of the binder resin in the toner is preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, and is preferably less than 100% by mass, more preferably 98% by mass or less, even more preferably 95% by mass or less.

As the quaternary ammonium salt compound X, from the viewpoint of charging stability, a polymeric quaternary ammonium salt-containing resin is preferred, and a quaternary ammonium salt-containing styrene-based resin is more preferred.

The quaternary ammonium salt-containing styrene-based resin is not particularly limited, but is preferably, for example, a copolymer of a styrene monomer (M1) and/or an (meth)acrylic acid alkyl ester monomer (M2) and a quaternary ammonium salt of a dialkylaminoalkyl (meth)acrylate monomer (M3).

The styrene monomer (M1) is styrene and does not include styrene derivatives such as α-methylstyrene, p-methylstyrene, and p-chlorostyrene.

Examples of (meth)acrylic acid alkyl ester monomers (M2) include methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, propyl (meth)acrylate, amyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, cyclohexyl (meth)acrylate, lauryl (meth)acrylate, and stearyl (meth)acrylate. The alkyl group preferably has 4 to 12 carbon atoms. Among these, butyl (meth)acrylate or 2-ethylhexyl (meth)acrylate is preferred, with butyl (meth)acrylate being more preferred.

The quaternary ammonium salt (M3) of a dialkylaminoalkyl (meth)acrylate monomer is represented by the formula (II):

(wherein ^R2 is a hydrogen atom or a methyl group, ^R3 is an alkylene group having 1 to 5 carbon atoms, and ^R4 to ^R6 each independently represent an alkyl group having 1 to 5 carbon atoms).
Preferred is a compound represented by the following formula:

In formula (II), ^R2 is preferably a methyl group. ^R3 includes a methylene group, an ethylene group, a propylene group, a butylene group, etc., of which an ethylene group is preferred. ^R4 to ^R6 include a methyl group, an ethyl group, a propyl group, an n-butyl group, a t-butyl group, etc., of which a methyl group or an ethyl group is preferred, and an ethyl group is more preferred.

Examples of dialkylaminoalkyl (meth)acrylates include dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, dipropylaminoethyl (meth)acrylate, dibutylaminoethyl (meth)acrylate, etc., and among these, diethylaminoethyl (meth)acrylate is preferred because it is inexpensive.

A method for producing a styrene-based resin containing a quaternary ammonium salt includes, for example, quaternizing a dialkylaminoalkyl (meth)acrylate using an alkyl paratoluenesulfonate ester in a conventional manner to obtain a quaternary ammonium salt of a dialkylaminoalkyl (meth)acrylate monomer (M3), mixing this with a styrene monomer (M1) and/or an alkyl (meth)acrylate monomer (M2), and copolymerizing the mixture in the presence of a polymerization initiator.

Examples of alkyl esters of paratoluenesulfonate include methyl paratoluenesulfonate, ethyl paratoluenesulfonate, and propyl paratoluenesulfonate. Of these, methyl paratoluenesulfonate is preferred because it is easy to quaternize.

The amount of paratoluenesulfonic acid alkyl ester used is preferably 0.8 moles or more, more preferably 1 mole or more, and preferably 1.5 moles or less, more preferably 1.2 moles or less, per mole of dialkylaminoalkyl(meth)acrylate to be reacted with it.

As the copolymerization method, any method such as solution polymerization, suspension polymerization, bulk polymerization, emulsion polymerization, etc. may be used, but solution polymerization is preferred because it is relatively easy to control the mass average molecular weight of the resulting copolymer and the reaction operation is easy.

Solvents used in solution polymerization include ketone-based solvents such as methyl ethyl ketone and methyl isobutyl ketone, alcohol-based solvents such as normal butanol and isobutanol, ester-based solvents such as ethyl acetate and isobutyl acetate, and aromatic hydrocarbon solvents such as toluene and xylene. Of these, ketone-based solvents and alcohol-based solvents are preferred from the viewpoint of the solubility of the copolymer.

Polymerization initiators that can be used include peroxide initiators such as tert-butylperoxy 2-ethylhexanoate, tert-amylperoxy 2-ethylhexanoate, 1,1-di(t-butylperoxy)cyclohexane, and dibenzoyl peroxide, and azo initiators such as 2,2'-azobis(2-methylbutyronitrile).

The amount of polymerization initiator used is preferably 0.5 parts by mass or more and 10 parts by mass or less per 100 parts by mass of the total monomers.

In the quaternary ammonium salt-containing styrene-based resin, the content of styrene monomer (M1) units in the total amount of styrene monomer (M1) units, (meth)acrylic acid alkyl ester monomer (M2) units, and dialkylaminoalkyl (meth)acrylate quaternary ammonium salt (M3) units is preferably 40% by mass or more, more preferably 50% by mass or more, and preferably 80% by mass or less, more preferably 75% by mass or less.

In the quaternary ammonium salt-containing styrene-based resin, the content of (meth)acrylic acid alkyl ester monomer (M2) units in the total amount of styrene monomer (M1) units, (meth)acrylic acid alkyl ester monomer (M2) units, and dialkylaminoalkyl (meth)acrylate quaternary ammonium salt (M3) units is preferably 5% by mass or more, more preferably 10% by mass or more, and is preferably 40% by mass or less, more preferably 35% by mass or less.

In the quaternary ammonium salt-containing styrene-based resin, the content of the quaternary ammonium salt (M3) units of dialkylaminoalkyl (meth)acrylate in the total amount of the styrene monomer (M1) units, the (meth)acrylic acid alkyl ester monomer (M2) units, and the quaternary ammonium salt (M3) units of dialkylaminoalkyl (meth)acrylate is preferably 0.5% by mass or more, more preferably 1% by mass or more, and is preferably 35% by mass or less, more preferably 30% by mass or less.

Commercially available products of the quaternary ammonium base-containing styrene-based resin include, for example, "FCA-201-PS" and "FCA-701-PT" (both manufactured by Fujikura Chemical Industries, Ltd.).

The softening point of the quaternary ammonium salt-containing styrene resin is preferably 140°C or lower, more preferably 135°C or lower, and even more preferably 130°C or lower, from the viewpoint of improving the grindability of the toner to obtain small toner particles and from the viewpoint of low-temperature fixability, and is preferably 90°C or higher, more preferably 95°C or higher, and even more preferably 100°C or higher, from the viewpoint of storage stability.

The glass transition temperature of the quaternary ammonium salt-containing styrene resin is preferably 90°C or lower, more preferably 85°C or lower, and even more preferably 80°C or lower, from the viewpoint of improving the grindability of the toner to obtain small toner particles and from the viewpoint of low-temperature fixability, and is preferably 35°C or higher, more preferably 40°C or higher, and even more preferably 45°C or higher, from the viewpoint of storage stability.

Other quaternary ammonium salt compounds X include, for example, compounds of formula (III):

(In the formula, R ⁷ to R ⁹ each independently represent an alkyl group having 1 to 5 carbon atoms, and R ¹⁰ represents an alkylene group having 1 to 5 carbon atoms.)
An example of a commercially available product of the quaternary ammonium salt compound represented by formula (III) is "Bontron P-51" (manufactured by Orient Chemical Industry Co., Ltd., R ⁷ to R ⁹ are butyl groups, R ¹⁰ is a methylene group).

The content of the quaternary ammonium salt compound X is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and even more preferably 5 parts by mass or more, based on 100 parts by mass of the total of the crystalline polyester resin and the amorphous resin A, from the viewpoint of charging stability, and is preferably 20 parts by mass or less, more preferably 18 parts by mass or less, and even more preferably 15 parts by mass or less, from the viewpoint of dispersibility in the binder resin.

The toner of the present invention may contain other charge control agents as long as the effects of the present invention are not impaired.

In addition to the binder resin and the quaternary ammonium salt compound X, the toner may contain additives such as colorants, release agents, charge control agents, magnetic powders, flowability improvers, conductivity adjusters, reinforcing fillers such as fibrous substances, antioxidants, and cleaning improvers.

As colorants, dyes, pigments, magnetic materials, etc. used as toner colorants can be used. Examples include carbon black, phthalocyanine blue, permanent brown FG, brilliant fast scarlet, pigment red 122, pigment green B, rhodamine B base, solvent red 49, solvent red 146, solvent blue 35, quinacridone, carmine 6B, isoindoline, disazo yellow, etc. In the present invention, the toner may be either a black toner or a color toner.

From the viewpoint of improving the image density and low-temperature fixability of the toner, the content of the colorant is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and preferably 40 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 10 parts by mass or less, per 100 parts by mass of the binder resin.

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

From the viewpoint of charge stability, the melting point of the release agent is preferably 60°C or higher, more preferably 70°C or higher, and from the viewpoint of low-temperature fixability, it is preferably 160°C or lower, more preferably 140°C or lower, even more preferably 120°C or lower, and even more preferably 110°C or lower.

The content of the release agent is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and even more preferably 1.5 parts by mass or more, relative to 100 parts by mass of the binder resin, from the viewpoints of the low-temperature fixability and charge stability of the toner and dispersibility in the binder resin, and is preferably 10 parts by mass or less, more preferably 8 parts by mass or less, and even more preferably 7 parts by mass or less.

The toner may be a toner obtained by any of the conventionally known methods such as the melt kneading method, the emulsion aggregation method, the suspension polymerization method, etc., and may also be a toner having a core-shell structure, but from the viewpoint of charge stability, a pulverized toner obtained by the melt kneading method is preferred. In the case of a pulverized toner obtained by the melt kneading method, for example, a binder resin containing a crystalline polyester resin and an amorphous resin A, a quaternary ammonium salt compound X, and, if necessary, raw materials such as a colorant, a release agent, and a charge control agent are uniformly mixed in a mixer such as a Henschel mixer, and then melt-kneaded in an internal kneader, a single-screw or twin-screw extruder, an open roll type kneader, etc., and cooled, pulverized, and classified to produce the toner.

In order to improve the transferability of the toner of the present invention, it is preferable to use an external additive. Examples of external additives include inorganic fine particles such as silica, alumina, titania, zirconia, tin oxide, and zinc oxide, and organic fine particles such as resin particles such as melamine-based resin fine particles and polytetrafluoroethylene resin fine particles, and two or more types may be used in combination. Among these, silica is preferable, and from the viewpoint of the transferability of the toner, hydrophobic silica that has been hydrophobized is more preferable.

Hydrophobic treatment agents for hydrophobizing the surface of silica particles include hexamethyldisilazane (HMDS), dimethyldichlorosilane (DMDS), cyclic silazane, silicone oil, aminosilane, octyltriethoxysilane (OTES), methyltriethoxysilane, etc.

From the viewpoint of the chargeability, fluidity, and transferability of the toner, the average particle diameter of the external additive is preferably 5 nm or more, more preferably 10 nm or more, and even more preferably 15 nm or more, and is preferably 250 nm or less, more preferably 200 nm or less, and even more preferably 90 nm or less.

The external additive process by mixing the toner particles with the external additives can be carried out according to conventional methods, and a mixer such as a Henschel mixer can be used.

From the viewpoint of the chargeability, fluidity, and transferability of the toner, the content of the external additive is preferably 0.05 parts by mass or more, more preferably 0.1 parts by mass or more, and even more preferably 0.3 parts by mass or more, per 100 parts by mass of the toner particles before treatment with the external additive, and is preferably 5 parts by mass or less, and more preferably 3 parts by mass or less.

The volume median particle diameter ( _D50 ) of the toner of the present invention is preferably 3 μm or more, more preferably 4 μm or more, and preferably 15 μm or less, more preferably 10 μm or less. In this specification, the volume median particle diameter ( _D50 ) means a particle diameter at which the cumulative volume frequency calculated by volume fraction is 50% calculated from the smallest particle diameter. In addition, when the toner is treated with an external additive, the volume median particle diameter of the toner particles before treatment with the external additive is regarded as the volume median particle diameter of the toner.

The toner of the present invention can be used as it is as a single-component developing toner, or mixed with a carrier as a two-component developing toner, in image forming devices using either a single-component developing method or a two-component developing method.

The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. The physical properties of the resins and the like can be measured by the following methods.

[Softening point of resin]
Using a flow tester "CFT-500D" (Shimadzu Corporation), 1g of sample is heated at a temperature increase rate of 6℃/min while applying a load of 1.96MPa with the plunger, and extruding the sample from a nozzle with a diameter of 1mm and length of 1mm. The plunger descent amount of the flow tester is plotted against the temperature, and the temperature at which half of the sample flows out is taken as the softening point.

[Maximum endothermic peak temperature of resin]
Using a differential scanning calorimeter "Q-100" (manufactured by TA Instruments Japan, Inc.), 0.01 to 0.02 g of sample is weighed into an aluminum pan and cooled from room temperature (25°C) to 0°C at a rate of 10°C/min, and maintained at 0°C for 1 minute. Then, measurements are performed at a rate of 10°C/min. The temperature of the peak with the largest peak area among the observed endothermic peaks is regarded as the maximum endothermic peak temperature. For crystalline resins, the maximum endothermic peak temperature is regarded as the melting point.

[Glass transition temperature of resin]
Using a differential scanning calorimeter "Q-100" (manufactured by TA Instruments Japan, Inc.), 0.01 to 0.02 g of sample is 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 is then heated at a rate of 10°C/min, and the endothermic peak is measured. The glass transition temperature is the temperature at the intersection of an extension of the baseline below the maximum endothermic peak temperature and a tangent line showing the maximum slope from the rising part of the peak to the top of the peak.

[Acid value of resin]
Measurements are performed based on the method of JIS K 0070:1992, except that the measurement solvent is changed from the ethanol and ether mixture specified in JIS K 0070 to a mixture of acetone and toluene (acetone:toluene = 1:1 (volume ratio)) for amorphous resins and a mixture of chloroform and dimethylformamide (chloroform:dimethylformamide = 7:3 (volume ratio)) for crystalline resins.

[Melting point of release agent]
Using a differential scanning calorimeter "Q-100" (manufactured by TA Instruments Japan, Inc.), 0.02 g of the sample is weighed into an aluminum pan and heated to 200°C, then cooled from 200°C to 0°C at a rate of 10°C/min. The sample is then heated at a rate of 10°C/min, the amount of heat is measured, and the maximum endothermic peak temperature is taken as the melting point.

[Volume Median Particle Size and CV Value of Resin Particles, Colorant Particles, Release Agent Particles, and Quaternary Ammonium Salt Compound Particles]
(1) Measuring device: Laser diffraction type particle size measuring device "LA-920" (manufactured by Horiba, Ltd.)
(2) Measurement conditions: Put the sample dispersion in a measurement cell, add distilled water, and measure the volume median particle size ( _D50 ) and volume average particle size at a temperature where the absorbance is in the appropriate range. The CV value is 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, Release Agent Particle Dispersion, and Quaternary Ammonium Salt Compound Particle Dispersion]
Using an infrared moisture meter "FD-230" (Kett Electric Laboratory Co., Ltd.), 5 g of the measurement sample is dried at a drying temperature of 150°C and measurement mode 96 (monitoring time 2.5 minutes, fluctuation range 0.05%), and the moisture content (mass%) of the dispersion is measured. The solid content concentration is calculated according to the following formula.
Solids concentration (mass%) = 100 - moisture (mass%)

[Volume Median Particle Size of Agglomerated Particles]
・Measuring instrument: "Coulter Multisizer (registered trademark) III" (manufactured by Beckman Coulter, Inc.)
Aperture diameter: 50 μm
・Analysis software: "Multisizer (registered trademark) III version 3.51" (Beckman Coulter, Inc.)
・Electrolyte: "Isoton (registered trademark) II" (Beckman Coulter, Inc.)
Measurement conditions: The sample dispersion is added to 100 mL of the electrolyte to adjust the concentration so that the particle size of 30,000 particles can be measured in 20 seconds, and then the 30,000 particles are measured and the volume median particle size ( _D50 ) is calculated from the particle size distribution.

[Average particle size of external additives]
The average particle size refers to the number-average particle size, and is calculated by measuring the particle sizes (average of major and minor axes) of 500 particles in a scanning electron microscope (SEM) photograph and averaging these by number.

[Toner Circularity]
The circularity of the fused particles is measured under the following conditions.
・Measuring device: Flow type particle image analyzer "FPIA-3000" (Sysmex Corporation)
Preparation of dispersion: A dispersion of toner particles is prepared by diluting with deionized water so that the solid content concentration is 0.001 to 0.05% by mass.
Measurement mode: HPF measurement mode

[Volume Median Particle Size ( _D50 ) of Toner]
・Measuring instrument: "Coulter Multisizer (registered trademark) III" (manufactured by Beckman Coulter, Inc.)
Aperture diameter: 50 μm
・Analysis software: "Multisizer (registered trademark) III version 3.51" (Beckman Coulter, Inc.)
・Electrolyte: "Isoton (registered trademark) II" (Beckman Coulter, Inc.)
Dispersion: Polyoxyethylene lauryl ether "EMULGEN (registered trademark) 109P" (manufactured by Kao Corporation, HLB (Griffin) = 13.6) was dissolved in the electrolyte to adjust the concentration to 5% by mass. Dispersion conditions: 10 mg of a measurement sample was added to 5 mL of the dispersion and dispersed for 1 minute using an ultrasonic disperser (machine name: US-1, manufactured by SND Corporation, output: 80 W). Thereafter, 25 mL of electrolyte was added and the mixture was further dispersed for 1 minute using the ultrasonic disperser to prepare a sample dispersion.
Measurement conditions: The sample dispersion is added to 100 mL of the electrolyte to adjust the concentration to a level that allows the particle size of 30,000 particles to be measured in 20 seconds, and then the 30,000 particles are measured and the volume median particle size ( _D50 ) is calculated from the particle size distribution.

Preparation of alkenyl succinic anhydride 1
(1) Propylene tetramer (manufactured by Nippon Oil Corporation, trade name: "Light Tetramer") was used and fractionated under heating conditions of 183 to 208°C to obtain an alkylene compound (a). The obtained alkylene compound (a) had 40 peaks in gas chromatography mass spectrometry described later. The distribution of the alkylene compounds was measured according to the analysis of alkylene compound A by mass spectrometry gas chromatography in JP 2014-013384 A, and was C ₉ H ₁₈ : 0.5 mass%, C ₁₀ H ₂₀ : 4 mass%, C ₁₁ H ₂₂ : 20 mass%, C ₁₂ H ₂₄ : 66 mass%, C ₁₃ H ₂₆ : 9 mass%, and C ₁₄ H ₂₈ : 0.5 mass% (6 peaks corresponding to alkylene compounds having 9 to 14 carbon atoms).

(2) 542.4 g of alkylene compound (a), 157.2 g of maleic anhydride, 0.4 g of antioxidant "Chelex-O" (SC Organic Chemicals, Triisooctyl phosphite), and 0.1 g of butylhydroquinone as a polymerization inhibitor were charged into a 1-liter autoclave manufactured by Nitto Koatsu Co., Ltd., and pressurized nitrogen replacement (0.2 MPaG) was repeated three times. After stirring was started at 60°C, the temperature was raised to 230°C over one hour and the reaction was carried out for six hours. The pressure when the reaction temperature was reached was 0.3 MPaG. After the reaction was completed, the mixture was cooled to 80°C, returned to normal pressure (101.3 kPa), and transferred to a 1-liter four-neck flask. The temperature was raised to 180°C with stirring, and the remaining alkylene compound was distilled off at 1.3 kPa over one hour. The mixture was then cooled to room temperature (25°C) and returned to normal pressure (101.3 kPa) to obtain 406.1 g of the desired alkenyl succinic anhydride A. The average molecular weight of alkenyl succinic anhydride A, calculated from the acid value, was 268.

Resin Production Example 1
The alcohol component and carboxylic acid component shown in Table 1 were placed in a 10-liter four-neck flask equipped with a thermometer, a stainless steel stirring rod, a downflow condenser, and a nitrogen inlet tube, and the temperature was raised to 200°C over 8 hours in a nitrogen atmosphere in a mantle heater. Then, an esterification catalyst shown in Table 1 was added, and the reaction was carried out at 8.0 kPa until the softening point shown in Table 1 was reached, obtaining crystalline polyester resins (resins C1 to C6). The physical properties are shown in Table 1.

Resin Production Example 2
The alcohol components shown in Table 1 were placed in a 10-liter four-neck flask equipped with a nitrogen inlet tube, a dehydration tube, a stirrer, and a thermocouple, and heated to 120°C. At 120°C, the carboxylic acid components shown in Table 1 were added, and the mixture was further heated to 160°C and polycondensed for 6 hours. Then, the raw material monomers of the styrene-based resin, the bireactive monomers, and the polymerization initiator shown in Table 1 were dropped over 1 hour using a dropping funnel. After maturing the addition polymerization reaction for 1 hour while maintaining the temperature at 160°C, the temperature was raised to 200°C over 8 hours and the reaction was carried out at 8.0 kPa for 30 minutes. Furthermore, the esterification catalyst shown in Table 1 was added, and the polycondensation reaction was carried out at 200°C for 1 hour, and the reaction was carried out at 8.0 kPa until the softening point shown in Table 1 was reached, to obtain crystalline composite resins (resins C7 and C8). The physical properties are shown in Table 1.

Resin Production Example 3
The alcohol component, carboxylic acid component other than trimellitic anhydride, esterification catalyst and esterification promoter shown in Table 2 were placed in a 5-liter four-neck flask equipped with a nitrogen inlet tube, a stirrer and a thermocouple, and the temperature was raised to 235°C under a nitrogen atmosphere, and polycondensation was carried out at 235°C for 6 hours. The temperature was then lowered to 210°C, trimellitic anhydride shown in Table 2 was added, and the mixture was reacted at 210°C for 1 hour, and then the reaction was continued at 210°C under a reduced pressure of 10 kPa until the softening point shown in Table 2 was reached, to obtain an amorphous polyester resin (resin AH1). The physical properties are shown in Table 2.

Resin Production Example 4
The alcohol component, trimellitic anhydride, sebacic acid, and carboxylic acid component other than fumaric acid, esterification catalyst, and esterification promoter shown in Table 2 were placed in a 5-liter four-neck flask equipped with a nitrogen inlet tube, a stirrer, and a thermocouple, and the temperature was raised to 235°C under a nitrogen atmosphere, and then polycondensation was carried out at 235°C for 6 hours. The temperature was then lowered to 160°C, and a mixture of the bireactive monomer, raw material monomer of the styrene resin, and polymerization initiator shown in Table 2 was dropped over 1 hour using a dropping funnel. After the dropping, the addition polymerization reaction was matured for 1 hour while maintaining the temperature at 160°C, and then the temperature was raised to 200°C and reduced pressure at 10 kPa for 1 hour. After opening the pressure, the temperature was lowered to 180°C, and trimellitic anhydride, sebacic acid, fumaric acid, and polymerization inhibitor shown in Table 2 were added, and the mixture was kept at 180°C for 1 hour, and then the temperature was raised from 180°C to 210°C at 10°C/h, and the reaction was carried out at 210°C for 1 hour. The reaction was further carried out at 210° C. under a reduced pressure of 10 kPa until the softening point shown in Table 2 was reached, to obtain an amorphous polyester resin (Resin AH2).

Resin Production Example 5
The alcohol component, the carboxylic acid component other than trimellitic anhydride, the esterification catalyst and the esterification promoter shown in Table 2 were placed in a 5-liter four-neck flask equipped with a nitrogen inlet tube, a stirrer and a thermocouple, and the temperature was raised to 235°C under a nitrogen atmosphere, and then polycondensation was carried out at 235°C for 6 hours. The temperature was then lowered to 160°C, and a mixture of the bireactive monomer, the raw material monomer of the styrene resin and the polymerization initiator shown in Table 2 was dropped over 1 hour using a dropping funnel. After the dropping, the addition polymerization reaction was matured for 1 hour while maintaining the temperature at 160°C, and then the temperature was raised to 200°C and reduced pressure at 10 kPa for 1 hour. After opening the pressure, the temperature was lowered to 180°C, and the trimellitic anhydride shown in Table 2 was added, and after keeping the temperature at 180°C for 1 hour, the temperature was raised from 180°C to 210°C at 10°C/h, and the reaction was carried out at 210°C for 1 hour. The reaction was further carried out at 210° C. under a reduced pressure of 10 kPa until the softening point shown in Table 2 was reached, thereby obtaining an amorphous polyester resin (Resin AL1).

Resin Production Example 6
The alcohol component, carboxylic acid component, esterification catalyst, and esterification promoter shown in Table 2 were placed in a 5-liter four-neck flask equipped with a nitrogen inlet tube, a stirrer, and a thermocouple, and the temperature was raised to 235°C under a nitrogen atmosphere, followed by polycondensation at 235°C for 6 hours. The reaction was further carried out at 235°C under a reduced pressure of 10 kPa until the softening point shown in Table 2 was reached, to obtain amorphous polyester resins (resins AL2 and AL3). The physical properties are shown in Table 2.

Resin Production Example 7
The alcohol component, carboxylic acid component other than trimellitic anhydride and adipic acid, esterification catalyst and esterification promoter shown in Table 2 were placed in a 5-liter four-neck flask equipped with a nitrogen inlet tube, a stirrer and a thermocouple, and heated to 235°C under a nitrogen atmosphere, and then polycondensed at 235°C for 6 hours. The temperature was then lowered to 210°C, and trimellitic anhydride and adipic acid shown in Table 2 were added, reacted at 210°C for 1 hour, and then further reacted at 210°C under a reduced pressure of 10 kPa until the softening point shown in Table 2 was reached, to obtain an amorphous polyester resin (resin AL4). The physical properties are shown in Table 2.

Examples 1 to 6, 8 to 9, 13 to 14 and Comparative Examples 1 and 2 [Melt-kneading method]
100 parts by mass of the binder resin shown in Table 3, 5 parts by mass of a colorant "ECB-301" (manufactured by Dainichi Seika Chemicals Co., Ltd., phthalocyanine blue (PB15:3)), 3 parts by mass of a release agent "Carnauba Wax C1" (manufactured by Kato Yoko Co., Ltd., melting point: 83° C.), 3 parts by mass of a release agent "HNP-9" (manufactured by Nippon Seiro Co., Ltd., paraffin wax, melting point: 75° C.), and 10 parts by mass of a polymer-type positively charged charge control agent "FCA-201-PS" (manufactured by Fujikura Chemicals Co., Ltd., softening point: 119° C., glass transition temperature: 65° C.) were mixed in a Henschel mixer.

The resulting mixture was melt-kneaded using a co-rotating twin-screw extruder with a total length of 1,560 mm, screw diameter of 42 mm, and barrel inner diameter of 43 mm at a screw rotation speed of 200 r/min and barrel set temperature of 100°C to obtain a molten kneaded product. The mixture was fed at a rate of 20 kg/h and the average residence time was approximately 18 seconds.

The resulting molten kneaded product was cooled, coarsely pulverized, pulverized in a jet mill, and classified using an air classifier (manufactured by Nippon Pneumatic Co., Ltd.) to obtain toner particles having a volume median particle size (D ₅₀ ) of 7.0 μm.

100 parts by mass of the obtained toner particles were mixed with 0.5 parts by mass of hydrophobic silica "TG820F" (manufactured by Cabot Corporation, hydrophobic treatment agent: HMDS and cyclic silazane, average particle size 8 nm) and 1.0 part by mass of hydrophobic silica "NA50Y" (manufactured by Nippon Aerosil Co., Ltd., hydrophobic treatment agent: silicone oil and aminosilane, average particle size 40 nm) as external additives in a Henschel mixer (manufactured by Mitsui Mining Co., Ltd.) at a rotation speed of 3000 r/min (circumferential speed 32 m/sec) for 3 minutes to obtain a toner.

Example 7
A toner was obtained in the same manner as in Example 1, except that 10 parts by mass of "BONTRON P-51" (manufactured by Orient Chemical Industries Co., Ltd.) was used instead of "FCA-201-PS" as the positively charged charge control agent.

Example 10
A toner was obtained in the same manner as in Example 1, except that the melt-kneading was performed using a continuous open-roll type twin-screw kneader "Kneedex" (manufactured by Mitsui Mining Co., Ltd.) instead of the same-rotating twin-screw extruder. The continuous open-roll type twin-screw kneader had a roll outer diameter of 0.14 m and an effective roll length of 0.8 m, and the operating conditions were a rotation speed of the high-rotation roll (front roll) of 75 r/min (circumferential speed 33 m/min), a rotation speed of the low-rotation roll (rear roll) of 50 r/min (circumferential speed 22 m/min), and a roll gap of 0.1 mm. The heating and cooling medium temperatures in the rolls were set as follows: the temperature of the raw material input side of the high-rotation roll was set to 140°C, the temperature of the kneaded material discharge side was set to 110°C, the temperature of the raw material input side of the low-rotation roll was set to 65°C, and the temperature of the kneaded material discharge side was set to 30°C. The supply speed of the raw material mixture was 10 kg/h, and the average residence time was about 5 minutes.

Example 11 [Emulsion aggregation method]
<Preparation of Aqueous Dispersion of Core Resin Particles>
600g of methyl ethyl ketone was put into a 5-liter container equipped with a stirrer, reflux condenser, dropping funnel, thermometer and nitrogen inlet tube, and 128g (60 parts by mass) of resin AH2 and 22g (10 parts by mass) of resin C1 were added at 60°C and dissolved. 5% by mass of sodium hydroxide aqueous solution was added to the obtained solution so that the degree of neutralization was 60 mol% with respect to the acid value of the resin, and the mixture was stirred for 30 minutes to obtain a mixture. Then, 675g of deionized water was added over 77 minutes. Next, while stirring at 250r/min, methyl ethyl ketone was distilled off at a temperature of 50°C or less under reduced pressure, and the solid content concentration of the aqueous dispersion was measured, and the solid content concentration of the aqueous dispersion was adjusted to 20% by mass with deionized water to obtain a core resin dispersion. The volume median particle size ( _D50 ) of the resin particles in the dispersion was 200nm, and the CV value was 24%.

<Preparation of Aqueous Dispersion of Shell Resin Particles>
600g of methyl ethyl ketone was put into a 5-liter container equipped with a stirrer, reflux condenser, dropping funnel, thermometer and nitrogen inlet tube, and 150g of resin AL4 was added at 60°C and dissolved. 5% by mass of sodium hydroxide aqueous solution was added to the obtained solution so that the degree of neutralization was 60 mol% with respect to the acid value of the resin, and the mixture was stirred for 30 minutes to obtain a mixture. Then, 675g of deionized water was added over 77 minutes. Next, while stirring at 250r/min, methyl ethyl ketone and a part of the water were distilled off at a temperature of 50°C or less under reduced pressure, and the solid content concentration of the aqueous dispersion was measured, and the solid content concentration of the aqueous dispersion was adjusted to 20% by mass with deionized water to obtain a shell resin dispersion. The volume median particle size ( _D50 ) of the resin particles in the dispersion was 110nm, and the CV value was 20%.

<Preparation of Quaternary Ammonium Salt Compound Dispersion>
In a 1-liter beaker, 100.0 g of a polymer-type positively charged charge control agent "FCA-201-PS" (manufactured by Fujikura Chemical Industries, Ltd.), which is a quaternary ammonium salt compound, 133.3 g of an anionic surfactant "Neopelex (registered trademark) G-15" (manufactured by Kao Corporation, 15% by mass sodium dodecylbenzenesulfonate aqueous solution), and 268.5 g of deionized water were mixed and dispersed at room temperature for 1 hour using a homogenizer "TKAGI HOMOMIXER 2M-03" (manufactured by Primix Corporation) at a rotation speed of the stirring blade of 8000 r/min. Then, 12 passes were performed at a pressure of 150 MPa using a homogenizer "Microfluidizer M-110EH" (manufactured by Microfluidics Co., Ltd.). Then, the mixture was passed through a 200-mesh filter, and deionized water was added so that the solid concentration was 12% by mass, to obtain a quaternary ammonium salt compound dispersion. The volume median particle size (D ₅₀ ) of the quaternary ammonium salt compound particles in the dispersion was 150 nm, and the CV value was 30%.

<Preparation of Colorant Dispersion>
In a 1-liter beaker, 116.2 g of colorant "ECB-301" (Dainichi Seikagaku Chemicals Co., Ltd., Phthalocyanine Blue (PB15:3)), 154.9 g of anionic surfactant "Neopelex (registered trademark) G-15" (Kao Corporation, 15% by weight aqueous solution of sodium dodecylbenzenesulfonate) and 260 g of deionized water were mixed and dispersed at room temperature for 3 hours using a homogenizer, and then deionized water was added to obtain a colorant dispersion having a solids concentration of 24% by weight. The volume median particle diameter ( _D50 ) of the colorant particles in the dispersion was 118 nm and the CV value was 27%.

<Preparation of release agent dispersion>
50 g of Fischer-Tropsch wax (manufactured by Nippon Seiro Co., Ltd., trade name: FNP0090, melting point: 90°C), 5 g of a cationic surfactant (manufactured by Kao Corporation, trade name: Sanisol B50) and 200 g of deionized water were heated to 95°C, and the paraffin wax was dispersed using a homogenizer, and then the mixture was dispersed using a pressure discharge homogenizer to obtain a release agent dispersion with a solid content concentration of 20 mass%. The volume median particle size ( _D50 ) of the release agent particles in the dispersion was 550 nm, and the CV value was 26%.

<Preparation of Toner Particles>
In a 3-liter four-neck flask equipped with a dehydration tube, a stirrer, and a thermocouple, 500 g of the core resin dispersion, 143 g of the quaternary ammonium salt compound dispersion, 36 g of the colorant dispersion, 33 g of the release agent dispersion, and 3.3 g of a 15% by mass aqueous solution of sodium dodecylbenzenesulfonate "Neopelex G-15" (manufactured by Kao Corporation, an anionic surfactant) were mixed at a temperature of 25° C. Next, while stirring the resulting mixture, a solution obtained by dissolving 40 g of ammonium sulfate in 570 g of deionized water and adding a 4.8% by mass aqueous solution of potassium hydroxide to adjust the pH to 8.2 was dropped over 10 minutes at 25° C., and the temperature was raised to 62° C. over 2 hours and maintained at 62° C. until the volume median particle size (D ₅₀ ) of the aggregated particles reached 6.9 μm, thereby obtaining a dispersion of aggregated particles (I).

While maintaining the temperature of the obtained dispersion of agglomerated particles (I) at 62° C., 215 g of the shell resin dispersion was added dropwise at a rate of 0.6 mL/min (0.6 g/min) to obtain a dispersion of agglomerated particles (II). The volume median particle size ( _D50 ) of the agglomerated particles (II) was 7.0 μm.

To the dispersion of the obtained aggregated particles (II), an aqueous solution of 20 g of sodium polyoxyethylene lauryl ether sulfate "EMAL E-27C" (Kao Corporation, anionic surfactant, effective concentration 27% by mass), 280 g of deionized water, and 40 g of 0.1 mol/L aqueous sulfuric acid solution was added. The temperature was then raised to 80°C over 1 hour, and the mixture was kept at 80°C for 30 minutes. After that, 10 g of 0.1 mol/L aqueous sulfuric acid solution was added, and the mixture was kept at 80°C for another 15 minutes. Then, 15 g of 0.1 mol/L aqueous sulfuric acid solution was added again, and the mixture was kept at 80°C until the circularity reached 0.970, to obtain a dispersion of fused particles (core-shell particles) in which the aggregated particles were fused.

The obtained core-shell particle dispersion was cooled to 30°C, and the dispersion was suction filtered to separate the solids, which were then washed with deionized water at 25°C and suction filtered at 25°C for 2 hours. The solids were then vacuum dried at 33°C for 24 hours using a vacuum constant temperature dryer "DRV622DA" (manufactured by ADVANTEC) to obtain toner particles. The particle size of the obtained toner particles was 7.0 μm and the circularity was 0.970.

100 parts by mass of the obtained toner particles were mixed with 0.5 parts by mass of hydrophobic silica "TG820F" (manufactured by Cabot Corporation, hydrophobic treatment agent: HMDS and cyclic silazane, average particle size 8 nm) and 1.0 part by mass of hydrophobic silica "NA50Y" (manufactured by Nippon Aerosil Co., Ltd., hydrophobic treatment agent: silicone oil and aminosilane, average particle size 40 nm) as external additives in a Henschel mixer (manufactured by Mitsui Mining Co., Ltd.) at a rotation speed of 3000 r/min (circumferential speed 32 m/sec) for 3 minutes to obtain a toner.

Example 12 [Suspension Polymerization Method]
In a 300 mL glass beaker, 77 g of styrene, 13 g of butyl acrylate, 10 g of resin C1, 5 g of colorant "ECB-301" (Dainichi Seikagaku Co., Ltd., phthalocyanine blue (PB15:3)), 10 g of polymeric positive charge control agent "FCA-201-PS" (Fujikura Kasei Co., Ltd.), and 6 g of release agent "HNP-9" (Nippon Seiro Co., Ltd., paraffin wax, melting point: 75.5°C) were added, stirred and mixed, and heated to 60°C to dissolve uniformly. Then, 4 g of polymerization initiator "V-65" (Wako Pure Chemical Industries, Ltd., 2,2'-azobis(2,4-dimethylvaleronitrile)) was added to prepare a resin solution. In a 1-liter glass beaker, 150 g of deionized water, 500 g of 10% by mass slurry of calcium phosphate tribasic (chemical formula: 3[ _Ca3 ( _PO4 ) ₂ ].Ca(OH) ₂ ) "TCP-10.U" (manufactured by Taihei Chemical Industry Co., Ltd.), and 0.004 g of anionic surfactant "Neopelex G-15" (manufactured by Kao Corporation, sodium dodecylbenzenesulfonate) were added and stirred to prepare an aqueous medium. The aqueous medium was heated to 60°C, and while maintaining the temperature at 60°C, the resin solution was added all at once. The mixture was stirred for 4 minutes at 12,000 rpm using a homogenizer "MARK II 2.5" (manufactured by Primix Corporation) to obtain a suspension.

The suspension was transferred to a separable flask equipped with a stirrer, reflux condenser, thermometer, and nitrogen inlet tube, and polymerized for 8 hours while stirring at 70°C and 200 r/min. The temperature was then raised to 80°C, and the remaining monomers were distilled off under reduced pressure. The mixture was cooled to 20°C while continuing to stir, and hydrochloric acid was added until the pH of the system was 1 or less. After washing and drying, toner particles were obtained. The particle size of the obtained toner particles was 7.0 μm.

100 parts by mass of the obtained toner particles were mixed with 0.5 parts by mass of hydrophobic silica "TG820F" (manufactured by Cabot Corporation, hydrophobic treatment agent: HMDS and cyclic silazane, average particle size 8 nm) and 1.0 part by mass of hydrophobic silica "NA50Y" (manufactured by Nippon Aerosil Co., Ltd., hydrophobic treatment agent: silicone oil and aminosilane, average particle size 40 nm) as external additives in a Henschel mixer (manufactured by Mitsui Mining Co., Ltd.) at a rotation speed of 3000 r/min (circumferential speed 32 m/sec) for 3 minutes to obtain a toner.

Test Example [Charging Stability of Toner]
Under high temperature and high humidity conditions of a temperature of 25°C and a relative humidity of 50%, 0.6 g of toner and 19.4 g of silicone ferrite carrier (manufactured by Kanto Denka Kogyo Co., Ltd., average particle size 90 μm) were placed in a 50 mL polyethylene container and mixed using a ball mill at 250 r/min. The charge amount of the toner was measured using a Q/M meter (manufactured by EPPING Co., Ltd.) by the following method.

After 60 or 600 seconds of mixing, a specified amount of toner and carrier mixture was placed in a cell attached to the Q/M meter, and only the toner was sucked through a 32 μm mesh sieve (stainless steel, twill weave, wire diameter: 0.0035 mm) for 90 seconds. The voltage change on the carrier that occurred at that time was monitored, and the value of [total amount of electricity after 90 seconds (μC) / amount of sucked toner (g)] was taken as the charge amount (μC/g). The ratio of the charge amount after 60 seconds of mixing to the charge amount after 600 seconds of mixing (charge amount after 60 seconds of mixing / charge amount after 600 seconds of mixing) was calculated to evaluate the charge stability. The results are shown in Table 3. The higher the value, the better the charge stability.

The above results show that the toners of Examples 1 to 10, 13, and 14 have good charge stability compared to Comparative Example 1, which contains a crystalline polyester resin with an excessively high ester group concentration, and Comparative Example 2, which contains a crystalline polyester resin that does not use ethylene glycol. Furthermore, the results of Examples 11 and 12 show that the toner of the present invention, which has excellent charge stability, can also be obtained using the emulsion aggregation method or suspension polymerization method.

The toner for developing electrostatic images of the present invention is suitable for use in developing latent images formed in electrophotography, electrostatic recording, electrostatic printing, and the like.

Claims (6)

A toner for developing electrostatic images containing a crystalline polyester resin, an amorphous resin A, and a quaternary ammonium salt compound X, the crystalline polyester resin being a polycondensate of an alcohol component containing 80 mol % or more of ethylene glycol and a carboxylic acid component containing an aliphatic dicarboxylic acid compound, and containing a crystalline polyester resin C having an ester group concentration of 6.0 mmol/g or more and 9.0 mmol/g or less and/or a composite resin containing the crystalline polyester resin C. The toner for developing electrostatic images according to claim 1, wherein the mass ratio of the crystalline polyester resin to the amorphous resin A is 3/97 or more and 30/70 or less. The toner for developing electrostatic images according to claim 1 or 2, wherein the ester group concentration of the crystalline polyester resin C is 6.0 mmol/g or more and 8.0 mmol/g or less. The toner for developing electrostatic images according to any one of claims 1 to 3, wherein the content of the quaternary ammonium salt compound X is 1 part by mass or more and 20 parts by mass or less per 100 parts by mass of the total of the crystalline polyester resin and the amorphous resin A. The toner for developing electrostatic images according to any one of claims 1 to 4, wherein the quaternary ammonium salt compound X is a resin containing a quaternary ammonium salt. The toner for developing electrostatic images according to any one of claims 1 to 5, wherein the alcohol component and/or the carboxylic acid component of the crystalline polyester resin C contains a monofunctional monomer.