JP2573287B2 - Method for producing toner for developing electrostatic images - Google Patents

Description

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

[Prior art and its problems]

Conventionally, toners for developing electrostatic images 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. It has been manufactured by a process of classifying and classifying products into 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.

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 color (chromatic) image formation, particularly in color (chromatic) images such as OHP, the hue of the transmitted image of the toner fixed image is required, and the surface of the fixed image is formed in order to make the transmitted light hardly diffusely reflected. It is necessary to form the toner more smoothly, and a spherical toner is required so that the toner can easily form a uniform layer and each toner is easily melted uniformly.
In addition, when the copying operation is repeated, the characteristic deterioration is small, and even when the toner is newly replenished in accordance with the consumption of the toner, the developer characteristic in the developing device does not always change. A toner having a uniform particle diameter has been required.

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. However, in a method of producing a toner by 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. As a method for obtaining toner particles having a uniform particle size in the suspension polymerization method, for example, it has been attempted to suspend a polymerizable composition containing a toner property imparting agent in a dispersion medium at a high temperature. In order to obtain oil droplet particles having a uniform particle size, it is necessary to lower the viscosity of the polymerizable composition. There is a need to. 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. Further, in order to obtain a toner having a narrow particle size distribution, a toner obtained by suspension polymerization can be classified and used. However, in the pulverization method, the defective toner that has been classified and removed can be recycled to the melt-kneading step and reused.
It is difficult to mix and reuse the ultrafine particles and coarse particles produced by the suspension polymerization with the polymerizable composition, which results in extremely low productivity.

Therefore, the present invention has been made in order 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 smile 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 or a mixture of water and a water-miscible organic solvent that dissolves the polymer but does not dissolve the polymer is used as a solvent, and the monomer exhibits swelling properties with respect to the monomer. The seed polymer particles, the dispersion stabilizer, the toner property imparting agent and the oil-soluble polymerization initiator are dissolved or dispersed in the solvent to increase the concentration of water in the dispersion or decrease the concentration of the water-miscible organic solvent. Or by changing the temperature of the dispersion system to at least one of the means for lowering the solubility of the monomer, so that the monomer, the colorant and the polymerization initiator are absorbed in the seed polymer particles, and the seed polymerization is performed. The object of the present invention is achieved by selectively polymerizing the monomers absorbed in the particles to increase the polymer particle size and produce toner particles.

[Action]

In the present invention, a water-miscible organic solvent that dissolves the monomer but does not dissolve the polymer or a mixture of the organic solvent and water is used as a solvent / seed polymerization pair particle for dissolving the monomer. Used as a dispersion medium for dispersion. That is, in the solvent / dispersion medium used in the present invention, the decrease in monomer solubility due to the addition of water is remarkable, and a monomer in an amount corresponding to the decrease in solubility is forcibly absorbed into the seed polymer particles, The polymer particles swell to the proper toner particle size. In order to cause forced swelling of the polymer particles, the seed polymer particles must of course be swellable in the form of a monomer. Also, the seed polymer particles must be present as stable and independent dispersed particles in the polymerization system, and for this purpose, a dispersion stabilizer must be added to the polymerization system. It is important that the initiation of polymerization is selectively performed only on the monomers absorbed by the seed polymer particles, and if the polymerization is started on the monomers dissolved in the dispersion medium, the resulting polymer is produced. Since the monomer is absorbed by the particles and particle growth occurs, it becomes difficult to obtain monodispersed polymer particles, so the polymerization initiator is oil-soluble and is absorbed by the seed particles together with the monomer. Is desirable. Also, the toner property imparting agent needs to be uniformly absorbed and adsorbed by the individual polymer particles, and is preferably oil-soluble like the polymerization initiator. It can be used by modifying the surface by surface treatment with a ring agent or the like to improve the affinity with the monomer.

As described above, the method of the present invention uses a decrease in the solubility of a monomer in a solvent / dispersion medium as a driving force to cause the seed polymer particles to absorb the monomer and forcibly reduce the size of the seed polymer to the toner size. It swells the particles.

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, for example by evaporating a water-miscible organic solvent to reduce its concentration in the system. It is to be understood that the means for effecting or reducing the temperature of the dispersion may be used alone or in combination of two or more. 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 water-miscible organic solvent-water mixture, the solubility of the monomer is more likely to decrease due to the temperature decrease than in other solvents.

As described above, according to the method of the present invention, the monomer and the toner property imparting agent are precipitated and absorbed in the seed polymer particles by utilizing the decrease in the solubility of the monomer in the specific solvent / dispersion medium. The seed polymer particles swell efficiently to the size of the toner within the time, and the selective polymerization of the monomers absorbed by the polymer particles becomes possible. It is possible to obtain a spherical electrostatic developing toner having a particle size distribution and a monodispersed particle size distribution.

(Preferred embodiment)

Monomer The monomer used in the present invention is an ethylenic illegal monomer having radical polymerizability, and 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.

Examples of halogenated olefin monomers include vinylidene chloride and vinylidene chloride, and examples of polyvinyl monomers include 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 in a volume ratio of 10: 1 to 3: 5, particularly in a volume ratio of 4: 3 to 3: 4.

Seed Polymer Particles The seed polymer particles used in the present invention exhibit swelling properties with respect to the aforementioned monomers, and are obtained by polymerizing one or more of the aforementioned monomers. It is. The polymer particles are generally formed from the same type of monomer as the monomer used, but may be formed by polymerization of a monomer different from this monomer. The former example is a combination of a styrene polymer particle and a styrene monomer, and the latter example is a combination of an acrylic polymer particle and a styrene monomer.

The seed polymer particles have a monodisperse particle size distribution, and the particle size is generally 0.01 to 20 μm, particularly 0.5 to 10 μm.
It is desirably within the range of μm. Such seed polymer particles can be easily obtained by a dispersion polymerization method, an emulsion polymerization method, or a polymer obtained by pulverization and classification known per se.

Dispersion stabilizer As a dispersion stabilizer for improving the dispersibility of seed polymer particles in a solvent / dispersion medium, known per se, polyvinyl alcohol, methyl cellulose, ethyl cellulose, polyacrylic acid, polyacrylimide, polyethylene oxide , Poly (hydroxystearic acid-g-
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.

Polymerization Initiator Any polymerization initiator can be used as long as it is oil-soluble. For example, as a radical polymerization initiator, azo compounds such as azobisisobutyronitrile and peroxides such as cumene hydroperoxide, t-butyl hydroperoxide, dicumyl peroxide, di-t-butyl peroxide, benzoyl peroxide, uraroyl peroxide and the like can be used. Those soluble in monomers such as oxides are used. 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. The toner property-imparting agent is preferably an oil-soluble one, but even a non-oil-soluble one can be used by modifying the surface by grafting or surface treatment with various coupling agents to improve the affinity with the monomer. become.

As the coloring agent, a known coloring agent that is usually used is used, and examples thereof include carbon black and lamp black (CI
No. 77266), chrome yellow (CINo. 14090), Hansa yellow (CINo. 11660, 11680, etc.), benzidine yellow (CINo. 21110, etc.), sllen yellow G (CINo. 706)
00), quinoline yellow (CINo. 47005), permanent orange GT (CINo. 12305), pyrazolone orange (CINo. 21110), Vulcan orange (CINo. 2116)
0), Watching Red (CINo.15865), Permanent Red (CINo.12310 etc.), Brilliant Carmine 3B (CINo.15850), Dupont Oil Red (CIN
o.26105), pyrazolone red (CINo.21120), lithol red (CINo.15630), rhodamine B lake (C.
I.No.45170) Lake Red C (CINo.15585), Rose Bengal (CINo.45435), Aniline Blue (CINo.5)
0405), Ultramarine Blue (CINo.77103), Calco Oil Blue (CINo.azoec Blue3), Methylene Blue Chloride (CINo.52015), Phthalocyanine Blue (CINo74160), Phthalocyanine Green (CINo.74)
260), Malachite Green Oxalate (CINo.4200
0) etc. and CI Solvent Yellow 2, CI Solvent Yellow 14, CI Solvent Yellow 60, CI Solvent Orange 7, CI Solvent Red 3, CI
Solvent Red 24, CI, Solvent Red 27,
CI Solvent Violet, 13, CI Solvent
Oil-soluble dyes such as Blue 7, CI Solvent Blue 35, CI Solvent Green 15, and CI Solvent Brown 5 are used. In particular, oil-soluble dyes are preferred in that they are absorbed together with the monomer in the seed polymer particles, and inorganic pigments can be grafted with polymer chains or surfaced with various coupling agents and long-chain alkylamines such as dodecylamine. It is preferable to improve the affinity with the monomer by surface modification by treatment or the like. These colorants are used in an amount of 1 to 30 parts by weight, preferably 5 to 20 parts by weight, per 100 parts by weight of the monomer. Also, in order to adjust the charging characteristics of the toner,
Conventionally used charge control agents can be used. For example, oil-soluble dyes such as nigrosine dye (CINo. 50415B), oil black (CINo. 26150) and spiron black, naphthenic acid, salicylic acid, octylic acid,
Fatty acids, resin acids manganese, iron, cobalt, lead, zinc,
Metal soaps such as cerium, calcium, nickel and the like or metal-containing azo dyes, pyrimidine compounds, alkyl salicylic acid metal chelates and the like can be suitably used to such an extent that the polymerization reaction is not hindered. Preferably, it is used in an amount of 2 to 40 parts by weight, particularly 2 to 15 parts by weight.

Polymerization According to the present invention, the monomer is first dissolved in a water-miscible organic solvent or a mixture thereof with water. The amount of the monomer dissolved varies considerably depending on the type and composition of the solvent and the monomer, but is generally 0.01 to 50% by weight, particularly 1 to 20% by weight.
Is suitable.

To this solution are added seed polymer particles, a dispersion stabilizer, a toner property imparting agent, and a polymerization initiator. The amount of the seed polymer particles 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 monomer species polymer particles and the system, generally 1: cause it is desirable to be present in 1 to 1:10 ⁹ especially 1:10 to 1:10 ⁶ weight ratio, whereas, seed weight in the dispersion The concentration of coalesced particles is generally from 0.01 to 50% by weight, in particular from 0.1 to 20% by weight.
It is good to use in the range of weight%. Also, the dispersion stabilizer is
It is preferably used in an amount of 0.1 to 30% by weight, especially 1 to 10% by weight, based on the seed polymer particles, while the polymerization initiator is used in an amount of 0.001 to 10% by weight, particularly 0.01 to 0.5% by weight per charged monomer.
It is better to use it.

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 precipitated and absorbed in the seed polymer particles by adding water to the polymerization system or further lowering the temperature. Generally, it is desirable that 50% by weight or more, particularly 90% by weight or more of the charged monomers be absorbed in the seed polymer particles. It is a remarkable feature of the present invention that this treatment is carried out within a very short time, and the absorption of a monomer such as a polymerization initiator and a colorant is simultaneously performed with the absorption of a monomer. Then, the monomers absorbed in the polymer particles 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 absorbed monomer is completed, and generally 0.1 to 30 hours is appropriate. The method of the present invention may be carried out in only one step, or may be carried out in a plurality of steps until the grains grow to a predetermined grain size. The resulting polymer generally has a grain size of 1 to 30 gm, especially 5 to 20 m, and is characterized by being highly monodisperse. The obtained polymer particles are separated by filtration and, if necessary, washed with water to obtain a dry toner product. If necessary, the toner particles are dusted with carbon black, hydrophobic silica, silicone oil, or the like to obtain a final toner.

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

(Example 1) Styrene 20 ml, ion-exchanged water 36 ml, ethanol 144 m
l, a solution of 284 g of azobisisobutyronitrile and 2 g of polyacrylic acid were placed in a three-neck separable flask equipped with a reflux condenser and reacted at 70 ° C. for 12 hours while stirring at 100 rpm under a nitrogen stream to complete the polymerization. . The polymer was monodispersed particles having a particle size of about 2 μm when observed with an optical microscope. 4 g of the polymer synthesized in this way is 600 g of ethanol and 30 g of styrene.
g, polyacrylic acid 1.5g, spiron black 1.5g, and
2.2'-azobis- (2.4-dimethylvaleronitrile) 1.
An emulsion was obtained by dispersing in 5 g of the solution. This is an emulsion.

Ethanol 100, carbon black 1.5 g and polyallyl alcohol 0.05 g were added and sufficiently dispersed using a ball mill. This is called a suspension.

500 g of ion-exchanged water was added dropwise at a rate of 5 g / min while vigorously stirring the resulting emulsion suspension mixture. When the emulsion was observed with an optical microscope, the polymer particles were swollen into black particles of 8 μm. Then, the emulsion was put into a 21-necked 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 reaction. After filtering the polymer, it was dried to obtain 30 g of a 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 diameter of 7.9 μm.

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

(Example 2) Styrene 14 ml, butyl acrylate 6 ml, ion-exchanged water 3
6 ml, ethanol 144 ml, azobisisobutyronitrile 28
2 mg and 2 g of polyacrylic acid were placed in a 300 ml three-neck separable flask equipped with a reflux condenser and reacted at 70 ° C. for 12 hours while stirring at 100 rpm under a nitrogen stream to complete the polymerization. Observation of the polymer with an optical microscope revealed that the polymer was monodispersed particles of about 2 μm. Styrene 33 containing 5 g of the polymer thus obtained, 600 g of ethanol, 600 g of ion-exchanged water, and 1.5 g of grafted carbon black grafted with styrene
g, 1 g of spiron black, 1.5 g of polyacrylic acid and 1.5 g of benzoyl peroxide to obtain an emulsion. The resulting emulsion was evacuated to 30 mm at 400 mmHg and 30% of the medium was evaporated. Although some evaporation of styrene was observed by this operation, as the methanol concentration in the emulsion decreased, the polymer particles swelled to about 12 μm, which was a true spherical black color. The obtained emulsion was put into a 21-necked 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 reaction. The polymer was filtered and dried to obtain 28 g of a toner.

Further measure the particle size distribution with a Coulter counter,
An image was formed by a copying machine.

As shown in Table 2, the particles were very monodisperse and had a particle size distribution. Also, a clear image was obtained as a copy image by the copying machine.

Example 3 A solution of 20 ml of methyl methacrylate, 36 ml of ion-exchanged water, 144 ml of isopropyl alcohol, 200 mg of 2.2'-azobisisobutyronitrile and 2 g of polyacrylic acid was placed in a 300 ml three-neck separable flask equipped with a reflux condenser. And polymerization was completed by the same operation as in Example 1. Observation of the polymer with an optical microscope revealed monodispersed polymer particles of about 1 μm.

4 g of the obtained polymer is isopropyl alcohol 600 m
l, 700 g of ion-exchanged water, 40 g of methyl methacrylate, 3 g of an oil-soluble dye (CI Solvent Blue 7), 1.5 g of polyvinylpyrrolidone, and 1.5 g of benzoyl peroxide to obtain an emulsion. Allow this emulsion to reach room temperature (approx.
(20 ° C) to -10 ° C at a rate of 2 ° C / min. −10
When this emulsion was observed with an optical microscope at a temperature of ° C., the particles were swollen to about 10 μm. 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 three-necked three-separable flask equipped with a reflux condenser and reacted at 70 ° C. for 9 hours while stirring under a nitrogen stream. The polymerization was completed. The polymer is filtered and dried to 90
g spherical blue toner was obtained.

A particle size distribution and a copied image were obtained from the obtained toner in the same manner as in Example 1. As shown in Table 3, the obtained toner had an extremely monodispersed particle size distribution, and the obtained copied image was a bright blue image. was gotten. Further, when an image was formed on the OHP transparency using this toner, a light-transmitting blue image was obtained.

(Example 4) Styrene 20 ml, ion-exchanged water 36 ml, ethanol 144 m
A solution of 284 mg of 1,2.2'-azobisisobutyronitrile and 2 g of polyacrylic acid was placed in a 300 ml three-neck separable flask equipped with a reflux condenser, and the polymerization was completed in the same manner as in Example 1. Observation of the polymer with an optical microscope revealed monodispersed polymer particles of about 1 μm.

35 g of ethanol, 60 g of ion-exchanged water, 30 g of methyl methacrylate, 3 g of an oil-soluble dye (CI Solvent Red 27), 1.5 g of lauryltrimethylammonium chloride, 2.2 g- (2.4-azobisisobutyro) The mixture was dispersed in a solution consisting of 1 g of nitrile) to obtain an emulsion.

While vigorously stirring the obtained emulsion, 5 g of sodium chloride was added little by little, and then 50 g of ion-converted water was added.
Was added dropwise at a rate of 5 g / min, and 150 g of ion-converted water was further added. Observation of this emulsion with an optical microscope revealed that the particles had swelled to a true spherical shape to about 10 μm and had a red color.

Put the above emulsion in a separable flask, 80
A polymerization reaction was performed at 9 ° C. for 9 hours to obtain a polymer. The toner particles obtained by filtration and drying are true spherical red particles, and the particle size distribution is extremely monodispersed as shown in Table-4. The copied image obtained by the toner has a clear red image. Was.

(Example 5) A polystyrene resin was pulverized and classified.
%, Resin particles having a particle size distribution of 83% for 1.45 to 1.85 μm and 12% for 1.85 μm or more and an average particle diameter of 1.67 μm were obtained. 600 g of ethanol, 30 g of styrene, 1.5 g of carbon black previously surface-treated with dodecylamine in methanol, 1.5 g of polyvinyl alcohol, 1.0 g of spirone black and 2.2'-azobis- (2.4-dimethylvaleronitrile) with the resin particles 4 1.5 g was mixed and dispersed to obtain an emulsion.

The obtained emulsion is heated from room temperature (about 20 ° C) to 2 ° C.
Cooled to -10 ° C at a rate of / min. Observation of this emulsion with an optical microscope at −10 ° C. revealed that the particles had a true spherical swelling of about 10.8 μm. 500 g of ion-exchanged water at 0 ° C. was added once to the emulsion at −10 ° C., put into a 21 separable flask equipped with a reflux condenser, and polymerized at 70 ° C. for 8 hours while stirring at 100 rpm under a nitrogen stream to complete the polymerization. Was. The toner particles obtained by filtering and drying the polymer were true spherical toner particles, and the particle size distribution was extremely monodispersed as shown in Table-5. A clear image was obtained from the copy image obtained with this toner.

[Effects of the Invention] According to the present invention, the solubility of a monomer in a water-miscible organic solvent which is a solvent for a monomer and a dispersion medium for seed polymer particles is reduced, By absorbing the amount of the monomer into the seed polymer particles corresponding to the above, the seed polymer particles can be efficiently swollen by the monomer within a very short time, and the seed polymer By polymerizing the monomer absorbed by the particles with high selectivity, a spherical toner having a desired toner particle size and an extremely 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.

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-61-215604 (JP, A) JP-A-59-61844 (JP, A) JP-A-59-58439 (JP, A) JP-A-63-1984 297402 (JP, A)

Claims (1)

(57) [Claims] A water-miscible organic solvent or a mixture of water and a water-miscible organic solvent which dissolves a monomer but does not dissolve a polymer thereof, Seed polymer particles showing swelling, dispersion stabilizer, toner property imparting agent and oil-soluble polymerization initiator are dissolved or dispersed in the solvent,
By increasing the concentration of water in the dispersion, reducing the concentration of the water-miscible organic solvent, or by employing at least one means of reducing the monomer solubility of changing the temperature of the dispersion, The method according to claim 1, wherein the monomer and the polymerization initiator are absorbed in the seed polymer particles, and the monomer absorbed in the seed polymer particles is selectively polymerized to increase the polymer particle diameter. A method for producing a toner for developing a charge image.