JP4866721B2 - Method for producing 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.

As a method for producing an electrophotographic toner, there are a melt kneading and pulverizing method and a wet manufacturing method such as an emulsion aggregation method. In the case of the melt kneading and pulverizing method, the toner particle shape is generally indefinite.
When the toner shape is irregular, the fluidity becomes insufficient even by the addition of a flow aid, and the fluidity decreases with time due to the movement of fine particles on the toner surface to the toner recesses due to mechanical elasticity. When the flow aid is embedded in the toner, developability, transferability, and cleaning properties may be deteriorated. In addition, when such toner is collected by cleaning and returned to the developing machine for use again, image quality is more likely to deteriorate. Further, if the flow aid is further increased in order to prevent these problems, black spots may be generated on the photoconductor or the aid particles may be scattered.
On the other hand, when a toner is produced by an emulsion aggregation method, it is generally necessary to heat the toner particles for a long time at a temperature higher than the glass transition point of the constituent resin in order to make the toner particles spherical. However, there is a problem that heating at a high temperature for a long time is accompanied by deterioration of pigment dispersibility in the particles and bleeding out of the release agent.
As a technique for controlling the shape of the toner particles at a low temperature, a method of effectively fusing and fusing by adding an organic solvent infinitely soluble in water and substantially lowering the glass transition temperature of the resin fine particles is known. (For example, refer to Patent Document 1). However, a substantial decrease in the glass transition point of the binder resin also causes a problem that the storage stability of the toner is deteriorated.
In addition, in the emulsion polymerization aggregation method, an example in which particles having a narrow size distribution are obtained by adding a surfactant such as alkylbenzene sulfonic acid during the particle growth process is known (for example, see Patent Document 2). No example has been known for controlling the shape.
Further, Patent Document 3 discloses a method of performing salting-out, aggregation, and fusion in the presence of a specific surfactant in styrene-acrylic toner particles, but it is not sufficient for controlling the shape thereof. There wasn't.

JP 2004-295028 A Japanese Patent Application Laid-Open No. 7-145684 Japanese Patent Laid-Open No. 2002-131978

  The present invention relates to a method for producing an electrophotographic toner capable of obtaining toner particles having a high degree of circularity, the particle shape being easily controlled at a low temperature, and an electrophotographic toner obtained by the method.

The present invention
(1) (I) a step of emulsifying a binder resin containing polyester in an aqueous medium,
(B) a step of agglomerating the emulsified particles in the emulsion obtained in the step (a) at a temperature of glass transition point + 20 ° C. or lower;
(C) Formula (1)
_{RO- (CH 2 CH 2 O)} nSO 3 M (1)
(R represents an alkyl group, M represents a monovalent cation, n represents the average number of moles added, and 0 <n ≦ 15.)
A step of adding 1.0% by weight or more to the binder resin to stop aggregation by adding at least one selected from alkyl ether sulfate ester salts and alkyl sulfate ester salts represented by:
(D) a step of aggregating the aggregated particles by heating at a temperature not lower than the glass transition point of the binder resin + 10 ° C. and not higher than the softening point of the binder resin −10 ° C. for not less than 2 hours;
And (2) an electrophotographic toner obtained by the production method described in (1) above,
I will provide a.

  According to the production method of the present invention, it is possible to provide an electrophotographic toner which can easily control the particle shape at a low temperature and can obtain toner particles having a high degree of circularity.

A method for producing the electrophotographic toner of the present invention will be described.
The method for producing an electrophotographic toner of the present invention includes (a) a step of emulsifying a binder resin containing a polyester in an aqueous medium (emulsification step), and (b) in the emulsion obtained in the step (a). A step of agglomerating the emulsified particles at a temperature of 20 ° C. or less (aggregation step), (c) at least one selected from alkyl ether sulfate ester salts represented by the following formula (1) and alkyl sulfate ester salts: A step of stopping aggregation by adding 1.0% by weight or more with respect to the binder resin (stopping step), and (d) the aggregated particles having a glass transition point of the binder resin of + 10 ° C. or higher and the binder resin. A softening point of −10 ° C. or lower for 2 hours or more for heating (unification step).
_{RO- (CH 2 CH 2 O)} nSO 3 M (1)
(R represents an alkyl group, M represents a monovalent cation, n represents the average number of moles added, and 0 <n ≦ 15.)

[(I) Emulsification process]
In the method for producing an electrophotographic toner of the present invention, first, in (i) an emulsification step, a binder resin containing polyester is emulsified in an aqueous medium.
Binder resin The binder resin contains polyester from the viewpoints of toner fixability and durability. The content of the polyester is preferably 60% by weight or more, more preferably 70% by weight or more, still more preferably 80% by weight or more, and substantially 100% by weight in the binder resin from the viewpoint of fixability and durability. Is more preferable. The polyester may be a crystalline polyester or an amorphous polyester.
Examples of binder resins other than polyester include known resins used in toners, such as styrene-acrylic resins, epoxy resins, polycarbonates, and polyurethanes.

In the present invention, as the raw material monomer for the polyester, known divalent or higher alcohol components and known carboxylic acid components such as divalent or higher carboxylic acids, carboxylic acid anhydrides, carboxylic acid esters and the like are used.
As the divalent alcohol component, the formula (I):

(In the formula, RO is an alkylene oxide, R is an alkylene group having 2 or 3 carbon atoms, x and y are positive numbers indicating the average number of added moles of alkylene oxide, and the sum of x and y is 1-16. , Preferably 1 to 8, more preferably 1.5 to 5), an adduct of bisphenol A alkylene oxide (average number of added moles 1 to 16), specifically, polyoxypropylene-2, 2-bis (4-hydroxyphenyl) propane, polyoxyethylene-2,2-bis (4-hydroxyphenyl) propane, etc., ethylene glycol, propylene glycol, neopentyl glycol, 1,4-butanediol, 1, Examples include 3-butanediol and 1,6-hexanediol.
Examples of the trihydric or higher polyhydric alcohol include sorbitol, pentaerythritol, glycerol, trimethylolpropane and the like.
These alcohol components may be used individually by 1 type, and may be used in combination of 2 or more type.

Examples of divalent carboxylic acid components include succinic acid, sebacic acid, fumaric acid, maleic acid, adipic acid, azelaic acid, dodecenyl succinic acid, dodecyl succinic acid and other aliphatic dicarboxylic acids, phthalic acid, terephthalic acid, isophthalic acid, etc. Examples thereof include alicyclic dicarboxylic acids such as aromatic dicarboxylic acids and cyclohexanedicarboxylic acids, and derivatives of these acids such as anhydrides and alkyl (C1 to C3) esters.
Examples of the trivalent or higher polyvalent carboxylic acid compounds include 1,2,4-benzenetricarboxylic acid (trimellitic acid), 2,5,7-naphthalenetricarboxylic acid, and aromatic carboxylic acids such as pyromellitic acid, and these Derivatives such as acid anhydrides and alkyl (1 to 3 carbon atoms) esters may be mentioned.
These carboxylic acid components may be used individually by 1 type, and may be used in combination of 2 or more type.

In the present invention, the polyester includes not only polyester but also polyester modified to such an extent that the characteristics are not substantially impaired. In the present invention, polyester is preferable. Examples of the modified polyester include grafting and blocking with phenol, urethane, epoxy and the like by the methods described in JP-A-11-133668, JP-A-10-239903, JP-A-8-20636, and the like. And a composite resin having two or more types of resin units including a polyester unit.
These polyesters may be used individually by 1 type, and may be used in combination of 2 or more type.

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.

From the viewpoint of the storage stability of the toner, the softening point of the polyester is preferably 70 to 165 ° C, more preferably 95 to 160 ° C. Moreover, 50-85 degreeC is preferable and 50-75 degreeC is more preferable for a glass transition point. The acid value of the polyester is preferably 1 to 50 mgKOH / g, more preferably 5 to 40 mgKOH / g, and more preferably 10 to 35 mgKOH / g from the viewpoint of stabilizing the emulsified particles and obtaining a small particle size toner with a sharp particle size distribution. Is more preferable. The desired softening point and acid value can be obtained by adjusting the condensation polymerization temperature and reaction time.
From the viewpoint of toner durability, the number average molecular weight of the polyester is preferably 1,000 to 100,000, more preferably 1,000 to 50,000, more preferably 1,000 to 12,000, and 2,000 to More preferably, 8,000. The number average molecular weight of the polyester is determined by gel permeation chromatography using polystyrene as a standard sample.

In the case where the binder resin contains a plurality of resins, the softening point, glass transition point, acid value and number average molecular weight of the binder resin mean each value as a mixture of the binder resins, Each value is preferably the same value as each value of the polyester.
Further, the binder resin for toner of the present invention can contain two kinds of polyesters having different softening points from the viewpoint of fixability and durability, and the softening point of one polyester (I) is 70 to 115 ° C. The softening point of the other polyester (b) is preferably 115 ° C. or higher and 165 ° C. or lower. The weight ratio (I / B) between the polyester (A) and the polyester (B) is preferably 10/90 to 90/10, more preferably 50/50 to 90/10.

The aqueous medium for emulsifying the aqueous medium binder resin 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 organic solvents that dissolve in water, such as methanol, ethanol, isopropanol, butanol, acetone, methyl ethyl ketone, and tetrahydrofuran. Among these, from the viewpoint of preventing mixing into the toner, alcohol-based organic solvents such as methanol, ethanol, isopropanol, and butanol, which are organic solvents that do not dissolve the resin, can be used. In the present invention, it is preferable to atomize the binder resin using only water without substantially using an organic solvent.

Preparation of Resin Emulsion In the present invention, first, resin particles containing a binder resin are prepared in an aqueous medium. The preparation of a resin dispersion containing the resin particles is performed by reducing the particle size of the resin particles. From the viewpoint of uniform particle size distribution of the toner obtained, it is preferable to emulsify the binder resin.
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, selenium yellow, quinoline yellow, permanent orange GTR, pyrazolone orange, vulcan orange, watch young red, permanent red, brilliantamine 3B, Brilliantamine 6B, Dupont Oil Red, Pyrazolone Red, Resol Red, Rhodamine B Lake, Lake Red C, Bengal, Aniline Blue, Ultramarine Blue, Calco Oil Blue, Methylene Blue Chloride, Phthalocyanine Blue, Phthalocyanine Green, Malachite Green Oxalate, etc. Various pigments, acridine, xanthene, azo, benzoquinone, azine, anthraquinone, indico, thioi Various dyes such as dico, phthalocyanine, aniline black, polymethine, triphenylmethane, diphenylmethane, thiazine, thiazole and xanthene may be used alone or in combination of two or more. it can.
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, tree wax, jojoba oil; animal waxes such as beeswax; mineral and petroleum systems such as montan wax, ozokerite, ceresin, paraffin wax, microcrystalline wax, Fischer-Tropsch wax Wax etc. are mentioned. These mold release agents can be used alone or in combination of two or more.
The content of the release agent is 100% by weight with respect to 100 parts by weight of the binder resin or, when a colorant is used, in consideration of the addition effect and the adverse effect on the chargeability, and the total amount of the binder resin and the colorant is 100. The amount is usually about 1 to 20 parts by weight, preferably 2 to 15 parts by weight with respect to parts by weight.

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 emulsifying the binder resin, from the viewpoint of improving the emulsification stability of the binder resin, preferably 10 parts by weight or less, more preferably 5 parts by weight with respect to 100 parts by weight of the binder resin. In the following, it is preferable that 0.1 to 3.5 parts by weight, more preferably 0.1 to 3 parts by weight, and still more preferably 0.5 to 2 parts by weight of a surfactant is present.

  Examples of the surfactant include anionic surfactants such as sulfate ester type, sulfonate type, phosphate ester type, and soap type; cationic surfactants such as amine salt type and quaternary ammonium salt type; polyethylene Nonionic surfactants such as glycol-based, alkylphenol ethylene oxide adduct-based, polyhydric alcohol-based and the like can be mentioned. 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, sodium alkyl naphthalene sulfonate, sodium dialkyl sulfosuccinate and the like. Among these, sodium dodecylbenzenesulfonate is preferable.
Specific examples of the cationic surfactant include alkylbenzene dimethyl ammonium chloride, alkyl trimethyl ammonium chloride, distearyl ammonium chloride and the like.

  Nonionic surfactants include, for example, polyoxyethylene nonylphenyl ether, polyoxyethylene oleyl ether, polyoxyethylene alkylaryl ethers such as polyoxyethylene lauryl ether, polyoxyethylene alkyl ethers, polyoxyethylene sorbitan Polyoxyethylene sorbitan esters such as monolaurate, polyoxyethylene sorbitan monostearate, polyoxyethylene fatty acid esters such as polyethylene glycol monolaurate, polytylene glycol monostearate, polyethylene glycol monooleate, oxy Examples include ethylene / oxypropylene block copolymers.

In the emulsification step, it is preferable to add an aqueous alkaline solution to the binder resin and disperse the binder resin and additives used as necessary.
The alkaline aqueous solution preferably has a concentration of 1 to 20% by weight, more preferably 1 to 10% by weight, and still more preferably 1.5 to 7.5% by weight. As for the alkali to be used, it is preferable to use an alkali that enhances the 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, after neutralizing at a temperature above the glass transition point of the binder resin, a resin dispersion can be produced by phase inversion emulsification by adding an aqueous medium at a temperature above the glass transition point. it can.

The addition rate of the aqueous medium is preferably from 0.1 to 50 g / min, more preferably from 0.5 to 40 g / min, and even more preferably from 1 to 30 g / min per 100 g of the resin from the viewpoint that emulsification can be effectively carried out. 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 resin emulsion include the same as the above-mentioned aqueous medium, preferably deionized water or distilled water.
The amount of the aqueous medium is preferably from 100 to 2,000 parts by weight, more preferably from 150 to 1,500 parts by weight, based on 100 parts by weight of the binder resin, from the viewpoint of obtaining uniform aggregated particles in the subsequent aggregation treatment. From the viewpoint of stability and handleability of the obtained emulsified particle liquid, the solid content concentration of the resin emulsion is preferably 7 to 50% by weight, more preferably 7 to 40% by weight, and still more preferably 10 to 30% by weight. The amount of the aqueous medium is selected so that In addition, non-volatile components, such as resin and a nonionic surfactant, are contained in solid content.

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 emulsion. By carrying out the emulsification at a temperature within the above range, the emulsification is carried out smoothly and no special apparatus is required for heating. From this point, the above temperature is the glass transition point of the binder resin + 10 ° C. or higher (meaning a temperature of “10 ° C. higher than the glass transition point”). Further, the softening point is preferably −5 ° C. or lower.
The volume median particle size (D ₅₀ ) of the resin particles in the resin emulsion thus obtained is preferably 0.02 to 2 μm, more preferably, in order to perform uniform aggregation in the subsequent aggregation treatment. It is 0.05-1 micrometer, More preferably, it is 0.05-0.6 micrometer. Here, “volume median particle size (D ₅₀ )” means a particle size at which the cumulative volume frequency calculated by the volume fraction is 50% when calculated from the smaller particle size. The measuring method is as described later.

As another method for obtaining a resin emulsion 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 can be 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.

[(B) Aggregation process]
(B) The aggregation step is a step of aggregating the emulsified particles in the emulsion obtained as described above at a temperature of glass transition point + 20 ° C. or lower.
In the aggregating step, an aggregating agent is added to effectively agglomerate. 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 inorganic metal salts include metal salts such as sodium sulfate, sodium chloride, calcium chloride, calcium nitrate, barium chloride, magnesium chloride, zinc chloride, aluminum chloride, aluminum sulfate, polyaluminum chloride, polyaluminum hydroxide, Examples thereof include inorganic metal salt polymers such as calcium sulfide. Examples of the inorganic ammonium salt include ammonium sulfate, ammonium chloride, and ammonium nitrate.
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.

  The water-soluble nitrogen-containing compound having a molecular weight of 350 or less is preferably a compound exhibiting acidity from the viewpoint of rapidly agglomerating primary particles, and a 10% by weight aqueous solution having a pH value of 4 to 6 at 25 ° C. Are preferable, and 4.2 to 6 are more preferable. From the viewpoint of chargeability at high temperature and high humidity, the molecular weight is preferably 350 or less, more preferably 300 or less. Examples of such water-soluble nitrogen-containing compounds include ammonium salts such as ammonium halide, ammonium sulfate, ammonium acetate, ammonium benzoate and ammonium salicylate, and quaternary ammonium salts such as tetraalkylammonium halide. From the viewpoint of properties, ammonium sulfate (pH value of 10 wt% aqueous solution at 25 ° C., hereinafter referred to as pH value: 5.4), ammonium chloride (pH value: 4.6), tetraammonium bromide (pH value: 5.6) ) And tetrabutylammonium bromide (pH value: 5.8).

  The amount of the flocculant used is preferably 50 parts by weight or less, more preferably 40 parts by weight or less, with respect to 100 parts by weight of the binder resin, from the viewpoint of toner charging properties, particularly charging characteristics in a high temperature and high humidity environment. More preferred are parts by weight or less. From the viewpoint of cohesiveness, the amount is preferably 1 part by weight or more, more preferably 3 parts by weight or more, and still more preferably 5 parts by weight or more with respect to 100 parts by weight of the binder resin. 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 further 5 to 30 parts by weight with respect to 100 parts by weight of the binder resin. preferable.

The addition of the flocculant is performed after adjusting the pH in the system, and then the glass transition point of the binder resin + 20 ° C. or lower, preferably the glass transition point + 10 ° C. or lower, more preferably the glass transition point + 5 ° C. or lower. To do. 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 a softening point of the binder resin of −100 ° C. or higher, more preferably at a softening point of −90 ° C. or higher. 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 emulsified particles in the resin emulsion.
The aggregated particles preferably have a volume median particle size (D ₅₀ ) in the range of 1 to 4 μm, more preferably 1 to 3.5 μm, and still more preferably 1 to 3 μm, from the viewpoint of reducing the particle size. The coefficient of variation (CV value) of the particle size distribution is preferably 30 or less, more preferably 25 or less, and still more preferably 23 or less.
The coefficient of variation (CV value) of the particle size distribution is expressed by the formula CV value = [standard deviation of fine particle diameter (μm) / volume median particle diameter (μm)] × 100
It is a value represented by That is, the smaller the CV value, the narrower the particle size distribution.

It is also possible to add a binder resin-containing fine particle dispersion to the obtained aggregated particle dispersion at once or divided into a plurality of times.
The binder resin-containing fine particle dispersion added to the aggregated particle dispersion can be prepared in the same manner as the above-mentioned resin emulsion, and may be the same as the resin emulsion used when creating the aggregated particles. It may be different.
The binder resin-containing fine particle dispersion preferably has a solid concentration of 7 to 50% by weight, more preferably 7 to 40% by weight, and still more preferably 10 from the viewpoint of stability as a dispersion and handling properties. It should be in the range of ˜30% by weight. Further, the volume median particle size (D ₅₀ ) of the fine particles in this dispersion is preferably 0.05 to 2 μm, more preferably 0.05 to 1 μm, and more preferably 0.05 to 0. 5 μm is more preferable.

  In addition to the binder resin, the binder resin-containing fine particles in the binder resin-containing fine particle dispersion to be added, as necessary, described in the resin emulsified particle creation step, a colorant, a release agent, a charge control agent, Furthermore, additives such as conductivity modifiers, extenders such as extender pigments, fibrous substances, antioxidants, and antioxidants can be appropriately contained.

[(C) Stop process]
Step (c) is a step of stopping aggregation by adding at least one selected from alkyl ether sulfate salts represented by the following formula (1) and alkyl sulfate ester salts.
_{RO- (CH 2 CH 2 O)} nSO 3 M (1)
(R represents an alkyl group, M represents a monovalent cation, n represents the average number of moles added, and 0 <n ≦ 15.)

In the formula (1), the alkyl group represented by R is preferably 4 to 16 carbon atoms, more preferably 6 to 14 carbon atoms, and still more preferably from the viewpoint of adsorptivity to aggregated particles and persistence to toner. Include those having 8 to 12 carbon atoms, and specifically include butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, dodecyl, tetradecyl, pentadecyl and the like. . The average added mole number n is 0 <n ≦ 15, but from the viewpoint of particle size control, it is preferably 0 <n ≦ 5, more preferably 0 <n ≦ 3. M is a monovalent cation, but from the viewpoint of particle size control, a monovalent metal or ammonium is preferable, sodium, potassium, lithium, or ammonium is more preferable, and sodium or ammonium is more preferable.
Specific examples of the alkyl ether sulfate salt used in the present invention include C ₁₂ H ₂₅ (OCH ₂ CH ₂ ) ₂ OSO ₃ Na, C ₁₂ H ₂₅ (OCH ₂ CH ₂ ) ₃ OSO ₃ Na, and the like.

The alkyl sulfate ester salt is not particularly limited, but from the viewpoint of adsorptivity to aggregated particles and persistence to toner, the formula (2)
RO-SO ₃ M (2)
(In the formula, R and M are the same as those in the formula (1).)
In particular, octyl sulfate sodium salt, decyl sulfate sodium salt, dodecyl sulfate sodium salt, tetradecyl sulfate sodium salt and the like are more preferably used, and dodecyl sulfate sodium salt is more preferable.
The alkyl ether sulfate ester salt and the alkyl sulfate ester salt represented by the above formula (1) may be used singly or in combination of two or more.

In the step (c), at least one addition amount selected from the alkyl ether sulfate ester salt and the alkyl sulfate ester salt is 1.0% by weight or more with respect to the binder resin from the viewpoint of aggregation stopping properties. The binder resin is preferably 1.2% by weight or more, more preferably 1.5% by weight or more, more preferably 2% by weight or more, and still more preferably 5% by weight or more. On the other hand, it is preferably 30% by weight or less, more preferably 20% by weight or less, and further preferably 15% by weight or less. Therefore, from the above viewpoint, the addition amount of at least one selected from the alkyl ether sulfate salt and the alkyl sulfate salt is preferably 1.0 to 20 parts by weight, more preferably 1 to the binder resin. 2 to 20 parts by weight, more preferably 1.5 to 20 parts by weight, more preferably 2 to 20 parts by weight, still more preferably 5 to 15 parts by weight.
These may be added in any form as long as they are added as described above, but are preferably added in an aqueous solution from the viewpoint of productivity. Each of the above salts may be added at once, or may be added intermittently or continuously. Further, it is preferable to sufficiently stir at the time of addition of the surfactant and after completion of the addition.

In the present invention, the surfactant is used as an aggregation terminator for stopping aggregation, and is therefore used after the addition of the aggregation agent. Specifically, the timing of addition, from the viewpoint of particle size control, a volume-median particle size of the aggregated particles (D ₅₀₎ is a volume median particle size of coalesced particles obtained in (D ₅₀₎ 90 to 120 % Is preferable, and more preferably 100 to 120%. Each volume-median particle size (D ₅₀ ) can be measured by the method described later.

[(D) Combined process]
In the step (d), particles aggregated in the step (b) and stopped in the step (c) are heated to a glass transition point of the binder resin + 10 ° C. or higher and a softening point of the binder resin −10 ° C. or lower. It is the process of heating and uniting for 2 hours or more.
The heating temperature is preferably the glass transition point of the binder resin + 10 ° C. or higher and the softening point −20 ° C. or lower from the viewpoint of the particle size, particle size distribution, shape control, and particle fusing property of the target toner. . The stirring speed is preferably a speed at which the aggregated particles do not settle.

  In the present invention, the heating in the coalescence step and the temperature increase thereby are preferably at least one selected from the alkyl ether sulfate salt and the alkyl sulfate ester salt in the step (c) from the viewpoint of productivity. It is preferable to perform heating and heating at the same time, during the addition, within 1 hour after the addition, or at two or more points of these. More preferably, it is performed within 1 hour after completion of the addition, and more preferably within 30 minutes.

Further, the heating at the above temperature in the step (d) is preferably performed until the aggregated particles are united and the circularity is satisfied. In the present invention, the heating is performed for 2 hours or more. The heating time is preferably 2.5 hours or more, and more preferably 3 hours or more, in order to achieve complete coalescence and sufficiently increase the circularity. The upper limit of the heating time is not particularly limited, but is preferably 12 hours or less, more preferably 8 hours or less, from the viewpoint of maintaining good dispersibility of components such as pigments in the aggregated particles.
If the heating time is heating at a temperature within the heating temperature range in the process, all the time is included, for example, during the temperature rise, the glass transition point of the binder resin + 10 ° C or more, And when it reaches a temperature within the range of the softening point of -20 ° C. or less and is maintained or fluctuates within the range, the time is also included.

  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.
From the viewpoint of high image quality, the volume-median particle size (D50) of the coalesced particles is preferably 1 to 10 μm, more preferably 2 to 8 μm, and even more preferably 3 to 8 μm.

[Electrophotographic toner]
The toner for electrophotography of the present invention is obtained by the above-described production method having steps (i) to (d), and has a spherical and small particle size suitable for high definition and high image quality, and a high accuracy particle size. The shape can be controlled and the particle size distribution is narrow.
The softening point of the toner is preferably 60 to 140 ° C., more preferably 60 to 130 ° C., and still more preferably 60 to 120 ° C. from the viewpoint of low-temperature fixability. Moreover, 30-80 degreeC is preferable from a durable viewpoint, and, as for a glass transition point, 40-70 degreeC is more preferable. In addition, the measuring method of a softening point and a glass transition point is based on these measuring methods in resin.

In the electrophotographic toner of the present invention, an auxiliary agent such as a fluidizing agent can be added to the toner particle surface as an external additive. External additives include known fine particles such as silica fine particles, titanium fine particles, alumina fine particles, cerium oxide fine particles, carbon black and other inorganic fine particles, and polymer fine particles such as polycarbonate, polymethyl methacrylate and silicone resin. Can be used. The number average particle diameter of the external additive is preferably 4 to 200 nm, 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.

From the viewpoint of high image quality, the volume median particle size (D ₅₀ ) of the toner particles is preferably 1 to 8 μm, more preferably 1 to 7 μm, more preferably 1 to 6 μm, and further preferably 2 to 6 μm. The average circularity of the toner is preferably 0.94 to 1.0, and more preferably 0.95 to 0.99.
In the present invention, the particle size of the toner can be measured by a laser diffraction type particle size measuring device, specifically, “LA-920” (manufactured by Horiba, Ltd.). The average circularity can be measured with a flow particle image analyzer, and specifically with 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, and more preferably 35 or less. In particular, the CV of the toner is preferably 25 or less, more preferably 22 or less. The toner of the present invention preferably has the above particle diameter and CV value. Here, the particle size and particle size distribution of the toner particles can be measured by the method described later.
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.

(Toner shape control method)
The present invention further comprises aggregating emulsified particles in an emulsion obtained by emulsifying a binder resin containing polyester in an aqueous medium at a temperature of glass transition point + 20 ° C. or lower.
_{RO- (CH 2 CH 2 O)} nSO 3 M (1)
(R represents an alkyl group, M represents a monovalent cation, n represents the average number of moles added, and 0 <n ≦ 15.)
At least one selected from the alkyl ether sulfate ester salt represented by the formula (1) and the alkyl sulfate ester salt is added in an amount of 1.0% by weight or more to the binder resin to stop the aggregation, and then the aggregated particles are bound. The present invention relates to a toner shape control method in which the glass transition point of the resin + 10 ° C. or higher and the softening point of the binder resin −10 ° C. or lower are heated and united for 2 hours or more.

  Details of each of the above steps are as described above. By such a method, in the present invention, the shape of the toner particles can be arbitrarily controlled, and the circularity is high, that is, the circularity is preferably 0.94 to 1.0, and more preferably 0.95 to 0. 99 toner particles can be obtained.

In the following examples and the like, each property value was measured and evaluated by the following method.
[Acid value of 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 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.

[Number average molecular weight of resin]
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 The binder resin is dissolved in chloroform so that the concentration is 0.5 g / 100 ml. Subsequently, this solution is filtered using a fluororesin filter having a pore size of 2 μm [manufactured by Sumitomo Electric Industries, Ltd., “FP-200”] to remove insoluble components to obtain a sample solution.

(2) Measurement of molecular weight distribution Tetrahydrofuran is flowed as a dissolving solution 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. In the calibration curve at this time, several types of monodisperse polystyrene (2.63 × 10 ³ , 2.06 × 10 ⁴ , 1.02 × 10 ⁵ manufactured by Tosoh Corporation), 2.10 × manufactured by GL Sciences Inc. 10 ³ , 7.00 × 10 ³ , 5.04 × 10 ⁴ ) are used as standard samples.
Measuring device: CO-8010 (manufactured by Tosoh Corporation)
Analysis column: GMHLX + G3000HXL (manufactured by Tosoh Corporation)

[Particle size of resin emulsified 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 (D ₅₀ ) is measured at a temperature at which the absorbance is in an appropriate range. The particle size distribution is indicated by a CV value (standard deviation of particle size distribution / volume median particle size (D ₅₀ ) × 100).

[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]
Measuring device: Flow type particle image analyzer (manufactured by Sysmex Corporation, “FPIA-
3000 ")
Measurement conditions: 1 ml is extracted from the toner particle dispersion, and diluted 20 times with distilled water to prepare a measurement sample solution. The count method is set to total count measurement (1000 effective analyzes), the measurement mode is set to HPF, the objective lens is set to 10 times, and the average circularity of the measurement sample solution is measured. The circularity of the particle is a value obtained by the ratio of the circumference of the 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.

Production Example 1 (Production of polyester resin A)
Polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane 8,320 g, Polyoxyethylene (2.0) -2,2-bis (4-hydroxyphenyl) propane 80 g, terephthalic acid 1,592 g and dibutyltin oxide (esterification catalyst) 32 g were reacted at 230 ° C. under normal pressure for 5 hours under a nitrogen atmosphere, and further reacted under reduced pressure. After cooling to 210 ° C., 1672 g of fumaric acid and 8 g of hydroquinone were added and reacted for 5 hours, and further reacted under reduced pressure to obtain polyester resin A. Polyester resin A had a softening point of 110 ° C., a glass transition point of 66 ° C., an acid value of 24.4 mgKOH / g, and a number average molecular weight of 3,760. When 1 kg of the obtained polyester resin A was sieved with a sieve having an opening diameter of 5.6 mm, nothing remained on the sieve.

Production Example 2 (Production of polyester resin B)
Polyoxypropylene (2.2) -2, 2-bis (4-hydroxyphenyl) propane 17,500 g, polyoxyethylene (2.0) -2, 2-bis (4-hydroxyphenyl) propane 16,250 g, 11,454 g of terephthalic acid, 1,608 g of dodecenyl succinic anhydride, 4,800 g of trimellitic anhydride and 15 g of dibutyltin oxide were placed in a four-necked flask equipped with a nitrogen introducing tube, a dehydrating tube, a stirrer and a thermocouple, The mixture was stirred at 220 ° C. in a nitrogen atmosphere and reacted until the softening point measured according to ASTM D36-86 reached 120 ° C. to obtain polyester resin B. Polyester resin B had a softening point of 121 ° C., a glass transition point of 65 ° C., an acid value of 18.5 mgKOH / g, and a number average molecular weight of 3,394. When 1 kg of the obtained polyester resin B was sieved with a sieve having an opening diameter of 5.6 mm, nothing remained on the sieve.

Production Example 3 (Manufacture of Masterbatch 1)
Henschel mixer so that 70 parts by weight of the fine powder of polyester resin A obtained in Production Example 1 and copper phthalocyanine slurry pigment (ECB-301: solid content of 46.2% by weight) manufactured by Dainichi Seika Co., Ltd. may be 30 parts by weight of pigment. Was mixed and wetted for 5 minutes. Next, this mixture was charged into a kneader mixer and gradually heated. The resin was melted at approximately 90 to 110 ° C. and kneaded in a state where water was mixed, and kneading was continued at 90 to 110 ° C. for 20 minutes while water was evaporated.
Further, the kneading was continued at 120 ° C. to evaporate the remaining water, followed by dehydration drying. Further, kneading was continued at 120 to 130 ° C. for 10 minutes. After cooling, the mixture was further kneaded with a heated three roll, cooled and coarsely crushed to obtain a crushed product (master batch 1) of a high-concentration colored composition containing a blue pigment at a concentration of 30% by weight. When this was placed on a slide glass, heated and melted, and observed with a microscope, all pigment particles were finely dispersed, and no coarse particles were observed. When 1 kg of the obtained master batch 1 was sieved with a sieve having an opening diameter of 5.6 mm, nothing remained on the sieve.

Production Example 4 (Production of resin emulsion 1)
In a 5 liter stainless steel kettle, 1866 g of polyester resin A, 1225 g of polyester resin B, 584.5 g of masterbatch 1, 35.00 g of nonionic surfactant (“Emulgen 430” manufactured by Kao), anionic A surfactant (“Neopelex G-15” manufactured by Kao Co., Ltd., 15% by weight aqueous solution of sodium dodecylbenzenesulfonate), 233.3 g, and potassium hydroxide aqueous solution (neutralizing agent, concentration: 5% by weight) of 1608 g were charged. The mixture was melted at 98 ° C. for 2 hours with stirring at 200 rpm to obtain a binder resin mixture. Next, a total of 6,639 g of deionized water was dropped at a rate of 35 g / min while stirring at 200 rpm with a chi-type stirrer to prepare a resin emulsion. Finally, the mixture was cooled to room temperature and passed through a 200 mesh (mesh: 105 μm) wire mesh to obtain an emulsion of resin fine particles (resin emulsion 1) containing 29% by weight of resin. The volume-median particle size (D ₅₀ ) of the primary particles was 0.151 μm, the coefficient of variation (CV value) in the particle size distribution was 24.7, and nothing remained on the wire mesh. Here, the polyester resin A and the polyester resin B mixed at 65/35 (wt / wt) had a softening point of 114 ° C. and a glass transition point of 66 ° C.

Example 1
600 g of Resin Emulsion 1 (resin content 29% by weight) was sampled and charged into a 2 L 3-neck separable flask at room temperature. Next, under stirring at 100 rpm with a Kai-type stirrer, 734 g of a 5.5 wt% ammonium sulfate aqueous solution as a flocculant was added to the dispersion and stirred at room temperature for 20 minutes. Thereafter, the mixed dispersion is heated from room temperature to 60 ° C. (temperature increase rate: 0.3 ° C./min) and held at 60 ° C. for 10 minutes, whereby a dispersion of aggregated particles having a volume-median particle size of 7.6 μm. Was made.
Next, 418 g of an aqueous 5.8% by weight anionic surfactant (“Emar E27C” manufactured by Kao Corporation: C ₁₂ H ₂₅ O (C ₂ H ₅ O) ₂ SO ₃ Na) (added to 15% by weight of resin) was added. Thereafter, the temperature was raised to 83 ° C. (temperature raising rate: 0.2 ° C./min) and the temperature was maintained. At that time, the particle size and circularity at each holding time at 83 ° C. were measured. The results are shown in Table 1. In the present example, during the temperature raising time up to 83 ° C., the time required to reach 83 ° C. after reaching the temperature of the glass transition point of the binder resin + 10 ° C. (74 ° C.) is 45 minutes. Yes, the heating time was each holding time + 45 minutes. The same applies to the following examples.

Example 2
In the same manner as in Example 1, a dispersion liquid of aggregated particles having a volume-median particle size of 7.6 μm was prepared.
Next, 418 g of an aqueous 2.7% by weight anionic surfactant (“Emar E-27C” manufactured by Kao Corporation: C ₁₂ H ₂₅ O (C ₂ H ₅ O) ₂ SO ₃ Na) (based on resin 7 wt%) was added. After the addition, the temperature was raised to 83 ° C. (temperature raising rate: 0.2 ° C./min) and the temperature was maintained. At that time, the particle size and circularity at each holding time at 83 ° C. were measured. The results are shown in Table 1.

Example 3
In the same manner as in Example 1, a dispersion liquid of aggregated particles having a volume-median particle size of 7.8 μm was prepared.
Next, 418 g of an aqueous 1.2% by weight anionic surfactant (“Emar E-27C” manufactured by Kao Corporation: C ₁₂ H ₂₅ O (C ₂ H ₅ O) ₂ SO ₃ Na) (based on resin 3 wt%) was added. After the addition, the temperature was raised to 83 ° C. (temperature raising rate: 0.2 ° C./min) and the temperature was maintained. At that time, the particle size and circularity at each holding time at 83 ° C. were measured. The results are shown in Table 1.

Example 4
In the same manner as in Example 1, a dispersion of aggregated particles having a volume-median particle size of 7.5 μm was prepared.
Next, 418 g of a 0.58 wt% anionic surfactant (“Emar E27C” manufactured by Kao Corporation: C ₁₂ H ₂₅ O (C ₂ H ₅ O) ₂ SO ₃ Na) aqueous solution (vs. resin 1.5 wt%) was added. After the addition, the temperature was raised to 83 ° C. (temperature raising rate: 0.2 ° C./min) and the temperature was maintained. At that time, the particle size and circularity at each holding time at 83 ° C. were measured. The results are shown in Table 1.

Example 5
In the same manner as in Example 1, a dispersion liquid of aggregated particles having a volume-median particle size of 8.3 μm was prepared.
Next, 418 g of an aqueous 2.7% by weight anionic surfactant (“Emar 20C” manufactured by Kao Corporation: C ₁₂ H ₂₅ O (C ₂ H ₅ O) ₃ SO ₃ Na) (based on 7% by weight of resin) was added. Thereafter, the temperature was raised to 83 ° C. (temperature raising rate: 0.2 ° C./min) and the temperature was maintained. At that time, the particle size and circularity at each holding time at 83 ° C. were measured. The results are shown in Table 1.

Reference example 1
In the same manner as in Example 1, an aggregated particle dispersion having a volume-median particle size of 6.7 μm was prepared.
Next, after adding 418 g of an aqueous 2.7% by weight anionic surfactant (“Emar 0” manufactured by Kao Corporation: C ₁₂ H ₂₅ OSO ₃ Na) (7% by weight of the resin), the temperature was raised to 83 ° C. The temperature rate was 0.2 ° C./min) and the temperature was maintained. At that time, the particle size and circularity at each holding time at 83 ° C. were measured. The results are shown in Table 1.

Comparative Example 1
In the same manner as in Example 1, a dispersion liquid of aggregated particles having a volume-median particle size of 6.8 μm was prepared.
Next, 418 g of 0.19 wt% anionic surfactant (“Emar E27C” manufactured by Kao Corporation: C ₁₂ H ₂₅ O (C ₂ H ₅ O) ₂ SO ₃ Na) aqueous solution (0.5 wt% resin) was added. After the addition, the temperature was raised to 83 ° C. (temperature raising rate: 0.2 ° C./min) and the temperature was maintained. At that time, the particle size and circularity at each holding time at 83 ° C. were measured. The results are shown in Table 1.

Comparative Example 2
In the same manner as in Example 1, an aggregated particle dispersion having a volume median particle size of 7.6 μm was prepared.
Next, after adding 418 g of an aqueous 2.7% by weight anionic surfactant (“Neopelex G15” manufactured by Kao Corporation: C ₁₂ H ₂₅ C ₆ H ₄ SO ₃ Na) (7% by weight of resin), 83 ° C. (Temperature rising rate 0.2 ° C./min) and the temperature was maintained. At that time, the particle size and circularity at each holding time at 83 ° C. were measured. The results are shown in Table 1.

Comparative Example 3
In the same manner as in Example 1, a dispersion of collected particles having a volume median particle size of 8.0 μm was prepared.
Next, after adding 418 g of an aqueous solution of 2.7% by weight anionic surfactant (“Latemul ASK” manufactured by Kao Corporation, dipotassium alkenyl succinate) (7% by weight of the resin), the temperature was raised to 83 ° C. 2 ° C./min) and the temperature was maintained. At that time, the particle size and circularity at each holding time at 83 ° C. were measured. The results are shown in Table 1.

  According to the production method of the present invention, the particle shape can be easily controlled at a low temperature and toner particles having a high degree of circularity can be obtained. Therefore, the toner of the present invention can be electrophotographic, electrostatic recording, electrostatic It can be suitably used for an electrophotographic toner used in a printing method.

Claims (7)

(A) a step of emulsifying a binder resin containing polyester in an aqueous medium;
(B) a step of agglomerating the emulsified particles in the emulsion obtained in the step (a) at a temperature of glass transition point + 20 ° C. or less using an inorganic ammonium salt as an aggregating agent ;
(C) Formula (1)
_{RO- (CH 2 CH 2 O)} n SO 3 M (1)
(R represents an alkyl group, M represents a monovalent cation, n represents an average number of added moles, and 0 <n ≦ 15.)
Adding 1.0% by weight or more of the alkyl ether sulfate ester salt represented by the binder resin to stop aggregation, and
(D) a step of aggregating the aggregated particles by heating at a temperature not lower than the glass transition point of the binder resin + 10 ° C. and not higher than the softening point of the binder resin −10 ° C. for not less than 2 hours;
A method for producing an electrophotographic toner comprising:   The method for producing an electrophotographic toner according to claim 1, wherein in formula (1), n is 2 ≦ n ≦ 15.   The method for producing an electrophotographic toner according to claim 1, wherein the alkyl ether sulfate ester salt is sodium polyoxyethylene (2-3) dodecyl ether sulfate.   The method for producing an electrophotographic toner according to claim 1, wherein the inorganic ammonium salt is ammonium sulfate. Produced by the production method according to any one of claims 1-4, containing an average circularity of 0.94 or more toner particles, the toner for electrophotography. The toner for electrophotography according to claim 5, wherein the toner particles have a volume-median particle diameter of 1 to 8 μm. The emulsified particles in the emulsion obtained by emulsifying the binder resin containing polyester in an aqueous medium are aggregated using an inorganic ammonium salt as a flocculant at a temperature of the glass transition point + 20 ° C. or less, and the formula (1 )
_{RO- (CH 2 CH 2 O)} n SO 3 M (1)
(R represents an alkyl group, M represents a monovalent cation, n represents an average number of added moles, and 0 <n ≦ 15.)
After adding 1.0 wt% or more of the alkyl ether sulfate ester salt represented by the binder resin to stop the aggregation, the aggregated particles are bonded to the glass transition point of the binder resin + 10 ° C. A method for controlling the shape of a toner, in which the resin is softened at a temperature of −10 ° C. or lower for 2 hours or more and united.