JP2595256B2 - Toner for developing electrostatic image and method for producing the same - Google Patents

Description

Description: 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 suspension polymerization method utilizing a dispersing action of a polymer emulsion. And a method for producing the above toner. The present invention also relates to a toner having a novel composite structure.

(Prior Art) In the field of electrophotography, toner is used for the purpose of visualizing an electrostatic image. The toner particles are composed of a composition in which a colorant and, if necessary, other compounding agents such as a charge control agent are mixed in a resin medium to have a certain particle size range, for example, a particle size range of 5 to 30 μm. As the resin medium, a resin having a desired electric detecting property and binding property, for example, a styrene-based resin is used, and as a coloring agent, carbon black or another organic or inorganic coloring pigment is used. Is done.

The most typical method for producing an electrophotographic toner comprises the steps of melt-kneading the above-described resin medium and colorant, cooling and pulverizing the kneaded composition, classifying the pulverized product, and adjusting the size to a certain particle size range. However, the yield of the toner obtained by this pulverization and 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, since the shape of the obtained particles is irregular, there is also a disadvantage that the fluidity of the toner is generally low and blocking is easily generated.

Conventionally, many proposals have been made for directly manufacturing a toner in a polymerization process of a toner resin. A typical example thereof is to dissolve a polymerization initiator soluble in the water-insoluble monomer and further add an additive such as a coloring agent, and then add an appropriate dispersant such as a water-soluble polymer to the composition. , An inorganic powder, a surfactant, and the like, are suspended in an aqueous solution by high-speed shearing stirring, and polymerized to produce colored polymer particles.

(Problems to be Solved by the Invention) However, in this suspension polymerization method, some of the monomer composition particles suspended in water unite in the polymerization process, and the particle size distribution is It is very broad and it is difficult to obtain a single particle size.

Further, a water-soluble polymer used as a dispersant, an inorganic dispersant, and a surfactant are adhered to the toner obtained by the suspension polymerization method. And electrophotographic properties are impaired, for example, causing a decrease in chargeability, fixability, and fluidity.

For this reason, in a suspension polymerization method toner using an inorganic dispersant, the inorganic dispersant present on the surface of the particles is separated and removed by an alkali treatment, an acid treatment, or the like. In addition, the residual inorganic dispersion is a hindrance to the electrophotographic characteristics described above.

Accordingly, it is an object of the present invention to provide a method for synthesizing a toner having excellent electrophotographic properties by a suspension polymerization method by solving the above-mentioned disadvantages of a conventional toner production method by a suspension polymerization method.

Another object of the present invention is to use a dispersant different from the conventional dispersant, and to have a uniform particle diameter, excellent charging properties, fixability, and fluidity without the need to remove the dispersant after polymerization. An object of the present invention is to provide a method for producing an electrophotographic toner.

Still another object of the present invention is to provide a toner having a novel electric and chemical dual structure and having an excellent combination of the above electrophotographic characteristics.

[Means for Solving the Problem] According to the present invention, a monomer composition containing a monomer component capable of being charged to one polarity in water and a color pigment is used, and a substantially emulsifier is used as a dispersant. Using a self-emulsifying polymer emulsion comprising a crosslinked polymer that does not contain and can be charged to the other polarity in water, and disperses the monomer composition in the polymer emulsion that is charged to the opposite polarity in water. And subjecting the mixture to suspension polymerization in the presence of a polymerization initiator.

According to the present invention, the average particle size is 1 to 30 as a whole.
μm, the spherical particles having one charge polarity and a thermoplastic polymer core having a fixing property, and an average having a charge polarity different from that of the core bonded to the surface of the core. And a coating of crosslinked polymer particles having a particle size of 0.01 to 1 μm.

(Operation) The present invention uses a polymer emulsion as a dispersant for suspension polymerization of a monomer composition, and combines a monomer composition and a polymer emulsion such that their charging polarities are opposite to each other. It is characterized by the following.

Generally, the size of the suspended particles of the oily substance varies depending on the suspending means, but is generally 1 μm.
The dispersed particle size of the polymer in the polymer emulsion is on the order of 0.01 to 1 μm.

When the polymer emulsion and the monomer composition are selected so as to have the above-mentioned charging polarity, and the monomer composition is dispersed in the polymer emulsion, a dispersion state shown in FIG. 1 is formed. That is, an aqueous dispersion having a structure in which the polymer emulsion particles 3 adhere to the surface of the dispersed oil droplets 2 of the monomer composition dispersed in the aqueous phase 1 is obtained. In the case of charged monomer suspension particles, the charged polymer emulsion particles are electrostatically adsorbed. In the case of charged monomer suspension particles, the charged polymer emulsion is electrostatically adsorbed and the polymer emulsion particles are adsorbed. Since the particles are firmly electrostatically bonded to the monomer droplets, there is no desorption of the particles, and the coalescence of the monomer droplets hardly occurs due to the electrostatic repulsion of the emulsion particles. As the polymerization of the monomer droplets proceeds with this dispersed structure, the toner having the electric double layer structure shown in FIG. 1 is formed.

The toner obtained by this suspension polymerization method has a remarkably small coalescence of monomer droplets in the polymerization step, and has a sharp particle size distribution, and is coated with a polymer having a fixed charging polarity. There is an advantage that the characteristics are excellent. In addition, since the dispersant present on the surface is essentially a water-insoluble polymer, it is not sensitive to humidity and has a low tendency to decrease in chargeability and fluidity even under high humidity conditions. Is formed from a thermoplastic polymer having a fixing property, and thus has an advantage that the fixing property is good.

In the present invention, since the particle size distribution is sharp, the toner yield is high, there is no need to remove a dispersant harmful to electrophotographic characteristics, and the process is simple.

(Preferred Embodiment of the Invention) In the present invention, in order to impart a predetermined charge polarity to the polymer emulsion and the monomer composition, an ethylenically unsaturated monomer having an anionic group or a cationic property is contained, or the polymer chain is added to the polymer chain. A method of incorporation or a method of blending a non-polymerizable organic compound having an anionic group or cationic property is employed. A suitable example of this is as follows.

Anionic monomer Acrylic acid, methacrylic acid, maleic anhydride, fumaric acid, itaconic anhydride, crotranic acid, tetrahydrophthalic anhydride, styrenesulfonic acid, 2-acrylamide-
2-methylpropanesulfonic acid and the like.

Cationic monomers Dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, diethylaminopropyl (meth) acrylate, N-aminoethylaminopropyl (meth) acrylate, vinylpyridine, 2-vinylimidazole, 2-hydroxy-3- Acryloxypropyltrimethylammonium chloride and the like.

Anionic Organic Compounds Homopolymers or copolymers containing the above anionic monomers in the chain, metal complexes of monoazo dyes, metal complexes of oxycarboxylic acids such as salicylic acid and naphthoic acid, and the like.

Cationic organic compounds Homopolymers or copolymers containing the above-mentioned cationic monomers in the polymer chain, oil-soluble dyes such as nigrosine base (CI 5045), oil black (CI 26150), spirone black, and other primary and secondary Grade or tertiary mamines, quaternary ammonium salts and the like.

As other ethylenically unsaturated monomers contained in the monomer composition or incorporated in the particles of the polymer emulsion, the following can be used.

Suitable examples of such monomers include vinyl aromatic monomers, acrylic monomers, vinyl ester monomers, vinyl ether monomers, diolefin monomers, monoolefin monomers, and the like. It is.

As monovinyl aromatic unit weight, In the formula, 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 group,
A substituent such as an alkoxy group, a monovinyl aromatic hydrocarbon such as styrene, α-methylstyrene, vinyltoluene, α-chlorostyrene,
O-, m-, p-chlorostyrene, p-ethylstyrene and divinylbenzene may be used alone or in combination of two or more. Further examples of the other monomers described above include the following.

In the formula, R ₃ is a hydrogen atom or a lower alkyl group, R ₄ is a hydrogen atom, a hydrocarbon group having up to 12 oxygen atoms, a hydroxyalkyl group,
Or a vinyl ester group, such as an acrylic monomer such as methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, phenyl acrylate, methyl methacrylate, hexyl methacrylate, methacrylic acid -2-ethylhexyl, β-hydroxyethyl acrylate, γ-hydroxyacrylate, propyl δ-hydroxyacrylate, ethyl β-hydroxymethacrylate, ethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, and the like.

In the formula, R ₅ is a hydrogen atom or a lower alkyl group, such as vinyl esters such as vinyl acid, vinyl acetate, and vinyl propionate.

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

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.

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

Monomer composition The monomer composition used in the present invention comprises (i) an ethylenically unsaturated monomer having a polar group, (ii) an ethylenically unsaturated monomer having a polar group and another ethylenically unsaturated monomer. Or (iii) a combination of an ethylenically unsaturated monomer and a non-polymerizable polar group-containing organic compound. These components are selected and combined from the components described above such that the monomer composition has a composition that forms a stable dispersed oil phase.

From the viewpoint of the fixability and the charging characteristics of the toner, the main component of the monomer is at least one selected from the group consisting of styrene, acrylates and methacrylates, and a monomer containing a cationic group or an anionic group is used. Particularly suitable are those which are contained in a concentration of from 0.1 to 20% by weight, especially from 0.5 to 10% by weight, based on the total monomer composition.

The monomer composition may contain a coloring agent for coloring the toner, for example, a dye or a pigment.

 Suitable examples of the coloring pigment are as follows.

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

Yellow pigment Yellow lead, zinc yellow, cadmium yellow, yellow iron oxide, mineral fast yellow, nickel titanium yellow, navels yellow, naphthol yellow S, Hanser yellow G, Hanser yellow 10G, benzidine yellow G, bunzidine yellow GR, Quinoline Yellow Lake, Permanent Yellow NCG, Tartrazine Lake.

Orange pigment Red mouth lead, molybdenum orange, permanent orange GTR, pyrazolo orange, Vulcan orange, indanthrene brilliant orange RK, benzidine orange G, indanthrene brilliant orange GK.

Red pigment Bengala, cadmium red, lead red, cadmium mercury sulfide, vermanent red 4R, lysole red, pyrazolone red, watching red calcium salt, lake red D, brilliant calming 6B, eosin lake, rhodamine lake B, alizarin lake, brilliant Carmin 3B.

Purple pigment Manganese purple, fast violet B, methyl violet lake.

Blue pigment Navy blue, cobalt blue, alkali blue lake, Victoria blue lake, phthalocyanine blue, metal-free phthalocyanine blue, partially chlorinated phthalocyanine blue, fast sky blue, indanthrene blue B
C.

Green pigments chrome green, chromium oxide, pigment green B, malachite green lake, fanal yellow green G.

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

Extender barite powder, barium carbonate, clay, silica, white carbon, talc, alumina white.

As a magnetic material pigment, conventionally, for example, triiron tetroxide (Fe ₃ O
₄ ), iron sesquioxide (γ-Fe ₂ O ₃ ), zinc iron oxide (ZnFe
₂ O ₄ ), yttrium iron oxide (Y ₃ Fe ₅ O ₁₂ ), cadmium oxide (CdFe ₂ O ₄ ), gadolinium oxide (Gd ₃ Fe ₅ O ₁₂ ), copper iron oxide (CuFe ₂ O ₄ ), lead iron oxide (PbFe ₁₂ O ₁₉ ), neodymium iron oxide (NdFeO ₃ ), barium iron oxide (BaFe ₁₂ O ₁₉ ), magnesium iron oxide (MgFe ₂ O ₄ ), iron manganese oxide (MnFe ₂
O ₄ ), lanthanum iron oxide (LaFeO ₃ ), iron powder (Fe), cobalt powder (Co), nickel powder (Ni) and the like are known. In the present invention, fine powders of these known magnetic materials are also used. Any one can be used.

Polymer Emulsion The polymer emulsion in the present invention is charged in a polarity opposite to that of the monomer composition used. Emulsion polymerization is carried out using a polar polymerization initiator such as sulphate or the above-mentioned cationic emulsion. It is obtained by emulsion copolymerization of a monomer containing a group or anionic group and a monomer containing no polar group. The polymer emulsion is a self-emulsifying polymer emulsion containing substantially no emulsifier, and has an emulsion particle size of 0.01 to 1 μm, particularly 0.1 to 0.7 μm.
m.

In order to prevent the polymer emulsion particles from being dissolved by the monomer used, it is necessary to introduce a crosslinked structure into the high polymer emulsion, and for this purpose divinylbenzene, ethylene glycol di (meth) acrylate, diallyl phthalate Etc. are used.

 Suitable examples of the polymer emulsion are as follows.

Acrylic acid-modified polystyrene emulsion Maleic anhydride-modified polystyrene emulsion Acrylic acid-modified styrene-divinylbenzene copolymer emulsion Methacrylic acid-modified styrene-butadiene copolymer emulsion, Acrylic acid-styrene- (meth) acrylate copolymer emulsion, diethylamino Ethyl (meth) acrylate- (meth) acrylate copolymer emulsion.

The polymer emulsion contains the anionic group or the cationic group in an amount of 1 to 300 meq / 100 g,
It is desirable that the compound be contained in a concentration of 10 to 100 meq / 100 g. If desired, pigments and dyes can also be included in the polymer emulsion particles.

Suspension Polymerization According to the present invention, the above-described monomer composition is dispersed in a polymer emulsion and subjected to suspension polymerization in the presence of a polymerization initiator. In this case, it is desirable that the monomer composition and the polymer emulsion be used in a weight ratio of 99: 1 to 50:50, particularly 98: 2 to 70:30.

Examples of the polymerization initiator include azo compounds such as azobisisobutyronitrile, cumene hydroperoxide, t-butyl hydroperoxide, dicumyl peroxide, di-t
Those soluble in monomers such as peroxides such as -butyl peroxide, benzoyl peroxide and lauroyl peroxide are used. In addition, a combination of ion radiation such as γ-ray and accelerated electron beam or ultraviolet rays and various photosensitizers is also used.

The amount of the monomer charged is preferably such that the amount of the monomer in the reaction medium is 1 to 50% by weight, particularly 5 to 30% by weight, based on the reaction medium. The colorant may be blended in an amount contained in the toner resin, and is generally one per monomer charge.
A suitable range is from 30 to 30% by weight, especially from 3 to 20% by weight. When a magnetic material is used for the pigment, it is generally appropriate to use 5 to 300% by weight, particularly 10 to 250% by weight, based on the charged amount of the monomer.

The amount of the initiator such as an azo compound and a peroxide may be a so-called catalyst appropriate amount, and is generally 0.1 to 10 per monomer charged.
It is preferred to use it in an amount of% by weight. The polymerization temperature and time may be those known in the art, and are generally 1 to 50 at a temperature of 40 to 100 ° C.
Time polymerization is sufficient. In addition, the stirring of the reaction system may be gentle stirring such that a homogeneous reaction occurs as a whole, and the polymerization is performed by replacing the reaction system with an inert gas such as nitrogen in order to prevent the polymerization from being inhibited by oxygen. You may.

Since the polymerization product after the reaction is obtained in the form of granules having the above-mentioned particle size range, the formed particles are filtered, washed with water or another solvent if necessary, and dried to obtain colored particles for toner.

If necessary, carbon black hydrophobic silica or the like is dusted on the colored particles for toner to obtain the final toner.

Toner The toner according to the present invention has an average particle diameter of 1 to
It consists of spherical particles in the range of 30 μm, in particular in the range of 5 to 20 μm, the striking feature of which is that the electrically double layered structure described previously has been introduced into these spherical particles. That is, the spherical particles have a charge polarity (or) and a core of a thermoplastic polymer having heat fixing property, and an average particle diameter bonded to the surface of the core and having a charge polarity different from that of the core. It consists of polymer fine particles of 0.01 to 1 μm, especially 0.1 to 0.7 μm. The polymer fine particles may be observed as spherical fine particles firmly bonded to the surface of the core, or may be embedded in the surface of the core.

This toner shows a charging polarity unique to the polymer fine particles present on the surface. In the toner for developing an electrostatic image, which is particularly suitable for the present invention, the core is chargeable, and the polymer fine particles on the surface are chargeable.

In general, it is desirable that the core has a softening point of 80 to 180 ° C., particularly 100 to 150 ° C. in terms of fixing property. The polymer fine particles are firmly bonded to the core, do not separate, and have excellent charging characteristics and excellent blocking resistance or fluidity due to the presence of the polymer fine particles on the surface. This is because the polymer fine particles obtained by emulsion polymerization have a considerably higher molecular weight than that of the suspension polymerization method. Further, by introducing a crosslinked structure into the polymer fine particles, the blocking resistance is further improved.

(Effect of the Invention) In the present invention, since an electric double layer is formed between the monomer oil phase and the emulsion particles on the surface thereof, the toner obtained by this suspension polymerization method is a method of combining monomer droplets in the polymerization step. In particular, there is an advantage that the particle size distribution is extremely sharp, and since the particles are coated with a polymer having a constant charge polarity, the charge characteristics are excellent. Also, since the dispersant present on the surface is essentially a water-insoluble polymer, it is not sensitive to humidity, and even under high humidity conditions, there is little tendency for the chargeability and fluidity to decrease,
Since the core of the spherical particles is formed of a thermoplastic polymer having a fixing property, there is an advantage that the fixing property is good.

In the present invention, since the particle size distribution is sharp, the toner yield is high, there is no need to remove a dispersant harmful to electrophotographic characteristics, and the process is simple.

(Examples) Hereinafter, examples and comparative examples will be described in more detail, but the present invention is not limited thereto.

Synthesis of Polymer Emulsion (Synthesis Example 1) 95 parts by weight of styrene 3 parts by weight of sodium styrene sulfonate 2 parts by weight of divinylbenzene were added to 900 parts by weight of water in which 1 part by weight of potassium persulfate was dissolved, and nitrogen was added in a four-necked flask. The mixture was reacted at 70 ° C. for 5 hours while stirring at 100 rpm in an atmosphere to obtain a charged emulsion-free emulsion having an average particle diameter of 0.2 μm. This is called an emulsion.

Synthesis Example 2 90 parts by weight of styrene 8 parts by weight of methacrylic acid 2 parts by weight of ethylene glycol dimethacrylate were polymerized in the same manner as in Synthesis Example 1 to obtain a charged emulsion having an average particle diameter of 0.3 μm. This is called an emulsion.

(Synthesis Example 3) 95 parts by weight of styrene 3 parts by weight of dimethylaminoethyl methacrylate 2 parts by weight of divinylbenzene was converted to 2,2'-azobis (2-amidinopropane) hydrochloride 1
Was added to 900 parts by weight of dissolved water and polymerized in the same manner as in Synthesis Example 1 to obtain a charged emulsion having an average particle diameter of 0.2 μm. This is called an emulsion.

(Synthesis Example 4) In Synthesis Example 1, sodium dodecyl sulfate 1 was added to the polymerization system.
A charged emulsion having an average particle size of 0.2 μm was obtained in the same manner as in Synthesis Example 1 except that the parts by weight were added. This is called an emulsion.

(Synthesis Example 5) A charged powder crosslinked emulsion having an average particle diameter of 0.2 µm was obtained in the same manner as in Synthesis Example 1 except that divinylbenzene was omitted in Synthesis Example 1. This is called an emulsion.

Production of Toner by Suspension Polymerization (Example 1) Monomer Composition Styrene 80 parts by weight n-butyl methacrylate 19 parts by weight Diethylaminoethyl methacrylate 1 part by weight Polypropylene wax (Biscol 550P) 1.5 parts by weight [manufactured by Sanyo Chemical Industries] Carbon black ( Printex L) 5 parts by weight [Mitsubishi Kasei Kogyo] Add 3 parts by weight of azobisisobutyronitrile to 350 parts by weight of water, add 50 parts by weight of emulsion, and use TK homomixer [manufactured by Tokushu Kika Kogyo] at 6000 rpm ,Ten
The suspension was dispersed for minutes. This was charged in a four-necked flask under a nitrogen atmosphere. While stirring at 80 rpm, polymerization was completed at 70 ° C. for 3 hours and further at 80 ° C. for 1 hour. This was filtered and dried to obtain a toner.

(Example 2) 85 parts by weight Monomer composition Styrene 2-ethylhexyl acrylate 14 parts by weight Nn butoxyacrylamide 1 part by weight Carbon black (MA-100) 5 parts by weight [Mitsubishi Kasei Kogyo] Asobisisobutyronitrile 3 parts by weight Was added to 350 parts by weight of water, and 50 parts by weight of the emulsion was added. The suspension polymerization was carried out in the same manner as in Example 1 to obtain a toner.

(Example 3) Monomer composition Styrene 99 parts by weight Acid phosoxyethyl methacrylate 1 part by weight Carbon black (# 88) [manufactured by Mitsubishi Kasei Kogyo] 5 parts by weight 2,2'-azobis- (2,4-dimethylvaleronitrile) ) 4
A part by weight was added to 350 parts by weight of water, and 50 parts by weight of the emulsion was added.

(Comparative Example 1) Monomer composition Styrene 80 parts by weight n-butyl methacrylate 20 parts by weight Charge control agent (Kayaset Black TRH) 1 part by weight Polypropylene wax (Viscol 550P) 1.5 parts by weight [manufactured by Sanyo Chemical Industries] Carbon black (pudding) TEX L) 5 parts by weight [Mitsubishi Kasei Kogyo Co., Ltd.] Azobisisobutyronitrile 3 parts by weight was added to 400 parts of a 2% aqueous polyvinyl alcohol solution, suspended and dispersed in the same manner as in Example 1, and polymerized to obtain a comparative toner. Was.

Comparative Example 2 Polymerization was carried out in the same manner as in Example 1 except that an emulsion was used instead of the emulsion. During polymerization, the particles are almost aggregated and coalesced, and the toner is
I could hardly get it.

(Comparative Example 3) Polymerization was completed in the same manner as in Example 1 except that an emulsion was used instead of the emulsion in Example 1, and a comparative toner was obtained.

(Comparative Example 4) Polymerization was carried out in the same manner as in Example 1 except that an emulsion was used instead of the emulsion. During the polymerization, the particles almost aggregated and coalesced, and almost no toner was obtained.

As described above, according to the Examples and Comparative Examples, in the production method of the present invention, it is understood that the polymerization is completed without the suspension particles being united and aggregated during the polymerization reaction, and a toner is generated.

The particle size distribution of the toner particles obtained in Examples and Comparative Examples was measured with a Coulter counter (manufactured by Coulter Electronics), and in order to check the environmental resistance, normal temperature and normal humidity (temperature 20 ° C., humidity 60%) The humidity was controlled for 24 hours in an environment of high temperature and high humidity (temperature of 35 ° C., humidity of 85%), and the change in the charge amount at the initial stage and after the humidity was measured. The measurement of the charge amount was performed by a blow-off method. The results are shown in Table 1 below.

As is clear from Table 1, the toner obtained by the production method of the present invention has few coarse and fine particles, has a sharp particle size distribution, and has high productivity. In addition, regarding the environmental resistance, the toner of the present invention shows that the polymer emulsion has excellent water resistance, so that the toner charge amount is less deteriorated even under high temperature and high humidity than the comparative toner.

[Brief description of the drawings]

FIG. 1 is a diagram showing a state in which a monomer composition is suspended and dispersed in an aqueous phase in which a polymer emulsion is dispersed in the present invention.

Claims (7)

(57) [Claims] 1. Use of a monomer composition comprising a monomer component capable of being charged to one polarity in water and a coloring pigment, and containing substantially no emulsifier as a dispersant and having the other polarity in water. Using a self-emulsifying polymer emulsion composed of a chargeable cross-linked polymer, the monomer composition is dispersed in the polymer emulsion charged in the opposite polarity in water, and suspended in the presence of a polymerization initiator. A method for producing a toner for developing an electrostatic image, which comprises turbid polymerization. 2. A monomer component in a monomer composition comprising: (i) an ethylenically unsaturated monomer having a polar group; (ii) an ethylenically unsaturated monomer having a polar group and another ethylenically unsaturated monomer. 2. The method according to claim 1, wherein the method is any one of a combination with a monomer, or (iii) a combination of an ethylenically unsaturated monomer and a non-polymerizable polar group-containing organic compound. 3. The method according to claim 1, wherein the polymer emulsion has an average particle size of 0.01 to 1 μm. 4. A method according to claim 1, wherein the monomer composition and the polymer emulsion are
2. The method according to claim 1, wherein the composition is used in a weight ratio of 99: 1 to 50:50. 5. The process according to claim 1, wherein, during the suspension polymerization, an aqueous dispersion having a structure in which a polymer emulsion adheres to the surface of oil droplets of the monomer composition is formed. 6. The process according to claim 1, wherein the polymerization initiator is an oil-based radical dispersing agent. 7. A thermoplastic polymer core having an average particle diameter in the range of 1 to 30 μm as a whole and having one polarity of charge and a fixing property, and a surface of the core. And a coating of a crosslinked polymer fine particle having an average particle size of 0.01 to 1 μm having a different charge polarity and bonded to the core.