JPH09197717A - Electrophotographic toner, its production and image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To narrow the particle size distribution and to improve the durability by chemically bonding a large amt. of a dye to the surfaces of particles formed by polymn. SOLUTION: A monomer having a radical chain transfer group and an ionic functional group is graft-polymerized to the surfaces of polymer particles formed by emulsion polymn., suspension polymn. or dispersion polymn. and a dye is chemically bonded to the polymer chains by an ion exchange reaction using a water-soluble org. solvent to produce colored particles. The monomer is, e.g. methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate or lauryl (meth) acrylate. The org. solvent is, e.g. methanol, ethanol, other alcohol, acetone or ethyl acetate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic toner for developing an electrostatic latent image or a magnetic latent image in an electrophotographic method, an electrostatic printing method or the like, a method for producing the same, and an image forming method.

[0002]

2. Description of the Related Art Conventional electrophotographic toners are generally prepared by melt-kneading a thermoplastic resin, a colorant and other additives,
Manufactured by crushing and classification. However, since these pulverized toners have a wide particle size distribution, they need to be classified. However, with this classification operation, it is difficult to produce a large amount of toner having a narrow particle size distribution, and the number of manufacturing processes is increased, which increases manufacturing costs.

On the other hand, polymerization methods such as emulsion polymerization, suspension polymerization and dispersion polymerization have been proposed as a method for directly producing polymer particles without the pulverization and classification steps. In these polymerization methods, a method of adding a colorant in the polymerization reaction (see JP-A-61-273552) or a method of dyeing with a dye or the like after preparation of particles (JP-A-3-1686)
No. 53, and Japanese Patent Laid-Open No. 4-271359) are proposed. In addition, capsule particles prepared by interfacial polymerization are known as an example of binding a dye to a polymer chain by ion exchange by graft polymerization in order to stabilize the chargeability (Japanese Patent Laid-Open No. 14255/1992).

However, in the method of adding a colorant during the polymerization reaction, it is not easy to disperse the colorant in the binder resin and it is difficult to control the dispersibility. Further, in the method of dyeing with a dye or the like after the preparation of the particles, the dye is merely attached to the surface of the particles, so there is a concern that durability may be lacking. Further, in the conventional ion exchange, there were few dyes and coloring was not sufficient.

[0005]

Therefore, the present invention solves the above-mentioned drawbacks, and a large amount of dye is chemically bonded to the surface of particles prepared by a polymerization method to obtain a narrow particle size distribution, and To provide an electrophotographic toner having excellent durability, a method for producing the same, and an image forming method using the electrophotographic toner.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies to solve the above problems, and as a result, emulsion polymerization,
On the polymer particle surface formed by suspension polymerization or dispersion polymerization,
After a monomer having a radical chain transfer group and an ionic functional group is graft-polymerized, a colored particle is created by chemically bonding a dye to a polymer chain by an ion exchange reaction using a water-soluble organic solvent to produce a colored particle. It has become possible to provide an electrophotographic toner having an improved adhesive force, improved durability, a narrow particle size distribution, a small charge distribution, and excellent chargeability. That is, the present invention has the following configurations.

(1) At least hydrophilicity is imparted to the surface of polymer particles formed by emulsion polymerization, suspension polymerization or dispersion polymerization via a monomer having a radical chain transfer group and an ionic functional group graft-polymerized. An electrophotographic toner comprising a dye bonded by an ion exchange reaction in an aqueous solvent containing an organic solvent.

(2) a step of forming polymer particles by emulsion polymerization, suspension polymerization or dispersion polymerization, a step of graft-polymerizing a monomer having a radical chain transfer group and an ionic functional group onto the surface of the particles, the above-mentioned ion A step of binding a dye to the functional group by an ion exchange reaction in an aqueous solvent containing at least a hydrophilic organic solvent, the method for producing an electrophotographic toner.

(3) In an image forming method comprising a step of forming a latent image on an image carrier, a step of developing the latent image with a developer, and a step of transferring the developed toner image onto a transfer body. An image forming method comprising using the developer containing the electrophotographic toner according to claim 1.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The polymer constituting the toner particles in the present invention can be polymerized by an emulsion polymerization method, a suspension polymerization method or a dispersion polymerization method, and is graft-polymerized with a monomer having a radical chain transfer group. It does not matter what kind it is. Specifically, poly (meth) acrylic acid methyl, poly (meth) acrylic acid ethyl, poly (meth) acrylic acid butyl, poly (meth) acrylic acid 2-ethylhexyl, poly (meth) acrylic acid lauryl and the like (meth ) Acrylic ester polymers, copolymers of acrylic acid esters and methacrylic acid esters, copolymers of styrene-based monomers and (meth) acrylic acid esters, ethylene-based polymers such as polyvinyl butyrate, polyethylene, and polypropylene. Polymers and their copolymers, styrene-butadiene copolymers, styrene-isoprene copolymers, styrene-based copolymers such as styrene-maleic acid copolymers, polyvinyl ethers, polyvinyl ketones, polyesters, polyamides, polyurethanes, etc. be able to.

The method for producing the toner particles of the present invention is as follows:
Polymerization methods such as emulsion polymerization, suspension polymerization, and dispersion polymerization, and further,
Membrane emulsification method, emulsion aggregation method and the like can be mentioned, but the above-mentioned polymerization method is suitable as a method for producing particles having a narrow particle size distribution and obtaining a desired particle size, and particularly, dispersion polymerization method is preferable. The size of the polymer particles is such that the average particle size is 1 to 20 μm.
m, preferably in the range of 3-8 μm.

In the dispersion polymerization method, a single or several kinds of monomers, a dispersion stabilizer and a polymerization initiator are dissolved in a solvent in which a monomer is dissolved but a polymer is not dissolved, and polymerization is carried out by stirring and heating. Is. As the solvent used here, for example, methanol, ethanol, propanol,
Alcohols such as butanol, ethylene glycol, propylene glycol, diethylene glycol, polyethylene alcohols such as triethylene glycol, methyl cellosolve, cellosolves such as ethyl cellosolve, acetone, ketones such as methyl ethyl ketone, ethers such as tetrahydrofuran, benzene, Hydrocarbons such as toluene and hexane, or water and the like can be used alone or in admixture of two or more. Various solvents are used, depending on the type of monomer and the desired particle size. The amount of the solvent used is 50 to 5000 parts by weight with respect to 100 parts by weight of the monomer,
A range of 250 to 2000 parts by weight is preferred.

Examples of dispersion stabilizers in dispersion polymerization include poly (meth) acrylic acid, poly (meth) acrylic acid salts, poly (meth) acrylic acid / poly (meth) acrylic acid ester copolymers, and poly (meth) acrylic acid. ) Acrylic acid / vinyl ether copolymer, poly (meth) acrylic acid / styrene copolymer, polystyrene sulfonic acid, cellulose such as methyl cellulose, ethyl cellulose, hydroxypropyl cellulose, carboxymethyl cellulose, polyvinyl alcohol, polyvinyl pyrrolidone, or various Surfactants such as anionic surfactants such as sodium dodecylbenzene sulfonate, sodium lauryl sulfate and sodium alkyldiphenyldisulfonate, and nonionic surfactants such as polyoxyethylene nonylphenyl ether. Rukoto can. The addition amount of the dispersion stabilizer is in the range of 0 to 25% by weight with respect to the monomer,
A range of 0.5 to 15% by weight is preferred.

The polymerization initiator for dispersion polymerization is preferably soluble in the monomer. For example, benzoyl peroxide,
Peroxides such as cumene hydroperoxide, t-butyl hydroperoxide lauroyl peroxide, and azo polymerization initiators such as azobisisobutyronitrile and azobisdimethylvaleronitrile can be used. The amount of the polymerization initiator used is in the range of 0.01 to 10% by weight with respect to the monomer,
A range of 3 to 6% by weight is more preferable.

As the monomer having a radical chain transfer group, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, (meth)
Butyl acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, lauryl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, benzyl (meth) acrylate, (meth ) Hydroxyethyl acrylate, hydroxypropyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, glycidyl (meth) acrylate, phenyl (meth) acrylate, and other (meth) acrylic acid esters, or acrylonitrile , Vinyl group-containing cyano compounds such as methacrylonitrile and cyanostyrene, fatty acid vinyl esters such as vinyl formate, vinyl acetate, vinyl propionate, vinyl caprylate and vinyl stearate, or ethyl vinyl ether, propyl vinyl ether, butyl vinyl Vinyl ethers such as nyl ether, hexyl vinyl ether, 2-ethylhexyl vinyl ether, and phenyl vinyl ether, or
Examples thereof include vinyl ketones such as methyl vinyl ketone and phenyl vinyl ketone, and vinyl aromatic compounds such as styrene, chlorostyrene, hydroxystyrene and α-methylstyrene.

These monomers have amino groups, pyridine,
Monomers substituted with halogen atom such as piperazine, chlorine, bromine, fluorine, cyano group, sulfone group, carboxyl group, carboester group, quaternary ammonium salt and the like can be used alone or in combination of two or more kinds. Or a combination of monomers which are not substituted with functional groups can be used. Among the above monomers, (meth) acrylic acid ester, vinyl ester compound, vinyl ester compound, vinyl ether compound and vinyl aromatic compound monomers are particularly preferable. The amount of polymer chains obtained from the monomers having these radical chain transfer groups is suitably in the range of 0.5 to 25% by weight, preferably 5 to 15% by weight, based on the toner body.

In the suspension polymerization method, a monomer in which a polymerization initiator is dissolved is suspended and dispersed in an aqueous solvent and heated to carry out polymerization. In that case, a dispersant can be used. As these monomers, polymerization initiators and dispersants, those used for dispersion polymerization can be used. In emulsion polymerization, a monomer is emulsified in an aqueous solvent and a water-soluble polymerization initiator is used for polymerization. In that case, a surfactant can be used. At this time, the monomer used in dispersion polymerization can be used. As the water-soluble polymerization initiator, potassium persulfate, ammonium persulfate, etc. can be used.

The method of graft polymerization is Ce
Using (IV) as a catalyst, on the toner particle surface, a monomer having a radical chain transfer group alone, or a method of redox polymerizing a monomer having a radical chain transfer group and another monomer copolymerizable therewith, and ,
Using Ce (IV) as a catalyst, after graft-polymerizing a monomer having two or more radical chain transfer groups, a radical polymerization initiator such as a peroxide or an azo compound, or a combination of a peroxide and a reducing agent is used. A method of radically polymerizing the above-mentioned monomer having a radical chain transfer group with another monomer copolymerizable with the monomer, for example, methacryloyloxyammonium chloride using the redox-based polymerization initiator is preferably used.

The radical polymerization initiator used in the above graft polymerization method is hydrogen peroxide, potassium persulfate,
Examples thereof include ammonium peroxodisulfate, alkyl hydroperoxides, dialkyl peroxides azisyl peroxides, peroxides and azo compounds. As the redox-based polymerization initiator, a combination of a peroxide such as persulfate, hydrogen peroxide, hydroperoxide and various reducing agents, for example, hydrogen peroxide and ferrous salt, benzoyl peroxide and dimethylaniline. , Potassium persulfate and NaH
SO _{3 and the} like can be mentioned.

As the monomer having two or more radical chain transfer groups, acrylates and methacrylates of polyhydric alcohols such as ethylene glycol diacrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, trimethylolpropane triacrylate, penta Erythritol dimethacrylate, etc .; Reaction products of acrylic acid with amines containing two or more acrylic groups; Polyvinyl alcohol polyvinyl ethers, such as ethylene glycol divinyl ether; Polycarboxylic acid polyvinyl esters, such as , Divinyl succinate, divinyl phthalate, etc .; aromatic compounds containing two or more vinyl groups,
For example, divinylbenzene, p-allylstyrene, etc. can be mentioned. The amount of polymer chains obtained from these monomers having two or more radical chain transfer groups is in the range of 0.05 to 10% by weight, preferably 0.05 to 2% by weight, based on the toner body. Are suitable.

The dye chemically bonded to the polymer chain by an ion exchange reaction may be one having a substituent capable of ion exchange with the functional group of the graft polymer of the monomer substituted with the functional group. Specific examples include acid red, acid orange, acid blue, acid violet, acid green, acid yellow, acid black, naphthol orange, fast green, fast red, methylene blue, basic violet, basic blue, and basic red. it can. The amount of the dye added is in the range of 0.01 to 20% by weight, preferably 5 to 5% by weight relative to the toner body.
A range of 15% by weight is suitable.

In the present invention, the chemical bonding of the dye by the ion exchange reaction needs to be performed in an aqueous solvent containing at least a hydrophilic organic solvent. By using the hydrophilic organic solvent, the solubility of the dye is improved, it becomes easy to secure a high-concentration dye solution, and high-concentration coloring is possible. In addition, it becomes possible to use a dye having a low solubility in water, and the range of dye selection is expanded.

Examples of the water-soluble organic solvent used in the ion exchange include alcohols such as methanol and ethanol, acetone, ethyl acetate and the like. Of these, methanol and ethanol are preferable. The ratio of the water-soluble organic solvent and water is not particularly limited, but the range of 20 to 60% by weight of the organic solvent relative to water is suitable.

The toner of the present invention has a charge controllability of
A chargeable substance may be added internally or may be chemically or physically attached to the particle surface. As the charge control monomer,
A halogen-containing monomer or the like can be used. Further, low-molecular-weight propylene, low-molecular-weight polyethylene, wax or the like may be added as an offset preventing agent. Furthermore, in order to impart fluidity, metal oxides and metal salts such as silicon oxide and aluminum oxide, ceramics, resins,
Fine particles such as carbon black may be added.

[0025]

【Example】

[Example 1] (Preparation of polymer particles) 425 ml of ethanol and 7.5 g of hydroxypropyl cellulose were placed in 1 liter of Separable France, and the mixture was heated to 65 ° C while stirring in a nitrogen stream. Polymerization was initiated by dropwise addition of a solution containing 15 g of methacrylate and 3.0 g of benzoyl peroxide dissolved therein. After 2 hours, the reaction temperature was raised to 75 ° C. and the reaction was continued for another 24 hours. After completion of the reaction, filtration, washing and drying were performed to obtain white spherical particles having a particle size of 8.1 μm.
As an index of particle size distribution, particle size distribution index = [(16 of volume
% Particle size / square particle value of 84% of volume) was found to be 1.13, and the particle size was almost uniform when observed with a scanning electron microscope.

(Binding of Dye by Graft Polymerization and Ion Exchange) To 50 g of the above white spherical particles, 2 g of ion exchanged water was added.
While adding 50 g and stirring, 1 N nitric acid 5 g, 10%
5 g of the cerium sulfate aqueous solution was added, then 1 g of ethylene glycol dimethacrylate was added, and the reaction was carried out at 15 ° C. for 3 hours. After completion of the reaction, filtration and washing with water were performed to obtain particles in which ethylene glycol dimethacrylate was graft-polymerized on the surface of the spherical particles. This is again suspended in ion-exchanged water, and 0.4 g of potassium persulfate, 5.0 g of methyl methacrylate, 0.6 g of methacryloyloxyammonium chloride, and 0.16 g of sodium hydrogen sulfite are sequentially added with stirring, and the mixture is heated to 20 ° C. After reacting for 3 hours with, after adding a solution of 0.5 g of Fast Red A (manufactured by Tokyo Kasei Co., Ltd.) in a mixed solvent of 25 ml of water and 25 ml of methanol,
Stir for 5 minutes, then filter, wash with water and dry to a particle size of 8.
3 μm red spherical toner was obtained. The particle size distribution index was 1.14, which was almost the same as before coloring.

(Evaluation) The red spherical toner was put in a modified machine of an electrophotographic copying machine Viverse 500 manufactured by Fuji Xerox Co., Ltd., and a copying test was conducted. As a result, a good copy was obtained even after 500 cycles.

Example 2 (Preparation of Polymer Particles) 425 ml of i-propanol and 7.5 g of hydroxypropyl cellulose were placed in 1 liter of Separable France, and the mixture was stirred in a nitrogen gas stream to give 7
While heating at 0 ° C., a solution obtained by dissolving 60 g of styrene, 15 g of butyl acrylate and 3.0 g of azobisbutyronitrile was added dropwise to initiate polymerization. The reaction temperature was increased to 7 after 2 hours.
The temperature was raised to 5 ° C. and the reaction was continued for another 24 hours. After the reaction,
After filtration, washing and drying, white spherical particles having a particle size of 6.2 μm were obtained. The particle size distribution index was 1.14.

(Binding of Dye by Graft Polymerization and Ion Exchange) To 50 g of the above white spherical particles, 2 g of ion exchanged water was added.
While adding 50 g and stirring, 1 N nitric acid 5 g, 10%
After adding 4 g of cerium sulfate aqueous solution, 1 g of ethylene glycol dimethacrylate, 5 g of methyl methacrylate and 0.6 g of methacryloyloxyammonium chloride and reacting at 20 ° C. for 3 hours, acid yellow (Tokyo Kasei Co., Ltd. (Manufactured by K.K.) 0.70 g was dissolved in a mixed solvent of 30 ml of water and 20 ml of ethanol, stirred for 5 minutes, filtered, washed with water and dried to obtain a yellow spherical toner having a particle size of 6.4 μm. The particle size distribution index was calculated to be 1.15, which was the same as before coloring and the particle size distribution was almost unchanged.

(Evaluation) The yellow spherical toner was put in a modified machine of an electrophotographic copying machine Viverse500 manufactured by Fuji Xerox Co., Ltd., and a copying test was conducted. As a result, a good copy was obtained even after 500 cycles.

[Example 3] (Preparation of polymer particles) 260 ml of ethanol and 165 m of methyl cellosolve in 1 liter of separable France.
1, and 10 g of polyvinylpyrrolidone were added, and a solution of 3.0 g of azobisbutyronitrile in 75 g of styrene was added dropwise while stirring in a nitrogen stream and heated at 65 ° C. to initiate polymerization. After 2 hours, the reaction temperature was raised to 75 ° C. and the reaction was continued for another 24 hours. After completion of the reaction, filtration, washing and drying were performed to obtain white spherical particles having a particle size of 4.9 μm.
The particle size distribution index was 1.14.

(Binding of Dye by Graft Polymerization and Ion Exchange) 40 g of the above-mentioned white spherical particles was added to 20 g of ion-exchanged water.
While adding 0 g and stirring, 4 g of 1 N nitric acid and 4 g of a 10% aqueous cerium ammonium sulfate solution were added, and then 1 g of ethylene glycol dimethacrylate was added, and the mixture was stirred at 15 ° C. for 3 days.
A time reaction was performed. After completion of the reaction, filtration and washing are performed,
Particles obtained by graft-polymerizing ethylene glycol dimethacrylate on the surface of spherical particles were obtained. The particles are suspended again in ion-exchanged water and, with stirring, 0.4 g of potassium persulfate,
Methyl methacrylate 4.0 g, sodium methacryl sulfonate 1.2 g, sodium bisulfite 0.16 g
Were sequentially added and reacted at 20 ° C. for 3 hours, 0.21 g of basic blue (manufactured by Tokyo Kasei) in methanol / water solution was added, and the mixture was stirred for 5 minutes. After completion of the reaction, filtration, washing with water and drying were carried out to obtain a blue spherical toner having a particle size of 5.0 μm. The particle size distribution index of this toner was 1.14, which was the same as before coloring.

(Evaluation) The blue spherical toner was put in a modified machine of an electrophotographic copying machine Viverse500 manufactured by Fuji Xerox Co., Ltd., and a copying test was conducted. As a result, a good copy was obtained even after 500 cycles.

Comparative Example 1 To 50 g of the white spherical particles obtained in Example 1, 5 g of Fast Red A (manufactured by Tokyo Kasei) and 1.0 g of sodium stearate were dispersed in 500 ml of water, and the mixture was placed in an autoclave at 120 ° C. Stained for 2 hours.
After dyeing, filtration and heating were performed to obtain red toner particles. Hydrophobic colloidal silica (RA200H, manufactured by Nippon Aerosil Co., Ltd.) was externally added to the toner particles in an amount of 0.1 wt%, and Example 1
When a copying test was conducted in the same manner as in, the image quality was fogged and unclear after 500 cycles.

(Charge Evaluation) 3 g of each of the colored toners obtained in Examples 1 to 3 and Comparative Example 1 and 100 g of an iron powder carrier surface-coated with a phenol resin were heated at a temperature of 20 ° C. and a humidity of 5 g.
When mixed in an environment of 0% and the charge amount was measured by the flow-off method, the results shown in Table 1 were obtained.

[0036]

[Table 1]

Comparative Example 2 To 50 g of the white spherical particles obtained in Example 1, 250 g of ion-exchanged water was added and stirred with 5 g of 1N nitric acid and 5 g of a 10% cerium sulfate aqueous solution.
After adding, 1 g of ethylene glycol dimethacrylate
Was added and reacted at 15 ° C. for 3 hours. After the reaction was completed, the particles were filtered and washed with water to obtain particles in which ethylene glycol dimethacrylate was graft-polymerized on the surface of spherical particles. This was resuspended in ion-exchanged water and stirred with potassium persulfate of 0.
4 g, 5.0 g of methyl methacrylate, 0.6 g of methacryloyloxyammonium chloride and 0.16 g of sodium hydrogen sulfite were sequentially added, and after reacting at 20 ° C. for 3 hours, 0.5 g of Fast Red A (manufactured by Tokyo Kasei) was added. Water 5
0 ml of the dissolved solution of the mixed solvent was added, and the mixture was stirred for 5 minutes. After that, it is filtered, washed with water, and dried to a particle size of 8.2μ.
m light red spherical toner particles were obtained. The particle size distribution index is
At 1.13, it was almost the same as before coloring. The light red spherical toner particles are electrophotographic copying machine Vi manufactured by Fuji Xerox Co., Ltd.
A copy test was carried out by putting it in a modified Vace 500 machine, and a good copy was obtained even after 500 cycles,
The concentration was lower than that in Example 1.

Comparative Example 3 Particles 50 produced by interfacial polymerization
To g, add 250 g of ion-exchanged water and stir 1
After adding 5 g of N nitric acid and 5 g of 10% cerium sulfate aqueous solution, 1 g of ethylene glycol dimethacrylate was added,
The reaction was carried out at 15 ° C for 3 hours. After completion of the reaction, filtration and washing with water were performed to obtain particles in which ethylene glycol dimethacrylate was graft-polymerized on the surface of the spherical particles. This was again suspended in ion-exchanged water, and potassium persulfate of 0.
4 g, 5.0 g of methyl methacrylate, 0.6 g of methacryloyloxyammonium chloride and 0.16 g of sodium hydrogen sulfite were sequentially added, and after reacting at 20 ° C. for 3 hours, Fast Red A (manufactured by Tokyo Chemical Industry Co., Ltd.) 0 .23
When g was stirred for 5 minutes, the oil inside oozes out.
Black toner was obtained by filtering, washing with water and drying.
Looking at the photo, the oil inside had disappeared and the particles were crushed.

[0039]

EFFECTS OF THE INVENTION The present invention employs the above-mentioned constitution, and after graft-polymerizing a monomer having a radical chain transfer group on the particle surface, the dye is bonded to the polymer chain by ion exchange to obtain a colorant. The adhesive strength was increased and the durability could be improved. Moreover, the concentration of the dye can be increased by using an organic solvent in the ion exchange. Further, particles having a narrow particle size distribution were obtained, and the functional group of the monomer having a radical chain transfer group made it possible to impart high chargeability without an external additive.

Claims (3)

[Claims] 1. A surface of a polymer particle formed by emulsion polymerization, suspension polymerization or dispersion polymerization, at least a hydrophilic organic group through a graft-polymerized monomer having a radical chain transfer group and an ionic functional group. An electrophotographic toner comprising a dye bonded by an ion exchange reaction in an aqueous solvent containing a solvent. 2. A step of forming polymer particles by emulsion polymerization, suspension polymerization or dispersion polymerization, a step of graft-polymerizing a monomer having a radical chain transfer group and an ionic functional group onto the particle surface, and the ionic property. And a step of binding a dye to the functional group by an ion exchange reaction in an aqueous solvent containing at least a hydrophilic organic solvent, the method for producing an electrophotographic toner. 3. An image forming method comprising a step of forming a latent image on an image carrier, a step of developing the latent image with a developer, and a step of transferring the developed toner image onto a transfer body. An image forming method comprising using the developer containing the electrophotographic toner according to claim 1.