JP2573296B2 - Manufacturing method of electrophotographic toner - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an electrophotographic toner, and more particularly, to a spherical electron having a monodisperse particle size distribution without generating fine particles and coarse particles. The present invention relates to a method for producing a photographic toner with high productivity.

[Prior art and its problems]

Conventionally, electrophotographic toners used in electrophotography, electrostatic printing, and the like are prepared by melting and kneading other additives such as a thermoplastic resin, a colorant and a charge control agent, and cooling and pulverizing the mixture to obtain a pulverized material. It has been manufactured by the process of classifying and adjusting to a certain particle size range. However, the yield of toner obtained by this pulverization / classification is extremely low, and a large amount of equipment is required for these operations, which makes the production cost of the toner extremely high. In addition, although the toner obtained by pulverization can provide a certain level of performance, it has also been recognized that the irregular shape of the toner results in poor fluidity of the toner and easy blocking in a developing device. . Further, amorphous toners have different triboelectrification properties due to the different way of accumulating the charge of each toner particle, and together with poor fluidity, the development characteristics are not kept constant as the development operation proceeds. The problem of causing image degradation has also been recognized.

On the other hand, in recent years, image forming apparatuses such as copiers using electrophotography have been required to have high reliability such as maintenance-free, multi-color imaging and high quality imaging. For example, in the formation of color (chromatic) images, particularly in color (chromatic) images such as OHP, the hue of the transmitted image itself of the toner-fixed image is required. Spherical toner is required so that the toner must be formed smoothly and the toner can easily form a uniform layer and each toner can be easily melted uniformly. And characteristic deterioration is small in repetition of copying work,
Even if new toner is replenished in accordance with the consumption of toner, the developer characteristics in the developing device do not always change, so that a more uniform toner, that is, a spherical and uniform particle diameter toner is required. It has become to.

As a method of solving the above-mentioned pulverized toner and the problem in the production thereof, and producing the spherical toner at a time during the polymerization process of the fixing resin, a toner production method by a suspension polymerization method has been proposed. As a problem in the toner production method by this suspension polymerization, it is possible to produce spherical particles of a practical toner size, but the particle size distribution of the obtained particles is very polydisperse and contains many ultrafine particles and coarse particles. It can happen. Therefore, as a method for solving this problem, for example, an attempt has been made to suspend a polymerizable composition containing a toner property imparting agent in a dispersion medium at a high temperature. In order to obtain the polymerizable composition, the polymerizable composition needs to have a low viscosity, and it is necessary to raise the temperature to substantially higher than the temperature at which the polymerization initiator decomposes, so that the polymerizable composition has a low viscosity. Therefore, the polymerization initiator is decomposed during granulation to rapidly generate radicals, the polymerization reaction does not proceed favorably, and the polymerization reaction itself is inhibited, so that a sufficiently satisfactory effect has not been obtained. As another solution,
Although the toner obtained by suspension polymerization can be classified and used, it is difficult to mix and reuse the ultrafine particles and coarse particles generated by suspension polymerization with the polymerizable composition. It makes the sex very low.

Therefore, the present invention has been made to solve the above-mentioned problems of the prior art, and an object of the present invention is to easily produce a spherical toner having an appropriate particle diameter without generating ultrafine particles and coarse particles. In addition, it is an object of the present invention to provide a method of manufacturing with high productivity.

Another object of the present invention is to provide a production method for obtaining toner particles having a spherical shape and a small difference in individual characteristics of the toner particles such as fluidity and triboelectricity.

[Means for solving the problem]

A water-miscible organic solvent which dissolves the monomer but does not dissolve the polymer or a mixture of the water-miscible organic solvent and water as a solvent, a monomer, a nucleus substance composed of inorganic fine particles, and a dispersion stabilizer Dissolving or dispersing an oil-soluble toner property imparting agent and an oil-soluble polymerization initiator in the solvent, increasing the concentration of water in the dispersion, decreasing the concentration of the water-miscible organic solvent, or dispersing the dispersion. By adopting at least one means for lowering the solubility of the monomer or by changing the temperature of the system, an oil droplet containing a monomer, a colorant, a toner property imparting agent and a polymerization initiator, mainly the core substance, The objective of the present invention is achieved by producing a toner particle by increasing the polymer particle diameter by selectively polymerizing the monomer in the oil droplet by forming a toner particle.

[Action]

In the present invention, a water-miscible organic solvent that dissolves the monomer but does not dissolve the polymer or a mixed solution of the organic solvent and water is dispersed with a solvent / nuclear substance for dissolving the monomer. Used as a dispersion medium for That is, in the solvent / dispersion medium used in the present invention, the decrease in the solubility of the monomer due to the addition of water is remarkable. Thus, oil droplets containing a toner property imparting agent such as a colorant and a polymerization initiator are formed. The polymerization of the monomers present in the oil droplets is started, and the produced polymer particles grow to an appropriate toner particle size.

The means of reducing monomer solubility is the simplest and most efficient way to add water, but this means is not limited to the addition of water,
It should be understood that, for example, means for evaporating the water-miscible organic solvent to reduce its concentration in the system or means for lowering the temperature of the dispersion may be used alone or in combination of two or more. is there. At this time, an electrolyte such as sodium chloride may be added to the system to promote the solubility reducing effect. In particular, it should be noted that in the system of the mixture of water-miscible organic solvent and water, the solubility of the monomer tends to decrease due to the decrease in temperature as compared with other solvents.

As described above, according to the method of the present invention, an oil droplet containing a monomer having a core material as a center and a toner property-imparting agent is utilized by utilizing the decrease in monomer solubility in a specific solvent / dispersion medium. By forming, the polymer particles efficiently generated within a short time grow to the toner size, and it becomes possible to selectively polymerize the monomers in the oil droplets formed around the core material, It is possible to obtain a spherical electrophotographic toner which has a fixing property and an electric detection property and has a particle size of a practical toner size and a monodispersed particle size distribution.

(Preferred embodiment)

Monomer The monomer used in the present invention is an ethylenically unsaturated monomer having radical polymerizability. Suitable examples thereof include a monovinyl aromatic monomer, an acrylic monomer and a vinyl ester monomer. Monomers, vinyl ether monomers, diolefin monomers, monoolefin monomers, halogenated olefin monomers, polyvinyl monomers and the like.

As the monovinyl aromatic monomer, the formula Wherein R ₁ is a hydrogen atom, a lower alkyl group or a halogen atom, and R ₂ is a hydrogen atom, a lower alkyl group, a halogen atom, an alkoxy group, an amino group, a nitro group, a vinyl group or a carboxyl group. Monovinyl aromatic hydrocarbons such as styrene, α-methylstyrene, vinyltoluene, α-chlorostyrene,
o-, m-, p-chlorostyrene, p-ethylstyrene, sodium styrenesulfonate, and divinylbenzene alone or in combination of two or more. Examples of other monomers described above include the following. Respectively.

formula (Wherein, R ₃ is a hydrogen atom or a lower alkyl group, R ₄ is a hydrogen atom, a hydrocarbon group having up to 12 carbon atoms, a hydroxyalkyl group,
A vinyl ester group or an aminoalkyl group), such as acrylic acid, methacrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, acrylic acid Phenyl, methyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, ethyl β-hydroxyacrylate, butyl γ-hydroxylate, butyl δ-hydroxyacrylate, ethyl β-hydroxy methacrylate, propyl γ-aminoacrylate Γ-N, N-diethylaminoacrylate, ethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, and the like.

formula Wherein R ₅ is a hydrogen atom or a lower alkyl group, for example, vinyl formate, vinyl acetate, vinyl propionate and the like.

formula Wherein R ₆ is a monovalent hydrocarbon group having up to 12 carbon atoms, for example, vinyl methyl ether, vinyl ethyl ether, vinyl-n-butyl ether, vinyl phenyl ether, vinyl cyclohexyl ether and the like.

formula Wherein each of R ₇ , R ₈ , and R ₉ is a hydrogen atom, a lower alkyl group, or a halogen atom, such as butadiene, isoprene, and chloroprene.

formula Wherein each of R ₁₀ and R ₁₁ is a hydrogen atom or a lower alcohol, such as ethylene, propylene, isoprene, butene-1, pentene-1, 4-methylpentene-1 and the like.

Halogenated olefin monomers include vinyl chloride,
Vinylidene chloride and the like can be mentioned, and as the polyvinyl monomer, divinylbenzene, diallyl phthalate, triallyl cyanurate and the like can be mentioned.

These monomers can be used alone or in combination of two or more. Preferred monomers are styrene, (meth) acrylate, styrene / (meth) acrylate, styrene / divinylbenzene.

Organic Solvents Water-miscible organic solvents include lower alcohols such as methanol, ethanol and isopropanol; polyhydric alcohols such as ethylene glycol, propylene glycol, butanediol, diethylene glycol and triethylene glycol; cellosolves such as methyl cellosolve and ethyl cellosolve; Ketones such as acetone and methyl ethyl ketone; ethers such as tetrahydrofuran; esters such as ethyl acetate; organic acids such as formic acid and acetic acid;
Among these, those which dissolve the monomer but do not dissolve the polymer are used in combination with the monomer. Organic solvents which are excellent in monomer solubility, can be mixed with water in any ratio, and are particularly useful for the purpose of the present invention, are lower alcohols such as ethanol.

The water-miscible organic solvent can be used alone or in the form of a mixture with water. In this latter case, it is desirable to contain water as much as possible within a range that does not practically lower the solubility of the monomer, and the mixing ratio is determined by the monomer and the organic solvent used.
When a lower alcohol is used as the organic solvent, the organic solvent and water can be used at a volume ratio of 10: 1 to 3: 5, particularly at a volume ratio of 4: 3 to 3: 4.

Nuclear Material The nuclear material used in the present invention is a nucleus when a monomer precipitated by utilizing a decrease in the solubility of the monomer in a specific solvent / dispersion medium forms an oil droplet, and at the same time, a It acts as a nucleus for coalescence.

The core material may be any conventionally known inorganic fine particles, such as, for example, Al
₂ O ₃ , MnO ₂ , SiO ₂ , SnO ₂ , ThO ₂ , TiO ₂ , ZnO, MoO ₃ , WO ₃ ,
Examples include silica, gold, silver, inorganic pigments, and magnetic powder.

When magnetic powder is used as a core material, a magnetic toner used in a magnetic one-component developing method or the like is manufactured. The magnetic powder may be any substance that can be magnetized by being placed in a magnetic field, for example, a ferromagnetic metal such as iron, cobalt, or nickel, or an alloy or compound such as magnetite, hematite, or ferrite.

When an inorganic pigment is used as a core material, a toner can be produced without adding a coloring agent. As the inorganic pigment, a commonly used known pigment can be used.

The core material has a monodisperse particle size distribution,
The particle size is generally 0.01-20 μm, especially 0.5-10 μm
Is desirably within the range.

Dispersion stabilizer In the present invention, it is preferable to use a dispersion stabilizer in order to improve the dispersibility of the core substance in the solvent / dispersion medium. Examples of such dispersion stabilizers include polyvinyl alcohol, methyl cellulose, ethyl cellulose, polyacrylic acid, polyacrylimide, polyethylene oxide, and poly (hydroxystearic acid-g-) which are known per se.
Polymer dispersion stabilizers such as a methyl methacrylate-co-methacrylic acid) copolymer, a nonionic surfactant, an anionic surfactant, a cationic surfactant, an amphoteric surfactant and the like are used.

Among these, a polymer dispersion stabilizer such as polyvinyl alcohol is preferable, and a good result is obtained in combination with an organic solvent-water mixture.

It is important that the polymerization is initiated selectively only for the monomers contained in the oil droplets. If the polymerization is started for the monomers dissolved in the dispersion solvent, the polymerization The monomer is absorbed by the coalesced particles, and particle growth starts to occur.Since monodispersed polymer particles are difficult to obtain, the polymerization initiator is oil-soluble and forms oil droplets with the monomer. It is desirable. Any such oil-soluble ones can be used. Examples of the radical polymerization initiator include azo compounds such as azobisisobutyronitrile, cumene hydroperoxide, t-butyl hydroperoxide, and dicumyl peroxide. And those which are soluble in monomers such as peroxides such as di-t-butyl peroxide, benzoyl peroxide and lauroyl peroxide. In the case of polymerization by ultraviolet rays, oil-soluble ones among known photopolymerization initiators can be used.

Toner property-imparting agent The toner property-imparting agent referred to in the present application means an agent used for imparting various properties to a toner, such as a colorant and a charge control agent.

It is necessary that a toner property imparting agent such as a colorant is also uniformly contained in individual oil droplets, and is oil-soluble like the polymerization initiator, and is desirably contained in the oil droplets together with the monomer. .

As the colorant, an oil-soluble dye is preferable from the above point,
For example, CI Solvent Yellow 2, CI Solvent Yellow 14, CI Solvent Yellow 60, C.I.
I. Solvent Orange 7, CI Solvent Red 3, CI Solvent Red 24, CI Solvent Red
Red 27, CI Solvent Violet 13, CI
Solvent Blue 7, CI Solvent Blue 3
5, CI Solvent Green 15, CI Solvent Green
Brown 5, etc. are used. These colorants are monomers
1 to 30 parts by weight per 100 parts by weight, especially 5 to 2 parts
0 parts by weight is preferred.

Further, a charge control agent can be used for the purpose of adjusting the charging characteristics of the toner. The charge control agent must also be oil-soluble in that it is contained in the oil droplets together with the monomer. For example, oil-soluble dyes such as nigrosine dye (CINo. 50415B), oil black (CINo. 26150), and spiron black Can be suitably used to such an extent that the polymerization reaction is not inhibited. Generally, it is preferable to use 1 to 40 parts by weight, particularly 2 to 15 parts by weight, per 100 parts by weight of the monomer.

Polymerization According to the present invention, first, a monomer is dissolved in a water-miscible organic solvent or a mixture thereof and water, and a nucleus substance composed of inorganic fine particles, a dispersion stabilizer, and an oil-soluble toner An imparting agent and a polymerization initiator are added. Alternatively, a suspension may be prepared by dispersing a nuclear substance in water, and a water-miscible organic solvent, a monomer, a dispersion stabilizer, a toner-characterizing agent such as a colorant, and a polymerization initiator may be added to the suspension.

The amount of the monomer dissolved varies considerably depending on the type and composition of the solvent and the monomer, but is generally in the range of 0.01 to 50% by weight, preferably 1 to 20% by weight. The amount of the nuclear material to be added also differs depending on the desired degree of increase in the particle size.
That is, in order to increase the particle size n times, n ³ times of monomers are required. The monomers in nuclear materials and systems, typically 1: it is desirable to be present in 1 to 1:10 ⁹ especially 1:10 to 1:10 ⁶ weight ratio, while the concentration of the nuclear material in the dispersion Is preferably used in the range of generally 0.01 to 50% by weight, particularly 0.1 to 20% by weight. The dispersion stabilizer is preferably used in an amount of 0.1 to 30% by weight, particularly 1 to 10% by weight, based on the core material, while the polymerization initiator is used in an amount of 0.001 to 10% by weight per charged monomer.
It is preferably used at a weight percentage of 0.01 to 0.5% by weight.

To this dispersion, add water, evaporate the solvent,
Alternatively, the solubility of the monomers in the system is reduced by lowering the temperature. According to the present invention, substantially all of the charged monomers can be contained in oil droplets by adding water to the polymerization system or further lowering the temperature. Generally, it is desirable that the oil be contained in oil droplets of 50% by weight or more, particularly 90% by weight or more of the charged monomers. It is a remarkable feature of the present invention that this treatment is performed within a very short time, and at the same time as the precipitation of the monomer, a toner property imparting agent such as a monomer, a polymerization initiator, and a colorant, centering on a nuclear substance. The formation of oil droplets is also performed. Next, the monomers contained in the oil droplets are polymerized. The polymerization is generally carried out in an inert atmosphere such as nitrogen at a temperature between -30 ° C and 90 ° C, especially between 30 ° C and 80 ° C. The polymerization time is such that the polymerization of the monomer in the oil droplets is completed, and generally 0.1 to 30 hours is appropriate. The method of the present invention may be performed in only one step, or may be performed in a plurality of steps until the particles grow to a predetermined particle size. The resulting polymer generally has a particle size of 1 to 30 μm, especially 5 to 20 μm.
And is highly monodisperse. The obtained polymer particles are separated by filtration, washed with water if necessary, and then dried to obtain a product. If necessary, these particles are dusted with carbon black, hydrophobic silica, silicone oil or the like to obtain the final toner.

 Hereinafter, the present invention will be described in more detail with reference to examples.

(Example 1) 600 g of ethanol, 600 g of water, and 600 g of ethanol completely removed from water and ethanol by distillation or ultrafiltration.
28 g of styrene, oil-soluble dye (CI Solvent Blue
7] 5 g, a charge control agent [Bontron E-82] 3 g, a polyacrylic acid 1.5 g and benzoyl peroxide 1.5 g solution,
1.8 mg of monodispersed molybdenum oxide particles (manufactured by Nippon Shokubai Chemical Industry Co., Ltd.) having an average particle size of 0.2 μm were dispersed to obtain a suspension. The suspension obtained was evacuated to 400 mmHg at 30 ° C. and 30% of the medium was evaporated. Although some evaporation of styrene was observed by this operation, a blue oil droplet of about 12 μm was formed as the methanol concentration in the emulsion decreased. The obtained emulsion is placed in a 2 liter, three-necked separable flask equipped with a reflux condenser under a nitrogen stream.
The reaction was carried out at 70 ° C. for 8 hours while stirring at 0 rpm to complete the polymerization reaction. After filtering the polymer, it was dried to obtain 28 g of a blue toner.

The particle size distribution of this toner was measured by a Coulter counter, and as shown in Table 1, it was a very monodisperse particle size distribution and was spherical particles having an average particle size of 11.8 μm.

Further, when the toner was placed in an electrophotographic copying machine DC2055 (manufactured by Mita Kogyo KK) to form an image, a clear blue image was obtained.

Example 2 1.4 g of silica [AEROSIL130] (manufactured by Nippon Aerosol) having an average particle diameter of 20 nm was dispersed in 1 liter of distilled water to obtain a suspension. 600 ml of isopropyl alcohol from which particles insoluble in water and ethanol have been completely removed by distillation or ultrafiltration, 700 g of water, 40 g of methyl methacrylate, 3 g of an oil-soluble dye [CI Solvent Blue 7], a charge control agent [Bontron E-82 3 g, polyvinylpyrrolidone 1.5 g, benzoyl peroxide 1.5 g in a solution consisting of the above suspension
1 ml was dispersed to obtain a suspension.

This suspension is cooled from room temperature (about 20 ℃) to 2 ℃ / min.
And cooled to -10 ° C. When the emulsion was observed with an optical microscope at -10 ° C, blue oil droplets of about 10 µm were formed. To the emulsion cooled to −10 ° C., 1000 g of ion-exchanged water at 0 ° C. is added all at once, and the mixture is placed in a 3-liter three-neck separable flask equipped with a reflux condenser and reacted at 70 ° C. for 8 hours while stirring under a nitrogen stream. The polymerization was completed.
After filtering the polymer, it was dried to obtain 90 g of a blue toner.

The particle size distribution of the obtained toner was measured in the same manner as in Example 1, and a copied image was obtained. As shown in Table 2, the particles were spherical particles having an extremely monodispersed particle size distribution. Also,
A clear blue image was obtained from the copy image obtained by the copying machine.
Further, when an image was formed on the OHP transparency using this toner, a blue image having a light-transmitting property was obtained.

(Example 3) 35 g of ethanol, 60 g of water, 30 g of methyl methacrylate, 3 g of an oil-soluble dye [CI Solvent Red 27], 3 g of a charge controlling agent [Bontron, by completely removing particles insoluble in water and ethanol by distillation or ultrafiltration E-82] 3
g, lauryl trimethyl ammonium chloride 1.5 g,
In a solution consisting of 1 g of 2.2 '-(2,4-azobisisobutyronitrile), 0.6 g of monodispersed silica particles (manufactured by Nippon Shokubai Kagaku Kogyo Co., Ltd.) having an average particle size of 1 μm was dispersed to obtain a suspension. While stirring the obtained suspension vigorously, 5 g of sodium chloride containing no particles insoluble in water and ethanol was added little by little, then 50 g of distilled water was dropped at a rate of 5 g / min, and 150 g of ion-exchanged water was further added. added. And
When this emulsion was observed with an optical microscope, it was approximately 10μ.
m red oil droplets had formed.

The above emulsion was placed in a 1-liter three-neck separable flask equipped with a reflux condenser, and subjected to a polymerization reaction at 80 ° C. for 9 hours under a nitrogen stream to obtain a polymer. The toner particles obtained by filtration and drying were truly spherical red particles, and the particle size distribution was extremely monodisperse as shown in Table 3, and the copied image obtained with the toner was a clear red image. . Further, when an image was formed on the OHP transparency using this toner, a red image having translucency was obtained.

(Example 4) 700 g of methanol and 700 g of water from which particles insoluble in water and ethanol were completely removed by distillation or ultrafiltration,
30 g of styrene, oil-soluble dye (CI Solvent Red 2
7] 5 g of a charge controlling agent [Bontron E-82] 3 g, polyvinyl alcohol 1.5 g and benzoyl peroxide 1.5 g were added to a monodisperse tungsten oxide (average particle size: about 2 μm) 1.5 g of monodispersed tungsten oxide (manufactured by Nippon Shokubai Chemical Industry). Was dispersed to obtain a suspension. After dripping 200 g of distilled water at a rate of 5 g / min while stirring the suspension vigorously, 800 g of distilled water was further added. When this emulsion was observed with an optical microscope, red oil droplets of about 8 μm were formed.

The above emulsion was charged into a 3-liter three-neck separable flask equipped with a reflux condenser, and reacted at 70 ° C. for 8 hours while stirring at 100 rpm under a nitrogen stream to complete the polymerization. The polymer was filtered and dried to obtain 27 g of a red toner.

The particle size distribution of the obtained toner particles was extremely monodispersed as shown in Table-4. The copy image obtained with this toner was a clear red image.

(Example 5) An average particle size of 5 µm having a particle size distribution shown in Table-5 (1).
Was dispersed using a ball mill in 100 g of distilled water in which 0.1 g of sodium dodecylbenzenesulfonate was dissolved. Excess surfactant of the suspension was removed by dialysis, and distilled water was added to make up a total of 730 g. In addition, ethanol is added to this suspension.
700 g, 30 g of styrene, 3 g of spiron black TRH, 1.5 g of polyvinyl alcohol and 1.5 g of azobis- (2,4-dimethylvaleronitrile) are dissolved, and the temperature is changed from room temperature (about 20 ° C.) to 2 ° C.
Cooled to -10 ° C at a rate of / min. Observation of this solution at −10 ° C. under an optical microscope revealed that black oil droplets of about 10 μm had been formed.

1000 g of ion-exchanged water at 0 ° C. is added to the emulsion at a time, and the mixture is placed in a 3 liter three-neck separable flask equipped with a reflux device and reacted at 70 ° C. for 8 hours while stirring at 100 rpm under a nitrogen stream to complete the polymerization. did. After filtering the polymer, it was dried to obtain 60 g of a magnetic toner.

The particle size distribution of the obtained toner was measured in the same manner as in the example. As shown in Table 5 (2), the particle size distribution was satisfactory as shown in Table 5 (2). Further, when the above magnetic toner was placed in a modified electrophotographic copying machine DC2055 (manufactured by Mita Kogyo Co.) modified for a one-component magnetic developer, an image was formed, and a clear image was obtained.

(Example 6) An average particle size of 5 μm having a particle size distribution shown in Table-6 (1).
4 g of phthalocyanine green was dispersed using a ball mill in 100 g of distilled water in which 0.8 g of sodium lauryl sulfate was dissolved.Excess surfactant of this suspension was removed by dialysis, and distilled water was further added to bring the total amount to 700 g. did. Next, 700 g of methanol, 30 g of methyl acrylate, and a charge control agent (Bontron E-82) 3 were added to the suspension.
g, polyvinyl alcohol 1.5 g and benzoyl peroxide 1.5
g was dissolved.

While stirring this suspension vigorously, 200g of distilled water
Was added. Observation of this emulsion with an optical microscope revealed that about 10 μm oil droplets containing only one green powder were formed at the center. This emulsion was equipped with a reflux condenser
Put into a 3-liter three-neck separable flask, 100r under a nitrogen stream
The reaction was carried out at 70 ° C. for 8 hours while stirring at pm to complete the polymerization. After filtering the polymer, it was dried to obtain 33 g of a green toner.

When the particle size distribution of the obtained toner was measured in the same manner as in Example 1, the particle size distribution was satisfactory as shown in Table-6 (2). Further, the copied image obtained with the toner was a clear green image.

[Effects of the Invention] According to the present invention, the solubility of a monomer in a water-miscible organic solvent that is a solvent for a monomer and a dispersion medium for a nucleus substance is reduced, and an amount commensurate with the decrease is obtained. By increasing the particle size of the polymer formed on the core material by precipitating the monomer and forming oil droplets centered on the core material, it can be performed efficiently in a very short time. Become
By polymerizing the monomer contained in the oil droplet with good selectivity, a spherical toner having a desired toner particle diameter and a sharp particle size distribution can be produced with high productivity. As a result, the toner obtained by the production method of the present invention has good fluidity, and a toner having a small difference in various characteristics such as charging characteristics of each particle can be obtained.

Claims (3)

(57) [Claims] A nucleus comprising a monomer and inorganic fine particles, wherein a solvent is a water-miscible organic solvent or a mixture of water and a water-miscible organic solvent which dissolves a monomer but does not dissolve the polymer. The substance, dispersion stabilizer, oil-soluble toner property-imparting agent and oil-soluble polymerization initiator are dissolved or dispersed in the solvent to increase the concentration of water in the dispersion or to decrease the concentration of the water-miscible organic solvent. Or at least one of means for lowering the solubility of the monomer in the dispersion system, thereby containing a monomer, a toner property-imparting agent and a polymerization initiator around the core material. A method for producing a toner for electrophotography, comprising forming oil droplets and selectively polymerizing monomers in the oil droplets to increase the polymer particle diameter. 2. The method according to claim 1, wherein the dispersion stabilizer is a polymer dispersion stabilizer. 3. The method according to claim 1, wherein the colorant is an oil-soluble dye.