JP4513359B2 - Cross-linked fine particles - Google Patents

Description

  The present invention relates to a crosslinked fine particle containing a fluorine atom and a hydrophilic group. The crosslinked fine particles are expected to have a low refractive index derived from fluorine atoms and good compatibility with a resin derived from a hydrophilic group.

In recent years, with the widespread use, enlargement, and outdoor use of liquid crystal display devices, weather resistance, visibility, antifouling properties, heat resistance, and the like under the use conditions have been demanded. Above all, improvement of the visibility of the display device is an important issue related to the main function of the display device, and various techniques for improving the visibility have been studied.
As such a technique, fine particles having a refractive index different from that of the base resin are dispersed in the base resin such as an antireflection film, a light diffusing film, and a light scattering film to control light reflection, diffusibility, and scattering. There is a way.

  For example, conventionally, a reflection type liquid crystal display device requires a reflection plate that reflects light such as room light and external light incident on the device, and this reflection plate has two functions of light reflection and scattering. Function is required. As a member that has a light scattering function, a light scattering film that produces scattering properties by mixing fine particles of different refractive index in transparent resin such as acrylic resin, epoxy resin, polyester resin, polyamide resin, polyurethane resin, polyimide resin, etc. is used. It has been. This light scattering film is required to have excellent light scattering properties and light transmission properties, and the light scattering properties indicate superior scattering properties as the refractive index difference between the base resin and the fine particles increases. Distribution is also greatly affected.

  When an inorganic powder such as glass, quartz, silicon oxide, calcium carbonate, titanium oxide, or zinc oxide is used as a light scattering agent, it is generally poor in uniform light scattering because the particle shape varies and the particle size varies greatly. There are problems such as low light transmission and roughening of the film surface. Therefore, by using organic resin fine particles such as internally crosslinked acrylic resin as a light scattering agent, the light transmittance is improved as compared with the case of using inorganic powder, but the refractive index difference between the fine particles and the base resin is small. In addition, there is a problem that a cleaning step is necessary because a stabilizer such as a surfactant and a dispersion stabilizer used at the time of resin fine particle synthesis has an adverse effect.

Therefore, the present inventors disclosed a method for synthesizing fine crosslinked particles in the absence of a dispersion stabilizer by using a specific initiator in JP-A-2001-278907. However, sufficient consideration has not been made in terms of refractive index. Therefore, in order to give a sufficient difference in refractive index from the base resin, introduction of a fluorine group was attempted. As the fluorine group content was increased, water and oil repellency originated from the fluorine group. It has been found that the particles may be biased in the film, and the practical physical properties may not be satisfied.
Japanese Patent Laid-Open No. 2001-278907

  That is, an object of the present invention is to provide monodispersed cross-linked fine particles that have a sufficient difference in refractive index from the base resin and do not cause unevenness in the coating film, for example, have excellent physical properties as a light scattering agent. There is.

  As a result of intensive studies to achieve the above object, the present inventor found that the fine particles of the present invention are suitable for achieving the above object, and completed the present invention.

That is, in the present invention, the non-crosslinkable monomer (A) and the crosslinkable monomer (B) containing the fluorine group-containing monomer are represented by the following formula (1) or the following formula (2) in a solvent. A light scattering agent comprising fine particles polymerized using a polymerization initiator ,
The fluorine group-containing monomer is 10 to 95% by weight based on the total amount of the monomer, and the crosslinkable or non-crosslinkable hydrophilic group-containing monomer is 1 to 10 based on the total amount of the monomer. It relates to a light scattering agent which is weight%.

Formula (1)

[Wherein, R ¹ and R ² each independently represents a hydrogen atom, an alkyl group or an aromatic group. ]

Formula (2)

[Wherein, R ³ and R ⁴ each independently represent an alkylene group or a divalent aromatic group. ]

Further, the present invention is characterized in that the crosslinkable monomer (B) is a polyfunctional monomer having a polymerizable unsaturated carboxylic acid residue and a reactive functional group other than the polymerizable unsaturated carboxylic acid residue. It relates to the light scattering agent .

Further, the present invention is a light scattering agent having a substantially uniform particle size, and the average particle size of the light scattering agent for the above light scattering agent which is a 0.1～8.0Myuemu.

Further, the present invention relates to an optical decomposition temperature of the scattering agent 240 ° C. or higher, to the light scattering agent which gel fraction and wherein the 95% or more.

The present invention also relates to the light scattering agent , wherein the solvent is a mixed solvent of water and alcohol.

In the present invention, in the absence of a dispersion stabilizer, the non-crosslinkable monomer (A) and the crosslinkable monomer (B) containing a fluorine group-containing monomer are represented by the following formula (1) or A method for producing a light scattering agent to be polymerized using a polymerization initiator represented by formula (2),
The fluorine group-containing monomer is 10 to 95% by weight based on the total amount of the monomer, and the crosslinkable or non-crosslinkable hydrophilic group-containing monomer is 1 to 10 based on the total amount of the monomer. The present invention relates to a method for producing a light scattering agent having a weight percentage.

Formula (1)

[Wherein, R ¹ and R ² each independently represent a hydrogen atom, an alkyl group or an aromatic group. ]

Formula (2)

[Wherein, R ³ and R ⁴ each independently represent an alkylene group or a divalent aromatic group. ]

  According to the present invention, monodispersed cross-linked fine particles having excellent physical properties as a light scattering agent that does not cause a bias in the coating film while having a sufficient refractive index difference from the base resin are obtained.

  The pre-crosslinked fine particles referred to in the present invention are fine particles whose inside is cross-linked at the end of polymerization, and can be fine particles having excellent solvent resistance and heat resistance due to cross-linking inside the particles.

  The crosslinkable monomer (B) of the present invention is a bifunctional or trifunctional or higher polyfunctional monomer having a functional group for imparting crosslinkability, and functions as a crosslinking agent. At least one of the functional groups of the crosslinkable monomer (B) is necessary to cause copolymerization with the non-crosslinkable monomer (A), and the remaining functional groups are used as functional groups for imparting crosslinkability. Function.

Examples of the functional group for imparting crosslinkability of the crosslinkable monomer (B) include vinyl groups, hydroxyl groups, epoxy groups, carboxyl groups, alkoxysilyl groups, and the like. Crosslinking by an addition reaction with a carboxy group or a hydroxyl group, crosslinking by hydrolysis and condensation reaction of an alkoxysilyl group, and the like are exemplified, but the invention is not particularly limited thereto.
However, when it cannot be expected that all the functional groups for imparting crosslinkability can participate in the crosslinking, a functional group for imparting unreacted crosslinkability may finally exist.

  Among them, cross-linking by radical polymerization of vinyl groups occurring during the growth of the polymer is preferable, and more preferably, each functional group from the viewpoint that aggregation and polydispersion of particles during polymerization hardly occur and heat resistance of the generated particles is good. Monomers with different reactivity are preferred. Specifically, a polymerizable unsaturated carboxylic acid residue such as a (meth) acrylic acid residue, a crotonic acid residue, a maleic acid residue, and an itaconic acid residue, and other than the polymerizable unsaturated carboxylic acid residue A compound having a reactive functional group is preferred. Examples of the reactive functional group other than the polymerizable unsaturated carboxylic acid residue include reactive functional groups such as a vinyl group, a hydroxyl group, an epoxy group, and an alkoxysilyl group.

For example, as the vinyl group, an unsaturated group-containing alkyl group having 1 to 11 carbon atoms such as ethenyl group, 1-propenyl group, allyl group, isopropenyl group, 1-butenyl group, 2-butenyl group, 2-pentenyl group, etc. An unsaturated group-containing aromatic group such as a styryl group or a cinnamyl group; a heterocyclic group-containing acrylic group such as a tetrahydrofurfuryl group;
Examples of the hydroxy group include hydroxyalkylene groups such as a hydroxy group, a hydroxymethylene group, and a hydroxyethylene group;
As an epoxy group, a glycidyl group;
Examples of the alkoxysilyl group include, but are not limited to, alkoxysilyl groups such as a trimethoxysilyl group and a triethoxysilyl group.

  Examples of the crosslinkable monomer (B) include allyl (meth) acrylate, 1-methylallyl (meth) acrylate, 2-methylallyl (meth) acrylate, 1-butenyl (meth) acrylate, (meth) acrylic acid 2 -Butenyl, 3-butenyl (meth) acrylate, 1,3-methyl-3-butenyl (meth) acrylate, 2-chloroallyl (meth) acrylate, 3-chloroallyl (meth) acrylate, (meth) acrylic acid o-allylphenyl, 2- (allyloxy) ethyl (meth) acrylate, allyl lactyl (meth) acrylate, citronellyl (meth) acrylate, geranyl (meth) acrylate, rosinyl (meth) acrylate, (meth) acrylic acid Cinnamyl, diallyl maleate, diallyl itaconic acid, vinyl (meth) acrylate, vinyl crotonate, vinyl oleate, vinyl linolenate, etc. Of unsaturated group-containing (meth) acrylic acid esters;

Heterocycle-containing (meth) acrylic acid esters such as (meth) acrylic acid glycidyl, (meth) acrylic acid (3,4-epoxycyclohexyl) methyl, (meth) acrylic acid tetrahydrofurfuryl; (meth) acrylic acid 2- Hydroxy (alkoxy) -containing (meth) acrylic acid esters such as hydroxyethyl, hydroxypropyl (meth) acrylate, 2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate;

Di (meth) acrylic acid ethylene glycol, di (meth) acrylic acid triethylene glycol, di (meth) acrylic acid tetraethylene glycol, tri (meth) acrylic acid trimethylolpropane, tri (meth) acrylic acid pentaerythritol, diacrylic acid Polyfunctional (meth) acrylic acid esters such as 1,1,1-trishydroxymethylethane, 1,1,1-trishydroxymethylethane triacrylate, 1,1,1-trishydroxymethylpropanetriacrylic acid;

3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-methacryloxypropyltriisopropoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, vinyltrimethoxy Alkoxysilyl group-containing monomers such as silane, vinyltriethoxysilane, vinyltris (2-methoxyethoxy) silane;

Divinyls such as divinylbenzene and divinyl adipate;
Diallyls such as diallyl isophthalate, diallyl phthalate and diallyl maleate; unsaturated carboxylic acids such as (meth) acrylic acid and itaconic acid;
Unsaturated carboxylic acid anhydrides such as itaconic anhydride and maleic anhydride; and the like are exemplified, but the invention is not particularly limited thereto.

Also, two or more of these can be used in combination. Moreover, it is preferable that the quantity of the monomer (B) in all the monomers is 5 to 30 weight%.
The non-crosslinkable monomer (A) is a monomer having no functional group for imparting the above crosslinkability, and includes methyl (meth) acrylate, ethyl (meth) acrylate, isopropyl (meth) acrylate, (meth) Propyl acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, n-amyl (meth) acrylate, isoamyl (meth) acrylate, (meth) acrylic acid n-hexyl, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate, octadecyl (meth) acrylate, cyclohexyl (meth) acrylate, Acrylic acid esters such as benzyl (meth) acrylate, isobornyl (meth) acrylate, and phenyl (meth) acrylate Kind;

Examples include styrene monomers such as styrene, vinyl toluene, α-methyl styrene, β-methyl styrene, o-methyl styrene, m-methyl styrene, p-methyl styrene, 1-butyl styrene, chlorostyrene, and the like. It is not limited. Moreover, these can also be used in combination of 2 or more types.

Among them, in order to sufficiently increase the difference in refractive index from the base resin, it is preferable to use a monomer having a relatively low refractive index that does not contain an aromatic group.
In addition, in order to bring out physical properties such as surface charge adjustment and storage stability, (meth) acrylic acid, 2- (meth) acryloyloxyethyl succinic acid, 2- (meth) acryloyloxyethylphthalic acid, 2- ( A carboxyl group-containing ester such as (meth) acryloyloxyethyl hexahydrophthalic acid may be used in an amount of 0 to 15% by weight based on the whole non-crosslinkable monomer (A).

  The fluorine group-containing monomer contained in the non-crosslinkable monomer (A) may be a compound that dissolves in the polymerization solvent and causes copolymerization with the non-crosslinkable monomer (A). For example, fluorine group-containing (meth) such as trifluoroethyl (meth) acrylate, tetrafluoropropyl (meth) acrylate, hexafluoropropyl (meth) acrylate, octafluoropentyl (meth) acrylate, heptadecafluorodecyl (meth) acrylate, etc. Examples of the acrylate include, but are not limited to, acrylate. Moreover, these can also be used in combination of 2 or more types.

  The fluorine group-containing monomer contained in the non-crosslinkable monomer (A) is preferably contained in an amount of 10 to 95% by weight based on the total amount of the non-crosslinkable monomer (A) and the crosslinkable monomer (B). If it is less than 10% by weight, sufficient light scattering properties are not exhibited.

  The hydrophilic group-containing monomer as used in the present invention is a compound having a polar group having a strong interaction with water, and is a compound that dissolves in a polymerization solvent and causes copolymerization with the non-crosslinkable monomer (A). It ’s fine. Examples of the hydrophilic group include, but are not limited to, a hydroxyl group, a carboxyl group, an amino group, a sulfonic acid group, and an oxyethylene group. In the above, it can serve as the functional group which provides the crosslinkability of this invention other than an oxyethylene group.

  Examples of the hydrophilic group-containing monomer in the present invention include 2-hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, glycerol (meth) acrylate, (meth ) Hydroxy-containing unsaturated compounds such as polyethylene glycol acrylate, polypropylene glycol (meth) acrylate, polyethylene glycol polypropylene glycol (meth) acrylate, 4-hydroxyvinylbenzene, 1-ethynyl-1-cyclohexanol, allyl alcohol;

Maleic acid, fumaric acid, itaconic acid, citraconic acid, or alkyl or alkenyl monoesters thereof, phthalic acid β- (meth) acryloxyethyl monoester, isophthalic acid β- (meth) acryloxyethyl monoester, terephthalic acid carboxyl-containing unsaturated compounds such as β- (meth) acryloxyethyl monoester, succinic acid β- (meth) acryloxyethyl monoester, (meth) acrylic acid, crotonic acid, cinnamic acid;

(Meth) acrylamide, N-methylol (meth) acrylamide, N-methoxymethyl- (meth) acrylamide, N-ethoxymethyl- (meth) acrylamide, N-propoxymethyl- (meth) acrylamide, N-butoxymethyl- (meta ) Monoalkylol (meth) acrylamide such as acrylamide, N-pentoxymethyl- (meth) acrylamide,
N, N-di (methylol) acrylamide, N-methylol-N-methoxymethyl (meth) acrylamide, N, N-di (methoxymethyl) acrylamide, N-ethoxymethyl-N-methoxymethylmethacrylamide, N, N- Di (ethoxymethyl) acrylamide, N-ethoxymethyl-N-propoxymethylmethacrylamide, N, N-di (propoxymethyl) acrylamide, N-butoxymethyl-N- (propoxymethyl) methacrylamide, N, N-di ( Dialkylol (meta) such as butoxymethyl) acrylamide, N-butoxymethyl-N- (methoxymethyl) methacrylamide, N, N-di (pentoxymethyl) acrylamide, N-methoxymethyl-N- (pentoxymethyl) methacrylamide Acrylic net Amide group-containing unsaturated compounds and the like;

Dialkylamino group-containing unsaturated compounds such as dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, methylethylaminoethyl (meth) acrylate, dimethylaminostyrene, diethylaminostyrene;

(Meth) acrylic acid dimethylaminoethyl methyl chloride salt, trimethyl-3- (1- (meth) acrylamide-1,1-dimethylpropyl) ammonium chloride, trimethyl-3- (1- (meth) acrylamidopropyl) ammonium chloride and The dialkylamino group-containing unsaturated compound such as trimethyl-3- (1- (meth) acrylamide-1,1-dimethylethyl) ammonium chloride is quaternized ammonium, and Cl ⁻ , Br ⁻ , I ^- a halogen ion or QSO ₃ of ^-: quaternary ammonium salt group-containing unsaturated compound having a (Q 1 -C 12 alkyl group carbon atoms);

Vinylsulfonic acid, allylsulfonic acid, methallylsulfonic acid, 2-sulfoethyl (meth) acrylate, 2-sulfobutyl (meth) acrylate, styrenesulfonic acid, sulfophenylallyl ether, sulfophenylmethallyl ether, 2-acrylamide-2 A sulfonic acid group-containing unsaturated compound such as methylpropanesulfonic acid;

Examples include (meth) acrylic acid methoxypolyethylene glycol, (meth) acrylic acid methoxypolypropylene glycol, (meth) acrylic acid phenoxypolyethylene glycol, and (meth) acrylic acid nonylphenol polyethylene oxide adducts. However, it is not particularly limited to these. Moreover, these can also be used in combination of 2 or more types.

  Among them, hydroxyl group-containing unsaturated compounds such as (meth) acrylic acid polyethylene glycol, (meth) acrylic acid polypropylene glycol, (meth) acrylic acid polyethylene glycol polypropylene glycol, etc., which also have relatively lipophilicity, or 2-acryloyloxyethylphthalic acid Carboxyl group-containing unsaturated compounds such as 2-acryloyloxyethyl hexahydrophthalic acid are preferred.

  The hydrophilic group-containing monomer is preferably contained in an amount of 1 to 10% by weight based on the total amount of the non-crosslinkable monomer (A) and the crosslinkable monomer (B). If it is less than 1% by weight, the unevenness of the particles in the coating film due to the water- and oil-repellency derived from the fluorine group cannot be improved.

  In the present invention, a dispersion stabilizer and a surfactant are not particularly used. However, when a dispersion stabilizer and a surfactant are necessary for imparting a function, they may be added. At this time, since the addition of the dispersion stabilizer and the surfactant does not affect the synthesis mechanism of the monodispersed crosslinked particles, the type and amount can be arbitrarily changed.

Examples of the dispersion stabilizer and surfactant include dispersion stabilizers such as polyvinyl alcohol and polyvinyl pyrrolidone that improve compatibility with polyvinyl chloride and styrene acrylic copolymer, and polyoxyethylene polyoxypropylene that improves compatibility with polypropylene. Nonionic surfactants such as block copolymers (Epan, manufactured by Daiichi Kogyo Seiyaku), polyether-modified silicone (Silwet, manufactured by Nihon Unicar), and quaternary ammonium salts used for antistatic effects (Cotamine, manufactured by Kao) ) And the like, and amphoteric surfactants such as alkyldimethylaminoacetic acid betaine (Amogen, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) and the like, but are not particularly limited thereto. Further, the dispersion stabilizer and the surfactant may be added during or after the polymerization.
The solvent used in the present invention is selected from those in which the monomer is homogeneously dissolved and the already crosslinked fine particles, which are polymers obtained by polymerizing the monomer, become insoluble. Examples of such solvents include alcohols such as methanol, ethanol, n-propanol, isopropanol, n-butanol, and t-butanol; ethers such as diethyl ether, isopropyl ether, butyl ether, methyl cellosolve, and tetrahydrofuran; acetone, methyl ethyl ketone, Examples include ketones such as diethyl ketone; mixed solvents of the above-mentioned solvents and water, and methanol, ethanol, or mixed solvents of these with water are particularly desirable. Furthermore, these solvents can be used in combination of two or more. The total amount of the monomer is preferably 10 to 30% by weight based on the total amount of the monomers. The amount of water in all solvents is preferably 0 to 70% by weight.

  As the initiator, a cationic water-soluble azo polymerization initiator is used. Basically, any compound that can make the end of the polymer chain cationic by an initiator may be used. For example, a compound represented by the formula (1) or a compound represented by the formula (2) can be mentioned.

R ¹ and R ^{2 in} formula (1) are each a hydrogen atom; an alkyl group such as a methyl group, an ethyl group or a propyl group; a hydroxyl group such as a hydroxymethyl group, a hydroxyethyl group or a hydroxypropyl group; a phenyl group or a benzyl group An aromatic group such as a group; a halogenated aromatic group such as a chlorophenyl group and a chlorobenzyl group; and a hydroxylated aromatic group such as a hydroxyphenyl group and a hydroxybenzyl group are not particularly limited thereto.

  Examples of formula (1) include 2,2′-azobis [2- (phenylamidino) propane] dihydrochloride (VA-545, manufactured by Wako Pure Chemical Industries), 2,2′-azobis {2- [N- ( 4-chlorophenyl) amidino] propane} dihydrochloride (VA-546, manufactured by Wako Pure Chemical Industries), 2,2'-azobis {2- [N- (4-droxyphenyl) amidino] propane} dihydrochloride (VA-548) , Wako Pure Chemical), 2,2'-azobis [2- (N-benzylamidino) propane] dihydrochloride (VA-552, Wako Pure Chemical), 2,2'-azobis [2- (N-allyl) Amidino) propane] dihydrochloride (VA-553, manufactured by Wako Pure Chemical Industries), 2,2'-azobis (2-amidinopropane) dihydrochloride (V-50, manufactured by Wako Pure Chemical Industries), 2,2'-azobis {2 -[N- (4-hydroxyethyl) amidino] propane} dihydrochloride (VA-558, manufactured by Wako Pure Chemical Industries).

R ³ and R ^{4 in} the formula (2) are each an alkylene group such as a methylene group, an ethylene group or a propylene group; a divalent alkylene group such as a hydroxymethylene group or a hydroxyethylene group; a divalent group such as a phenylene group or a biphenylene group. Although an aromatic group is mentioned, it is not specifically limited to these.

  Examples of formula (2) include 2,2-azobis [2- (5-methyl-2-imidazolin-2-yl) propane] dihydrochloride (VA-041, manufactured by Wako Pure Chemical Industries), 2,2-azobis [2- (2-imidazolin-2-yl) propane] dihydrochloride (VA-044, manufactured by Wako Pure Chemical Industries), 2,2-azobis [2- (4,5,6,7-tetrahydro-1H-1, 3-diazepin-2-yl) propane] dihydrochloride (VA-054, manufactured by Wako Pure Chemical Industries), 2,2-azobis [2- (3,4,5,6-tetrahydropyrimidin-2-yl) propane] dihydro Chloride (VA-058, manufactured by Wako Pure Chemical Industries), 2,2-azobis [2- (5-hydroxy-3,4,5,6-tetrahydropyrimidin-2-yl) propane] dihydrochloride (VA-059, Japanese Manufactured by Kojun Pharmaceutical Co., Ltd.), 2,2-azobis {2- [1- (2-hydroxyethyl) -2-imidazolin-2-yl] propane} dihydrochloride (VA-060, manufactured by Wako Pure Chemical Industries), 2,2- Azobis [2- (2-imidazolin-2-yl) propane] (VA-061, Wako Jun And the like). The cationic water-soluble azo initiator is preferably 0.01 to 1.00% by weight based on the total amount of the monomers.

  Further, in controlling the particle size, a nonionic polymerization initiator may be used in combination with the cationic water-soluble azo polymerization initiator. By using a nonionic polymerization initiator, the particle diameter, which was in the range of 0.1 to 3.0 μm with only the cationic water-soluble azo polymerization initiator, can be expanded to 8.0 μm.

  As the nonionic polymerization initiator, basically, any compound that dissolves in a polymerization solvent and generates radicals by heat and does not cause the polymer terminal to become ionic by the initiator may be used. For example, 2,2-azobis (4-methoxy-2,4-dimethylvaleronitrile) (V-70, manufactured by Wako Pure Chemical Industries), 2,2'-azobis (2,4-dimethylvaleronitrile) (V-65 2,2'-azobisisobutyronitrile (V-60, manufactured by Wako Purechemical), 2,2'-azobis (2-methylbutyronitrile) (V-59, Wako Purechemical) 1,1'-azobis (cyclohexane-1-carbonitrile) (V-40, Wako Pure Chemical Industries), 1-[(1-cyano-1-methylethyl) azo] formamide (V-30, sum) Azonitrile compounds such as 2-Phenylazo-4-methoxy-2,4-dimethyl-valeronitrile (V-19, Wako Pure Chemicals), 2,2'-azobis [2-methyl-N- [ 1,1-bis (hydroxymethyl) -2-hydroxyethyl] propionamide] (VA-080, manufactured by Wako Pure Chemical Industries), 2,2'-azobis [2-methyl-N- [1,1-bis (hydroxy Methyl) ethyl] propionamide] (VA-082, Wako Pure Chemical Industries, Ltd.), 2,2 ' -Azobis [2-methyl-N- [2- (1-hydroxybutyl)]-propionamide] (VA-085, manufactured by Wako Pure Chemical Industries), 2,2'-azobis [2-methyl-N- (2- Hydroxyethyl) -propionamide] (VA-086, manufactured by Wako Pure Chemical Industries), 2,2'-azobis (2-methylpropionamide) dihydrate (VA-088, manufactured by Wako Pure Chemical Industries), 2,2'-azobis [ N- (2-propenyl) -2-methylpropionamide] (VF-096, Wako Pure Chemicals), 2,2'-azobis (N-butyl-2-methylpropionamide) (VAm-110, Wako Pure Chemicals) ), 2,2'-azobis (N-cyclohexyl-2-methylpropionamide) (Vam-111, manufactured by Wako Pure Chemical Industries), etc., 2,2'-azobis (2,4,4-trimethylpentane) ) (VR-110, manufactured by Wako Pure Chemical Industries, Ltd.), 2,2'-azobis (2-methylpropane) (VR-160, manufactured by Wako Pure Chemical Industries, Ltd.) and other nonionic azo polymerization initiators such as alkylazo compounds, methyl ethyl ketone Oxide (Perme H, manufactured by NOF Corporation), cyclohexanone peroxide (Perhexa H, manufactured by NOF Corporation), methylcyclohexanone peroxide (Perhexa Q, manufactured by NOF Corporation), methyl acetoacetate peroxide (Percure SA, manufactured by NOF Corporation), acetylacetone peroxide ( Ketone peroxides such as Percure A, manufactured by NOF Corporation,

1,1-bis (t-hexylperoxy) 3,3,5-trimethylcyclohexane (Perhexa TMH, manufactured by NOF Corporation), 1,1-bis (t-hexylperoxy) cyclohexane (Perhexa HC, manufactured by NOF Corporation) 1,1-bis (t-butylperoxy) 3,3,5-trimethylcyclohexane (Perhexa 3M, manufactured by NOF Corporation), 1,1-bis (t-butylperoxy) cyclohexane (Perhexa C, manufactured by NOF Corporation) ), 1,1-bis (t-butylperoxy) cyclododecane (Perhexa CD, manufactured by NOF Corporation), 2,2-bis (t-butylperoxy) butane (Perhexa 22, manufactured by NOF Corporation), n-butyl 4,4-bis (t-butylperoxy) valerate (Perhexa V, manufactured by NOF), 2,2-bis (4,4-di-t-butylperoxycyclohexyl) propane (Pertetra A, manufactured by NOF) Peroxyketals such as

t-butyl hydroperoxide (Perbutyl H-69, manufactured by NOF Corporation), p-menthane hydroperoxide (Permenta H, manufactured by NOF Corporation), diisopropylbenzene hydroperoxide (Park Mill P, manufactured by NOF Corporation), 1,1, 3,3-tetramethylbutyl hydroperoxide (Perocta H, manufactured by NOF Corporation), cumene hydroperoxide (Perkmill H-80, manufactured by NOF Corporation), t-hexyl hydroperoxide (Perhexyl H, manufactured by NOF Corporation), etc. Hydroperoxides,

2,5-dimethyl-2,5-bis (t-butylperoxy) hexyne-3 (Perhexin 25B, manufactured by NOF Corporation), di-t-butyl peroxide (Perbutyl D, manufactured by NOF Corporation), t-butyl kumi Luperoxide (Perbutyl C, manufactured by Nippon Oil & Fats), 2,5-dimethyl-2,5-bis (t-butylperoxy) hexane (Perhexa 25B, manufactured by Nippon Oil & Fats), Dicumyl peroxide (Park Mill D, manufactured by Nippon Oil & Fats) ), Dialkyl peroxides such as α, α'-bis (t-butylperoxy) diisopropylbenzene (Perbutyl P, manufactured by NOF Corporation),

Octanoyl peroxide (Perroyl O, manufactured by Nippon Oil & Fats), Lauroyl peroxide (Perroyl L, manufactured by Nippon Oil & Fats), Stearoyl peroxide (Perroyl S, manufactured by Nippon Oil & Fats), Succinic Acid Peroxide (Perroyl SA, manufactured by Nippon Oil & Fats) , Benzoyl peroxide (Niper BW, manufactured by NOF Corporation), Isobutyryl peroxide (Perroyl IB, manufactured by NOF Corporation), 2,4-dichlorobenzoyl peroxide (Niper CS, manufactured by NOF Corporation), 3,5,5-trimethyl Diacyl peroxides such as hexanoyl peroxide (Perroyl 355, manufactured by NOF Corporation),

Di-n-propyl peroxydicarbonate (Perroyl NPP-50M, manufactured by NOF Corporation), Diisopropyl peroxydicarbonate (Perroyl IPP-50, manufactured by NOF Corporation), Bis (4-t-butylcyclohexyl) peroxydicarbonate ( Parroyl TCP, manufactured by Nippon Oil & Fats, Di-2-ethoxyethyl peroxydicarbonate (Perroyl EEP, manufactured by Nippon Oil & Fats), Di-2-ethoxyhexyl peroxydicarbonate (Perroyl OPP, manufactured by Nippon Oil & Fats), Di-2- Peroxydicarbonates such as methoxybutyl peroxydicarbonate (Perroyl MBP, manufactured by NOF Corporation) and di (3-methyl-3-methoxybutyl) peroxydicarbonate (Perroyl SOP, manufactured by NOF Corporation),

α, α'-bis (neodecanoylperoxy) diisopropylbenzene (Daiper ND, manufactured by NOF Corporation), cumylperoxyneodecanoate (Park Mill ND, manufactured by NOF Corporation), 1,1,3,3-tetramethyl Butyl peroxyneodecanoate (Perocta ND, manufactured by NOF Corporation), 1-cyclohexyl-1-methylethylperoxyneodecanoate (Percyclo ND, manufactured by NOF Corporation), t-hexylperoxyneodecanoate (Perhexyl) ND, manufactured by NOF Corporation, t-butyl peroxyneodecanoate (perbutyl ND, manufactured by NOF Corporation), t-hexyl peroxypivalate (perhexyl PV, manufactured by NOF Corporation), t-butyl peroxypivalate (perbutyl) PV, manufactured by NOF Corporation), 1,1,3,3, -tetramethylbutylperoxy-2-ethylhexanoate (Perocta O, manufactured by NOF Corporation) 2,5-dimethyl-2,5-bis ( 2-ethylhexanoylperoxy) hexane (Perhexa 250, manufactured by NOF Corporation), 1-cyclohexyl-1-methylethylperoxy-2-ethylhexanoate (Percyclo O, manufactured by NOF Corporation), t-hexylperoxy 2 -Ethylhexanoate (Perhexyl O, manufactured by NOF Corporation), t-butyl peroxy 2-ethylhexanoate (Perbutyl O, manufactured by NOF Corporation), t-butyl peroxyisobutyrate (Perbutyl IB, manufactured by NOF Corporation) , T-hexyl peroxyisopropyl monocarbonate (Perhexyl I, manufactured by NOF Corporation), t-butyl peroxymaleic acid (Perbutyl MA, manufactured by NOF Corporation), t-butyl peroxy 3,5,5-trimethylhexanoate (Perbutyl 355, manufactured by NOF Corporation), t-butyl peroxylaurate (Perbutyl L, manufactured by NOF Corporation), 2,5-dimethyl-2,5-bis (m-toluoy) Luperoxy) hexane (Perhexa 25MT, manufactured by NOF Corporation), t-butyl peroxyisopropyl monocarbonate (Perbutyl I, manufactured by NOF Corporation), t-butyl peroxy 2-ethylhexyl monocarbonate (Perbutyl E, manufactured by NOF Corporation), t- Hexyl peroxybenzoate (Perhexyl Z, manufactured by Nippon Oil & Fats), 2,5-dimethyl-2,5-bis (benzoylperoxy) hexane (Perhexa 25Z, manufactured by Nippon Oil & Fats), t-butyl peroxyacetate (Perbutyl A, Japan Oil), t-butyl peroxy-m-toluoyl benzoate (perbutyl ZT, manufactured by Nippon Oil & Fats), t-butyl peroxybenzoate (perbutyl Z, manufactured by Nippon Oil & Fats), bis (t-butylperoxy) isophthalate ( Peroxyesters such as

t-Butylperoxyallyl monocarbonate (Peromer AC, manufactured by NOF Corporation), t-butyltrimethylsilyl peroxide (Perbutyl SM, manufactured by NOF Corporation), 3,3 ', 4,4'-tetra (t-butylperoxycarbonyl) ) Organic peroxides such as benzophenone (BTTB-50, manufactured by NOF Corporation), 2,3-dimethyl-2,3-diphenylbutane (NOFMER BC, manufactured by NOF Corporation), etc., but are particularly limited to these. It is not a thing. In particular, the use of a nonionic radical polymerization initiator having a low 10-hour half-life temperature can effectively increase the particle size with a small amount. Further, the nonionic polymerization initiator is 0 to 10.0% by weight based on the total amount of the monomer, and it is preferable to add the cationic water-soluble azo polymerization initiator at the same time.

  The synthesis of the already crosslinked fine particles of the present invention is performed, for example, by uniformly mixing the non-crosslinkable monomer (A) and the crosslinkable monomer (B) containing 10 to 95% by weight of the fluorine group-containing monomer in the solvent. Dissolve, remove dissolved oxygen, heat to 60 ° C., and dissolve the cationic water-soluble azo polymerization initiator in ion-exchanged water, or dissolve the cationic water-soluble azo polymerization initiator in ion-exchanged water At the same time, the nonionic polymerization initiator is added and synthesized by heating and stirring for 3 to 10 hours.

  Alternatively, the non-crosslinkable monomer (A) and the crosslinkable monomer (B) are uniformly dissolved in the solvent, the dissolved oxygen is removed, and after heating to 60 ° C., the cationic water-soluble azo polymerization initiator is added. The nonionic polymerization initiator is added at the same time as the one dissolved in ion exchange water or the one obtained by dissolving the cationic water-soluble azo polymerization initiator in ion exchange water, and heated and stirred for 3 to 10 hours. The non-crosslinkable monomer (A) and the crosslinkable monomer (B) containing 10 to 95% by weight of the fluorine group-containing monomer in the already crosslinked fine particle dispersion are dissolved, and the nonionic polymerization initiator is dissolved. Add and synthesize by heating and stirring for 3-10 hours.

  When the conversion after polymerization is not sufficient, an initiator is added after the completion of polymerization in an amount of 0.1 to 2% by weight based on the total amount of monomers. As the initiator to be added, any ordinary oil-soluble radical polymerization initiator can be used without any problem. For example, 2,2-azobis (4-methoxy-2,4-dimethylvaleronitrile) (V-70, manufactured by Wako Pure Chemical Industries), 2,2'-azobis (2,4-dimethylvaleronitrile) (V-65 2,2'-azobisisobutyronitrile (V-60, manufactured by Wako Purechemical), 2,2'-azobis (2-methylbutyronitrile) (V-59, Wako Purechemical) Azonitrile compounds, such as octanoyl peroxide (Perroyl O, manufactured by NOF Corporation), lauroyl peroxide (Perroyl L, manufactured by NOF Corporation), stearoyl peroxide (Perroyl S, manufactured by NOF Corporation), succinic acid peroxide ( Parroyl SA (manufactured by NOF), benzoyl peroxide (NIPER BW, NOF), isobutyryl peroxide (PAROIL IB, NOF), 2,4-dichlorobenzoyl peroxide (Niper CS, NOF), 3,5,5-trimethylhex Diacyl peroxides such as octanoyl peroxide (Peroyl 355, NOF),

Di-n-propyl peroxydicarbonate (Perroyl NPP-50M, manufactured by NOF Corporation), Diisopropyl peroxydicarbonate (Perroyl IPP-50, manufactured by NOF Corporation), Bis (4-t-butylcyclohexyl) peroxydicarbonate ( Parroyl TCP, manufactured by Nippon Oil & Fats, Di-2-ethoxyethyl peroxydicarbonate (Perroyl EEP, manufactured by Nippon Oil & Fats), Di-2-ethoxyhexyl peroxydicarbonate (Perroyl OPP, manufactured by Nippon Oil & Fats), Di-2- Peroxydicarbonates such as methoxybutyl peroxydicarbonate (Perroyl MBP, manufactured by NOF Corporation) and di (3-methyl-3-methoxybutyl) peroxydicarbonate (Perroyl SOP, manufactured by NOF Corporation),

hydroperoxides such as t-butyl hydroperoxide (Perbutyl H-69, manufactured by NOF Corporation), 1,1,3,3-tetramethylbutyl hydroperoxide (Perocta H, manufactured by NOF Corporation),

Dialkyl peroxides such as di-t-butyl peroxide (Perbutyl D, manufactured by NOF Corporation), 2,5-dimethyl-2,5-bis (t-butylperoxy) hexane (Perhexa 25B, manufactured by NOF Corporation),

α, α'-bis (neodecanoylperoxy) diisopropylbenzene (Daiper ND, manufactured by NOF Corporation), cumylperoxyneodecanoate (Park Mill ND, manufactured by NOF Corporation), 1,1,3,3-tetramethyl Butyl peroxyneodecanoate (Perocta ND, manufactured by NOF Corporation), 1-cyclohexyl-1-methylethylperoxyneodecanoate (Percyclo ND, manufactured by NOF Corporation), t-hexylperoxyneodecanoate (Perhexyl) ND, manufactured by NOF Corporation, t-butyl peroxyneodecanoate (perbutyl ND, manufactured by NOF Corporation), t-hexyl peroxypivalate (perhexyl PV, manufactured by NOF Corporation), t-butyl peroxypivalate (perbutyl) PV, manufactured by NOF Corporation), 1,1,3,3, -tetramethylbutylperoxy-2-ethylhexanoate (Perocta O, manufactured by NOF Corporation) 2,5-dimethyl-2,5-bis ( 2-ethylhexanoylperoxy) hexane (Perhexa 250, manufactured by NOF Corporation), 1-cyclohexyl-1-methylethylperoxy-2-ethylhexanoate (Percyclo O, manufactured by NOF Corporation), t-hexylperoxy 2 -Ethylhexanoate (Perhexyl O, manufactured by NOF Corporation), t-butyl peroxy 2-ethylhexanoate (Perbutyl O, manufactured by NOF Corporation), t-butyl peroxyisobutyrate (Perbutyl IB, manufactured by NOF Corporation) Organic peroxides such as peroxyesters such as t-hexyl peroxyisopropyl monocarbonate (Perhexyl I, manufactured by NOF Corporation) and t-butyl peroxymaleic acid (Perbutyl MA, manufactured by NOF Corporation). However, it is not particularly limited to these.

  The already crosslinked fine particles of the present invention are obtained as monodispersed fine particles having excellent heat resistance and solvent resistance. Further, particles having a desired particle diameter in the range of 0.1 to 8.0 μm can be obtained depending on the composition of the monomer (A), the selection of the amount of water, and the amount of the nonionic polymerization initiator. The heat resistance in the present invention means that the decomposition temperature of the already crosslinked fine particles is 240 ° C. or higher, and the solvent resistance means that the gel fraction in methyl ethyl ketone is 95% or higher. The decomposition temperature and gel fraction are measured using the obtained crosslinked microparticles after vacuum drying at 80 ° C. for 12 hours after removing the solvent from the crosslinked crosslinked microparticle dispersion after polymerization. The decomposition temperature is measured using a commercially available thermogravimetric measurement (TG) apparatus at a heating rate of 10 ° C./min in a nitrogen atmosphere. In the present invention, the weight loss at the time of temperature rise occurs in one stage, and the temperature at which the peak of the differential thermogravimetric (DTG) curve is maximized is called the decomposition temperature. The gel fraction as used in the present invention means that when crosslinked fine particles are dispersed in methyl ethyl ketone and left at 23 ° C. and 65% for 24 hours, the solvent is removed by centrifugation, and vacuum drying is performed at 80 ° C. for 6 hours. Say weight change rate.

  The decomposition temperature of the crosslinked fine particles of the present invention is 240 ° C. or higher, and the gel fraction in methyl ethyl ketone is 95% or higher. In the present invention, a fine particle dispersion having a particle size distribution with a coefficient of variation of 10% or less is referred to as a monodispersed fine particle dispersion. The coefficient of variation can be obtained, for example, by observing fine particles with an optical microscope and measuring the diameter thereof. The coefficient of variation is expressed as a percentage of the standard deviation divided by the average value. The variation coefficient of the cross-linked fine particle dispersion of the present invention is as uniform as 0.1 to 10%.

  Since the crosslinked fine particles of the present invention are excellent in heat resistance and solvent resistance, they can be dispersed in an arbitrary solvent that does not dissolve the crosslinked fine particles using a process such as stripping. When this method is used, since the drying process is not performed, the crosslinked fine particle dispersion can be obtained while the particles are not agglomerated and are dispersed in the primary particles. In this step, the concentration of the crosslinked fine particle dispersion can be arbitrarily changed from 1 to 50% by weight. If it exceeds 50% by weight, the distance between the particles becomes small, and a stable dispersion state cannot be maintained, and the particles are aggregated.

  Further, as a feature of the present invention, the crosslinked fine particles can be formed into fine particles having a narrow particle size distribution of 0.1 to 8.0 μm by using a cationic water-soluble azo polymerization initiator without using a dispersion stabilizer and a surfactant. It is.

  Next, the present invention will be described specifically by way of examples. In the examples, “parts” and “%” are all based on weight unless otherwise specified.

Example 1
74.0 parts of methanol, 11.0 parts of water, 0.75 parts of methacrylic acid (manufactured by Wako Pure Chemical Industries), 13.5 parts of trifluoroethyl methacrylate (manufactured by Wako Pure Chemical Industries), a reactor equipped with a stirrer, reflux condenser, thermometer and nitrogen introduction tube 0.75 parts of allyl methacrylate (manufactured by Wako Pure Chemical Industries, Ltd.) was charged, and dissolved oxygen was removed by flowing nitrogen gas. After heating the reactor to 60 ° C, 0.02 part of 2,2'-azobis (2-amidinopropane) dihydrochloride (V-50, Wako Pure Chemical Industries) dissolved in 0.5 part of ion-exchanged water and 2,2 ' -Azobis (4-methoxy-2,4-dimethylvaleronitrile) (V-70, Wako Pure Chemical Industries, Ltd.) 0.02 part was added at the same time and heated and stirred for 6 hours, then benzoyl peroxide (Nyper BW, manufactured by NOF Corporation) was added. 0.015 part was added, and the mixture was further stirred with heating for 2 hours to obtain a monodispersed cross-linked fine particle dispersion having a solid content of 15%, a particle size of 1.70 μm, and a coefficient of variation of 3.45%.

Examples 2-7
Monodispersed cross-linked fine particles are polymerized in the same manner as in Example 1 except that methanol, water, monomer type, composition ratio, nonionic initiator type, and charged amount are charged in the amounts shown in Table 1 in advance. A dispersion was obtained.

Comparative Example 1
A reactor similar to Example 1 was charged with 75.0 parts of methanol, 9.80 parts of water, 14.25 parts of trifluoroethyl methacrylate (manufactured by Wako Pure Chemical Industries), and 0.75 part of allyl methacrylate (manufactured by Wako Pure Chemical Industries), and nitrogen gas was passed to dissolve dissolved oxygen. Removed. After the reactor was heated to 60 ° C., 0.025 part of 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile) (V-70, manufactured by Wako Pure Chemical Industries, Ltd.) was added at the same time, followed by heating and stirring for 6 hours. , 0.015 part of benzoyl peroxide (Niper BW, manufactured by NOF Corporation) was added, and the mixture was further stirred for 2 hours to obtain a monodispersed cross-linked fine particle dispersion with a solid content of 15%, particle size of 1.68μm, and coefficient of variation of 3.66%. It was.

Comparative Example 2
Monodispersed cross-linked fine particles are polymerized in the same manner as in Example 1 except that methanol, water, monomer type, composition ratio, nonionic initiator type, and charged amount are charged in the amounts shown in Table 1 in advance. A dispersion was obtained.

The measurement methods of the physical properties and characteristics of the crosslinked fine particles and the crosslinked fine particle dispersions in Examples and Comparative Examples are as follows.
The particle size and coefficient of variation of pre-crosslinked fine particles are calculated by observing the particles with an optical microscope (BX60 manufactured by OLYMPUS), and measuring the diameter of 100 particles using image analysis and measurement software (Mac Scope manufactured by Mitani Corp.). did.

  The heat resistance, solvent resistance, and light scattering characteristics of the crosslinked fine particles are obtained by centrifuging the crosslinked fine particle dispersions obtained in the above-mentioned Examples and Comparative Examples, and then preparing a powder obtained by vacuum drying the precipitate at 80 ° C. overnight. use.

The heat resistance of cross-linked fine particles is determined by the decomposition temperature by TG / DTA (TG / DTA200 manufactured by Seiko Instruments) and the optical microscope of fine particle shape after pressurizing at 200 ° C and 100kg / cm ² for 3 minutes with a pressure press (BX60 manufactured by OLYMPUS) ) Evaluation was made by observation.

The solvent resistance of the crosslinked fine particles was evaluated from the gel fraction of the crosslinked fine particles when 2.0 g of the crosslinked fine particles were dispersed in 98 g of methyl ethyl ketone.
The following acrylic resin solution is used as the base resin for evaluating the bias of the already crosslinked fine particles in the coating film.

(Preparation of acrylic resin solution)
A reaction vessel was charged with 800 parts of cyclohexanone, heated to 100 ° C. while injecting nitrogen gas into the vessel, and a mixture of the following monomer and thermal polymerization initiator was added dropwise at the same temperature over 1 hour to carry out a polymerization reaction.
60.0 parts of styrene
Methacrylic acid 60.0 parts
Methyl methacrylate 65.0 parts
Butyl methacrylate 65.0 parts
Azobisisobutyronitrile 10.0 parts After the addition, the mixture was further reacted at 100 ° C. for 3 hours, and then 2.0 parts of azobisisobutyronitrile dissolved in 50 parts of cyclohexanone was added. The reaction was continued for 1 hour to obtain an acrylic resin solution having a weight average molecular weight of about 40,000.
After cooling to room temperature, about 2 g of the resin solution was sampled, heated and dried at 180 ° C. for 20 minutes to measure the nonvolatile content, and cyclohexanone was added to the previously synthesized resin solution so that the nonvolatile content was 20 wt%. To prepare an acrylic resin solution.

25 g of the resulting acrylic resin solution was mixed with 7 g of trimethylolpropane triacrylate (NK ester ATMPT, manufactured by Shin-Nakamura Chemical Co., Ltd.), 10 g of already crosslinked fine particles, 1.0 g of photoinitiator (Irgacure 907, manufactured by Ciba Geigy), and 57 g of cyclohexanone. The obtained resin coating solution was applied to a glass plate of 100 mm x 100 mm x 1.1 mm with a spin coater, dried at 70 ° C for 20 minutes, exposed to ultraviolet light with an integrated light intensity of 150 mJ using an ultra high pressure mercury lamp, and then 230 ° C For about 1 hour to prepare a coating film of about 3 μm. The obtained coated substrate was observed and evaluated with an optical microscope (BX60 manufactured by OLYMPUS).
Table 1 shows the results obtained in the examples and comparative examples.

  The crosslinked fine particles obtained in both Examples and Comparative Examples were fine particles having a decomposition temperature of 240 ° C. or higher, no particle melting after pressure pressing, and having a gel fraction of 95% or higher and good heat resistance and solvent resistance.

In Comparative Examples 1 and 2, a hydrophilic group-containing monomer is not copolymerized, and unevenness of particles occurs in the coating film, resulting in a portion where no particles are present.
On the other hand, since the hydrophilic group-containing monomer was copolymerized in the examples, the particles were uniformly present throughout the coating film. In particular, for Examples 3 to 7 using 2- (meth) acryloyloxyethyl hexahydrophthalic acid and polyethylene glycol monomethacrylate having relatively lipophilicity, the effect is remarkably exhibited.

The crosslinked fine particles of the present invention can be widely used for fillers, additives and the like. In addition, since the particle diameters are uniform, it can be expected to be used as a partition wall agent, a space adjusting agent or the like, or since it has a low refractive index, a refractive index adjusting agent, a light diffusing agent, a light interference agent and the like.

Claims (6)

Using a polymerization initiator represented by the following formula (1) or the following formula (2) in a solvent, a non-crosslinkable monomer (A) containing a fluorine group-containing monomer and a crosslinkable monomer (B). A light scattering agent containing fine particles obtained by polymerization,
The fluorine group-containing monomer is 10 to 95% by weight based on the total amount of the monomer, and the crosslinkable or non-crosslinkable hydrophilic group-containing monomer is 1 to 10 based on the total amount of the monomer. Light scattering agent that is weight percent.
Formula (1)

[Wherein, R ¹ and R ² each independently represents a hydrogen atom, an alkyl group or an aromatic group. ]
Formula (2)

[Wherein, R ³ and R ⁴ each independently represent an alkylene group or a divalent aromatic group. ] 2. The crosslinkable monomer (B) is a polyfunctional monomer having a polymerizable unsaturated carboxylic acid residue and a reactive functional group other than the polymerizable unsaturated carboxylic acid residue. Light scattering agent . 3. The light scattering agent according to claim 1, wherein the light scattering agent has a substantially uniform particle diameter, and the average particle diameter of the light scattering agent is 0.1 to 8.0 [mu] m. Light scattering agent decomposition temperature of 240 ° C. or more, the light scattering agent in accordance with claim 1, wherein the gel fraction is 95% or more. The light scattering agent according to claim 1, wherein the solvent is a mixed solvent of water and alcohol. In the absence of a dispersion stabilizer,
Using a polymerization initiator represented by the following formula (1) or the following formula (2) in a solvent, a non-crosslinkable monomer (A) containing a fluorine group-containing monomer and a crosslinkable monomer (B). A method for producing a light scattering agent to be polymerized, comprising:
The fluorine group-containing monomer is 10 to 95% by weight based on the total amount of the monomer, and the crosslinkable or non-crosslinkable hydrophilic group-containing monomer is 1 to 10 based on the total amount of the monomer. Manufacturing method of light scattering agent which is weight%.
Formula (1)

[Wherein, R ¹ and R ² each independently represents a hydrogen atom, an alkyl group or an aromatic group. ]
Formula (2)

[Wherein, R ³ and R ⁴ each independently represent an alkylene group or a divalent aromatic group. ]