JP2012062389A - Method of manufacturing hydrophilic polymer particle, and hydrophilic polymer particle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydrophilic resin particle excellent in monodispersibility which can acquire sufficient hydrophilicity by using a small amount of the resin particles without reducing a refractive index.SOLUTION: The method of manufacturing a hydrophilic polymer particle includes: a step which obtains a seed particle by polymerizing 1-20 pts.wt of a monomer expressed by general formula (1), wherein Rdenotes H or CH, m denotes 1-50, and n denotes 1-50, with a monomer mixture containing 100 pts.wt of the other vinyl monomer; and a step in which the seed particle is made to absorb a monomer mixture which contains at least 50 wt.% of a hydrophobic monomer to be polymerized, wherein the hydrophilic polymer particle includes at least 0.0028 wt.% of a polymer derived from the monomer expressed by the general formula (1), and has the contact angle of at most 96°.

Description

  The present invention relates to a method for producing hydrophilic polymer particles and hydrophilic polymer particles. More specifically, the present invention is an excellent product obtained by a seed polymerization method using seed particles obtained by polymerizing a monomer mixture containing a specific monomer having a surface activity in a predetermined ratio. The present invention relates to a method for producing hydrophilic polymer particles having both monodispersity and hydrophilicity, and hydrophilic polymer particles.

  Polymer particles (resin particles) are used in a wide range of fields such as liquid crystal spacers, chromatographic fillers, and diagnostic reagents. Moreover, it is used also in the field | areas of display apparatuses, such as a light diffusing plate, a light-diffusion film, and an anti-glare film. In the above-mentioned field, if polymer particles having a particle diameter outside the desired range are mixed, the polymer particles having a particle diameter outside the desired range cause problems in the application. Moreover, if it does not have hydrophilicity, the problem that the obtained polymer particle aggregates may be caused. Therefore, development for obtaining polymer particles having both excellent monodispersity and hydrophilicity has been continuously performed.

  Various methods have been disclosed as methods for obtaining polymer particles excellent in monodispersity and hydrophilicity. For example, by absorbing a monomer containing a vinyl monomer having a surface-active ability having a specific structure in the seed particles, the seed particles are excellent in hydrophilicity and excellent in preventing the particles from falling off from the coating film. It is disclosed that monodisperse resin particles can be obtained (see Patent Document 1).

JP 2009-235273 A

  In Patent Document 1, by using a vinyl-based monomer having a specific structure and a surface-active ability as a polymerizable monomer or an aqueous medium that is absorbed by seed particles, oil droplets of the polymerizable monomer are formed. Hydrophilic particles having stable and excellent monodispersibility are obtained.

However, Patent Document 1 has a problem that sufficient hydrophilicity is difficult to obtain if the amount of the vinyl monomer having a specific structure used is small. In addition, since the vinyl monomer having this specific structure has a low refractive index, a hydrophobic monomer having a high refractive index, such as a styrene monomer, is particularly used when used in a large amount to obtain hydrophilicity. In order to impart hydrophilicity to resin particles mainly composed of a monomer, there is a problem that the refractive index of the obtained resin particles is lowered.
It is an object of the present invention to provide a method for producing hydrophilic resin particles excellent in monodispersibility and hydrophilic resin particles that can obtain sufficient hydrophilicity with a small amount of use without lowering the refractive index. .

  As a result of intensive studies to solve the above problems, the inventors of the present invention perform seed polymerization using seed particles obtained by polymerizing a monomer mixture containing a monomer having a specific structure. Thus, the present inventors have found that polymer particles having excellent hydrophilicity and monodispersibility can be easily obtained even when the amount of the monomer having a specific structure is small. According to the present invention, even when used for styrene resin particles, there is almost no decrease in refractive index.

Thus, according to the present invention, the following general formula (1)
(In the formula, R1 is H or CH ₃ , m is 1 to 50, and n is 1 to 50)
A step of obtaining seed particles by polymerizing a monomer mixture containing 1 to 20 parts by weight of a monomer represented by formula (100) and 100 parts by weight of a vinyl monomer other than the general formula (1); A method of producing a hydrophilic polymer particle comprising a step of absorbing and polymerizing a monomer mixture containing 50% by weight or more of a hydrophobic monomer in the particle, wherein the hydrophilic polymer particle has the general formula There is provided a method for producing hydrophilic polymer particles, comprising 0.0028% by weight or more of the monomer-derived polymer represented by (1) and having a contact angle of 96 ° or less.

Moreover, according to the present invention, the following general formula (1)
(In the formula, R1 is H or CH ₃ , m is 1 to 50, and n is 1 to 50)
Hydrophobic to seed particles obtained by polymerizing a monomer mixture containing 1 to 20 parts by weight of a monomer represented by formula (100) and 100 parts by weight of a vinyl monomer other than the general formula (1) It is obtained by absorbing and polymerizing a monomer mixture containing 50% by weight or more of monomers, and contains 0.0028% by weight or more of the polymer derived from the monomer represented by the general formula (1), Hydrophilic polymer particles having a contact angle of 96 ° or less are provided.

In the production method of the present invention, polymer particles having excellent hydrophilicity and monodispersibility can be easily obtained by using a small amount of the monomer-derived polymer of the general formula (1).
Further, the hydrophilic polymer particles obtained by the present invention contain the monomer-derived polymer of the general formula (1) in a minimum ratio necessary for obtaining hydrophilicity and monodispersity. Therefore, the low refractive index which is the disadvantage which the monomer of General formula (1) has hardly reveals. Therefore, polymer particles having high hydrophilicity and monodispersity can be provided without sacrificing the refractive index.

  In addition, when the monomer mixture containing 50% by weight or more of the hydrophobic monomer is used in an amount of 80 to 350 parts by weight based on 1 part by weight of the seed particles, the hydrophilicity having both high hydrophilicity and monodispersity. The conductive polymer particles can be provided with higher productivity.

When the vinyl monomer other than the general formula (1) is a (meth) acrylic monomer and the hydrophobic monomer is a monofunctional styrenic monomer, Hydrophilic polymer particles having monodispersibility can be provided.
Moreover, when the said hydrophilic polymer particle has a refractive index of 1.56-1.60, a polymer particle more suitable for use as an optical product use etc. can be provided.

The method for producing hydrophilic polymer particles according to the present invention (hereinafter also referred to as “polymer particles” or “resin particles”)
The following general formula (1)
(In the formula, R1 is H or CH ₃ , m is 1 to 50, and n is 1 to 50)
A step of obtaining seed particles by polymerizing a monomer mixture containing 1 to 20 parts by weight of a monomer represented by formula (100) and 100 parts by weight of a vinyl monomer other than the general formula (1); And a step of causing the particles to absorb and polymerize a monomer mixture containing 50% by weight or more of a hydrophobic monomer. The obtained hydrophilic polymer particles contain 0.0028 wt% or more of the monomer-derived polymer represented by the general formula (1) and have a contact angle of 96 ° or less.

(Seed particles)
The seed particles used to obtain the polymer particles include 1 to 20 parts by weight of the monomer represented by the general formula (1) and 100 parts by weight of a vinyl monomer other than the general formula (1). Polymers derived from monomer mixtures containing are included.
(1) Monomer having general formula (1)
(In the formula, R1 is H or CH ₃ , m is 1 to 50, and n is 1 to 50)
In the monomer represented by the formula, hydrophilic sites are likely to appear on the surface of the polymer particles, and particles with high hydrophilicity can be obtained by adding a small amount.
When m is larger than 50, the polymerization stability may be lowered and coalescence particles may be generated. When n is larger than 50, the polymerization stability may be lowered and coalescence particles may be generated. A preferred range of m and n is 1-30.

  A commercially available product can be used as the monomer of the general formula (1). An example is the Blemmer series manufactured by Nippon Oil & Fats. Furthermore, among the Blemmer series, Blemmer 50PEP-300, Blemmer 70PEP-350B, and the like are suitable for the present invention.

  The monomer of the general formula (1) is used in the range of 1 to 20 parts by weight with respect to 100 parts by weight of the vinyl monomer other than the general formula (1) described below. When the amount used is less than 1 part by weight, the polymer particles obtained by lacking the amount of the monomer of the general formula (1) in the polymer particles obtained by seed polymerization become insufficient in hydrophilicity and dispersed. May decrease. On the other hand, if it exceeds 20 parts by weight, polymerization aggregation of seed particles may be caused. A more preferable usage amount is in the range of 1 to 15 parts by weight.

(2) Vinyl monomers other than general formula (1) Examples of vinyl monomers other than general formula (1) include (meth) acrylic monomers. Specifically, acrylic acid or its ester such as acrylic acid, methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, 2-ethylhexyl acrylate, methacrylic acid, n-butyl methacrylate, methacrylic acid 2-ethylhexyl, methyl methacrylate, ethyl methacrylate, isobutyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, isobornyl methacrylate, 2-hydroxyethyl methacrylate, 2-methoxyethyl methacrylate, glycidyl methacrylate, tetrahydrofluorate methacrylate Examples include methacrylic acid or esters thereof such as furyl, diethylaminoethyl methacrylate, trifluoroethyl methacrylate, heptadecafluorodecyl methacrylate. These (meth) acrylic monomers can be used alone or in combination of two or more. Moreover, (meth) acryl means methacryl or acryl.

  Examples of vinyl monomers other than (meth) acrylic monomers include those having a vinyl group such as styrene, p-methylstyrene, α-methylstyrene, and vinyl acetate. The said polymerizable monomer can be used individually or in combination of 2 or more types.

(3) Method for producing seed particles A seed particle is a single amount for producing seed particles of 1 to 20 parts by weight of the monomer of the general formula (1) and 100 parts by weight of a vinyl monomer other than the general formula (1). It is obtained by polymerizing the body mixture. Here, the seed particles may be formed by one polymerization or may be formed through two or more multi-stage polymerizations. As a method for producing seed particles, a known method such as an emulsion polymerization method, a soap-free emulsion polymerization method or a suspension polymerization method can be used. Considering the uniformity of the seed particle size and the simplicity of the production method, the emulsion polymerization method and the soap-free emulsion polymerization method are preferable. When seed particles are obtained through two or more multistage polymerizations, the addition of the monomer of the general formula (1) may be used at any stage, but is preferably used at the last stage. It may also be used at all stages. The ratio of the monomer of the general formula (1) to the vinyl monomer other than the general formula (1) in the seed particles used for the production of the polymer particles is as described above.

Hereinafter, the seed polymerization method applied to the production of seed particles may be referred to as “preliminary seed polymerization method”, and the seed particles used in the preliminary seed polymerization method may be referred to as “preliminary seed particles”.
Further, the weight average molecular weight of the seed particles may be adjusted by adjusting the amount of the polymerization initiator used or adjusting the amount of the molecular weight modifier added.

  As the polymerization initiator, benzoyl peroxide, lauroyl peroxide, orthochlorobenzoyl peroxide, orthomethoxybenzoyl peroxide, 3,5,5-trimethylhexanoyl peroxide, t-butylperoxy-2-ethylhexanoate, Organic peroxides such as di-t-butyl peroxide; 2,2′-azobisisobutyronitrile, 1,1′-azobiscyclohexanecarbonitrile, 2,2′-azobis (2,4-dimethylvalero) Nitrile), 2,2-azobis [2- (2-imidazolin-2-yl) propane] hydrogen dichloride, 2,2-azobis [2- (2-imidazolin-2-yl) propane] disulfate dihydrate 2,2-azobis (2-amidinopropane) hydrogen chloride, 2,2-azobis [N- (2-carboxyethyl) -2-methylpro Pionamidine] hydrate, 2,2-azobis {2- [1- (2-hydroxyethyl) -2-imidazolin-2-yl] propane} hydrogen dichloride, 2,2-azobis [2- (2- Imidazolin-2-yl) propane], 2,2-azobis (1-imino-1-pyrrolidino-2-ethylpropane) hydrogen chloride, 2,2-azobis {2-methyl-N- [1,1-bis] (Hydroxymethyl) -2-hydroxyethyl] propionamide}, 2,2-azobis [2-methyl-N- (2-hydroxyethyl) propionamide], 2,2-azobis (N-hydroxyethylisobutyramide), Azo compounds such as 4,4-azobis (4-cyanopentanoic acid), azobisisobutyronitrile, azobis (2,4dimethylvaleronitrile), ammonium persulfate, Potassium sulfate, persulfate salts such as sodium persulfate, benzoyl peroxide, acetyl peroxide, methyl ethyl ketone peroxide, t- butyl peroxide, organic peroxides such as dicumyl peroxide. You may use the said polymerization initiator individually or in combination of 2 or more types. The addition amount of the polymerization initiator is preferably 0.1 to 3 parts by weight with respect to 100 parts by weight of the monomer mixture.

  As the molecular weight modifier, α-methylstyrene dimer, mercaptans such as n-octyl mercaptan and t-dodecyl mercaptan, and halogenated hydrocarbons such as carbon tetrachloride can be used. The amount of the molecular weight modifier used is preferably 0.01 to 10 parts by weight per 100 parts by weight of the total amount of monomers used for the polymerization. More preferably, it is 0.05 to 5 parts by weight.

  The polymerization is performed in an aqueous medium. In the aqueous medium, the monomer mixture and optionally preliminary seed particles are mixed. The preliminary seed particles may be added in advance to the aqueous medium, or may be added to a mixed liquid (emulsified liquid) of the monomer mixture and the aqueous medium. The mixing can be performed, for example, by adding the monomer mixture to an aqueous medium and dispersing the mixture with a fine emulsifier such as a homogenizer, an ultrasonic processor, or a nanomizer.

  The aqueous medium is not particularly limited, and examples thereof include water or a mixed medium of water and a water-soluble organic solvent (for example, a lower alcohol such as methanol or ethanol). The aqueous medium is preferably used in the range of 100 to 1000 parts by weight and more preferably in the range of 200 to 500 parts by weight with respect to 100 parts by weight of the monomer mixture.

The seed particles may be isolated from the polymerization system or may be used as they are for the production of polymer particles without isolation.
In addition, the monomer represented by the general formula (1) may be used when producing preliminary seed particles or polymer particles described later as long as the properties of the polymer particles according to the present invention are not impaired.

(Method for producing hydrophilic polymer particles)
The polymer particles can be obtained by causing the seed particles obtained by the above-described process to absorb and polymerize a monomer mixture containing 50% by weight or more of a hydrophobic monomer (seed polymerization).
(1) Monomer mixture The monomer mixture contains at least 50% by weight or more of a hydrophobic monomer. Here, the term “hydrophobic” means that the solubility in water at 25 ° C. is 1 g / L or less.

  Examples of the hydrophobic monomer include monofunctional styrene monomers such as styrene, p-methylstyrene, p-chlorostyrene, and α-methylstyrene, polyfunctional styrene monomers such as divinylbenzene, butyl acrylate, Examples include 2-ethylhexyl acrylate, butyl methacrylate, and trimethylolpropane triacrylate. These monomers can be used alone or in combination of two or more.

  The monomer mixture may consist only of a hydrophobic monomer, but may contain other monomers having a solubility in water at 25 ° C. of more than 1 g / L. The other monomer is used in an amount of 50% by weight or less in the monomer mixture. Here, the hydrophobic monomer is preferably contained in an amount of 60% by weight or more in the monomer mixture. More preferably 80% by weight or more is contained.

Other monomers include acrylic esters such as methyl acrylate, ethyl acrylate and diethylaminoethyl acrylate, methacrylic esters such as methyl methacrylate, ethyl methacrylate and diethylaminoethyl methacrylate, ethylene glycol mono (meth) Glycol esters of (meth) acrylic acid such as acrylate and polyethylene glycol mono (meth) acrylate, alkyl vinyl ethers such as methyl vinyl ether and ethyl vinyl ether, vinyl esters such as vinyl acetate and vinyl butyrate, N-methylacrylamide, N- N-alkyl substituted (meth) acrylamides such as ethyl acrylamide, N-methyl methacrylamide, N-ethyl methacrylamide, nitrile such as acrylonitrile, methacrylonitrile, etc. It can be used Le acids. Moreover, polyfunctional monomers, such as ethylene glycol di (meth) acrylate, can also be used by mixing with acrylic acid esters or methacrylic acid esters. These monomers can be used alone or in combination of two or more.
Other preferable monomers among the above are methyl acrylate, ethyl acrylate, methyl methacrylate, and ethyl methacrylate.

(2) Other members used for seed polymerization The seed polymerization is usually performed in an aqueous medium. Examples of the aqueous medium include water and a mixed medium of water and a water-soluble solvent (for example, lower alcohol).
The aqueous medium may contain a surfactant. As the surfactant, any of anionic, cationic, nonionic and zwitterionic compounds can be used.

  Examples of the anionic surfactant include fatty acid oils such as sodium oleate and castor oil potassium, alkyl sulfate salts such as sodium lauryl sulfate and ammonium lauryl sulfate, alkylbenzene sulfonates such as sodium dodecylbenzenesulfonate, and alkylnaphthalene sulfone. Acid salts, alkane sulfonates, dialkyl sulfosuccinates such as sodium dioctyl sulfosuccinate, alkenyl succinates (dipotassium salts), alkyl phosphate esters, naphthalene sulfonate formalin condensates, polyoxyethylene alkylphenyl ether sulfates Examples thereof include salts, polyoxyethylene alkyl ether sulfates such as sodium polyoxyethylene lauryl ether sulfate, and polyoxyethylene alkyl sulfate salts.

Nonionic surfactants include, for example, polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene fatty acid ester, sorbitan fatty acid ester, polyoxysorbitan fatty acid ester, polyoxyethylene alkylamine, glycerin fatty acid ester, oxy Examples include ethylene-oxypropylene block polymers.
Examples of the cationic surfactant include alkylamine salts such as laurylamine acetate and stearylamine acetate, and quaternary ammonium salts such as lauryltrimethylammonium chloride.

Examples of the zwitterionic surfactant include lauryl dimethylamine oxide and phosphate ester or phosphite ester surfactants.
You may use the said surfactant individually or in combination of 2 or more types. Of the above surfactants, anionic surfactants are preferred from the viewpoint of dispersion stability during polymerization. The addition amount of the surfactant can be 0.0001 to 1 part by weight with respect to 100 parts by weight of the aqueous medium.

  Examples of the polymerization initiator to be added as needed include benzoyl peroxide, lauroyl peroxide, orthochlorobenzoyl peroxide, orthomethoxybenzoyl peroxide, 3,5,5-trimethylhexanoyl peroxide, and t-butyl peroxide. Organic peroxides such as oxy-2-ethylhexanoate and di-t-butyl peroxide; 2,2′-azobisisobutyronitrile, 1,1′-azobiscyclohexanecarbonitrile, 2,2 ′ -Azo compounds such as azobis (2,4-dimethylvaleronitrile). The polymerization initiator is preferably used in the range of 0.1 to 1 part by weight with respect to 100 parts by weight of the monomer mixture.

In order to suppress the generation of emulsified particles in the aqueous system in the polymerization step, water-soluble polymerization inhibitors such as nitrites, sulfites, hydroquinones, ascorbic acids, water-soluble vitamin Bs, citric acid, polyphenols, etc. May be used.
A dispersion stabilizer may be added to the aqueous medium. Examples of the dispersion stabilizer include water-soluble polymers such as polyvinyl alcohol, hydroxyethyl cellulose, and carboxymethyl cellulose. The addition amount of the dispersion stabilizer can be 0.1 to 20 parts by weight with respect to 100 parts by weight of the aqueous medium.

(3) Polymerization conditions A monomer mixture containing 50% by weight or more of a hydrophobic monomer is absorbed by the seed particles and polymerized. It is preferable that the said monomer mixture is 80-350 weight part with respect to 1 weight part of seed particles. More preferably, it is 150 to 300 parts by weight. If the monomer mixture absorbed by the seed particles is less than 80 parts by weight, the ratio of the seed particles increases, so that the productivity may deteriorate. On the other hand, when it exceeds 350 parts by weight, the absorption of the monomer into the seed particles becomes insufficient, and the monodispersibility may be lowered.
The polymerization temperature and polymerization time can be appropriately selected according to the type of monomer and polymerization initiator. The polymerization temperature is preferably 25 to 110 ° C, more preferably 60 to 90 ° C.
When the polymerization temperature is 60 to 90 ° C., the polymerization time can be 1 to 20 hours. The polymerization may be performed in an inert gas atmosphere inert to the polymerization, such as a nitrogen atmosphere.

  After polymerization is complete, the polymer particles are centrifuged as necessary to remove the aqueous medium, washed with water and / or solvent, and then dried and isolated. The method for isolating the polymer particles obtained by seed polymerization from the aqueous medium is not particularly limited. For example, a spray drying method represented by a spray dryer, a heated rotating drum represented by a drum dryer, and the like. And a method of adhering to the substrate and drying, or a freeze-drying method.

(Hydrophilic polymer particles)
The hydrophilic polymer particles of the present invention contain 0.0028% by weight or more of the polymer derived from the monomer of the general formula (1). If the amount contained is less than 0.0028% by weight, the hydrophilicity of the hydrophilic polymer particles may be insufficient. On the other hand, when the amount is too large, the refractive index of the obtained polymer particles may be lowered, and the cost may be increased. Preferably, it is 0.0028 wt% or more and less than 0.25 wt%, more preferably 0.0028 or more and less than 0.15 wt%, particularly preferably 0.003 wt% or more and less than 0.1 wt%.
The content of the polymer derived from the monomer of the general formula (1) in the polymer particles is the amount of the monomer mixture to be absorbed with the seed particles containing the polymer derived from the monomer of the general formula (1) to be used. It can be easily adjusted by adjustment.

  The polymer particles of the present invention are excellent in hydrophilicity, and the contact angle serving as an index for evaluating hydrophilicity is 96 ° or less. Preferably, it is 90-96 degrees, and 90-95 degrees is more preferable. Here, the contact angle refers to an angle between the solid layer and the liquid generated when the liquid is dropped on the solid layer. In addition, the measuring method of a contact angle is demonstrated in the column of an Example.

  Furthermore, although the polymer particles of the present invention contain a polymer derived from the monomer of the general formula (1), there is almost no decrease in the refractive index. The refractive index of the polymer particles is preferably 1.56 to 1.6, more preferably 1.59 to 1.6. In addition, the measuring method of a refractive index is demonstrated in the Example column.

  The particle diameter of the polymer particles of the present invention can be freely designed according to the particle diameter of the seed particles and the mixing ratio of the polymerizable monomer and the seed particles. The polymer particles of the present invention can be suitably used as monodisperse polymer particles having a particle size of 0.3 to 20 μm and a CV value of 15% or less. In addition, the measuring method of an average particle diameter and a coefficient of variation (CV value) is demonstrated in the Example column.

  The polymer particles of the present invention can be used as a light diffusing agent. In addition to light diffusing agents, paints such as LCD spacers, silver salt film surface modifiers, magnetic tape film modifiers, thermal paper running stabilizers, etc., rheology control agents, matting agents, etc.・ Chemical field such as ink and adhesive, medical field such as antigen-antibody reaction test particle, cosmetic field such as slip agent and extender pigment, low shrinkage agent of resin such as unsaturated polyester, paper, dental material, anti It can be used in general industrial fields such as blocking agents, matting agents, and resin modifiers.

(Manufacture of optical sheets)
Although an example of the manufacturing method of the optical sheet using the polymer particle of this invention is described below, it is not limited only to this method.

  The polymer particles of the present invention are mixed and stirred together with a binder resin and a solvent to prepare a resin composition for an optical sheet.

  The binder resin is not particularly limited as long as it is used in the field according to required properties such as transparency, particle dispersibility, light resistance, moisture resistance and heat resistance. Examples of the binder resin include (meth) acrylic resin, (meth) acrylic urethane resin, urethane resin, polyvinyl chloride resin, polyvinylidene chloride resin, melamine resin, styrene resin, alkyd resin, Phenolic resins, epoxy resins, polyester resins, (meth) acrylic silicone resins, alkylpolysiloxane resins, silicone resins, silicone alkyd resins, silicone urethane resins, silicone polyester resins, silicone acrylic resins, etc. Examples thereof include fluorine resins such as modified silicone resins, polyvinylidene fluoride, and fluoroolefin vinyl ether polymers. These binder resins may be thermoplastic, or curable resins such as thermosetting resins, ultraviolet curable resins, and electron beam curable resins. Of these binder resins, (meth) acrylic resins having excellent transparency are preferred.

  In addition to the above, organic binder resins such as synthetic rubber and natural rubber, inorganic binder resins, and the like can also be used. Examples of the organic binder resin include ethylene-propylene copolymer rubber, polybutadiene rubber, styrene-butadiene rubber, and acrylonitrile-butadiene rubber. Examples of the inorganic binder resin include silica sol, alkali silicate, silicon alkoxide, their (hydrolyzed) condensate, and phosphate. These may be used alone or in combination of two or more.

  As such a binder resin, a curable resin capable of forming a crosslinked structure by a crosslinking reaction is preferable from the viewpoint of improving the durability of the optical sheet resin composition. The binder resin can be cured under various curing conditions. As a curing type, a room temperature curing type, a heat curing type, an ultraviolet ray or an electron beam curing type, or the like can be adopted.

  The solvent contained in the optical sheet resin composition is not particularly limited as long as it can be easily applied to the base film described later, but includes, for example, toluene, xylene, and the like. Aromatic solvents such as isopropyl alcohol, n-butyl alcohol, propylene glycol methyl ether and dipropylene glycol methyl ether; ester solvents such as butyl acetate, ethyl acetate and cellosolve acetate; acetone, methyl ethyl ketone, methyl isobutyl Examples thereof include ketone solvents such as ketones and dimethylformamide. These solvents may be used alone or in combination of two or more.

  Moreover, the resin composition for optical sheets may contain crosslinking agent components such as a curing agent, a crosslinking agent, and a curing catalyst. By containing a crosslinking agent component in the optical sheet resin composition, the polymer in the binder resin can be crosslinked by the crosslinking agent component. There are no particular restrictions on the amount of addition, addition and dispersion method of the crosslinking agent component.

  Furthermore, if the resin composition for optical sheets is a range which does not impair the effect of this invention, it may contain the other component as needed. Examples of other components include pigments, dyes, plasticizers, polymerization stabilizers, antioxidants, fluorescent brighteners, ultraviolet absorbers, and antistatic agents. These may be used alone or in combination of two or more.

  The optical sheet can be obtained by forming the above-mentioned resin composition layer for an optical sheet on at least one surface of the base film by means such as coating. The coating method is not particularly limited, although it can be performed by various methods such as a roll coating method and a spray coating method.

  The material of the base film is not particularly limited as long as it has transparency. Examples thereof include polyester resins, polystyrene resins, polycarbonate resins, and cycloolefin resins. The thickness of the base film is preferably in the range of 5 to 300 μm. When it is thinner than 5 μm, handling during coating, printing, and secondary processing becomes difficult, and workability may be reduced. On the other hand, when it is thicker than 300 μm, the visible light transmittance of the base material itself is lowered, and the brightness of the optical sheet may be lowered. At least one surface of the surface of the base film is subjected to an easy adhesion treatment such as applying an easy adhesion treatment agent or applying a corona treatment in order to improve adhesion with the resin composition layer for the optical sheet. It is more preferable that it is applied.

  In addition to the method for producing an optical sheet by the coating method described above, an optical sheet may be produced by an extrusion method in which a mixture of a base resin and polymer particles is formed into an extruded sheet using an extruder and a T die.

  Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited thereto.

First, measurement methods and calculation methods in Examples and Comparative Examples will be described.
(Measurement of average particle size of seed particles)
The average particle diameter of the seed particles is measured by LS230 type manufactured by Beckman Coulter. Specifically, 0.1 g of seed particles and 10 m of a 0.1% nonionic surfactant solution are added and mixed for 2 seconds with a touch mixer TOUCHMIXER MT-31 manufactured by Yamato Kagaku. Thereafter, the test tube is dispersed for 10 minutes using a commercially available ultrasonic cleaner, ULTRASONIC CLEARNER VS-150, manufactured by Velvo Crea. The dispersed material is measured while irradiating ultrasonic waves with a model LS230 manufactured by Beckman Coulter. The optical model at that time is measured according to the refractive index of the created particles.

(Measurement of average particle size and coefficient of variation)
The average particle diameter is measured by performing calibration using a 50 μm aperture in accordance with Reference MANUAL FOR THE COULTER MULTISIZER (1987) published by Coulter Electronics Limited.
Specifically, 0.1 g of polymer particles are predispersed in 10 ml of 0.1% nonionic surfactant using a touch mixer and ultrasonic waves, and this is provided with ISOTON II (Beckman Coulter, Inc .: for measurement) In a beaker filled with (electrolyte), drop with a dropper while stirring gently, and adjust the reading of the densitometer on the main body screen to about 10%. Next, an aperture size of 50 μm, a current of 800, a gain of 4, and a polarity of + are input to the body of a Coulter Multisizer II (manufactured by Beckman Coulter, Inc .: measuring device) and measured manually. During the measurement, the beaker is gently stirred to the extent that bubbles do not enter, and the measurement is terminated when 100,000 polymer particles are measured. The average value of volume weight (arithmetic average particle size in volume% mode: volume median diameter) is calculated as the average particle size (x) of the polymer particles.
The coefficient of variation (Cv value) is a value calculated from the standard deviation (σ) and the average particle diameter (x) by the following formula.
Cv value (%) = (σ / x) × 100

(Calculation of content of polymer derived from monomer of general formula (1))
(1) Calculation of content in seed particles Amount of general formula (1) ÷ total monomer amount × 100
(Example: When 16 g of the general formula (1) is mixed in 320 g of the monomer (including the general formula), 16 ÷ 320 × 100 = 5%)
(2) Calculation of Content in Polymer Particles (Seed Particle Amount × Solid Content) ÷ Total Monomer Amount × 100 × Content in Seed Particles (Example: 5 g of General Formula (1) is added to 800 g of monomer) When 51 g of seed particles containing 1% (solid content 16.7%) are mixed, 51 × 0.167 ÷ 800 × 100 × 0.05 = 0.053%)
(Or content in seed particles ÷ swelling ratio)
It can be calculated by the ratio of the amount of monomer used for preparing polymer particles ÷ the amount of seed particles charged × the general formula (1) contained in the seed particles.

(Refractive index of polymer particles)
The optical refractive index of the polymer particles is measured by the Becke method. Specifically, it is performed as follows.
Resin particles are placed on a slide glass, and a refractive liquid (manufactured by CARGILLE: Cargill standard refractive liquid) is dropped. Mix resin particles and refraction liquid well and irradiate sodium lamp from below. When the contour of the particle is observed from the upper part and the contour is not visible, it is assumed that the refractive index of the refractive liquid and the resin particle are equal.

(Contact angle)
The contact angle of the hydrophobic powder is measured using a wet tester manufactured by Sanki Piotech. A fixed amount of powder is put into a Y-type cell to form a powder layer. A liquid (pure water) is allowed to flow at a constant flow rate, and the contact angle is measured from the capillary pressure of the powder layer with respect to the liquid. Even if the liquid reaches the lower surface of the powder layer, the liquid does not penetrate and the liquid level of the pressure measuring tube rises, and the pressure in the measuring tube rises according to Boyle's law, but reaches the capillary pressure of the powder layer. Then, the liquid begins to penetrate the powder layer, and the pressure increase deviates from Boyle's law. This is detected and the capillary pressure (Pc) is measured. The contact angle is obtained from the obtained data by the following formula.
The contact angle measurement range in this apparatus is 90 ° to 180 °, and the closer to 90 °, the more hydrophilic.
γL: liquid surface tension rc: capillary radius A: powder layer cross-sectional area L: powder layer thickness ΔP: air pressure loss Q: air flow rate μ: air (gas) viscosity K0: Kozeny-Carman constant g : Gravity acceleration

(Evaluation of coating unevenness)
A solution in which toluene and methyl ethyl ketone are mixed 1: 1 with a dispersion solution in which 140 parts by weight of an acrylic binder (trade name: manufactured by Mitsubishi Rayon Co., Ltd .: Dianar LR-102) is mixed with 100 parts by weight of polymer particles. Of 260 parts by weight. This is stirred for 3 minutes with a centrifugal stirrer. The resulting solution is allowed to stand for 3 hours and then stirred again for 3 minutes with a centrifugal stirrer. Subsequently, the obtained solution is apply | coated on a PET film using a 100 micrometer coater. The obtained film is dried for 1 hour in a drier kept at 70 ° C. to obtain a light diffusion film.
Appearance evaluation of unevenness (bad appearance) of the obtained light diffusing film is performed and evaluated according to the following criteria.
◎: No unevenness perceived by eyes, extremely excellent appearance ○: Excellent appearance with slight unevenness slightly confirmed Δ: Some unevenness is confirmed in some places ×: Fine on the entire surface Extremely bad appearance with obvious unevenness

Example 1
(1-1) Production of first-stage seed particles In a separable flask equipped with a stirrer, a thermometer and a reflux condenser, 1300 g of ion-exchanged water, 320 g of methyl methacrylate (MMA) and 1-octanethiol as a molecular weight regulator A solution in which 3 g was dissolved was added, and the temperature was raised to 70 ° C. in a nitrogen atmosphere while stirring. A solution obtained by dissolving 1.6 g of ammonium persulfate as a polymerization initiator in 300 g of ion-exchanged water was continuously added and stirred at 70 ° C. for 12 hours to carry out a polymerization reaction. By this polymerization reaction, a dispersion (solid content 16.7%) containing polymethyl methacrylate particles (hereinafter referred to as seed particles 1) having an average particle size of 0.5 μm was obtained.

(1-2) Production of second stage seed particles In a separable flask equipped with a stirrer, a thermometer and a reflux condenser, 1300 g of ion-exchanged water, 304 g of methyl methacrylate, and poly (ethylene glycol-propylene glycol) monomethacrylate (Blemmer) 50PEP-300: manufactured by NOF Corporation, m is about 3.5, n is about 2.5) 16 g of 1-octanethiol as a molecular weight regulator was dissolved. Further, 160 g of a dispersion of seed particles 1 was added, and the temperature was raised to 70 ° C. in a nitrogen atmosphere while stirring. A solution obtained by dissolving 1.6 g of ammonium persulfate as a polymerization initiator in 300 g of ion-exchanged water was continuously added and stirred at 70 ° C. for 12 hours to carry out a polymerization reaction. By this polymerization reaction, a dispersion (solid content 16.7%) containing polymethyl methacrylate particles (hereinafter referred to as seed particles 2) having an average particle size of 0.9 μm was obtained.

(1-3) Production of polymer particles Monomer prepared by dissolving 8 g of t-butylperoxy-2-ethylhexanate in a vinyl monomer composed of 40 g of methyl methacrylate, 520 g of styrene, and 240 g of ethylene glycol dimethacrylate. A mixture was obtained. This monomer mixture was mixed with 800 g of ion-exchanged water containing 8 g of sodium dioctyl sulfosuccinate as a surfactant to obtain a mixed solution. The obtained mixed solution was treated with T.W. It was put into K homomixer Mark 2.5 type (made by Tokushu Kika Kogyo Co., Ltd.) and treated at 9000 rpm for 10 minutes to obtain an emulsion. To this emulsion, 51 g of seed particle 2 dispersion was added and stirred at 30 ° C. for 4 hours. When the dispersion after stirring was observed with an optical microscope, it was found that the monomer in the emulsion was completely absorbed by the seed particles. To this stirred dispersion, 2400 g of 88% part-saponified polyvinyl alcohol 4% aqueous solution and 0.64 g of sodium nitrite were added. Thereafter, the monomer in the dispersion was polymerized at 70 ° C. for 3 hours. Subsequently, it stirred at 105 degreeC for 2.5 hours, and the organic peroxide was decomposed | disassembled. Then, solid content was obtained by filtration. The solid content was taken out, and dried at 60 ° C. for 12 hours with a vacuum dryer. As a result, polymer particles were obtained.

(1-4) Evaluation of polymer particles The obtained polymer particles were monodisperse particles having an average particle diameter of 5.8 μm, a CV value of 10.1%, a refractive index of 1.56, and a contact angle of 94.4 °. It was. In addition, the content of Blemmer 50PEP-300 in the polymer particles was 0.053% by weight. In addition, when the film was created using the obtained polymer particle, the coating unevenness of the film was not at all ((double-circle)).

(Example 2)
(2-1) Manufacture of first-stage seed particles Average particle size is the same as Example 1 (manufacture of first-stage seed particles) except that 50 PEP300 is 3.2 g and MMA is 316.8 g. A dispersion (solid content: 16.7%) containing polymethyl methacrylate particles (hereinafter referred to as seed particles 3) having a diameter of 0.49 μm was obtained.

(2-2) Production of polymer particles A monomer mixture in which 8 g of t-butylperoxy-2-ethylhexanate was dissolved in a vinyl monomer composed of 480 g of styrene and 320 g of ethylene glycol dimethacrylate was obtained. This monomer mixture was mixed with 800 g of ion-exchanged water containing 6.4 g of sodium dioctyl sulfosuccinate as a surfactant (6.4 times the critical micelle concentration) to obtain a mixed solution. The obtained mixed solution was treated with T.W. It was put into K homomixer Mark 2.5 type (made by Tokushu Kika Kogyo Co., Ltd.) and treated at 9000 rpm for 10 minutes to obtain an emulsion. To this emulsion, 18 g of a dispersion of seed particles 3 was added and stirred at 30 ° C. for 4 hours. When the dispersion after stirring was observed with an optical microscope, it was found that the monomer in the emulsion was completely absorbed by the seed particles. To this stirred dispersion, 2400 g of 88% part-saponified polyvinyl alcohol 4% aqueous solution and 0.64 g of sodium nitrite were added. Thereafter, the monomer in the dispersion was polymerized at 70 ° C. for 3 hours. Subsequently, it stirred at 105 degreeC for 2.5 hours, and the organic peroxide was decomposed | disassembled. Then, solid content was obtained by filtration. The solid content was taken out, and dried at 60 ° C. for 12 hours with a vacuum dryer. As a result, polymer particles were obtained.

(2-3) Evaluation of polymer particles The obtained polymer particles were monodisperse particles having an average particle diameter of 2.9 µm, a CV value of 13.3%, a refractive index of 1.56, and a contact angle of 96 °. In addition, the content of Blemmer 50PEP-300 in the polymer particles was 0.0038% by weight. In addition, when the film was created using the obtained polymer particle, the coating unevenness of the film was not at all ((double-circle)).

Example 3
(3-1) Production of first-stage seed particles The same as Example 1 (production of first-stage seed particles).
(3-2) Production of second-stage seed particles Instead of poly (ethylene glycol-propylene glycol) monomethacrylate (Blenmer 50PEP-300: manufactured by NOF Corporation, m is about 3.5, and n is about 2.5) Poly (ethylene glycol-propylene glycol) monomethacrylate (Blenmer 70PEP-350: manufactured by NOF Corporation, m is about 5 and n is about 2). A dispersion (solid content 16.7%) containing polymethyl methacrylate particles (hereinafter referred to as seed particles 4) having an average particle size of 0.9 μm was obtained by the same operation as in the production.

(3-3) Production of Polymer Particles Polymer particles were obtained in the same manner as in Example 1 (Production of polymer particles) except that seed particles 4 were used instead of seed particles 2.
(3-4) Evaluation of polymer particles The obtained polymer particles were monodisperse particles having an average particle diameter of 5.8 μm, a CV value of 11.2%, a refractive index of 1.56, and a contact angle of 95.1 °. It was. In addition, the content of Blemmer 70PEP-350 in the polymer particles was 0.053% by weight. In addition, when the film was created using the obtained polymer particle, the coating unevenness of the film was not at all ((double-circle)).

Example 4
(4-1) Production of first-stage seed particles In a separable flask equipped with a stirrer, a thermometer and a reflux condenser, 1300 g of ion-exchanged water, 313.6 g of methyl methacrylate (MMA), poly (ethylene glycol-propylene glycol) ) Monomethacrylate (Blemmer 50PEP-300: manufactured by NOF Corporation, m is about 3.5, n is about 2.5) 6.4g was charged with 3g of 1-octanethiol as a molecular weight regulator. The temperature was raised to 70 ° C. in a nitrogen atmosphere with stirring. A solution obtained by dissolving 1.6 g of ammonium persulfate as a polymerization initiator in 300 g of ion-exchanged water was continuously added and stirred at 70 ° C. for 12 hours to carry out a polymerization reaction. By this polymerization reaction, a dispersion (solid content 16.7%) containing polymethyl methacrylate particles (hereinafter referred to as seed particles 5) having an average particle diameter of 0.5 μm was obtained.

(4-2) Production of polymer particles A monomer mixture in which 10 g of t-butylperoxy-2-ethylhexanate was dissolved in a vinyl monomer composed of 600 g of styrene and 400 g of ethylene glycol dimethacrylate was obtained. This monomer mixture was mixed with 1000 g of ion-exchanged water containing 8 g of sodium dioctylsulfosuccinate as a surfactant (6.4 times the critical micelle concentration) to obtain a mixed solution. The obtained mixed solution was treated with T.W. It was put into K homomixer Mark 2.5 type (made by Tokushu Kika Kogyo Co., Ltd.) and treated at 9000 rpm for 10 minutes to obtain an emulsion. To this emulsion, 23 g of a dispersion of seed particles 5 was added and stirred at 30 ° C. for 4 hours. When the dispersion after stirring was observed with an optical microscope, it was found that the monomer in the emulsion was completely absorbed by the seed particles. To this stirred dispersion, 2000 g of a 88% part-saponified polyvinyl alcohol 4% aqueous solution and 0.6 g of sodium nitrite were added. Thereafter, the monomer in the dispersion was polymerized at 70 ° C. for 3 hours. Subsequently, it stirred at 105 degreeC for 2.5 hours, and the organic peroxide was decomposed | disassembled. Then, solid content was obtained by filtration. The solid content was taken out, and dried at 60 ° C. for 12 hours with a vacuum dryer. As a result, polymer particles were obtained.

(4-3) Evaluation of polymer particles The obtained polymer particles were monodisperse particles having an average particle diameter of 2.9 μm, a CV value of 12.4%, a refractive index of 1.56, and a contact angle of 95.6 °. It was. In addition, the content of Blemmer 50PEP-300 in the polymer particles was 0.0076% by weight. In addition, when the film was created using the obtained polymer particle, the coating unevenness of the film was not at all ((double-circle)).

(Example 5)
(5-1) Production of first-stage seed particles In a separable flask equipped with a stirrer, a thermometer and a reflux condenser, ion-exchanged water 600 g, methyl methacrylate (MMA) 190 g, poly (ethylene glycol-propylene glycol) mono A solution prepared by dissolving 2 g of 1-octanethiol as a molecular weight regulator in 10 g of methacrylate (Blemmer 50PEP-300: manufactured by NOF Corporation, m is about 3.5, n is about 2.5) and stirred. The temperature was raised to 70 ° C. in a nitrogen atmosphere. A solution obtained by dissolving 1 g of ammonium persulfate as a polymerization initiator in 200 g of ion-exchanged water was continuously added and stirred at 70 ° C. for 12 hours to carry out a polymerization reaction. By this polymerization reaction, a dispersion containing polymethyl methacrylate particles (hereinafter referred to as seed particles 6) having a solid content of 20% and an average particle diameter of 0.6 μm was obtained.

(5-2) Production of polymer particles A monomer mixture in which 10 g of t-butylperoxy-2-ethylhexanate was dissolved in a vinyl monomer composed of 720 g of styrene and 80 g of divinylbenzene was obtained. This monomer mixture was mixed with 1000 g of ion-exchanged water containing 6.4 g of sodium dioctylsulfosuccinate as a surfactant (6.4 times the critical micelle concentration) to obtain a mixed solution. The obtained mixed solution was treated with T.W. It was put into K homomixer Mark 2.5 type (made by Tokushu Kika Kogyo Co., Ltd.) and treated at 9000 rpm for 10 minutes to obtain an emulsion. To this emulsion, 26 g of a dispersion of seed particles 6 was added and stirred at 30 ° C. for 4 hours. When the dispersion after stirring was observed with an optical microscope, it was found that the monomer in the emulsion was completely absorbed by the seed particles. To this stirred dispersion, 2000 g of a 88% part-saponified polyvinyl alcohol 4% aqueous solution and 0.6 g of sodium nitrite were added. Thereafter, the monomer in the dispersion was polymerized at 70 ° C. for 3 hours. Subsequently, it stirred at 105 degreeC for 2.5 hours, and the organic peroxide was decomposed | disassembled. Then, solid content was obtained by filtration. The solid content was taken out, and dried at 60 ° C. for 12 hours with a vacuum dryer. As a result, polymer particles were obtained.

(5-3) Evaluation of polymer particles The obtained polymer particles were monodisperse particles having an average particle diameter of 3.0 μm, a CV value of 11.1%, a refractive index of 1.59, and a contact angle of 95.2 °. It was. In addition, the content of Blemmer 50PEP-300 in the polymer particles was 0.033% by weight. In addition, when the film was created using the obtained polymer particle, the coating unevenness of the film was not at all ((double-circle)).

(Comparative Example 1)
(6-1) Production of first-stage seed particles The same as Example 1 (production of first-stage seed particles).
(6-2) Production of second-stage seed particles Example 1 (second-stage seed particles) except that 320 g of methyl methacrylate was used without using poly (ethylene glycol-propylene glycol) monomethacrylate. A dispersion containing polymethylmethacrylate particles (hereinafter referred to as seed particles 7) having an average particle size of 1.0 μm was obtained by the same operation as in (Production).

(6-3) Production of Polymer Particles Polymer particles were obtained in the same manner as in Example 1 (Production of polymer particles) except that seed particles 7 were used instead of seed particles 2.
(6-4) Evaluation of polymer particles The obtained polymer particles were monodisperse particles having an average particle diameter of 5.9 μm, a CV value of 13.2%, a refractive index of 1.56, and a contact angle of 100.9 °. It was. The polymer particles do not contain poly (ethylene glycol-propylene glycol) monomethacrylate. In addition, when the film was created using the obtained polymer particle, the coating nonuniformity like a stripe was confirmed in a part of film ((triangle | delta)).

(Comparative Example 2)
(7-1) Production of first-stage seed particles The same as Example 1 (production of first-stage seed particles).
(7-2) Production of second-stage seed particles The same as Comparative Example 1 (production of second-stage seed particles).
(7-3) Production of Polymer Particles 0.424 g of poly (ethylene glycol-propylene glycol) monomethacrylate (Blenmer 50PEP-300: manufactured by NOF Corporation, m is about 3.5, n is about 2.5) Except for addition of 0.053%, polymer particles were obtained by the same operation as in Comparative Example 1 (Production of polymer particles).
(6-4) Evaluation of polymer particles The obtained polymer particles were monodisperse particles having an average particle diameter of 5.9 μm, a CV value of 12.4%, a refractive index of 1.56, and a contact angle of 99 °. . In addition, the content of Blemmer 50PEP-300 in the polymer particles was 0.053% by weight as in Example 1. In addition, when the film was created using the obtained polymer particle, the coating nonuniformity like a stripe was confirmed in a part of film ((triangle | delta)).

(Comparative Example 3)
(8-1) Production of first-stage seed particles The same as Example 1 (production of first-stage seed particles).
(8-2) Production of second-stage seed particles The same as Comparative Example 1 (production of second-stage seed particles).
(8-3) Production of polymer particles Poly (ethylene glycol-propylene glycol) monomethacrylate (Blenmer 50PEP-300: manufactured by NOF Corporation, m is about 3.5, and n is about 2.5. ) Polymer particles were obtained in the same manner as in Comparative Example 1 (Production of polymer particles) except that 160 g (20% by weight of polymer particles) was added.
(8-4) Evaluation of polymer particles The obtained polymer particles were monodisperse particles having an average particle diameter of 5.7 μm, a CV value of 9.1%, a refractive index of 1.54, and a contact angle of 94.6 °. It was. In addition, the content of Blemmer 50PEP-300 in the polymer particles was 16.7% by weight. In addition, when a film was prepared using the obtained polymer particles, there was no coating unevenness, but the appearance was deteriorated due to a decrease in the refractive index (Δ).

(Comparative Example 4)
(9-1) Production of first-stage seed particles In a separable flask equipped with a stirrer, thermometer and reflux condenser, ion-exchanged water 600 g, methyl methacrylate (MMA) 200 g and 1-octanethiol as a molecular weight regulator A solution in which 2 g was dissolved was added, and the temperature was raised to 70 ° C. in a nitrogen atmosphere while stirring. A solution obtained by dissolving 1 g of ammonium persulfate as a polymerization initiator in 200 g of ion-exchanged water was continuously added and stirred at 70 ° C. for 12 hours to carry out a polymerization reaction. By this polymerization reaction, a dispersion containing polymethyl methacrylate particles (hereinafter referred to as seed particles 8) having a solid content of 20% and an average particle diameter of 0.6 μm was obtained.

(9-2) Production of polymer particles A monomer mixture in which 10 g of t-butylperoxy-2-ethylhexanate was dissolved in a vinyl monomer composed of 720 g of styrene and 80 g of divinylbenzene was obtained. This monomer mixture was mixed with 1000 g of ion-exchanged water containing 6.4 g of sodium dioctylsulfosuccinate as a surfactant (6.4 times the critical micelle concentration) to obtain a mixed solution. The obtained mixed solution was treated with T.W. It was put into K homomixer Mark 2.5 type (made by Tokushu Kika Kogyo Co., Ltd.) and treated at 9000 rpm for 10 minutes to obtain an emulsion. To this emulsion, 26 g of a dispersion of seed particles 8 was added and stirred at 30 ° C. for 4 hours. When the dispersion after stirring was observed with an optical microscope, it was found that the monomer in the emulsion was completely absorbed by the seed particles. To this stirred dispersion, 2000 g of a 88% part-saponified polyvinyl alcohol 4% aqueous solution and 0.6 g of sodium nitrite were added. Thereafter, the monomer in the dispersion was polymerized at 70 ° C. for 3 hours. Subsequently, it stirred at 105 degreeC for 2.5 hours, and the organic peroxide was decomposed | disassembled. Then, solid content was obtained by filtration. The solid content was taken out, and dried at 60 ° C. for 12 hours with a vacuum dryer. As a result, polymer particles were obtained.

(9-3) Evaluation of polymer particles The obtained polymer particles were monodisperse particles having an average particle diameter of 3.1 µm, a CV value of 12.4%, a refractive index of 1.59, and a contact angle of 108 °. In addition, when the film was created using the obtained polymer particle, the coating nonuniformity like a stripe was confirmed in a part of film ((triangle | delta)).
Table 1 summarizes the amounts and results of the raw materials used in Examples 1 to 5 and Comparative Examples 1 to 4.

50PEP-300: poly (ethylene glycol-propylene glycol) monomethacrylate (Blemmer 50PEP-300: manufactured by NOF Corporation, m is about 3.5, n is about 2.5)
70PEP-350: poly (ethylene glycol-propylene glycol) monomethacrylate (Blemmer 70PEP-350: manufactured by NOF Corporation, m is about 5, n is about 2)
MMA: methyl methacrylate St: styrene EGDMA: ethylene glycol dimethacrylate DVB: divinylbenzene

From the results of Examples and Comparative Examples, 1 to 20 parts by weight of poly (ethylene glycol-propylene glycol) monomethacrylate which is a monomer represented by the general formula (1) according to the present invention and vinyl other than the general formula (1). Polymer particles using seed particles obtained by polymerizing a monomer mixture for producing seed particles containing 100 parts by weight of a system monomer are monodisperse particles excellent in hydrophilicity but are refracted. It turns out that the rate is also high.
In Comparative Example 2, poly (ethylene glycol-propylene glycol) monomethacrylate (50PEP300) was added so as to have the same content as the polymer particles in Example 1 when the polymer particles were produced. The same results (effects) could not be obtained. The reason for this is that 50PEP300 contained in the seed particles is dispersed as seed particles throughout the system, but when added to the third stage, the seed particles are more uniformly distributed as a whole due to the difference in SP value of the monomers. This is probably because it is not dispersed.

Claims (5)

The following general formula (1)
(In the formula, R1 is H or CH ₃ , m is 1 to 50, and n is 1 to 50)
A step of obtaining seed particles by polymerizing a monomer mixture containing 1 to 20 parts by weight of a monomer represented by formula (100) and 100 parts by weight of a vinyl monomer other than the general formula (1); A method of producing a hydrophilic polymer particle comprising a step of absorbing and polymerizing a monomer mixture containing 50% by weight or more of a hydrophobic monomer in the particle, wherein the hydrophilic polymer particle has the general formula A method for producing hydrophilic polymer particles, comprising 0.0028% by weight or more of the monomer-derived polymer represented by (1) and having a contact angle of 96 ° or less.   The method for producing hydrophilic polymer particles according to claim 1, wherein the monomer mixture containing 50% by weight or more of the hydrophobic monomer is used in an amount of 80 to 350 parts by weight with respect to 1 part by weight of the seed particles. The following general formula (1)
(In the formula, R1 is H or CH ₃ , m is 1 to 50, and n is 1 to 50)
Hydrophobic to seed particles obtained by polymerizing a monomer mixture containing 1 to 20 parts by weight of a monomer represented by formula (100) and 100 parts by weight of a vinyl monomer other than the general formula (1) It is obtained by absorbing and polymerizing a monomer mixture containing 50% by weight or more of monomers, and contains 0.0028% by weight or more of the polymer derived from the monomer represented by the general formula (1), Hydrophilic polymer particles having a contact angle of 96 ° or less.   The hydrophilic monomer according to claim 3, wherein the vinyl monomer other than the general formula (1) is a (meth) acrylic monomer, and the hydrophobic monomer is a monofunctional styrene monomer. Polymer particles.   The hydrophilic polymer particle according to claim 3 or 4, wherein the hydrophilic polymer particle has a refractive index of 1.56 to 1.60.