JP5112833B2 - Toner for electrophotography - Google Patents

Description

  The present invention relates to an electrophotographic toner used in an electrophotographic method, an electrostatic recording method, an electrostatic printing method, and the like, and a method for producing the same.

In recent years, in the field of electrophotography, development of a small particle size toner excellent in fixability has been desired from the pursuit of high image quality. However, when a small particle toner containing a binder resin mainly composed of polyester is produced by a melt kneading pulverization method, pulverization control is difficult.
Therefore, as a technique for producing toner by a wet method, for example, a method for producing toner by emulsion polymerization of a toner composition containing a vinyl-based polymerizable monomer, polyester using polyethylene glycol as a raw material, and a colorant is disclosed. (See Patent Document 1).
In addition, in order to improve low-temperature fixability and toner storage stability, a toner manufactured by a wet method using a crystalline polyester as a core and an ionomer resin made from polyethylene glycol as a shell is disclosed (patent) Reference 2).

JP 2007-79576 A JP 2006-267527 A

However, in the technique described in the above-mentioned patent document, the resin particles in the resin dispersion are not sufficiently reduced in particle size, and the resulting toner has insufficient circularity. Although the particle diameter is small, it has been found that the obtained toner has a low glass transition point and poor storage stability.
An object of the present invention is to provide an electrophotographic toner having a small particle size, high circularity, excellent image characteristics, and excellent storage stability, and a method for producing the electrophotographic toner.

The present invention
(1) An electrophotographic toner obtained by a production method comprising a step of forming a binder resin containing polyester into toner particles in an aqueous medium, wherein the polyester comprises polyethylene glycol having a number average molecular weight of 150 to 2,000. An electrophotographic toner obtained by polycondensing an alcohol component and a carboxylic acid component containing 4 to 40 mol%,
(2) A resin dispersion obtained by dispersing a resin containing polyester in an aqueous medium, wherein the polyester contains 4 to 40 mol% of polyethylene glycol having a number average molecular weight of 150 to 2000 and a carboxylic acid component A resin dispersion for toner obtained by condensation polymerization of

(3) (a) a step of neutralizing a resin containing polyester with a basic compound in an aqueous medium to obtain resin particles;
(B) a step of aggregating and coalescing the resin particles obtained in step (a);
A method for producing an electrophotographic toner comprising: an electron obtained by polycondensing an alcohol component containing 4 to 40 mol% of a polyethylene glycol having a number average molecular weight of 150 to 2000 and a carboxylic acid component. A method for producing a photographic toner, and (4) a method for producing a toner having a step of converting a binder resin containing polyester into toner particles in an aqueous medium, and a polyethylene glycol having a number average molecular weight of 150 to 2,000 is used. A polyester for electrophotographic toner obtained by condensation polymerization of an alcohol component and a carboxylic acid component, which are contained in an amount of ˜40 mol%,
About.

  According to the present invention, it is possible to provide an electrophotographic toner having a small particle size, high circularity, excellent image characteristics, and excellent storage stability, and a method for producing the same.

Hereinafter, the electrophotographic toner of the present invention and the production method thereof will be described.
The electrophotographic toner of the present invention is an electrophotographic toner obtained by a production method including a step of forming a binder resin containing polyester into toner particles in an aqueous medium, and the polyester has a number average molecular weight of 150. It is obtained by condensation polymerization of an alcohol component containing 4 to 40 mol% of polyethylene glycol of ˜2000 and a carboxylic acid component.

[Polyester for electrophotographic toner and binder resin containing polyester]
The polyester for electrophotographic toner of the present invention is obtained by polycondensing an alcohol component and a carboxylic acid component containing 4 to 40 mol% of polyethylene glycol having a number average molecular weight of 150 to 2,000. In the present invention, polyethylene glycol is a glycol having two or more oxyethylene groups.
From the viewpoint of the emulsifiability of the binder resin containing polyester and the storage stability of the obtained toner, the number average molecular weight of polyethylene glycol is preferably 150 to 1800, more preferably 150 to 1500, and more preferably 180 to More preferably, it is 1200. The number average molecular weight of polyethylene glycol can be measured by the GPC method described later. Moreover, when using several polyethylene glycol from which a number average molecular weight differs, the weighted average (with respect to the usage-amount) of the number average molecular weight of each polyethylene glycol should just satisfy the said range.

The content of polyethylene glycol in the alcohol component is preferably 4 to 38 mol% from the viewpoint of the emulsifiability of the binder resin containing polyester and the storage stability of the obtained toner. It is more preferable that it is 4 to 30 mol% .

  If the contribution of the oxyethylene group in the binder resin containing polyester is small, the emulsifiability of the binder resin containing polyester in the case of toner particle formation by the emulsion aggregation method is deteriorated. In particular, the raw material monomer for the binder resin The content is noticeable when the content is less than 1.6% by weight. On the other hand, if the contribution due to the oxyethylene group is too large, the glass transition point (Tg) of the binder resin is reduced, which causes deterioration in storage stability when the toner is produced. The content is remarkable at more than 22% by weight. Therefore, from the viewpoint of emulsifying property of the binder resin containing polyester in the case of toner particle formation by the emulsion aggregation method and storage stability of the obtained toner, the content ratio (% by weight) of polyethylene glycol in the raw material monomers of all resins is 1.6 to 22 wt%, preferably 3 to 18 wt%, more preferably 5 to 15 wt%.

  By setting the molecular weight of polyethylene glycol and the content in the alcohol component within the above ranges, a toner having a small particle size and a high glass transition point (Tg) can be obtained. In particular, when a toner is obtained by an emulsion aggregation method, which is a production method including a step of aggregating and coalescing resin particles containing a binder resin containing polyester, a small particle size is obtained by emulsifying the binder resin containing polyester. Resin particles can be obtained. When the resin particles are agglomerated to obtain a toner, the resin particles are easily agglomerated into circular particles, the circularity of the obtained toner is increased, and a high-quality printed matter can be obtained. The Tg of the toner is largely derived from the Tg of the binder resin. By using resin particles having a high Tg, a toner having a high Tg can be easily obtained, and a toner having good storage stability can be obtained. Therefore, a toner having both high image quality and excellent storage stability by using resin particles having a small particle size and high Tg obtained by setting the molecular weight of polyethylene glycol and the content thereof in the alcohol component within the above range. It is thought that it can be obtained.

  In the present invention, alcohol components other than the polyethylene glycol can be used as the raw material component of the polyester. As such, any known dihydric or higher alcohol can be used, and examples of the dihydric alcohol include bisphenol A alkylene oxide adduct, ethylene glycol, 1,2-propylene glycol, and 1,4. -Butanediol, neopentyl glycol, polyethylene glycol, polypropylene glycol, hydrogenated bisphenol A and the like. Examples of the trihydric or higher polyhydric alcohol include sorbitol, pentaerythritol, glycerin, trimethylolpropane and the like. Of these, from the viewpoint of resin emulsification and toner fixing properties, an alkylene oxide adduct of bisphenol A, such as an ethylene oxide adduct of bisphenol A, a propylene oxide adduct of bisphenol A, is preferred. Preferred examples include polyoxypropylene-2,2-bis (4-hydroxyphenyl) propane, polyoxyethylene-2,2-bis (4-hydroxyphenyl) propane and the like. The said alcohol component may be used individually by 1 type, and may be used in combination of 2 or more type.

As a carboxylic acid component as a raw material component, a known divalent or trivalent or higher carboxylic acid component can be used. Divalent carboxylic acids include terephthalic acid, isophthalic acid, phthalic acid, phthalic anhydride, oxalic acid, malonic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, succinic acid, adipic acid, alkyl group Or, aliphatic dicarboxylic acids such as succinic acid substituted with an alkenyl group, anhydrides of those acids, alkyl (carbon number 1 to 3) esters of those acids, and the like. From the viewpoint of improving the storage stability of the toner, it is preferable to use at least one carboxylic acid selected from terephthalic acid, isophthalic acid, phthalic acid, and phthalic anhydride. From the above viewpoint, these carboxylic acids are preferably contained in the carboxylic acid component in a total amount of 50 mol% or more, more preferably 60 mol% or more, and further preferably 70 mol% or more.
The said carboxylic acid component may be used individually by 1 type, and may be used in combination of 2 or more type.

Examples of the trivalent or higher polyvalent carboxylic acid compounds include aromatic carboxylic acids such as 1,2,4-benzenetricarboxylic acid (trimellitic acid), 2,5,7-naphthalenetricarboxylic acid, pyromellitic acid, and Derivatives such as these acid anhydrides and alkyl (C1-C3) esters are mentioned, and among these, trimellitic acid and its acid anhydride are preferred from the viewpoint of being inexpensive and easy to control the reaction. This carboxylic acid component may be used individually by 1 type, and may be used in combination of 2 or more type.
In the present invention, from the viewpoint of toner fixability, the carboxylic acid component preferably contains the above-described trivalent or higher polyvalent carboxylic acid. The content thereof is preferably 5 to 40 mol%, more preferably 10 to 40 mol%, and further preferably 15 to 40 mol% in the total carboxylic acid component, from the viewpoint of hot offset resistance of the toner.

The polyester can be produced, for example, by subjecting an alcohol component and a carboxylic acid component to condensation polymerization at a temperature of about 180 to 250 ° C. in an inert gas atmosphere using an esterification catalyst as necessary.
As the esterification catalyst, an esterification catalyst such as a tin compound such as dibutyltin oxide or tin dioctylate or a titanium compound such as titanium diisopropylate bistriethanolamate can be used. The amount of the esterification catalyst used is preferably 0.01 to 1 part by weight, more preferably 0.1 to 0.6 part by weight, based on 100 parts by weight of the total amount of the alcohol component and the carboxylic acid component.
The polyester may be composed of two or more kinds of polyesters having different physical properties such as a softening point.

From the viewpoint of storage stability of the toner, the softening point of the polyester is preferably 70 to 165 ° C. The glass transition point is preferably 50 to 85 ° C, more preferably 50 to 65 ° C. The acid value is preferably 6 to 35 mgKOH / g, more preferably 10 to 35 mgKOH / g, and still more preferably 15 to 35 mgKOH / g, from the viewpoint of manufacturability during emulsification. The desired softening point, glass transition point and acid value can be obtained by adjusting the charging ratio of alcohol and carboxylic acid, the temperature of condensation polymerization, and the reaction time.
From the viewpoint of the durability of the toner, the number average molecular weight of the polyester is preferably 1,000 to 10,000, and more preferably 2,000 to 8,000.

  Further, the polyester may be modified to such an extent that the characteristics are not substantially impaired. For example, the modified polyester may be grafted or blocked with phenol, urethane, epoxy or the like by the method described in JP-A-11-133668, JP-A-10-239903, JP-A-8-20636, etc. Polyester.

The binder resin containing the polyester of the present invention preferably has the same softening point, glass transition point, acid value, and number average molecular weight as those of the polyester of the present invention.
In this invention, other well-known resin other than the said polyester can be contained. For example, polyester other than the polyester, styrene acrylic copolymer, epoxy, polycarbonate, polyurethane and the like can also be used. From the viewpoint of emulsifying property of the binder resin containing polyester and toner fixing property, the polyester is In the binder resin, 70% by weight is preferable, 80% by weight is more preferable, 90% by weight is further preferable, and substantially 100% by weight is particularly preferable.
The polyester for toner of the present invention is used for the production of the following electrophotographic toner.

[Electrophotographic toner and method for producing the same]
The toner for electrophotography of the present invention is obtained by a production method including a step of forming a binder resin containing the polyester into toner particles in an aqueous medium, and obtains a toner having a small particle size and high circularity. From the viewpoint, an emulsion aggregation method, which is a production method including a step of aggregating and coalescing resin particles containing a binder resin containing the polyester, is preferable. Hereinafter, the emulsion aggregation method will be described.
The method for producing an electrophotographic toner of the present invention comprises (a) a step of neutralizing a resin containing a polyester with a basic compound in an aqueous medium to obtain resin particles, and (b) a step (a). A step of agglomerating and coalescing the obtained resin particles, wherein the polyester is obtained by polycondensing an alcohol component containing 4 to 40 mol% of polyethylene glycol having a number average molecular weight of 150 to 2000 and a carboxylic acid component. It is preferable that

(Process (a))
Step (a) is a step of obtaining resin particles by neutralizing a binder resin containing polyester in an aqueous medium with a basic compound.
Aqueous medium The aqueous medium is mainly composed of water. From the environmental viewpoint, the content of water in the aqueous medium is preferably 80% by weight or more, more preferably 90% by weight or more, more preferably 95% by weight or more, and further preferably 100% by weight.
Examples of components other than water include alcohols such as methanol, ethanol, isopropanol, and butanol, and organic solvents that dissolve in water such as acetone, methyl ethyl ketone, and tetrahydrofuran. Among these, the alcohol-based organic solvent that is an organic solvent that does not dissolve the resin can be used from the viewpoint of preventing mixing into the toner. In the present invention, it is preferable to atomize the resin using only water without substantially using an organic solvent.

Resin Particles Containing Binder Resin Containing Polyester When producing the electrophotographic toner of the present invention, first, resin particles containing a binder resin containing polyester in an aqueous medium are dispersed in a resin dispersion containing the resin particles. Prepare as The resin dispersion containing the resin particles is preferably prepared by emulsifying the resin from the viewpoint of reducing the particle size of the resin particles and achieving a uniform particle size distribution of the obtained toner.
The resin particles in the resin emulsion obtained by emulsifying the binder resin in the aqueous medium include, as necessary, a colorant, a release agent, a charge control agent, a fibrous substance, etc. together with the binder resin. Additives such as reinforcing fillers, antioxidants, anti-aging agents and the like can be included.

The colorant is not particularly limited, and any known colorant can be used. Specifically, carbon black, inorganic composite oxide, chrome yellow, hansa yellow, benzidine yellow, quinoline yellow, permanent red, brilliantamine 3B, brilliantamine 6B, rhodamine B rake, lake red C, Bengal, aniline blue, Various pigments such as ultramarine blue, phthalocyanine blue, phthalocyanine green, and various dyes such as acridine, xanthene, azo, benzoquinone, indico, phthalocyanine, aniline black, polymethine, and triphenylmethane Species can be used alone or in combination of two or more.
The content of the colorant is preferably 20 parts by weight or less, more preferably 0.01 to 10 parts by weight with respect to 100 parts by weight of the binder resin.

As release agents, low molecular weight polyolefins such as polyethylene, polypropylene and polybutene; silicones having a softening point upon heating; fatty acid amides such as oleic acid amide, erucic acid amide, ricinoleic acid amide and stearic acid amide; carnauba Plant waxes such as wax, rice wax, candelilla wax and tree wax; animal waxes such as beeswax; mineral and petroleum waxes such as montan wax, ozokerite, ceresin, paraffin wax and Fischer-Tropsch wax. These release agents can be used alone or in combination of two or more.
The content of the release agent is 100 weight parts of the resin in consideration of the effect of addition and the adverse effect on the chargeability of the toner, or in the case of using the colorant, the total amount of the binder resin and the colorant is 100 weight. The amount is usually about 1 to 20 parts by weight, preferably 2 to 15 parts by weight with respect to parts.

Examples of charge control agents include metal salts of benzoic acid, metal salts of salicylic acid, metal salts of alkyl salicylic acid, metal salts of catechol, metal-containing (chromium, iron, aluminum, etc.) bisazo dyes, tetraphenylborate derivatives, quaternary Examples thereof include ammonium salts and alkylpyridinium salts.
The content of the charge control agent is preferably 10 parts by weight or less, and more preferably 0.01 to 5 parts by weight with respect to 100 parts by weight of the binder resin.

In the present invention, when the binder resin containing polyester is emulsified, from the viewpoint of improving the emulsion stability of the resin, it is preferably 10 parts by weight or less, more preferably 5 parts by weight with respect to 100 parts by weight of the binder resin. It is preferable that the surfactant is present in an amount of not more than 1 part by weight, more preferably 0.1 to 3 parts by weight, still more preferably 0.5 to 2 parts by weight.
Examples of the surfactant include anionic surfactants such as sulfate ester, sulfonate, and soap; cationic surfactants such as amine salt type and quaternary ammonium salt type; polyethylene glycol type and alkylphenol ethylene Nonionic surfactants such as oxide adducts are listed. Among these, ionic surfactants such as anionic surfactants and cationic surfactants are preferable. The nonionic surfactant is preferably used in combination with an anionic surfactant or a cationic surfactant. Although the said surfactant may be used individually by 1 type, you may use it in combination of 2 or more type.

Specific examples of the anionic surfactant include dodecyl benzene sulfonic acid, sodium dodecyl benzene sulfonate, sodium dodecyl sulfate, sodium alkyl ether sulfate, and the like. Among these, sodium dodecylbenzenesulfonate is preferable.
Specific examples of the cationic surfactant include alkyl benzene dimethyl ammonium chloride.
Nonionic surfactants include, for example, polyoxyethylene alkyl aryl ethers such as polyoxyethylene oleyl ether and polyoxyethylene lauryl ether or polyoxyethylene alkyl ethers and polyoxyethylene sorbitan monostearate and other polyoxyethylene alkyl aryl ethers. Examples include ethylene sorbitan esters, polyoxyethylene fatty acid esters such as polyethylene glycol monostearate, and oxyethylene / oxypropylene block copolymers.

In the step (a), it is preferable to add a basic compound to the resin and disperse the binder resin and additives used as necessary.
The basic compound is preferably used as an aqueous solution, and the aqueous solution preferably has a concentration of 1 to 20% by weight, more preferably 1 to 10% by weight, and 1.5 to 7.5% by weight. More preferred is a concentration. As the basic compound to be used, it is preferable to use a compound that enhances its surface activity when the polyester becomes a salt. Specific examples thereof include monovalent alkali metal hydroxides such as potassium hydroxide and sodium hydroxide.
After dispersion, neutralize at a temperature above the glass transition point of the binder resin, and then emulsify by adding an aqueous medium at a temperature above the glass transition point of the binder resin, thereby dispersing the resin containing resin particles. A liquid can be produced.

The addition rate of the aqueous medium is preferably 0.1 to 50 g / min, more preferably 0.5 to 40 g / min, and still more preferably 1 to 100 g per 100 g of the binder resin from the viewpoint that emulsification can be effectively performed. 30 g / min. This addition rate is generally maintained until an O / W type emulsion is substantially formed, and there is no particular limitation on the addition rate of water after the formation of the O / W type emulsion.
Examples of the aqueous medium used for the production of the emulsion include the same as the above-described aqueous medium, and deionized water or distilled water is preferable.
The amount of the aqueous medium is preferably 100 to 2,000 parts by weight, and more preferably 150 to 1,500 parts by weight with respect to 100 parts by weight of the binder resin, from the viewpoint of obtaining uniform aggregated particles in the subsequent aggregation step. From the viewpoint of stability and handleability of the obtained resin dispersion, the solid content concentration of the resin dispersion is preferably 7 to 50% by weight, more preferably 7 to 40% by weight, and still more preferably 10 to 35% by weight. The amount of the aqueous medium is selected so that The solid content includes non-volatile components such as a binder resin and a nonionic surfactant.

Further, the temperature at this time is preferably in the range of not less than the glass transition point and not more than the softening point of the binder resin from the viewpoint of preparing a fine resin dispersion. By carrying out at a temperature within the above range, emulsification is carried out smoothly and no special apparatus is required for heating. From this point, the temperature is preferably equal to or higher than the (glass transition point + 10 ° C.) of the resin (meaning “temperature higher by 10 ° C. than the glass transition point”, hereinafter the same notation is similarly understood). , (Softening point −5) ° C. or lower is preferable.
The volume median particle size (D50) of the resin particles in the resin dispersion thus obtained is preferably 50 to 550 nm, more preferably 50 to 300 nm in order to perform uniform aggregation in the subsequent aggregation treatment. More preferably, it is 50-250 nm, More preferably, it is 50-200 nm. Here, “volume median particle size (D50)” means a particle size at which the cumulative volume frequency calculated by the volume fraction is 50% when calculated from the smaller particle size.

As another method for obtaining a resin dispersion by emulsifying a binder resin in an aqueous medium, for example, first, a polycondensable monomer as a target resin particle raw material in an aqueous medium, for example, mechanical share or A method of emulsifying and dispersing by ultrasonic waves or the like is mentioned. At this time, if necessary, additives such as a polycondensation catalyst and a surfactant are also added to the water-soluble medium. And polycondensation is advanced by, for example, heating the solution. For example, when the binder resin is polyester, the above-mentioned polyester polycondensable monomer and polycondensation catalyst can be used, and the above-mentioned surfactants can be used similarly.
Usually, polycondensation resins do not proceed in an aqueous medium in principle because they are dehydrated during polymerization. However, for example, when a polycondensable monomer is emulsified in an aqueous medium together with a surfactant that causes micelles to form in the aqueous medium, the monomer is placed in a micro hydrophobic field in the micelle. Then, dehydration occurs, and the generated water can be discharged into an aqueous medium outside the micelles to allow polymerization to proceed. In this way, a dispersion in which polycondensation resin particles are emulsified and dispersed in an aqueous medium is obtained with low energy.

(Process (b))
Step (b) is a step of aggregating and coalescing the resin particles obtained in step (a).
Aggregating step In the aggregating step, an aggregating agent is added for effective aggregation. In the present invention, as an aggregating agent, a quaternary salt cationic surfactant, polyethyleneimine or the like is used in an organic system, and an inorganic metal salt, an inorganic ammonium salt, a divalent or higher metal complex, or the like is used in an inorganic system. Examples of the inorganic metal salt include metal salts such as sodium sulfate, sodium chloride, and calcium chloride, and inorganic metal salt polymers such as polyaluminum chloride and polyaluminum hydroxide. Examples of the inorganic ammonium salt include ammonium sulfate and ammonium chloride.

  Of the aggregating agents, monovalent salts are preferably used from the viewpoint of achieving highly accurate toner particle size control and a sharp particle size distribution. Here, the monovalent salt means that the valence of the metal ion or cation constituting the salt is 1. As the monovalent salt, organic flocculants such as quaternary salt cationic surfactants and inorganic flocculants such as inorganic metal salts and ammonium salts are used. In the present invention, water-soluble water having a molecular weight of 350 or less is used. A nitrogen-containing compound is preferably used.

As such a water-soluble nitrogen-containing compound, from the viewpoint of productivity, for example, ammonium sulfate (pH value of a 10 wt% aqueous solution at 25 ° C., hereinafter referred to as pH value: 5.4), ammonium chloride (pH value: 4. 6), tetraethylammonium bromide (pH value: 5.6), and tetrabutylammonium bromide (pH value: 5.8) are preferred.
The amount of the flocculant used is preferably 50 parts by weight or less, more preferably 40 parts by weight or less, and more preferably 30 parts by weight with respect to 100 parts by weight of the resin, from the viewpoint of toner charging properties, particularly charging characteristics in a high temperature and high humidity environment. More preferred are: Moreover, from a cohesive viewpoint, 1 weight part or more is preferable with respect to 100 weight part of resin, 3 weight part or more is more preferable, and 5 weight part or more is still more preferable. Considering the above points, the amount of monovalent salt used is preferably 1 to 50 parts by weight, more preferably 3 to 40 parts by weight, and still more preferably 5 to 30 parts by weight with respect to 100 parts by weight of the resin.

The flocculant is added after adjusting the pH in the system to a temperature of (glass transition point of resin + 20 ° C.) or less, preferably (glass transition point + 10 ° C.) or less, more preferably (glass transition point + 5 ° C.). ) At a temperature below. By carrying out at the said temperature, a particle size distribution is narrow and uniform agglomeration can be performed. The addition is preferably performed at (softening point−100 ° C.) or more of the resin, and more preferably (softening point−90 ° C.) or more. In this case, the pH in the system is preferably 2 to 10, more preferably 2 to 8, and further preferably 3 to 7 from the viewpoint of achieving both the dispersion stability of the mixed solution and the cohesiveness of the resin particles.
The flocculant can be added as an aqueous medium solution. The flocculant may be added at one time, or may be added intermittently or continuously. Furthermore, it is preferable to sufficiently stir at the time of adding the monovalent salt and after the addition is completed.

In this way, aggregated particles are prepared by aggregating the resin particles in the resin dispersion.
The aggregated particles preferably have a volume-median particle size (D50) of 1 to 10 μm, more preferably 2 to 9 μm, and still more preferably 2 to 6 μm, from the viewpoint of reducing the toner particle size. The coefficient of variation (CV value), which is an index indicating the sharpness of the particle size distribution, is preferably 45 or less, more preferably 30 or less, and even more preferably 28 or less, from the viewpoint of obtaining a high image.
The coefficient of variation (CV value) of the particle size distribution is expressed by the formula CV value = [standard deviation of particle size distribution (μm) / volume median particle size (μm)] × 100
It is a value represented by
In the present invention, it is preferable to add a surfactant after aggregating the resin particles, and at least one selected from the group consisting of alkyl ether sulfates, alkyl sulfates, and linear alkylbenzene sulfonates is added. More preferably.
The amount of the surfactant added is preferably from 0.1 to 15 parts by weight, more preferably from 0.1 to 15 parts by weight, based on 100 parts by weight of the resin constituting the aggregated particles, from the viewpoints of aggregation stopping properties and persistence to the toner. 1 to 10 parts by weight, more preferably 0.1 to 8 parts by weight.

In the present invention, from the viewpoint of preventing the release of a release agent or the like, or in the color toner, the charge amount between the respective colors is set to the same level, the resin particles obtained in the step (a) (hereinafter referred to as the aggregation) The resin particles of the present invention are sometimes referred to as “resin particles of the present invention”, and other resin fine particles can be added at once or divided into a plurality of times. Conversely, the resin particles of the present invention can be added to other resin fine particles at once or divided into a plurality of times for aggregation.
Other resin fine particles added to the resin particles of the present invention are not particularly limited, and can be prepared, for example, in the same manner as the emulsified particles of the present invention.
In the present invention, the other resin fine particles may be the same as or different from the resin fine particles of the present invention. From the viewpoint of low-temperature fixability and storage stability of the toner, the present invention is preferable. The resin fine particles different from the resin particles are added at a later time or divided into a plurality of times.
In this step, the other resin particles may be mixed with the aggregated particles obtained by adding the flocculant as described above to the dispersion of the resin particles of the present invention.
In the present invention, the addition timing of the other resin fine particles is not particularly limited. However, from the viewpoint of productivity, it is preferable that the addition of the flocculant is performed until the coalescence step.

In this step, the resin particle dispersion of the present invention may be mixed with aggregated particles obtained by adding an aggregating agent to the other resin fine particles.
The blending ratio of the resin particles of the present invention and other resin fine particles (resin particles of the present invention / other resin fine particles) is 0.1 to 2.0 by weight from the viewpoint of achieving both low temperature fixability and storage stability. Preferably, it is 0.2 to 1.5, more preferably 0.3 to 1.0.
The obtained agglomerated particles are subjected to a step of coalescing the agglomerated particles (a coalescence step).

Combined Step In the present invention, the aggregated particles obtained in the aggregation step are heated and combined. In the coalescence process, the temperature in the system is preferably equal to or higher than the temperature in the system in the aggregation process, but the target toner particle size, particle size distribution, shape control, and particle fusing property In view of the above, the glass transition point or higher of the resin is preferable, (softening point + 20 ° C) or lower is more preferable, (glass transition point + 5 ° C) or higher and (softening point + 15 ° C) or lower is more preferable, (glass transition point + 10 ° C). ) And more preferably (softening point + 10 ° C.) or less. The stirring speed is preferably a speed at which the aggregated particles do not settle.
In the present invention, the coalescence step may be performed simultaneously with the aggregation step, for example, by continuously raising the temperature or by raising the temperature to a temperature at which aggregation and coalescence can be performed and then continuing stirring at that temperature. it can.
From the viewpoint of improving the image quality of the toner, the volume median particle size (D50) of the coalesced particles is preferably 1 to 10 μm, more preferably 2 to 8 μm, still more preferably 3 to 8 μm.

The obtained coalesced particles become toner particles through a solid-liquid separation process such as filtration, a washing process, and a drying process. Here, in order to ensure sufficient charging characteristics and reliability as a toner, it is preferable to perform cleaning with an acid in order to remove metal ions on the toner surface in the cleaning step. Further, it is preferable to completely remove the added nonionic surfactant by washing, and washing with an aqueous solution below the cloud point of the nonionic surfactant is preferred. The washing is preferably performed a plurality of times.
In the drying step, any method such as a vibration type fluidized drying method, a spray drying method, a freeze drying method, a flash jet method, or the like can be employed. The water content after drying of the toner particles is preferably adjusted to 1.5% by weight or less, more preferably 1.0% by weight or less, from the viewpoint of chargeability of the toner.

The softening point of the electrophotographic toner of the present invention is preferably 105 to 200 ° C., more preferably 105 to 180 ° C., and further preferably 105 to 160 ° C. from the viewpoint of expansion of the fixing temperature range. The glass transition point is preferably from 30 to 80 ° C., more preferably from 40 to 70 ° C., from the viewpoint of improving the low-temperature fixability and storage stability of the toner. The method for measuring the softening point and the glass transition point of the toner is in accordance with these measurement methods for the binder resin.
From the viewpoint of high image quality, the volume median particle size (D50) of the toner particles is preferably 1 μm or more, and more preferably 2 μm or more. Moreover, 9 micrometers or less are preferable, 8 micrometers or less are more preferable, and 7 micrometers or less are still more preferable.

In addition, since toner with a high degree of circularity is in point contact between the photoconductor and the toner, the contact area is small, transferability is excellent, and image defects such as voids are less likely to occur. ˜0.98 is preferable, 0.96 to 0.98 is more preferable, and 0.965 to 0.975 is still more preferable. The degree of circularity can be measured by a flow type particle image analyzer, specifically by FPIA-3000 (Sysmex Corporation). In the present invention, the circularity of a particle is a value obtained by the ratio of the circumference of a circle equal to the projected area / the circumference of the projected image. The more circular the particle is, the closer the circularity is to 1.
Further, the CV values of the above-mentioned aggregated particles, coalesced particles and toner particles are all preferably 45 or less, more preferably 35 or less, and still more preferably 30 or less.
The particle size and particle size distribution of the toner particles can be measured by the method described later.

The toner particles obtained as described above are used as the electrophotographic toner of the present invention by adding an additive such as a fluidizing agent as an external additive to the toner particle surface. can do. As the external additive, known fine particles such as inorganic fine particles such as silica fine particles, titanium oxide fine particles, alumina fine particles, and cerium oxide fine particles whose surface is hydrophobized, and polymer fine particles such as polycarbonate and polymethyl methacrylate can be used. The number average particle diameter of the external additive is preferably 4 to 500 nm, more preferably 4 to 200 nm, and still more preferably 8 to 30 nm. The number average particle diameter of the external additive is determined using a scanning electron microscope or a transmission electron microscope.
The amount of the external additive is preferably 1 to 5 parts by weight and more preferably 1.5 to 3.5 parts by weight with respect to 100 parts by weight of the toner before processing with the external additive.
The toner for electrophotography obtained by the present invention can be used as a one-component developer or as a two-component developer by mixing with a carrier.

[Resin dispersion for toner]
The resin dispersion for toner of the present invention is a resin dispersion obtained by dispersing a resin containing polyester in an aqueous medium, and the polyester contains 4 to 40 mol% of polyethylene glycol having an average molecular weight of 150 to 2000. It is obtained by polycondensing an alcohol component and a carboxylic acid component. Each requirement constituting the binder resin dispersion for toner is as described above.

Hereinafter, the present invention will be described more specifically with reference to examples.
In the following examples and the like, each property value was measured and evaluated by the following method.
[Acid value of binder resin]
Measured according to JIS K0070. However, the measurement solvent was a mixed solvent of acetone and toluene (acetone: toluene = 1: 1 (volume ratio)).

[Softening point and glass transition point of binder resin]
(1) Softening point Using a flow tester (Shimadzu Corporation, “CFT-500D”), a 1 g sample was heated at a heating rate of 6 ° C./min, a load of 1.96 MPa was applied by a plunger, a diameter of 1 mm, Extrude from a 1 mm long nozzle. Plot the flow tester drop by the flow tester against the temperature, and let the softening point be the temperature at which half the sample flowed out.
(2) Glass transition point Using a differential scanning calorimeter (“DSC210” manufactured by Seiko Denshi Kogyo Co., Ltd.), the temperature was raised to 200 ° C., and the temperature of the sample cooled to 0 ° C. at a temperature lowering rate of 10 ° C./min was raised. Measure at a rate of 10 ° C / min. The temperature at the intersection of the baseline extension line below the maximum peak temperature of endotherm and the tangent line showing the maximum slope from the peak rising portion to the peak apex is read as the glass transition point.

[Particle size of resin particles, aggregated particles, coalesced particles and release agent particles]
(1) Measuring apparatus: Laser scattering type particle size measuring machine (LA-920, manufactured by HORIBA, Ltd.)
(2) Measurement conditions: Distilled water is added to the measurement cell, and the volume-median particle size (D50) is measured at a temperature where the absorbance falls within an appropriate range. The particle size distribution is represented by a CV value (standard deviation of particle size distribution / volume median particle size (D50) × 100).

[Number average molecular weight of polyethylene glycol]
The molecular weight distribution is measured by gel permeation chromatography and the number average molecular weight is calculated by the following method.
(1) Preparation of sample solution Polyethylene glycol is dissolved in tetrahydrofuran so that the concentration is 0.5 g / 100 ml. Subsequently, this solution is filtered using a fluororesin filter having a mesh of 0.45 μm [manufactured by Advantech Co., Ltd., “DISMIC-25JP”] to remove insoluble components to obtain a sample solution.
(2) Molecular weight distribution measurement Using the following apparatus, tetrahydrofuran is flowed at a flow rate of 1 ml / min, and the column is stabilized in a constant temperature bath at 40 ° C. 100 μl of the sample solution is injected therein and measurement is performed. The molecular weight of the sample is calculated based on a calibration curve prepared in advance. The calibration curve at this time includes several types of monodisperse polystyrene (2.63 × 10 ³ , 2.06 × 10 ⁴ , 1.02 × 10 ⁵ made by Tosoh, 2.10 × 10 ³ made by GL Sciences, 7.00 × 10 ³ , 5.04 × 10 ⁴ ) are used as standard samples.
Measuring device: HLC-8220 GPC (manufactured by Tosoh Corporation)
Analytical column: GMH _XL + G3000H _XL (manufactured by Tosoh Corporation)

[Solid concentration of resin dispersion and release agent dispersion]
Using an infrared moisture meter (Ketto Science Laboratory Co., Ltd .: FD-230), 5 g of the emulsion was wet at a drying temperature of 150 ° C. and in a measurement mode 96 (monitoring time 2.5 minutes / variation width 0.05%). Measure the moisture content of the base. The solid content was calculated according to the following formula.
Solid content (%) = 100-M
M: wet base moisture (%) = [(W−W0) / W] × 100
W: Sample weight before measurement (initial sample weight)
W0: Sample weight after measurement (absolute dry weight)

[Toner particle size]
・ Measuring machine: Coulter Multisizer II (Beckman Coulter, Inc.)
・ Aperture diameter: 50μm
・ Analysis software: Coulter Multisizer AccuComp version 1.19 (manufactured by Beckman Coulter)
・ Electrolyte: Isoton II (Beckman Coulter)
-Dispersion: Emulgen 109P (manufactured by Kao Corporation, polyoxyethylene lauryl ether, HLB: 13.6) is dissolved in the electrolyte so as to have a concentration of 5% by weight to obtain a dispersion.
-Dispersion condition: 10 mg of a measurement sample is added to 5 mL of the dispersion, and dispersed for 1 minute with an ultrasonic disperser, and then 25 mL of an electrolyte is added, and further dispersed for 1 minute with an ultrasonic disperser. A sample dispersion is prepared.
Measurement conditions: The sample dispersion is added to 100 mL of the electrolytic solution to adjust the particle size of 30,000 particles to a concentration that can be measured in 20 seconds, and then 30,000 particles are measured and the particle size distribution thereof. To determine the volume-median particle size (D50).

[Toner circularity]
The number average circularity was determined under the following conditions: Preparation of dispersion: 50 mg of toner was added to 5 ml of an aqueous polyoxyethylene lauryl ether solution (Kao Corp., Emulgen 109P HLB13.6, 5 wt% aqueous solution) After dispersing with a disperser for 1 minute, 20 ml of distilled water was added, and further dispersed with an ultrasonic disperser for 1 minute to obtain a toner dispersion.
Measurement device: Flow-type particle image analyzer (FIPA-3000 manufactured by Sysmex Corporation)
・ Measurement mode: HPF measurement mode

Production Examples 1 to 5 and Comparative Production Examples 1 to 4 (Production of Polyesters A to I)
Raw material monomers other than trimellitic acid shown in Table 1 and 20 g of tin (II) octylate were placed in a 5-liter four-necked flask equipped with a nitrogen introduction tube, a dehydration tube, a stirrer, and a thermocouple under a nitrogen atmosphere. After reacting at 230 ° C. for 8 hours, vacuum reaction was performed at 8.3 kPa for 1 hour. Further, trimellitic acid shown in Table 3 was added at 210 ° C. and reacted at normal pressure (101.3 kPa) for 1 hour, and then reacted at 8.3 kPa until a desired softening point was reached. I (Polyesters A to E in Production Examples 1 to 5 and Polyesters F to I in Comparative Production Examples 1 to 4) were obtained, respectively. Table 1 shows the monomer composition and properties of each resin.

PO2.2: polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane EG: ethylene glycol (ethylene glycol Wako first grade manufactured by Wako Pure Chemical Industries, Ltd.)
PEG-200: polyethylene glycol; number average molecular weight 200 (polyethylene glycol 200 manufactured by Wako Pure Chemical Industries, Ltd., Wako first grade)
PEG-1000: polyethylene glycol; number average molecular weight 1000 (Wako Pure Chemical Industries, Ltd., polyethylene glycol 1,000, Wako first grade)
PEG-4000: polyethylene glycol; number average molecular weight 4000 (polyethylene glycol 4,000, Wako first grade, manufactured by Wako Pure Chemical Industries, Ltd.)
TPA: terephthalic acid IPA: isophthalic acid TMA: trimellitic anhydride

Example 1 (Production of resin particle dispersion A)
In a 2 liter stainless steel kettle, 300 g of polyester A, 22.5 g of dimethylquinacridone pigment “ECR186Y: (manufactured by Dainichi Seika Co., Ltd.)” and anionic surfactant “Neopelex G-15 (manufactured by Kao Corporation)” dodecyl Sodium benzenesulfonate (solid content: 15% by weight) 20.0 g, nonionic surfactant “Emulgen 430 (manufactured by Kao)” polyoxyethylene (26 mol) oleyl ether (HLB: 16.2) 3.0 g, In addition, 183.0 g of 5 wt% potassium hydroxide aqueous solution was dispersed at 25 ° C. with stirring at 200 r / min with a chi-type stirrer. The contents were stabilized at 95 ° C. and held for 2 hours under stirring at 200 r / min with a chi-type stirrer. Subsequently, 544.5 g of deionized water was added at 3 g / min while stirring at 200 r / min with a Kai-type stirrer. Further, the temperature in the system was maintained at 95 ° C. while deionized water was added dropwise. After completion of dropping, the mixture was cooled and a dispersion A in which resin particles were dispersed was obtained through a 150 mesh (mesh: 105 μm) wire mesh. The resin particles in the obtained resin particle dispersion A had a volume median particle size (D50) of 153 nm and a solid content concentration of 31.3% by weight, and no resin component remained on the wire mesh.

Example 2 (Production of resin particle dispersion B)
In Example 1, resin particle dispersion B was obtained in the same manner except that 300 g of polyester B and 179.4 g of potassium hydroxide aqueous solution were used instead of polyester A, and 547.5 g of deionized water was added at 3 g / min. It was. The volume median particle size (D50) of the resin particles in the obtained resin particle dispersion B was 164 nm, the solid content concentration was 30.5% by weight, and no resin component remained on the wire mesh.

Example 3 (Production of resin particle dispersion C)
In Example 1, resin particle dispersion C was obtained in the same manner except that 300 g of polyester C and 160.8 g of potassium hydroxide aqueous solution were used instead of polyester A, and 563.0 g of deionized water was added at 3 g / min. It was. The resin particles in the obtained resin particle dispersion C had a volume median particle size (D50) of 125 nm and a solid content concentration of 30.7% by weight, and no resin component remained on the wire mesh.

Example 4 (Production of resin particle dispersion D)
In Example 1, resin particle dispersion D was obtained in the same manner except that 300 g of polyester D and 171.6 g of an aqueous potassium hydroxide solution were used instead of polyester A, and 554 g of deionized water was added at 3 g / min. The resin particles in the obtained resin particle dispersion D had a volume median particle size (D50) of 135 nm and a solid content concentration of 30.8% by weight, and no resin component remained on the wire mesh.

Example 5 (Production of resin particle dispersion E)
In Example 1, resin particle dispersion E was obtained in the same manner except that 300 g of polyester E and 145.2 g of aqueous potassium hydroxide solution were used instead of polyester A, and 576.0 g of deionized water was added at 3 g / min. It was. The volume median particle size (D50) of the resin particles in the obtained resin particle dispersion E was 144 nm, the solid content concentration was 31.6 wt%, and no resin component remained on the wire mesh.

Comparative Example 1 (Production of resin particle dispersion F)
A resin particle dispersion F was obtained in the same manner as in Example 1, except that 300 g of polyester F and 153.6 g of an aqueous potassium hydroxide solution were used instead of polyester A, and 569.0 g of deionized water was added at 3 g / min. It was. The resin particles in the obtained resin particle dispersion F had a volume median particle size (D50) of 1854 nm and a solid content concentration of 28.9% by weight, and no resin component remained on the wire mesh.

Comparative Example 2 (Production of resin particle dispersion G)
A resin particle dispersion G was obtained in the same manner as in Example 1 except that 300 g of polyester G and 158.4 g of aqueous potassium hydroxide were used instead of polyester A, and 565.0 g of deionized water was added at 3 g / min. It was. The resin particles in the obtained resin particle dispersion G had a volume median particle size (D50) of 135 nm and a solid content concentration of 30.2% by weight, and no resin component remained on the wire mesh.

Comparative Example 3 (Production of resin particle dispersion H)
In Example 1, the resin particle dispersion H was obtained in the same manner except that 300 g of polyester H and 151.8 g of potassium hydroxide aqueous solution were used instead of polyester A, and 570.5 g of deionized water was added at 3 g / min. It was. The resin particles in the obtained resin particle dispersion H had a volume median particle size (D50) of 147 nm and a solid content concentration of 30.2% by weight, and no resin component remained on the wire mesh.

Comparative Example 4 (Production of resin particle dispersion I)
A resin particle dispersion I was obtained in the same manner as in Example 1, except that 300 g of polyester I and 182.4 g of potassium hydroxide aqueous solution were used instead of polyester A, and 545.0 g of deionized water was added at 3 g / min. It was. The volume-average particle size (D50) of the resin particles in the obtained resin particle dispersion I was 2241 nm, the solid content concentration was 28.8% by weight, and no resin component remained on the wire mesh.

Production Example 6 (Production of release agent dispersion A)
In a 1 liter beaker, 3.57 g of an aqueous solution of dipotassium alkenyl succinate “Latemul ASK (manufactured by Kao Corporation), effective concentration 28%” was dissolved in 400 g of deionized water, and then carnauba wax (manufactured by Kato Yoko Co., Ltd.). , Melting point 85 ° C.) 100 g was dispersed. While maintaining this dispersion at a temperature of 90 to 95 ° C., a dispersion treatment was performed with an Ultrasonic Homogenizer 600W (manufactured by Nippon Seiki Co., Ltd.) for 30 minutes to obtain a dispersion A. The volume median particle size (D50) of the release agent in the obtained dispersion A was 0.47 μm, the CV value was 26, and the solid content concentration was 23% by weight.

Example 6
(Production of aggregated particles)
500 g of the resin particle dispersion A was placed in a 2 liter container, and 65.68 g of the release agent dispersion A was added and mixed well at 22 ° C. with stirring at 100 r / min with a Kai-type stirrer. Next, a solution obtained by dissolving 12.0 g of ammonium sulfate in 508 g of deionized water was added dropwise at 4 mL / min. Thereafter, while stirring, the mixture was heated to 60 ° C. at a temperature rising rate of 1.27 ° C./min, and held at 60 ° C. until the volume-median particle size became about 6 μm to produce aggregated particles.
[Production of coalesced particles]
Anionic surfactant “Emar E-27C (manufactured by Kao)” 5.42 g of sodium polyoxyethylene lauryl ether sulfate was added and heated at a heating rate of 1 ° C./min, and the temperature of the dispersion reached 87 ° C. At that time, the heating was stopped and the mixture was cooled to room temperature while stirring. The contents were suction filtered, washed and dried to obtain coalesced particles. The volume-median particle size (D50) of the coalesced particles was 7.5 μm.

[Production of toner]
To 100 parts by weight of the coalesced particles, 1.0 part by weight of hydrophobic silica (R972 manufactured by Nippon Aerosil Co., Ltd., number average particle size: 16 nm) was externally added using a Henschel mixer to obtain a toner. The obtained toner had a volume-median particle size (D50) of 6.8 μm and a circularity of 0.978. When the storage stability and transfer efficiency were evaluated by the following methods, the degree of aggregation was 8.7 and the concentration was 1.5.

Examples 7 to 10 and Comparative Examples 5 to 8
A toner was obtained in the same manner as in Example 6 except that the resin particle dispersion A was replaced with 500 g of each of the resin particle dispersions B to I in the production of the aggregated particles of Example 6. Table 2 shows the volume-median particle size (D50), circularity, storage stability, and transfer efficiency of the obtained toner.

[Toner preservation]
10 g of toner was placed in a 20 ml polybin and stored in an open state in an environment of a temperature of 50 ° C. and a relative humidity of 40 RH for 48 hours. After storage, the degree of aggregation was measured with a powder tester (manufactured by Hosokawa Micron Corporation) to evaluate the storage stability. In addition, the aggregation degree using a powder tester was calculated | required as follows.
Place three different sieves in the order of 250 μm on the upper stage, 149 μm on the middle stage, and 74 μm on the lower stage on the powder tester's shaking table, place 2 g of toner on it and vibrate, and measure the weight of the toner remaining on each sieve To do.
The measured toner weight is applied to the following equation and calculated to obtain the degree of aggregation [%]. The lower the degree of aggregation, the better.
Aggregation degree [%] = a + b + c
a = (weight of residual toner on upper stage) / 2 [g] × 100
b = (middle stage residual toner weight) / 2 [g] × 100 × (3/5)
c = (lower stage residual toner weight) / 2 [g] × 100 × (1/5)

[Image characteristics of toner]
A toner was mounted on a color printer “MICROLINE 5400” (manufactured by Oki Data) to print a solid image. At this time, the amount of toner on the photoconductor for the solid image is adjusted to 0.40 to 0.50 mg / cm ² , the machine is stopped during the printing of the solid image, and the mending is performed on the photoconductor after passing through the transfer portion. A tape was affixed, the toner that was not transferred and remained on the photoconductor was transferred to a mending tape, and the mending tape was peeled off from the photoconductor. The hues of the peeled and unused mending tapes were measured by X-Rite, the transfer efficiency was measured based on the color difference ΔE, and the toner image characteristics were evaluated. As for the transfer efficiency, the smaller the density ΔE, the better the image characteristics.

From the above results, polyester resin particle dispersions A to E containing polyethylene glycol as the alcohol component, the number average molecular weight of polyethylene glycol being 150 to 2000, and 4 to 40 mol% of polyethylene glycol in the total alcohol component. Each of the resin particles had a small particle size. In addition, electrophotographic toners produced using these resin particles are excellent in storability and high in circularity, and high image quality was obtained on printed matter printed using these toners.
On the other hand, as in each of Comparative Examples 1, 4 and 5, 8, polyesters F and I in which the number average molecular weight of polyethylene glycol is less than 150, or the content of polyethylene glycol in the total alcohol is less than 4 mol%. In both cases, the emulsifiability was not sufficient and only resin particles having a large particle diameter were obtained. Therefore, the toner produced using these resin particles has a low circularity and the printed image has a low image quality. Further, as in each of Comparative Examples 2, 3, and 6, 7, polyesters G and H having a polyethylene glycol number average molecular weight of greater than 2000 or a polyethylene glycol content of all alcohol components greater than 40%. In both cases, the obtained resin particles had a small particle size but a low Tg, and the storage stability when used as a toner was poor.

  The toner for electrophotography of the present invention is used in electrophotography, electrostatic recording method, electrostatic printing method and the like because it has a small particle size, high circularity, excellent image characteristics, and excellent storage stability. It can be suitably used as an electrophotographic toner.

Claims (6)

An electrophotographic toner obtained by a production method comprising a step of forming a binder resin containing polyester into toner particles in an aqueous medium, wherein the polyester comprises 4 to 40 polyethylene glycol having a number average molecular weight of 150 to 2000. A method for producing an electrophotographic toner obtained by polycondensation of an alcohol component and a carboxylic acid component containing mol% ,
A method for producing an electrophotographic toner, wherein the step of forming a binder resin containing polyester into toner particles includes a step of aggregating and coalescing the resin particles containing the binder resin . The method for producing an electrophotographic toner according to claim 1, wherein a content of the polyethylene glycol in a raw material monomer of the binder resin is 1.6 to 22% by weight. (A) a step of neutralizing a resin containing polyester with a basic compound in an aqueous medium to obtain resin particles, and (b) a step of aggregating and coalescing the resin particles obtained in step (a),
Producing how the electrophotographic toner of claim 1 or 2, wherein having. The method for producing an electrophotographic toner according to claim 1, wherein the volume-median particle diameter of the electrophotographic toner is 1 μm or more and 9 μm or less. The method for producing an electrophotographic toner according to claim 1, wherein the electrophotographic toner has a circularity of 0.95 to 0.98. The method for producing a toner for electrophotography according to any one of claims 1 to 5, wherein the polyester has a glass transition point of 50 to 65 ° C.