JPH01309070A - Electrostatic charge image developing toner and production of same - Google Patents

Abstract

PURPOSE:To form an image superior in gradation and resolution by dispersing a specified polymerizable composition into an aqueous medium, forming proper- sized drops, and subjecting them to suspension polymerization to obtain porous toner particles having a cross-linked structure and proper heat meltability and proper strength. CONSTITUTION:The polymer particles in a toner size is obtained by mixing a polymerizable monomer containing a monomer capable of cross-linking in an amount of 0.01-1wt.% of the total monomer and a colorant as well as additives for providing toner characteristics in a hydrophobic organic solvent in a solvent to monomer weight ratio of 9:1 to 8:2, and subjecting it to suspension polymerization. The toner particles having pores in the inside of each particle made of a resin having a proper cross-linked structure are obtained by drying the obtained polymerized particles in a reduced pressure and evaporating the organic solvent contained in the insides of the particles, thus permitting the obtained toner to prevent crushing at the time of fixing and trailing of images and accordingly, to obtain a sharp image high in resolution and superior in gradation.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a toner for developing an electrostatic latent image formed in electrophotography, electrostatic printing, electrostatic recording, etc., and a method for producing the same. More specifically, the present invention relates to a toner that does not cause image collapse during fixing and provides a high-resolution image, and a method for manufacturing the same.

(Prior art) In the electrophotographic method, an electrostatic latent image formed on the photoreceptor by charging and exposure to light is developed with the toner, and the developed toner image is transferred to a support such as transfer paper. The toner image is fixed on the support by a pressure roller and/or the electrostatic latent image is visualized. After the toner image is transferred to the support, the remaining toner on the photoreceptor is scraped off by a cleaning member to prepare for the next image formation.

The above-mentioned toners are 1 to 3 in which a colorant, a charge control agent, and, if necessary, a toner characteristic imparting agent such as magnetic particles are dispersed in a fixing resin.
These toners are resin particles with a particle size of 0 μm, and these toners are used for two-component development in which a developer is formed by mixing with a carrier, and for developing electrostatic latent images as a one-component developer using only toner.

In recent years, in image forming apparatuses such as copying machines that use the above-mentioned development method, copying machines capable of faster copying have been developed and used in order to obtain a large number of copies of various types. . On the other hand, personal use copying machines have come to be used in general households, and a wide variety of originals such as photographs and various pamphlets are being used to be copied. At the same time, in order to obtain clearer images, toners have been improved not only in their excellent development properties but also in their fixing properties.

In the development process, in order to faithfully reproduce the original image,
The toner exhibits excellent fluidity within the developer, making the amount of each toner particle band uniform, and preventing the migration of uncharged particles to areas other than the latent image and the accumulation of toner in the developer due to excessively charged particles. It is necessary to prevent capri and image density from decreasing. To this end, a toner with a uniform particle size distribution and excellent fluidity is desired.

In the fixing process, it is required to quickly fix the image onto the transfer material without causing offset. Toner fixing methods include pressure bonding, which fixes using only pressure, and heat and pressure bonding, which fixes by applying pressure and heat. Heat and pressure bonding allows for high-speed fixing, reduces the occurrence of fixing defects, and is superior in fixing efficiency. Many methods are used.

(Problems to be Solved by the Invention) The above-mentioned heat and pressure bonding method is a method in which the toner on the transfer material is crushed by pressure using pressure and a heating roller, and at the same time, the toner is melted and fused onto the transfer material. be.

However, even if the fixing properties to the transfer material are good in the fixing process, when the toner image that has been developed with high reproducibility and faithful to the original image is transferred and fixed onto the transfer material in the developing process, there is a risk of immersion due to pressure. The flow of the toner caused by the toner melting causes the image to spread, and in particular, images with half-tones or fine lines such as photographs lose resolution, resulting in images lacking clarity.

Therefore, the present invention has been made to solve the problems seen in the conventional toner mentioned above, and has excellent gradation properties.
An object of the present invention is to provide a toner capable of forming images with high resolution and a method for manufacturing the same.

Furthermore, another object of the present invention is to provide a toner having good mechanical strength and good cleaning properties, and a method for producing the same.

(Means for Solving the Problems) According to the present invention, in a toner for developing an electrostatic image in which a colorant is dispersed in a binder resin, the binder resin is extracted with a Soxhlet extractor using toluene as a solvent. The resin ratio is 2
Consisting of a polymer having a crosslinked structure of 5 to 70%,
The particles have pores and a static bulk density of 0. 1 to 0. 32
g/cm', the conventional problems are solved and the objects of the present invention are achieved.

Further, according to the present invention, the weight ratio of the polymerizable monomer containing 0.01 to 1% of the crosslinking monomer, the toner characteristic imparting agent such as a colorant, and the polymerizable monomer is 9:1 to 1%. A polymerizable composition consisting of a 2:8 mixture of hydrophobic organic solvents is poured into an aqueous dispersion medium, and then suspended and granulated to perform a polymerization reaction. Toner particles having a crosslinked structure having both heat meltability and strength are obtained, and the object of the present invention is achieved.

・ (Function) As a result of intensive study by the present inventors, particles are composed of chain polymers that exhibit a specific degree of crosslinking and spread three-dimensionally,
By having an appropriate amount of pores throughout the particles, it is possible to prevent the image from spreading during the fixing process, thereby preventing a decrease in resolution, and toner with good durability, fluidity, and cleanability. I discovered that.

In other words, by imparting a certain degree of crosslinking to the above-mentioned toner, it can withstand mechanical impact caused by stirring operations in a developing device, and maintains hardness that allows the toner to maintain its fluidity. Even if the above-mentioned toner is crushed by pressure during fixing, since there are holes in the particles and the resin component per particle is coarse, it will not spread in the lateral direction, and even when melted by heating. Since it is made of a cross-linked polymer, the molten toner components have a strong tendency to agglomerate, and since there is little resin component per particle, it is possible to prevent image bleeding due to melting, resulting in a reduction in resolution due to image spreading. can be effectively prevented.

A method for obtaining a toner that is made of a binder resin whose constitutional unit is a polymer chain having a crosslinked structure and has pores inside the particles and near the surface is 0.01 to 1% by weight based on the total monomers.
A polymerizable monomer containing a crosslinkable monomer, a toner characteristic imparting agent including a colorant, and a hydrophobic organic solvent in a weight ratio of 9:1 to 8:2 to the polymerizable monomer. Suspension polymerization is carried out using a polymerizable composition that is a mixture of the above to obtain toner-sized polymer particles, and the obtained polymer particles are dried under reduced pressure to remove the organic solvent contained in the particles. The toner of the present invention can be efficiently produced by continuous evaporation.

As the polymerizable monomer used in the present invention, radically polymerizable monomers are used, and suitable examples of these monomers include vinyl aromatic monomers, acrylic monomers, and vinyl esters. These include monomers, vinyl ether monomers, diolefin monomers, monoolefin monomers, and the like.

The vinyl aromatic monomer has the following formula: In the formula, R1 is a hydrogen atom, a lower alkyl group, or a halogen atom, and R2 is a hydrogen atom, a lower alkyl group, a halogen atom, an alkoxy group, a nitro group, or a vinyl group. , vinyl aromatic hydrocarbons such as styrene, α-methylstyrene, vinyltoluene, α-chlorostyrene, 0-
Examples include 1m-1P-chlorostyrene, P-ethylstyrene, and divinylbenzene alone or in combination of two or more, and other monomers mentioned above include the following.

An acrylic monomer, such as methyl acrylate, of the formula, where R1 is a hydrogen atom or a lower alkyl group, and R4 is a hydrogen atom, a hydrocarbon group having up to 12 carbon atoms, a hydroxyalkyl group, or a vinyl ester group. , ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, phenyl acrylate, methyl methacrylate, hexyl methacrylate,
2-ethylhexyl methacrylate, ethyl β-hydroxyacrylate, propyl T-hydroxyacrylate,
σ-hydroxybutyl acrylate, β-hydroxyethyl methacrylate, ethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, etc.

Nohinyl esters, such as vinyl formate, vinyl acetate, vinyl propionate, etc., wherein R1 is a hydrogen atom or a lower alkyl group.

Vinyl ethers of the formula, wherein R6 is a monovalent hydrocarbon group having up to 12 carbon atoms, such as vinyl-n-butyl ether, vinyl phenyl ether, vinyl cyclohexacyl ether, etc.

Diolefins, especially butadiene, isoprene, and chloroprenes of the formula, wherein each of R1, R1, and R9 is a hydrogen atom, a lower alkyl group, or a halogen atom.

Monoolefins of the formula, in which R1° and Ro are each a hydrogen atom or a lower alkyl group, particularly ethylene, propylene, isobutylene, phthene-1, pentene-1,4-methylpentene-1, etc.

Among the above monomers, monomers suitable for controlling molecular weight distribution, etc. are styrene monomers, acrylic monomers, and the like.

Examples of crosslinkable monomers include the following, although some of them overlap with the above-mentioned polymerizable monomers. Aromatic divinyl compounds such as divinylbenzene and divinylnaphthalene, carboxylic acid esters having two double bonds such as ethylene glycol diacrylate, ethylene glycol dimethacrylate, and 1,3-butanediol dimethacrylate, divinylaniline, divinyl ether, Divinyl compounds such as divinyl sulfide and divinyl sulfone and compounds having three or more vinyl groups are used alone or in combination of two or more. The ratio of these crosslinking monomers to the total amount of polymerizable monomers is 0.
01 to 1% by weight, especially 0.1 to 0.5% by weight are preferably used.

If the crosslinkable monomer exceeds 1% by weight outside the above range, the softening point of the toner will rise extremely and the fixing temperature will rise significantly, making it unsuitable for practical use.
If the amount is less than % by weight, a crosslinked structure cannot be obtained, so that filtration cannot be performed during filtration after polymerization, and agglomeration may occur.

Hydrophobic organic solvents to be mixed with the above polymerizable monomers include benzene, toluene, xylene, ethylbenzene, diethylbenzene, tetrahydrofuran, cyclohexane,
Known hydrophobic organic solvents such as dichloromethane, dichloroethane, chloroform, carbon tetrachloride, trichloroethane, tetrachloroethane, chlorobenzene, fluorobenzene, anisole, methoxytoluene, and dibutyl ether are used.

Although these organic solvents vary depending on the polymerizable monomers used, a weight ratio of 9:1 to 2:8, particularly 7:3 to 3, is preferably used with respect to the total amount of polymerizable monomers.

If the amount of organic solvent is less than the above range, pores cannot be created in the particles, and if it is more than the above range, the resulting toner will have poor mechanical strength and will crumble in the developing device, resulting in fine powder. Generates toner.

Further, examples of the toner characteristic imparting agent added to the polymerizable composition include colorants and the following additives.

As the coloring agent, various pigments and dyes (hereinafter simply referred to as coloring pigments) described below can be used by incorporating them into the monomer.

Black pigments carbon black, acetylene black, lamp black, aniline black.

Yellow pigments yellow lead, zinc yellow, cadmium yellow, yellow iron oxide, mineral first yellow, nickel titanium yellow, nabels yellow, naphthol yellow S1 Hansa yellow 10G1 benzidine yellow G, quinoline yellow lake, permanent yellow NGG, tartrazine lake.

Orange pigment red yellow lead, molybdenum orange, permanent orange GTR, pyrazolone orange, palkan orange, indanthrene brilliant orange RK, benzidine orange G1 indanthrene brilliant orange GK.

Red pigments red pigment Red Garla, Cadmium Red, Red Lead, Mercury Cadmium Sulfide, Permanent Orange 4R, Lysol Red, Pyrazolone Red, Watching Red Calcium Salt, Lake Red D1 Brilliant Carmine 6B, Eosin Lake, Rhodamine Lake B, Alizarin Lake , Brilliant Carmine 3B.

Purple pigment Manganese Purple, First Violet B1 Methyl Violet Lake.

Blue pigments navy blue, cobalt blue, alkali blue lake, Victoria blue lake, phthalocyanine blue, metal-free phthalocyanine blue, phthalocyanine blue partially chlorinated product, first sky blue, indanthremble-BC
.

Green pigment chrome green, chromium oxide, pigment green B1
Malachite Green Lake, Fanal Yellow Green G.

white pigment Zinc white, titanium oxide, antimony white, zinc sulfide.

Extender pigments Palite powder, barium carbonate, clay, silica, white carbon, talc, aluminum white, and to.

As the magnetic material pigment, for example, triiron tetroxide (Fes04
), iron sesquioxide (r-Fezes), zinc iron oxide (ZnFe*Oa), iron yttrium oxide (Y3Fe
sO+ z), cadmium oxide (GdJe50tz)
, iron oxide w4 (CuFe204), iron oxide complex (PbFe
tzO+*), neodymium iron oxide (NdFeOs),
Barium iron oxide (BaFelzO+w), magnesium iron oxide (MgFe, 04), iron manganese oxide (Mn
Fet04), lanthanum iron oxide (LaFeOz), iron powder (Fe), cobalt powder (Co), nickel powder (Ni)
However, in the present invention, any of these known fine powders of magnetic materials can be used.

The colorant is preferably used in an amount of 1 to 30 parts by weight, particularly 2 to 20 parts by weight, per 100 parts by weight of the polymerizable monomer.

Further, wax may be added and mixed into the monomer in order to improve fixing properties and prevent offset.

Examples of the wax component include various waxes such as low molecular weight polypropylene, low molecular weight polyethylene, and paraffin wax. The average molecular weight of these waxes is preferably 2,000 to 15,000, particularly 3,000 to 10,000.

The wax is generally 1 to 5 parts by weight, particularly 1 to 5 parts by weight, per 100 parts by weight of the polymerizable monomer. It is preferred to use 5 to 3 parts by weight.

Further, in order to control the triboelectric charge of the toner, a charge control agent may be added and mixed into the monomer. For example, nigrosine, monoazo dye, zinc hexadecyl succinate, alkyl ester of naphthoic acid or alkyl Strongly polar substances called charge control agents are used in this field, such as amides, nitrofumic acid, N,N''-tetramethyldiaminebenzophenone, N,N'-tetramethylbenzidine, triazine, and salicylic acid metal complexes.

These charge control agents are 0 per 100 parts by weight of the polymerizable monomer.
．． 0.1 to 10 parts by weight, especially 0.1 to 5 parts by weight.

As a polymerization initiator for polymerizing the polymerizable composition consisting of the above polymerizable monomer, a hydrophobic organic solvent, and other additives, azo compounds such as azobisisobutyronitrile, cumene hydroperoxide, t-butyl Oil-soluble initiators such as peroxides such as hydroperoxide, dicumyl peroxide, di-t-butyl peroxide, benzoyl peroxide, lauroyl peroxide, etc. are used. In addition, combinations with ionizing radiation such as T-rays and accelerated electron beams and various sensitizers are also used. Although it varies depending on the monomer and initiator used, the oil-soluble initiator mentioned above is used in an amount of 0.05 to 15 parts by weight, particularly 0.1 to 1 part by weight, per 100 parts by weight of the polymerizable monomer.
0 parts by weight are preferably used.

A polymerizable composition consisting of the above polymerizable monomer, a hydrophobic organic solvent, and other additives has a 0.0% polymerizable composition. A dispersion stabilizer containing 1 to 10% of O is added to water in which it is dissolved or dispersed, suspended and granulated to form oil droplets, and a polymerization reaction is performed to obtain particles with a particle size of 5 to 30 μm.
In particular, it is produced as spherical polymer particles of 8 to 12 μm.

The obtained polymer particles have a weight average molecular weight of 3.
0000 to 200000, especially 50000 to 150
000 is preferred; if it exceeds the above range, the fixable temperature range (lower limit fixing temperature) will be high; if it is below the above range, the strength of the toner will be weak and fine powder will be generated in the developing device, causing toner scattering.

The crosslinked structure of the polymer particles is characterized by a resin extraction rate in the range of 25 to 70% by weight, particularly 3% by weight, using a Soxhlet extractor using toluene as a solvent.
It is necessary that the content is from 0 to 55% by weight, and within the above range, the cohesiveness and hardness of the toner when melting will be good, and spreading of the toner image during fixing can be prevented.
This stabilizes the fluidity of the toner.

If the extraction rate exceeds the above range, the polymer particles will aggregate during filtration after polymerization, making it impossible to filtrate. Furthermore, if it is less than the above range, it will have a strong crosslinked structure, which will significantly increase the fixing temperature, making it unsuitable for practical use.

The degree of pores in the polymer particles varies depending on the monomer used, but the static bulk density of the polymer particles produced at -&1 is 0.
．． 1 to 0. 32g/cm', especially 0°2 to 0.
It is preferable that the particle size be 28 g/c+++3; if it is larger than the above range, the porosity per particle becomes too large, resulting in poor durability and causing the generation of fine powder toner in the developing device.

In addition, if it is smaller than the above range, the toner collapse due to the pressure during fixing will spread and no improvement in resolution can be expected.The above bulk density is measured using a tap densityr that measures toner particles in a 100 cc cylinder. This is the measured value.

Since the toner of the present invention obtained by suspension polymerization has a spherical shape and an uneven surface, it has particularly good fluidity and cleanability.

Furthermore, if necessary, an abrasive substance may be added to the toner of the present invention in order to further clean the photoreceptor. For example, talc, kaolin, barium sulfate, etc. , surface-treated aluminum silicate, titanium dioxide, calcium carbonate, antimony trioxide, barium titanate, calcium titanate, strontium titanate, magnesium oxide, calcium silicate, zinc oxide, etc. are preferred, especially colloidal silica, surface treated Treated hydrophobic silica is preferred. The above polishing, material,
In particular, the addition of hydrophobic silica improves the fluidity of toners and developers. The abrasive material has an average particle size of 1 to 100 μm.
In particular, those having a diameter of 10 to 30 μm are preferable. These abrasive substances are preferably added in an amount of 0.01 to 1 part by weight per 100 parts by weight of the toner. .

If it is less than 1 part by weight, the fluidity of the toner will be poor;
If the amount exceeds parts by weight, the photoreceptor tends to be easily damaged.

In addition, toner may be sprinkled with carbon black, aluminum oxide, etc. for the purpose of adjusting the electrical resistance of the toner.
These electrical resistance adjusters are 0.00% per 100 parts by weight of toner.
It is preferable to add 0.01 to 1 part by weight.

A more detailed explanation will be given below using experimental examples. In the experimental examples, the resolution was evaluated by obtaining a copy image using a resolution test chart. In addition, a copy image was obtained from a photographic original, and the gradation was evaluated.

(Experimental Example 1) Styrene 35 parts by weight n-butyl acrylate 15 parts by weight Grafted carbon black 2.5 parts by weight (MA-100, manufactured by Mitsubishi Kasei) Divinylbenzene 0.25 parts by weight 1 part Toluene
2.75 parts by weight of the above mixture
% PVA aqueous solution and mixed with 400 parts by weight of PVA aqueous solution and stirred at 6000 rpm using TK Homooxer (Tokushu Kikaku type).
The mixture was stirred for 10 minutes to obtain a suspension dispersion having an average particle size of 13 μm.

This suspension dispersion was polymerized at 60° C. for 8 hours while stirring at 60 to 80 rpm under a nitrogen atmosphere.

Next, the suspension was filtered to separate the reaction product and the solution. Then, the obtained reaction product was dehydrated, washed, and further dried under reduced pressure to evaporate water on the surface of the resin particles and toluene contained therein. As a result, a porous toner with a particle size of 12 μm was obtained. This toner had an extraction rate of 40% by weight using a Soxhlet extractor using toluene as a solvent. Also,
The static bulk density was 0.18 g/cm'. Using this toner, an electrophotographic copying machine DC-2055 (manufactured by Sanda Kogyo Co., Ltd.)
When forming an image, the resolution was 7 lines/m.
A clear image of m was formed, and the image copied from the photographic original was an image with gradation that was faithfully reproduced from the original. In addition, during printing of 20,000 sheets, no fine powder was generated even during agitation in the developing device, and durability, fluidity, and cleanability were also good. In addition, when similar image evaluation was performed on a toner obtained by polymerizing without toluene from the above recipe, the resolution was 4 lines/mm, and the image reproduced from a photographic original had poor gradation, resulting in a dark image. became.

(Experimental Example 2) In Experimental Example 1, the amount of divinylbenzene was changed to 0°35.0
．． 55.0.70.0.85.0.90, and the other toners are generated in the same manner, toners ■, ■, ■,
■、■ Closed.

When these toners were used to form images in the same manner as in Experimental Example 1 and their fixing properties were examined, it was found that toners (2) and (2) containing more than 0.80 parts by weight of divinylbenzene had extremely poor fixing properties and were practically unusable. Met. This shows that the amount of crosslinking monomer added is up to about 1% based on the total monomers. In addition, the extraction rate and static bulk density of the other toners (1), (2), and (2) were measured using a Soxhlet extractor.

Then, image evaluation was performed in the same manner as in Experimental Example 1.

Images created with any toner have a resolution of 7 lines or more, and
It also had excellent gradation. In addition, the fluidity and cleaning properties during printing were also good.

(Experimental Example 3) In Experimental Example 1, the amount of divinylbenzene was set to 0゜l010.
．． 0.051.0.005.0.0025, and other toners were produced in the same manner.However, in the case of toner containing 0.0025 parts by weight of divinylbenzene, particles agglomerated during filtration, resulting in toner I couldn't get it.

From this, it was found that a toner could not be obtained if the amount of crosslinkable monomer added was less than 0.01% based on the total monomers. The obtained toners were designated as toners i, ii, and iii in descending order of the amount of crosslinkable monomer, and the same evaluation as in Experimental Example 1 was performed by measuring the extraction rate using a Soxhlet extractor and the static bulk density.

Images created with any toner have a resolution of 7 lines or more, and
It also had excellent gradation. Furthermore, the fluidity and cleaning properties of the toner seemed to be good.

(Experimental Example 4) In Example 1, the amount of divinylbenzene was set to 0.005 parts by weight, and the amount of toluene was varied from 50 parts by weight to 100.0 parts by weight.
A toner was prepared in the same manner except that the amount was increased to 150, 200, and 250 parts by weight.

When images were formed and evaluated using these toners in the same manner as in Example 1, the toner prepared with a toluene amount of 250 parts by weight had a static bulk density of 0.08 g/cm'', and the toner could be easily aged in a short period of time. The toners were crushed and produced fine powder, making them unusable.The extraction rate and static bulk density using a Soxhlet extractor were measured for other toners as toners a, b, c, and d, starting from the one with the least amount of toluene. , the same image evaluation as in Experimental Example 1 was performed.

Copy images were obtained using the above toner in the same manner as in Experimental Example 1, and each item was evaluated.

Both toners have mechanical strength that can withstand stirring operations in the developing device, and the resulting images have a resolution of 7 lines/m.
m or more, the resolution was high, and the copied image from the photographic original had high gradation that was faithful to the original. Furthermore, the fluidity and cleaning properties were also good.

(Experimental Example 5) Toners were prepared in the same manner as in Experimental Example 1, except that the amount of divinylbenzene was 0.75 parts by weight, and the amount of toluene was 45, 30, 15, and 10.5 parts by weight. The toners are referred to as toners A, B, C, and D, respectively. Since these toners were satisfactory in fixability and durability, the extraction rate and static bulk density of each toner were measured, and Experimental Example 1
Copy images were obtained in the same manner as above, and each item was evaluated.

(Hereinafter referred to as margins) Toners A, B, and C all had a resolution of 7 lines or more, but toner D had a resolution of 4 lines, and the reproduced image from the photographic original also had a large difference in shading (in the middle tone part). The image was unclear.Furthermore, the fluidity and cleaning properties of the toner were both good.

From the above experimental examples, the toner of the present invention can prevent smearing due to pressure during fixing and image spreading due to flow of molten toner, and can form clear images with high resolution and excellent gradation. Furthermore, it can be seen that the spherical toner having irregularities on the surface has good cleaning properties.

(Effects of the Invention) According to the present invention, the resin component is made of a resin component having an appropriate crosslinked structure,
A toner with pores inside the particles is obtained, and the copied image layer obtained with this toner does not collapse during fixing or cause image bleeding, resulting in a clear image with high resolution and excellent gradation. Become.

Further, due to the appropriate hardness and surface roughness, a toner with excellent fluidity and cleanability can be obtained.

Claims (3)

[Claims] (1) In a toner for electrostatic image development in which a colorant is dispersed in a binder resin, the ratio of the binder resin to the resin extracted by a Soxhlet extractor using toluene as a solvent is 25 to 70.
%, has pores within the particles, and has a static bulk density of 0.1 to 0.32 g/cm^3
A toner for developing electrostatic images. (2) The toner for developing an electrostatic image according to claim 1, wherein the particles are spherical in shape and have irregularities on the surface. (3) A polymerizable monomer containing 0.01 to 1% of a crosslinking monomer, a toner characteristic imparting agent such as a colorant, and a hydrophobic compound having a weight ratio of 9:1 to 2:8 to the polymerizable monomer. A polymerizable composition consisting of a mixture of aqueous organic solvents is suspended and granulated in an aqueous dispersion medium, a polymerization reaction is carried out, and the filtered and purified polymer particles are dried under reduced pressure. A method for producing a toner for developing an electrostatic image.