JPH0762044A - Production of monodisperse polymer particle - Google Patents

Abstract

PURPOSE:To obtain monodisperse polymer particles having uniform, large and monodisperse particle diaineters and excellent dispersibility in solvent and useful as matting agent, slippery agent, etc., by forming an aqueous dispersion of a specific polymer complex and polymerizing a vinyl monomer using the dispersion as a seed. CONSTITUTION:This polymer particles can be produced by forming an aqueous dispersion of a polymer complex composed of a nonionic water-soluble polymer and an ionic water-soluble polymer and polymerizing a radically polymerizable vinyl monomer using the aqueous dispersion of the polymer complex as a seed. The aqueous dispersion of the polymer complex is produced preferably by (A) polymerizing a monomer having ionic group in the presence of a nonionic water-soluble polymer or (B) polymerizing a monomer having nonionic hydrophilic group in the presence of an ionic water-soluble polymer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing polymer particles having a large particle size and being monodispersed.

[0002]

2. Description of the Related Art Dispersion polymerization and suspension polymerization are known as methods for producing polymer particles. In the dispersion polymerization disclosed in JP-A-4-132705, alcohol or the like is used as a dispersion medium to produce particles of a micron order. In addition, JP-A-4-3
In the suspension polymerization disclosed in Japanese Patent No. 14704, a monomer is emulsified and polymerized.

However, these methods have problems that it is difficult to control the particle size of the obtained polymer and that the particle size distribution of the polymer particles is wide. Further, there is a problem that the selection range of the monomers used is narrow.

As a method for controlling the particle size of the polymer particles, there is a so-called multistage swelling method. In the multi-step swelling method disclosed in Japanese Patent Laid-Open No. 64-81810, polymer particles are produced by repeatedly adding a monomer to seed polymer particles, allowing them to swell, and polymerizing. In this method, the particle size of the obtained polymer can be controlled by adjusting the number of times the monomer is added and the amount added.

However, since it is a method in which a monomer is added in multiple stages and swelled and polymerized, there is a problem that the manufacturing process is complicated. Furthermore, since it is a method in which a monomer is added and swelled to carry out polymerization, there is a problem that it is difficult to obtain polymer particles having a crosslinked bond. There is also a problem that an emulsifier, a solvent and the like are mixed in the polymer particles.

[0006] In Japanese Patent Laid-Open No. 4-293921, a monodisperse particle having a uniform particle size is prepared by polymerizing a crosslinkable vinyl monomer to form an ion complex in an aqueous dispersion of a polymer containing a carboxyl group or a salt thereof. Of polymer particles. However, since the polymer particles obtained by such a method contain an ion complex as a component, there is a problem that the morphology changes depending on the ionic component in water. There is also a problem that the chemical resistance is poor and the moisture resistance is low.

An object of the present invention is to solve the above-mentioned conventional problems and to provide a method capable of producing polymer particles having a large particle size and comprising a monodispersed vinyl polymer. .

[0008]

The production method according to the present invention comprises a step of forming an aqueous dispersion of a polymer complex consisting of a nonionic water-soluble polymer and an ionic water-soluble polymer, and a step of forming the polymer complex. And a step of polymerizing one or more kinds of radical-polymerizable vinyl monomers with the aqueous dispersion as a seed.

In the first embodiment of the production method according to the present invention, an ionic water-soluble polymer is formed by polymerizing a monomer having an ionic group in the presence of a nonionic water-soluble polymer, and this polymerization is carried out. To form an aqueous dispersion of the polymer complex, and the vinyl monomer is polymerized using this as a seed.

Further, in the second embodiment of the production method according to the present invention, a nonionic water-soluble polymer is formed by polymerizing a monomer having a nonionic hydrophilic group in the presence of an ionic water-soluble polymer, By this polymerization, an aqueous dispersion of the polymer complex is formed, and the vinyl monomer is polymerized using this as a seed.

In the production method according to the present invention, the nonionic water-soluble polymer and the ionic water-soluble polymer may be mixed in a polymer state to form an aqueous dispersion of the polymer complex. In such mixing of polymers, it may be difficult to form an aqueous dispersion of a uniform and fine polymer complex. Therefore, as in the first embodiment and the second embodiment described above, It is preferable to form an aqueous dispersion of a polymer complex by polymerizing monomers constituting the other polymer in the presence of one polymer.

The nonionic water-soluble polymer used in the present invention
Can be dissolved in water or dispersed to 1 μm or less
A polymer having a nonionic hydrophilic group is preferable. Hydrophilic group
Are, for example, -OH, -O-, -CONR- (R
Is hydrogen or eg C₁~ C ₆Substitution of alkyl group of
Indicates a group. ), And -CONR₂(R is hydrogen or
If C₁~ C₆Represents a substituent such as an alkyl group. )
You can get it. Average molecular weight is 1,000 or more and 100,000
The following are preferred. In addition, as the structure of the polymer,
Any structure such as a branched type, a graft type and a block type may be used.

Specific examples of such a nonionic water-soluble polymer include partially saponified PVA, polyethylene oxide, polyamide, polyvinylpyrrolidone, polypropylene oxide and the like.

The ionic water-soluble polymer used in the present invention is preferably a polymer having an ionic hydrophilic group which is soluble in water or dispersible to 1 μm or less. The ionic hydrophilic group includes anions, cations, betaines and amphoteric groups. Examples of the anion include -COOH and -S.
Examples include groups such as O ₃ H, —PO ₄ H, and —OSO ₃ H. As the cation, —NR ₃ (R represents hydrogen or a substituent such as a C _{1 to} C ₆ alkyl group), —
Examples include groups such as N =. As betaine, -NR ₂
—C ₂ H ₄ —COO (R is hydrogen or, for example, C _{1 to} C ₆
Represents a substituent such as an alkyl group. ), -NR ₂ -C ₂
Examples thereof include H ₄ —SO ₃ (R represents hydrogen or a substituent such as a C _{1 to} C ₆ alkyl group). Examples of the amphoteric compound include compounds containing a —NR—C ₂ H ₄ —COOH (R represents hydrogen or a substituent such as a C _{1 to} C ₆ alkyl group) group.

The number average molecular weight is preferably 1,000 or more and 100,000 or less. Further, the structure may be any of linear, branched, graft, block and the like. Specific examples of such an ionic water-soluble polymer include polymethacrylic acid, polyacrylic acid, styrene-maleic acid copolymer, polyvinylpyridine, polyethyleneimine,
Carboxyl group-containing polyester, methacrylic acid, acrylic acid, allylamine, dimethylaminopropylmethacrylamide, dimethylaminopropylacrylamide, dimethylaminoethyl acrylate, dimethylmethacryloxyethyl t-butylacrylamidesulfonate (3-sulfopropyl) ammonium betaine Examples thereof include copolymers containing more than one type.

The polymerization initiator used in the present invention is not particularly limited, but a polymerization initiator which is soluble in water by 0.04% by weight or more is preferable. Examples of such a polymerization initiator include persulfate, azobisisobutylnitrile, azobis (2-aminopropane) dihydrochloride, azobis (2-methyl-N-bishydroxymethyl-2-hydroxyethylpropionamide), azobis. −
2-Hydroxymethylpropionitrile, azobisvaleric acid, benzoyl peroxide, t-butylperoxymaleic acid and the like can be mentioned.

The monomer having an ionic group that gives an ionic water-soluble polymer that can be used in the first embodiment of the production method of the present invention has a radical polymerizable group and an ionic group, and is Monomers that dissolve in 0.05% by weight or more are preferred. As the ionic group, for example, −
_{COOH, -SO 3 H, -NR 2} (R represents a substituent such as an alkyl group of hydrogen or for example C ₁ -C _6.), May be mentioned betaines, amphoteric group.

Specific examples of the monomer having an ionic group include methacrylic acid, acrylic acid, allylamine,
Examples thereof include dimethylaminopropyl methacrylamide, dimethylaminopropyl acrylamide, dimethylaminoethyl acrylate, and dimethylmethacryloxyethyl (3-sulfopropyl) ammonium betaine t-butylacrylamide sulfonate.

The monomer having a nonionic hydrophilic group that can be used in the second embodiment of the production method of the present invention is preferably a monomer having a polymerizable group soluble in water in an amount of 2.3% by weight or more. As such a monomer, an ethylene oxide adduct of methyl methacrylate,
Examples thereof include a monomer having an amide group and / or an OH group. More specifically, methoxy polyethylene glycol methacrylate, phenoxy polyethylene glycol methacrylate, hydroxy polyethylene glycol methacrylate, methoxyethyl methacrylate, acrylamide, methylenebisacrylamide, dimethylacrylamide acryloylmorpholine, isopropylacrylamide, 2-hydroxylethyl methacrylate, 2-hydroxypropyl methacrylate. , 3-hydroxypropyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 3-hydroxypropyl acrylate and the like.

In the first and second embodiments of the production method of the present invention, in the presence of one of the nonionic water-soluble polymer and the ionic water-soluble polymer, The other monomer that gives the water-soluble polymer is polymerized to form an aqueous dispersion of the polymer complex.
An aqueous dispersion of such a polymer complex can be formed by polymerizing by adding a polymerization initiator to a dispersion liquid of one polymer and a monomer that gives the other polymer and heating.

The weight ratio of one polymer to the other polymer is preferably 1: 9 to 9: 1. Outside this range, a stable polymer complex may not be formed.

The amount of the polymerization initiator added is 9: 1 in terms of the weight ratio of the monomer that gives the other polymer to the polymerization initiator.
A ratio of ~ 199: 1 is preferred. If the amount of the polymerization initiator is too small, it may be difficult to form the polymer complex, and if the amount of the polymerization initiator is too large, it may not be possible to form a stable complex.

The polymerization temperature is not particularly limited, but can be appropriately selected depending on the polymerization initiator, and is generally 5
It is selected within the range of 0 to 90 ° C. The polymerization time is also not particularly limited, but is appropriately selected depending on the polymerization initiator and is generally selected within the range of 0.5 to 8 hours.

The concentration of the dispersion liquid of the polymer that gives one water-soluble polymer and the other water-soluble polymer is not particularly limited, but is preferably in the range of 0.3 to 30% by weight. . If the concentration is too low, it may be difficult to form a polymer complex, and if the concentration is too high, a stable dispersion may not be obtained.

According to the production method of the present invention, one or more radically polymerizable vinyl monomers are polymerized with the polymer complex aqueous dispersion thus formed as a seed.

As the radically polymerizable vinyl monomer used in the present invention, a monomer having one or two or more radically polymerizable groups can be used. Examples of the monomer having one radical polymerizable group include (meth) acrylate, polymerizable aromatic compound, carboxyl group-containing monomer, hydroxyl group-containing monomer, nitrogen-containing alkyl (meth) acrylate, polymerizable amide, and polymerizable Examples thereof include nitriles, vinyl halides, α-olefins, vinyl carboxylates, and diene compounds.

Examples of the (meth) acrylate include methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, n-butyl acrylate, n-butyl methacrylate, isobutyl acrylate, 2-ethylhexyl acrylate, lauryl methacrylate and phenyl acrylate. Can be mentioned.

As the polymerizable aromatic compound, styrene,
Examples include α-methylstyrene, vinyl ketone, t-butylstyrene, parachlorostyrene, vinylnaphthalene, and the like.

Examples of the carboxyl group-containing monomer include acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid and fumaric acid. As the hydroxyl group-containing monomer, 2-hydroxyethyl acrylate, 2
-Hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate, hydroxybutyl methacrylate, allyl alcohol, methallyl alcohol and the like can be mentioned.

Examples of nitrogen-containing alkyl (meth) acrylates include dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, dimethylaminopropyl acrylate, dimethylaminopropyl methacrylate and dimethylaminopropyl methacrylamide.

Examples of the polymerizable amide include acrylic acid amide, methacrylic acid amide, N-methylol acrylamide and N-methoxymethyl acrylamide.

Examples of the polymerizable nitrile include acrylonitrile and methacrylonitrile. Examples of vinyl halides include vinyl chloride, vinyl bromide, vinyl fluoride and the like.

Examples of α-olefins include ethylene and propylene. Examples of vinyl carboxylate compounds include vinyl acetate and vinyl propionate.

Examples of the diene compound include butadiene and isoprene. Examples of the monomer having two or more radically polymerizable groups used in the present invention include a polymerizable unsaturated monocarboxylic acid ester of polyhydric alcohol, a polymerizable unsaturated alcohol ester of polybasic acid, and two or more vinyl groups. And an addition compound of an epoxy group-containing ethylenically unsaturated group monomer and a carboxyl group-containing ethylenically unsaturated group monomer.

Examples of the polymerizable unsaturated monocarboxylic acid ester of polyhydric alcohol include ethylene glycol diacrylate, ethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate and 1,3-butylene glycol diester. Methacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, 1,4-butanediol diacrylate, neopentyl glycol diacrylate, neopentyl glycol diacrylate, 1,6-hexanediol diacrylate, 1,6- Hexanediol dimethacrylate, pentaerythritol diacrylate, pentaerythritol dimethacrylate, pentaerythritol triacryle DOO, pentaerythritol trimethacrylate, pentaerythritol tetraacrylate, pentaerythritol tetramethacrylate, glycerol diacrylate, glycerol dimethacrylate, glycerol Acro alkoxy dimethacrylate,
1,1,1-Trishydroxymethylethane diacrylate, 1,1,1-Trishydroxymethylethane dimethacrylate, 1,1,1-Trishydroxymethylethane triacrylate, 1,1,1-Trishydroxymethylethane Trimethacrylate, 1,1,1-trishydroxymethylpropane diacrylate, 1,
1,1-trishydroxymethylpropane dimethacrylate and the like can be mentioned.

Examples of the polymerizable unsaturated alcohol ester of polybasic acid include diallyl terephthalate, diallyl phthalate and triallyl trimellitate. Divinylbenzene etc. can be mentioned as an aromatic compound substituted by two or more vinyl groups.

As the addition compound of the epoxy group-containing ethylenically unsaturated group monomer and the carboxyl group-containing ethylenically unsaturated group monomer, glycidyl acrylate, glycidyl methacrylate and acrylic acid, methacrylic acid, crotonic acid, Examples thereof include addition products with maleic acid and the like.

The amount of the radical-polymerizable vinyl monomer added is preferably 1:99 to 40:60 in terms of the weight ratio of the aqueous dispersion of the polymer complex to the vinyl monomer. If the amount of the polymer complex aqueous dispersion is too small, a large amount of aggregates may be generated, and a stable dispersion may not be obtained. On the contrary, if the amount of the complex water dispersion is too large, it may be difficult to control the particle size.

The monodisperse polymer particles according to the present invention are the monodisperse polymer particles which can be produced by the above-mentioned production method, and are the monodisperse polymer particles having an average particle diameter of 1 to 50 μm. Is a vinyl polymer particle in which a polymer complex consisting of a water-soluble polymer and an ionic water-soluble polymer is present in the surface layer, and the weight ratio of polymer complex: vinyl polymer is 1:99 to 40:60. It is characterized by that. According to the above-mentioned production method of the present invention, the vinyl monomer is polymerized using the polymer complex as a seed. In the polymer particles obtained as a result, the polymer complex is mainly present in the surface layer.

In the polymer particles after polymerization, 50% or more, more preferably 80% or more of the polymer complex contained in the particles is present in the particle surface layer. The content of such a polymer complex in the polymer particles can be quantified by titrating the ionic component forming the polymer complex. For example, the amount of the polymer complex on the surface of the polymer particles and the amount of the polymer complex existing independently of the polymer particles in the dispersion liquid can be quantified by titrating the dispersion liquid obtained after the polymerization. Here, the amount of the ionic component obtained by titration of the dispersion liquid is defined as A.

Further, the dispersion liquid after the polymerization is separated into polymer particles and a supernatant liquid by centrifugation or the like, and the ionic component of the supernatant liquid is titrated to obtain a high concentration independent of the polymer particles in the dispersion liquid. The amount of molecular complex can be quantified. Here, when the amount of the ionic component obtained by titration of the supernatant liquid is B, the amount of the polymer complex existing on the surface of the polymer particles can be obtained as AB. Moreover, since the amount of the ionic component used in the synthesis of the polymer complex is known in advance, if this amount is C, the amount of the polymer complex existing inside the polymer particles is determined as C-A. be able to.

The above can be summarized as follows. Amount of ionic component determined by titration of dispersion: A Amount of ionic component determined by titration of supernatant: B Amount of ionic component used in the synthesis of polymer complex: C Amount of polymer complex = AB-Amount of polymer complex present inside polymer particles = CA-Amount of polymer complex present independently from polymer particles in dispersion = B

[0043]

In the production method of the present invention, polymer particles are produced by polymerizing a radically polymerizable vinyl monomer using an aqueous dispersion of a polymer complex as a seed. In the present invention, the polymer particles are grown by the two processes of swelling and particle agglomeration, so that the respective polymer particles are made to have substantially the same particle size, and as a result, the particle size is large and the particle size is uniform. In other words, it can be monodisperse polymer particles.

According to the present invention, it is not necessary to add and polymerize a monomer in multiple stages as in the prior art, and polymer particles can be produced by a one-step operation, so that the monomer to be used is limited. There is no. Further, it becomes possible to form a cross-linking bond in the polymer particles to obtain a polymer particle having a high degree of cross-linking.

Further, in the polymer particles obtained by the production method of the present invention, the polymer complex is mainly present in the surface layer. Therefore, by washing the obtained polymer particles with an acid or a base, The polymer complex on the surface can be easily removed. Therefore, a polymer particle having excellent solvent dispersibility can be obtained.

[0046]

EXAMPLES The present invention will be described below with reference to specific examples. In addition, a part shows a weight part. Example 1 10 parts of partially saponified polyvinyl alcohol (Gosenol GH-17: manufactured by Nippon Synthetic Chemical Industry Co., Ltd.), 10 parts of methacrylic acid, 4,4'-in a reaction vessel equipped with a stirrer, a cooler, a temperature control device and a nitrogen introducing tube. Azobis (4-cyanovaleric acid)
0.2 parts and 880 parts of deionized water were charged and heated to 80 ° C. with stirring and kept for 1 hour. To this, 2 parts of 4,4'-azobis (4-cyanovaleric acid) was added, and subsequently 80 parts of styrene was added dropwise over 2 hours. After that, polymerization was carried out for 1 hour to complete the reaction. The obtained suspension was filtered through a 400-mesh wire net and observed with a scanning electron microscope to find that it was a monodisperse particle having an average particle diameter of 2 μm. The monodispersity was evaluated by the weight percentage of particles contained in the range of 0.5D to 2D with respect to the average particle diameter (D). In the polymer particles obtained in this example, 95% by weight of particles are 0.5D to 2D.
Was included in the range.

The concentration of the carboxyl group as an ionic component was measured using an aqueous potassium hydroxide solution, and the amount of the polymer complex independently present on the surface of the polymer particles, inside the polymer particles, and in the dispersion liquid was measured. Was measured. First, the dispersion of polymer particles after polymerization was subjected to neutralization titration with an aqueous solution of potassium hydroxide to measure the concentration of carboxyl groups, which was 0.108 mol / kg, and the total amount of the dispersion was 0.982 kg. . Therefore, the amount (A) of carboxyl groups in the dispersion is 0.106 mol. Next, the dispersion liquid of the polymer particles was centrifuged at a centrifugal acceleration of 50,000 G, and the obtained supernatant liquid was similarly neutralized and titrated. As a result, the concentration of carboxyl groups in the supernatant was 0.030 mol / kg, and the total amount of the supernatant was 0.
It was 88 kg. Therefore, the amount (B) of carboxyl groups present independently of the polymer particles in the dispersion is 0.026 mol.

On the other hand, the amount (C) of the carboxyl group used when synthesizing the polymer complex is 0.116 mol based on the addition amounts of methacrylic acid and 4,4'-azobis (4-cyanovaleric acid). Therefore, the amount of carboxyl groups (A-B) present on the polymer particle surface was 0.080 mo.
1 (69%), the amount of carboxyl groups present inside the polymer particles (C-A) was 0.010 mol (9%), and carboxyl groups present independently from the polymer particles in the dispersion liquid. (B) is 0.026 mol (2
2%). As is clear from these results, it is found that in the polymer particles, the polymer complex is present in large amounts on the surface of the polymer particles.

Comparative Example 1 A reaction vessel equipped with a stirrer, a cooler, a temperature control device and a nitrogen inlet tube was charged with 10 parts of partially saponified polyvinyl alcohol (Gosenol GH-17: manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) and 880 parts of deionized water. The mixture was heated to 80 ° C. with stirring and kept for 1 hour. To this, 2 parts of 4,4'-azobis (4-cyanovaleric acid) was added, and subsequently 80 parts of styrene was added dropwise over 2 hours. After that, polymerization was carried out for 1 hour to complete the reaction.
The obtained suspension was difficult to filter with a 400-mesh wire net, and when the residue and the filtration were observed with a scanning electron microscope, the residue was aggregates of 50 μm, and the filtrate was 0.1 to 0.2.
It was a fine particle of μm.

Examples 2 to 8 In the same manner as in Example 1, the polymer component, the monomer component, the polymerization initiator and pure water shown in Table 1 were charged into a reaction vessel and heated to 80 ° C. with stirring. Hold for 1 hour.
Next, the initiator shown in Table 1 was added, and then the monomers shown in Table 1 were added dropwise over 2 hours, followed by polymerization for 1 hour to complete the reaction. The obtained suspension was filtered through a 400-mesh wire net and observed with a scanning electron microscope to measure the average particle size and particle size distribution. The results are shown in Table 1.

[0051]

[Table 1]

The symbols shown in Table 1 are as follows. ACVA: 4,4'-azobis (4-cyanovaleric acid) DVB: divinylbenzene EGDM: ethylene glycol dimethacrylate ST: styrene MMA: methacrylic acid nBA: n-butyl acrylate 100 ml of the suspension obtained in Example 2 was added. 0.05 mol
After decanting with 100 ml of 1 / l potassium hydroxide solution three times and further decanting with 100 ml of pure water three times, freeze-drying and dispersing in xylene, a dispersion liquid without particle aggregation was obtained. On the other hand, dry particles that were not washed were not dispersed in xylene. When the washed particles were dispersed again in water and titrated with a potassium hydroxide solution, no carboxyl group was present.

As is clear from the results shown in Table 1, the polymer particles obtained in Examples 2 to 8 are monodisperse polymer particles having a narrow particle size distribution.

[0054]

INDUSTRIAL APPLICABILITY In the present invention, a radically polymerizable vinyl monomer is polymerized by using an aqueous dispersion of a polymer complex as a seed. During this polymerization process, particles grow by agglomeration. Obtained as polymer particles having a substantially uniform particle size. Therefore, a polymer particle having a large particle size and being monodispersed can be obtained.

Further, the monodisperse polymer particles obtained according to the production method of the present invention have a polymer complex in the surface layer, and the polymer complex can be easily removed by an acid or a base. Therefore, it is possible to obtain monodisperse polymer particles having excellent solvent dispersibility.

Since the monodisperse polymer particles obtained by the production method of the present invention are such large-diameter and monodisperse polymer particles, they are glossy in the fields of paints, electronic devices, medical care, etc. It can be used as an eraser, a coloring material, a medical material, a lubricant, an electronic material and the like.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Keizo Ishii 19-17 Ikedanaka-cho, Neyagawa-shi, Osaka Japan Paint Co., Ltd.

Claims (4)

[Claims] 1. A step of forming an aqueous dispersion of a polymer complex composed of a nonionic water-soluble polymer and an ionic water-soluble polymer; one or two species using the aqueous dispersion of the polymer complex as a seed. A method for producing monodisperse polymer particles, which comprises the step of polymerizing the above radically polymerizable vinyl monomer. 2. The ionic water-soluble polymer is formed by polymerizing a monomer having an ionic group in the presence of the nonionic water-soluble polymer, and by this polymerization, an aqueous dispersion of the polymer complex is formed. It is formed,
The method for producing the monodisperse polymer particles according to claim 1. 3. The nonionic water-soluble polymer is formed by polymerizing a monomer having a nonionic hydrophilic group in the presence of the ionic water-soluble polymer, and by this polymerization, an aqueous dispersion of the polymer complex. The method for producing monodisperse polymer particles according to claim 1, wherein: 4. A vinyl polymer, which is a monodisperse polymer particle having an average particle diameter of 1 to 50 μm and in which a polymer complex consisting of a nonionic water-soluble polymer and an ionic water-soluble polymer is present in the surface layer. Monodisperse polymer particles, wherein the weight ratio of the high molecular weight complex to the vinyl polymer is 1:99 to 40:60.