Resin microparticles and method for producing same

Abstract

The present invention addresses the problem of providing resin microparticles having excellent heat resistance and transparency, a narrow particle size distribution, and small particle diameters. As a means for solving the problem, the present invention provides resin microparticles containing hydrolyzable silicon compound units having a group that reacts with a radical-polymerizable unsaturated group and a hydrolyzable silyl group, a monofunctional (meth)acrylic monomer unit, a polyfunctional (meth)acrylic monomer unit, and a thiol compound unit.

Description

[Technical field]

[0001] The present invention relates to resin microparticles and a method for producing the same, and more particularly to resin microparticles containing (a) hydrolyzable silicon compound units having a hydrolyzable silyl group and a group reactive with a radically polymerizable unsaturated group, (b) monofunctional (meth)acrylic monomer units, (c) polyfunctional (meth)acrylic monomer units, and (d) thiol compound units, and a method for producing the resin microparticles. [Background technology]

[0002] Resin films have been widely used for a long time as packaging materials and other applications. In recent years, their applications have expanded, and in particular, the properties required of resin films for optical components and electronic devices have become more advanced. There is a demand for improving productivity while maintaining the high quality. Resin films are often stored in rolls. When stored in rolls, the resin films may stick to each other at the overlapping areas, resulting in problems such as poor slipperiness and peelability. To address this problem, it is known to add various fillers such as organic particles or inorganic particles to the resin film as anti-sticking agents (anti-blocking agents). Representative fillers include silica as inorganic particles and (meth)acrylic resin fine particles as organic particles.

[0003] The advantages of using inorganic particles as a filler include high hardness and the ability to prevent sticking with a small amount of addition, but the disadvantage is that due to the nature of the material, a refractive index difference occurs between the filler and the resin film, which can cause a loss of transparency. On the other hand, when organic particles are used as a filler, it is advantageous that they can provide anti-sticking properties while maintaining the transparency of the resin film. For this reason, various organic particles have been developed and are used in resin films that require high quality.

[0004] Patent Document 1 describes the use of organic polymer particles containing an antioxidant as an antiblocking agent for a film. By including an antioxidant in the organic polymer particles, heat resistance can be improved. Patent Document 2 describes silicone polymer particles having a core-shell shape that maintains high transparency and hardness. Patent Document 3 describes swollen seed polymer particles using polysiloxane particles as seed particles. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 5572383 [Patent Document 2] JP 2009-173694 A [Patent Document 3] Patent No. 5599674 Summary of the Invention [Problem to be solved by the invention]

[0006] When organic particles, particularly resin fine particles, are used as an anti-sticking agent (anti-blocking agent) for optical films, it is known that narrow particle size distribution and smaller particle diameter are preferable because they have less effect on film haze. In addition, when resin fine particles are used as an anti-sticking agent (anti-blocking agent), there is a problem that resin scum is generated due to heat load applied during resin compounding, which deteriorates the yield during film production. Therefore, it is necessary to use resin fine particles that are resistant to heat load and have excellent heat resistance.

[0007] The organic polymer particles described in Patent Document 1 contain an antioxidant. Antioxidants with high antioxidant properties often have bulky molecular structures, making them difficult to apply to polymerization methods using water as a medium other than suspension polymerization. Therefore, it is difficult to obtain organic polymer particles that have sufficient characteristics in terms of particle size distribution and particle diameter and have more precise optical properties. The polymer particles described in Patent Document 2 are expected to have better optical properties than inorganic particles, but because they are made of a silicone-based polymer, there is a risk that the silicone component will cause a difference in refractive index within the film, increasing haze, making it difficult to produce polymer particles with high transparency. The swollen seed polymer particles described in Patent Document 3 are produced by sol-gel seed polymerization using polysiloxane particles as seed particles, and are expected to have better optical properties. On the other hand, the hurdles of required properties such as transparency for recent optical films are increasing, and the influence of the polysiloxane seed particle portion on film haze can no longer be ignored, making it difficult to obtain swollen seed polymer particles with high transparency.

[0008] An object of the present invention is to provide fine resin particles which are excellent in heat resistance and transparency, have a narrow particle size distribution, and have a small particle diameter. [Means for solving the problem]

[0009] As a result of intensive research into solving the above problems, the inventors have found that the above problems can be solved by resin microparticles containing (a) hydrolyzable silicon compound units having a reactive group copolymerizable with a vinyl monomer, (b) monofunctional (meth)acrylic monomer units, (c) polyfunctional (meth)acrylic monomer units, and (d) thiol compound units, and have thus completed the present invention. That is, the present invention provides the following resin fine particles and a method for producing resin fine particles. Item 1: Resin fine particles containing (a) a hydrolyzable silicon compound unit having a hydrolyzable silyl group and a group reactive with a radically polymerizable unsaturated group, (b) a monofunctional (meth)acrylic monomer unit, (c) a polyfunctional (meth)acrylic monomer unit, and (d) a thiol compound unit. Item 2: The resin fine particles according to item 1, wherein the content of silicon element in the resin fine particles as measured by fluorescent X-ray analysis is 0.03% by mass or more and 1% by mass or less. Item 3: The resin fine particles according to Item 1 or 2, further comprising (e) a monofunctional vinyl monomer unit having an aromatic ring in the molecular structure. Item 4: The resin fine particles according to any one of Items 1 to 3, wherein the (b) monofunctional (meth)acrylic monomer unit contains a (meth)acrylic acid alkyl ester unit having an alkyl group carbon number of 2 or more. Item 5: The resin fine particles according to any one of Items 1 to 4, which have a heat loss rate of 2.5% or less when heat-treated at 280° C. for 1 hour in a nitrogen atmosphere. Item 6: The resin fine particles according to any one of Items 1 to 5, which have a 3% thermal decomposition temperature of 350° C. or higher in a nitrogen atmosphere. Item 7: The resin fine particles according to any one of Items 1 to 6, which have a volume average particle size of 0.05 μm or more and 3 μm or less. Item 8: The resin fine particles according to any one of Items 1 to 7, having a coefficient of variation of the volume average particle diameter of 25% or less. Item 9: Measurement range as below; (Measurement range) Particle size measurement range: 0.5μm~200μm, Measurement range of particle circularity: 0.97~1.00, 9. The resin fine particles according to any one of items 1 to 8, wherein the number of particles having a size of 5 μm or more among 300,000 resin fine particles is 1 or less. Item 10: The resin fine particles according to any one of Items 1 to 9, further comprising (f) a reactive surfactant unit. Item 11: A resin fine particle granule formed by agglomerating a plurality of the resin fine particles according to any one of items 1 to 10. Item 12: The resin fine particles according to any one of items 1 to 11, which are used as an anti-sticking agent for a resin film. Item 13: The resin fine particles according to item 12, wherein the resin film is a resin film for optical applications. Item 14: A first step of preparing seed particles by emulsion polymerization or soap-free polymerization of a monomer component containing a monofunctional (meth)acrylic monomer; and a second step of absorbing a mixture containing a hydrolyzable silicon compound having a hydrolyzable silyl group and a group reactive with a radically polymerizable unsaturated group, a monofunctional (meth)acrylic monomer, a polyfunctional (meth)acrylic monomer and a thiol compound into the seed particles and polymerizing the mixture; A method for producing resin fine particles having the above structure. Item 15: The method for producing resin microparticles according to Item 14, wherein the mixture used in the second step further contains a monofunctional vinyl monomer having an aromatic ring in its molecular structure. Item 16: The method for producing resin fine particles according to Item 14 or 15, further comprising a step of classifying the obtained resin fine particles using a filter having an absolute filtration accuracy of 5 μm or less. Item 17: A method for producing a resin microparticle granule, comprising granulating and drying the resin microparticles obtained by the method for producing resin microparticles according to any one of items 14 to 16. Effect of the Invention

[0010] According to the present invention, it is possible to provide resin microparticles having excellent heat resistance and transparency, a narrow particle size distribution, and a small particle diameter. By using the resin microparticles as an anti-sticking agent for resin films, particularly as an anti-sticking agent for resin films for optical applications, it becomes possible to stably produce resin films for optical applications having high transparency. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The resin fine particles and the method for producing the resin fine particles of the present invention will be described in detail below. In this specification, the term "(meth)acrylic monomer" refers to an acrylic monomer or a methacrylic monomer, and the term "(meth)acrylate" refers to an acrylate or a methacrylate.

[0012] [Resin fine particles] The resin microparticles of the present invention are resin microparticles containing (a) hydrolyzable silicon compound units having a hydrolyzable silyl group and a group that reacts with a radically polymerizable unsaturated group, (b) monofunctional (meth)acrylic monomer units, (c) polyfunctional (meth)acrylic monomer units, and (d) thiol compound units. The resin fine particles of the present invention may further contain (e) a monofunctional vinyl monomer unit having an aromatic ring in the molecular structure and / or (f) a reactive surfactant unit.

[0013] <(a) Unit> The (a) unit in the resin fine particles of the present invention is a unit derived from a hydrolyzable silicon compound having a hydrolyzable silyl group and a group reactive with a radically polymerizable unsaturated group.

[0014] The hydrolyzable silyl group contained in the hydrolyzable silicon compound is a silicon atom to which 1 to 3 hydrolyzable groups are bonded, and is a silicon-containing group that can undergo a condensation reaction in the presence of moisture or a crosslinking agent, etc., and if necessary, using a catalyst, etc., to form a siloxane bond and undergo crosslinking. The hydrolyzable group of the hydrolyzable silyl group is not particularly limited, and may be, for example, one or more selected from the group consisting of a hydrogen atom, a halogen atom, a hydroxyl group, an alkoxy group, a phenoxy group, an aryloxy group, an acyloxy group, a ketoximate group, an amino group, an amide group, an acid amide group, an aminooxy group, an iminoxy group, a mercapto group, an alkenyloxy group, and an oxime group. Among them, an alkoxysilyl group is preferred because it undergoes a gentle hydrolysis reaction and is easy to handle. Examples of the alkoxysilyl group include trialkoxysilyl groups such as a trimethoxysilyl group, a triethoxysilyl group, a triisopropoxysilyl group, and a triphenoxysilyl group; dialkoxysilyl groups such as a propyldimethoxysilyl group, a methyldimethoxysilyl group, and a methyldiethoxysilyl group; and monoalkoxysilyl groups such as a dimethylmethoxysilyl group and a dimethylethoxysilyl group. A trialkoxysilyl group is preferred, and a trimethoxysilyl group and a triethoxysilyl group are more preferred.

[0015] The group other than the hydrolyzable group bonded to the silicon atom in the hydrolyzable silyl group is not particularly limited, and examples thereof include one or more selected from the group consisting of alkyl groups having 20 or less carbon atoms, such as methyl groups, ethyl groups, propyl groups, and isopropyl groups, alkenyl groups having 20 or less carbon atoms, aryl groups having 6 to 30 carbon atoms, and arylalkyl groups having 7 to 30 carbon atoms.

[0016] The group that reacts with the radically polymerizable unsaturated group contained in the hydrolyzable silicon compound is not particularly limited as long as it is a group that reacts with a radically polymerizable unsaturated group such as a (meth)acryloyl group, a (meth)acrylamide group, a vinyl group, or a styryl group. Examples of groups that react with the radically polymerizable unsaturated groups contained in the hydrolyzable silicon compound of the present invention include one or more groups selected from the group consisting of radically polymerizable unsaturated groups such as (meth)acryloyl groups, (meth)acrylamide groups, vinyl groups, and styryl groups, mercapto groups, hydroxyl groups, and amino groups.

[0017] In the present invention, examples of the hydrolyzable silicon compound having a hydrolyzable silyl group and a group that reacts with a radically polymerizable unsaturated group include at least one selected from the group consisting of vinyltrimethoxysilane, vinyltriethoxysilane, p-styryltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, and 3-mercaptopropyltrimethoxysilane. These may be used alone or in combination of two or more.

[0018] <(b) Unit> The (b) unit in the resin fine particles of the present invention is a unit derived from a monofunctional (meth)acrylic monomer. The monofunctional (meth)acrylic monomer is not particularly limited as long as it is a compound having only one (meth)acryloyl group in the molecule. For example, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, isopentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, etc. and the like; (meth)acrylic acid alkyl esters having an alkyl group of 1 to 20 carbon atoms, such as dodecyl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate, octadecyl (meth)acrylate, isostearyl (meth)acrylate, nonadecyl (meth)acrylate, and eicosyl (meth)acrylate; and (meth)acrylic acid alicyclic esters having an alicyclic structure in the ester moiety, such as cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, and dicyclopentanyl (meth)acrylate.Preferred are methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, isopentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and isooctyl (meth)acrylate. One or more of (meth)acrylic acid alkyl esters having an alkyl group carbon number of 1 to 10, such as butyl (meth)acrylate, (meth)acrylic acid alkyl esters, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentanyl (meth)acrylate, etc., are particularly preferred for applications requiring heat resistance. These monofunctional (meth)acrylic monomers may be used alone or in combination of two or more.

[0019] <(c) Unit> The (c) unit in the resin fine particles of the present invention is a unit derived from a polyfunctional (meth)acrylic monomer. The polyfunctional (meth)acrylic monomer is not particularly limited as long as it is a compound having two or more radical polymerizable unsaturated groups such as (meth)acryloyl groups in the molecule. For example, one or more selected from the group consisting of ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, decaethylene glycol di(meth)acrylate, pentadecaethylene glycol di(meth)acrylate, pentacontahexaethylene glycol di(meth)acrylate, 1,3-butylene di(meth)acrylate, allyl (meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tetraacrylate, dipentaerythritol hexa(meth)acrylate, etc. are listed. Among these, ethylene glycol di(meth)acrylate (particularly ethylene glycol dimethacrylate) and allyl (meth)acrylate (allyl methacrylate) are preferred. These polyfunctional (meth)acrylic monomers may be used alone or in combination of two or more.

[0020] <(d) Unit> The (d) unit in the resin fine particles of the present invention is a unit derived from a thiol compound. The thiol compound is not particularly limited as long as it is a compound having a thiol group in the molecule, and examples of the thiol compound include monofunctional thiol compounds and polyfunctional thiol compounds. The thiol compound functions as a chain transfer agent and becomes a structural unit of the polymer microparticles. In a radical polymerization system in which a hydrolyzable silicon compound having a hydrolyzable silyl group and a group reactive with a radically polymerizable unsaturated group, a monofunctional (meth)acrylic monomer, and a polyfunctional (meth)acrylic monomer are polymerized, the thiol compound receives a radical from a growing polymer chain to stop the extension of the polymer chain, and generates a new radical to start the growth reaction of another polymer chain. This makes it possible to make the molecular weight of the resin microparticles uniform, and to make the particle size distribution uniform.

[0021] The monofunctional thiol compound is not particularly limited as long as it is a compound having one thiol group in the molecule. For example, thiol compounds such as 1-butanethiol, 1-octanethiol, 1-decanethiol, 1-dodecanethiol, 1-hexadecanethiol, and tert-dodecanethiol; acid compounds having a thiol group such as thioglycolic acid, 3-mercaptopropionic acid, and mercaptosuccinic acid, or esters thereof, may be used. These monofunctional thiol compounds may be used alone or in combination of two or more.

[0022] The polyfunctional thiol compound is not particularly limited as long as it is a compound having two or more thiol groups in the molecule. For example, 1,2-ethanedithiol, 1,3-propanedithiol, 1,4-butanedithiol, 1,6-hexanedithiol, 1,8-octanedithiol, 1,2-cyclohexanedithiol, decanedithiol, ethylene glycol bisthioglycolate, ethylene glycol bisthiopropionate, ethylene glycol bisthioglycolate (EGTG), 1,4-butanediol bisthiopropionate (BDTP), trimethylolpropane tristhioglycolate (TMTG ... Examples of the polyfunctional thiol compounds include one or more selected from the group consisting of trimethylsilylpropane tris(thio)propionate, pentaerythritol tetrakisthioglycolate (PETG), pentaerythritol tetrakisthiopropionate, dipentaerythritol hexathiopropionate, trimercaptopropionic acid tris(2-hydroxyethyl)isocyanurate, 1,4-dimethylmercaptobenzene, 2,4,6-trimercapto-s-triazine, 2-(N,N-dibutylamino)-4,6-dimercapto-s-triazine, etc. These polyfunctional thiol compounds may be used alone or in combination of two or more. Among these, one or more selected from the group consisting of ethylene glycol bisthioglycolate (EGTG), 1,4-butanediol bisthiopropionate (BDTP), trimethylolpropane tristhioglycolate (TMTG), and pentaerythritol tetrakisthioglycolate (PETG) are preferred.

[0023] <(e) Unit> The resin fine particles of the present invention may contain units (e) in addition to the units (a) to (d). The (e) unit is a unit derived from a monofunctional vinyl monomer having an aromatic ring in the molecular structure.

[0024] The monofunctional vinyl monomer having an aromatic ring in its molecular structure is a monomer having an aromatic ring in its molecule and one radically polymerizable unsaturated group such as a (meth)acryloyl group, a (meth)acrylamide group, a vinyl group, or a styryl group. For example, one or more types selected from the group consisting of a monofunctional aromatic hydrocarbon monomer, a polyfunctional aromatic hydrocarbon monomer, and an aromatic ring-containing (meth)acrylic acid ester monomer may be used. These monofunctional vinyl monomer units having an aromatic ring in their molecular structure may be used alone or in combination of two or more types.

[0025] Examples of the monofunctional aromatic hydrocarbon monomer include at least one selected from the group consisting of styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene (vinyltoluene), α-methylstyrene, m-ethylvinylbenzene, p-ethylvinylbenzene, vinylbenzoic acid, styrenesulfonic acid, sodium styrenesulfonate, ammonium styrenesulfonate, and other styrenesulfonates, vinylnaphthalene, and allylbenzene. Among these, styrene, α-methylstyrene, and sodium styrenesulfonate are preferred. These monofunctional aromatic hydrocarbon monomers may be used alone or in combination of two or more.

[0026] Examples of aromatic ring-containing (meth)acrylic acid ester monomers include one or more selected from the group consisting of (meth)acrylic acid esters having an aromatic ring in their molecular structure, such as benzyl (meth)acrylate, phenyl (meth)acrylate, and phenoxyethyl (meth)acrylate, 2-(meth)acryloyloxyethyl phthalic acid, etc. In the present invention, (meth)acrylic acid ester monomers having an aromatic ring in their molecular structure, such as benzyl (meth)acrylate, are treated as "monofunctional vinyl monomers having an aromatic ring in their molecular structure."

[0027] <(f) units> The resin fine particles of the present invention may contain a (f) unit in addition to the (a) to (d) units. The (f) unit is a unit derived from a reactive surfactant. Examples of the reactive surfactant include one or more selected from the group consisting of anionic reactive surfactants and nonionic reactive surfactants. Examples of the anionic reactive surfactant include one or more selected from the group consisting of anionic reactive surfactants listed in the <Surfactant> section of the [Method for producing resin microparticles] described below. Examples of the nonionic reactive surfactant include one or more selected from the group consisting of nonionic reactive surfactants listed in the <Surfactant> section of the [Method for producing resin microparticles] described below.

[0028] <Other units> The resin fine particles of the present invention may contain units other than the units (a) to (f) (hereinafter referred to as "other units"). Examples of the other units include units derived from one or more monomers selected from the group consisting of fatty acid vinyl ester monomers, halogenated olefin monomers, vinyl cyanide monomers, unsaturated carboxylic acid monomers, unsaturated polycarboxylic acid ester monomers, unsaturated carboxylic acid amide monomers, methylolated unsaturated carboxylic acid amide monomers, polyfunctional aromatic hydrocarbon monomers, and polyfunctional allyl monomers.

[0029] Examples of fatty acid vinyl ester monomers include vinyl acetate, vinyl propionate, etc. These fatty acid vinyl ester monomers may be used alone or in combination of two or more. Examples of halogenated olefin monomers include vinyl chloride, vinylidene chloride, tetrafluoroethylene, vinylidene fluoride, etc. These halogenated olefin monomers may be used alone or in combination of two or more. An example of the vinyl cyanide monomer is (meth)acrylonitrile. The unsaturated carboxylic acid monomer includes unsaturated carboxylic acids, their salts or anhydrides, such as (meth)acrylic acid, crotonic acid, maleic acid, fumaric acid, their ammonium or metal salts, maleic anhydride, etc. These unsaturated carboxylic acid monomers may be used alone or in combination of two or more.

[0030] The unsaturated polycarboxylate monomer includes unsaturated dicarboxylate monoesters, their salts, and unsaturated dicarboxylate diesters, such as monobutyl maleate, ammonium or metal salts thereof, dimethyl maleate, etc. These unsaturated polycarboxylate monomers may be used alone or in combination of two or more. Examples of the unsaturated carboxylic acid amide monomer include (meth)acrylamide, diacetone (meth)acrylamide, etc. These unsaturated carboxylic acid amide monomers may be used alone or in combination of two or more. Examples of the methylolated unsaturated carboxylic acid amide monomer include N-methylol acrylamide, N-methylol methacrylamide, methylolated diacetone acrylamide, and ethers of these monomers with alcohols having a carbon number of 1 to 8. These methylolated unsaturated carboxylic acid amide monomers may be used alone or in combination of two or more.

[0031] Examples of the polyfunctional aromatic hydrocarbon monomer include one or more selected from the group consisting of m- or p-divinylbenzene, 1,3-, 1,8-, 1,4-, 1,5-, 2,3-, 2,6-, or 2,7-divinylnaphthalene, 4,4'-, 4,3'-, 2,2'-, or 2,4-divinylbiphenyl, 1,2-, 1,3-, or 1,4-diisopropenylbenzene, 1,2-divinyl-3,4-dimethylbenzene, and derivatives thereof. These polyfunctional aromatic hydrocarbon monomers may be used alone or in combination of two or more. Examples of the polyfunctional allyl monomer include diallyl phthalate, triallyl cyanurate, etc. These polyfunctional allyl monomers may be used alone or in combination of two or more.

[0032] <Composition of resin particles> The ratio of the amounts of each unit constituting the resin fine particles can be appropriately determined depending on the application of the resin fine particles, the desired properties, etc., and is not particularly limited. The amount of (a) hydrolyzable silicon compound units having a hydrolyzable silyl group and a group reactive with a radically polymerizable unsaturated group is, when the total of the units (a) to (d) is taken as 100 mass%, for example, 0.1 mass% or more, preferably 0.5 mass% or more, and for example, 10 mass% or less, preferably 5 mass% or less. The (b) monofunctional (meth)acrylic monomer unit is, for example, 10% by mass or more, preferably 15% by mass or more, and for example, 90% by mass or less, preferably 85% by mass or less, when the total of the (a) to (d) units is 100% by mass. The (c) polyfunctional (meth)acrylic monomer unit is, for example, 3% by mass or more, preferably 5% by mass or more, and for example, 50% by mass or less, preferably 40% by mass or less, when the total of the (a) to (d) units is 100% by mass. The (d) thiol compound unit is, when the total of the (a) to (d) units is 100% by mass, for example, 0.1% by mass or more, preferably 0.3% by mass or more, and for example, 5% by mass or less, preferably 3% by mass or less. The amount of the monofunctional vinyl monomer unit (e) having an aromatic ring in its molecular structure is 0% by mass or more, for example 5% by mass or more, and for example 70% by mass or less, preferably 60% by mass or less, when the total amount of the units (a) to (e) is 100% by mass. The (f) reactive surfactant unit is, when the total of the (a) to (d) and (f) units is 100% by mass, 0% by mass or more, for example, 0.1% by mass or more, preferably 0.3% by mass or more, and for example, 5% by mass or less, preferably 3% by mass or less.

[0033] <Silicon content in resin particles measured by X-ray fluorescence analysis> The resin fine particles of the present invention preferably have a silicon content of 0.03% by mass or more and 1% by mass or less, more preferably 0.05% by mass or more and 0.50% by mass or less, as measured by fluorescent X-ray analysis. The resin fine particles exhibiting such properties are very excellent in heat resistance and do not affect haze or the like when made into a film. The silicon element in the resin microparticles in the present invention means the silicon element in the resin that comprises "hydrolyzable silicon compound unit having hydrolyzable silyl group and radical polymerizable unsaturated group reactive group, monofunctional (meth)acrylic monomer unit, polyfunctional (meth)acrylic monomer unit, and thiol compound unit" that constitutes the resin microparticles.The method for measuring the content of silicon element in the resin microparticles by fluorescent X-ray analysis can be, for example, the method described in the examples below.

[0034] <Weight loss rate when heated for 1 hour at 280℃ in a nitrogen atmosphere> The resin fine particles of the present invention preferably have a heat loss rate of 2.5% or less when heat-treated for 1 hour at 280° C. in a nitrogen atmosphere. Resin fine particles exhibiting such characteristics have very excellent heat resistance. The rate of weight loss upon heat treatment at 280° C. for 1 hour in a nitrogen atmosphere can be measured by the method described in the Examples below, for example.

[0035] <3% pyrolysis temperature under nitrogen atmosphere> The resin fine particles of the present invention preferably have a 3% thermal decomposition temperature of 350° C. or higher in a nitrogen atmosphere. The 3% thermal decomposition temperature in a nitrogen atmosphere means that the temperature at which the mass of the resin particles decreases by 3% when the resin particles are heated from near room temperature is 350° C. or higher. Resin particles that exhibit such characteristics have excellent heat resistance. The 3% thermal decomposition temperature in a nitrogen atmosphere can be measured, for example, by the method described in the Examples below.

[0036] <Volume average particle size> The volume average particle diameter (volume average primary particle diameter) of the resin fine particles of the present invention is not particularly limited and can be appropriately set according to the purpose and use. For example, it is 0.05 μm or more, preferably 0.07 μm or more, more preferably 0.1 μm or more, and for example, 3 μm or less, preferably 2 μm or less, more preferably 1.5 μm or less. The volume average particle size can be measured, for example, using a laser scattering / diffraction particle size distribution analyzer manufactured by Beckman Coulter, Inc. Specific examples of the method for measuring the volume average particle size include the method described in the Examples below.

[0037] <Variation coefficient of volume average particle size> The coefficient of variation of the volume average particle diameter of the resin fine particles of the present invention is not particularly limited and can be appropriately set depending on the purpose and application, for example, 25% or less, preferably 20% or less, more preferably 17% or less. The coefficient of variation of the volume average particle diameter of the resin fine particles is a value calculated from the following formula (1), and represents the distribution width of the data. Coefficient of variation (%) = standard deviation × 100 / volume average primary particle size (1) Here, the volume average particle size (volume average primary particle size) of the resin fine particles and its standard deviation can be measured, for example, by using a laser scattering / diffraction type particle size distribution measuring device manufactured by Beckman Coulter. The coefficient of variation of the volume average particle size can be obtained, for example, by the method described in the Examples below.

[0038] <Number of particles 5μm or larger out of 300,000> The resin fine particles of the present invention preferably have a particle size of 5 μm or more of 1 or less per 300,000 particles in the following measurement range. (Measurement range) Particle size measurement range: 0.5μm~200μm Measurement range of particle circularity: 0.97 to 1.00

[0039] Examples of a method for reducing the number of particles of 5 μm or more to 1 or less among 300,000 resin microparticles include a method of classifying the resin microparticles. Examples of the classification method include a method of classifying by centrifugal force using a centrifuge or air classifier, and a method of classifying by passing through a mesh or filter with a desired mesh size and absolute filtration accuracy, but are not particularly limited. In particular, by passing the polymer microparticle slurry obtained by the polymerization reaction through a filter with the desired absolute filtration accuracy to perform wet classification of the resin microparticles, it is possible to adjust the number of particles of 5 μm or more out of 300,000 resin microparticles. The number of particles of 5 μm or more out of 300,000 particles can be measured using, for example, the method described in the Examples below.

[0040] <Resin fine particle granules> The fine resin particle granules of the present invention are formed by agglomerating a plurality of fine resin particles. The resin microparticle granules can be obtained by subjecting the resin microparticle slurry obtained in the polymerization step to spray drying, freeze granulation drying, or other means. In spray drying, for example, a spray dryer can be used in which the inlet temperature of the resin microparticle slurry is 80° C. or higher and 220° C. or lower, and the outlet temperature of the resin microparticle granules is 50° C. or higher and 100° C. or lower. The obtained granules may be easier to handle than the resin microparticles themselves. The resin fine particle granules can be classified as necessary to make the particle size uniform. Classification can be performed by a known method. The volume average particle size of the resin fine particle granules is not particularly limited and can be, for example, 5 to 200 μm, and preferably 10 to 100 μm.

[0041] The obtained resin microparticle granules may be crushed to form resin microparticles. Examples of the crushing method include a dry crushing method using a mechanical crusher such as a blade mill, a super rotor, a hammer mill, and an airflow crusher such as a nanogrinding mill (jet mill), and a wet crushing method using a bead mill, a ball mill, etc. The resin microparticles dispersed by crushing may have good dispersibility in a solvent.

[0042] <Applications of resin particles> The resin microparticles of the present invention have excellent heat resistance and transparency, a narrow particle size distribution, and a small particle diameter. Taking advantage of these characteristics, the resin microparticles of the present invention can be used for various applications. For example, they can be used as an anti-sticking agent (anti-blocking agent) for resin molded products (resin films), a modifier for various resin molded products, optical components such as light diffusers and anti-glare / low-reflection optical components, paint additives, spacers between minute parts of various electronic devices, pore-forming agents for various battery components, core particles of conductive microparticles that are responsible for electrical connection, etc. For example, the resin fine particles themselves can be mixed with a resin as an anti-sticking agent (anti-blocking agent) for a resin film to form a resin composition, and a resin molded product such as a film can be formed. In particular, the resin fine particles of the present invention have excellent heat resistance and transparency, a narrow particle size distribution, and a small particle diameter, so that even if the amount of the resin fine particles is increased when preparing a resin composition for forming a film, the effect on the haze of the film can be suppressed. In addition, the generation of resin scum due to the heat load applied during resin compounding is suppressed, and there is little risk of the yield being deteriorated. By using these resin microparticles as an anti-sticking agent for resin films, particularly as an anti-sticking agent for resin films for optical applications, it becomes possible to stably produce optical components with high transparency, for example, optical films such as anti-glare films and light diffusion films, and light diffusers.

[0043] [Method of manufacturing resin particles] The method for producing resin microparticles of the present invention is not particularly limited, as long as it is a method that at least hydrolyzable silicon compound having a group that reacts with hydrolyzable silyl group and radical polymerizable unsaturated group, monofunctional (meth)acrylic monomer, polyfunctional (meth)acrylic monomer, and thiol compound react to form resin microparticles.For example, in addition to the above-mentioned compound, if necessary, polymerization initiator, liquid medium, surfactant, etc. are used, and known polymerization methods such as suspension polymerization, seed polymerization, swelling seed polymerization, seed emulsion polymerization, emulsion polymerization, soap-free polymerization, mini-emulsion polymerization, micro-emulsion polymerization, solution polymerization and dispersion polymerization can be mentioned. Among these, emulsion polymerization, soap-free polymerization, swelling seed polymerization, seed emulsion polymerization, and dispersion polymerization are preferred because they can give the desired resin fine particles having a uniform particle size distribution.

[0044] When swelling seed polymerization or seed emulsion polymerization is selected, seed particles that will become the cores of the desired resin particles are prepared before obtaining the desired resin particles. These seed particles are generally prepared by emulsion polymerization or soap-free polymerization. The seed particles can generally be obtained by polymerizing a monomer mixture containing one or more of the above-mentioned monofunctional (meth)acrylic monomers and monofunctional vinyl monomers having an aromatic ring in the molecular structure. In this case, it is preferable to add a monomer having a functional group capable of condensing with a hydrolyzable silicon compound unit to the monomer mixture. The monomer having a functional group capable of condensing with the hydrolyzable silicon compound unit is not particularly limited, but examples thereof include vinyl monomers having an epoxy group in the molecular chain, vinyl monomers having a hydroxyl group in the molecular chain, and hydrolyzable silicon compound units having a reactive group capable of copolymerizing with the above-mentioned vinyl monomers.

[0045] Examples of the vinyl monomer having an epoxy group in the molecular chain include one or more selected from the group consisting of glycidyl methacrylate, allyl glycidyl ether, allyl glycidyl phthalate, and allyl glycidyl hexahydrophthalate. Examples of vinyl monomers having a hydroxyl group in the molecular chain include one or more selected from the group consisting of 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 2-hydroxylethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxybutyl methacrylate, 2-hydroxybutyl acrylate, 2-hydroxy-3-phenoxypropyl acrylate, glycerin monoallyl ether, neopentyl glycol monoallyl ether, o-allylphenol, glycerin monomethacrylate, polyethylene glycol monomethacrylate, polypropylene glycol monomethacrylate, polyethylene glycol propylene glycol monomethacrylate, polyethylene glycol tetramethylene glycol monomethacrylate, propylene glycol polybutylene glycol monomethacrylate, polyethylene glycol monoacrylate, and polypropylene glycol monoacrylate. As the monomer having a functional group capable of condensing with these hydrolyzable silicon compound units, one type may be used alone, or two or more types may be used in combination.

[0046] <Polymerization initiator> The polymerization initiator for producing the resin microparticles of the present invention is not particularly limited, and any known polymerization initiator can be used. In the case of emulsion polymerization or soap-free polymerization, it is preferable to use a thermally decomposable water-soluble polymerization initiator, and in the case of seed polymerization or suspension polymerization, it is preferable to use a thermally decomposable oil-soluble polymerization initiator. As a polymerization initiator for producing the resin fine particles of the present invention, it is preferable to use a radical polymerization initiator, in particular a thermal polymerization initiator.

[0047] Among the radical polymerization initiators, examples of the water-soluble polymerization initiator include one or more selected from the group consisting of persulfates (e.g., ammonium persulfate, potassium persulfate, sodium persulfate, etc.), hydrogen peroxide, organic peroxides, nitrile-azo compounds, etc. Among the radical polymerization initiators, examples of the oil-soluble polymerization initiator include organic peroxides such as cumene hydroperoxide, di-tert-butyl peroxide, dicumyl peroxide, benzoyl peroxide, lauroyl peroxide, dimethylbis(tert-butylperoxy)hexane, dimethylbis(tert-butylperoxy)hexyne-3, bis(tert-butylperoxyisopropyl)benzene, bis(tert-butylperoxy)trimethylcyclohexane, butyl-bis(tert-butylperoxy)valerate, 2-ethylhexaneperoxy acid tert-butyl, dibenzoyl peroxide, paramenthane hydroperoxide, and tert-butyl peroxybenzoate; 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), 2,2'-azobis(2-isopropyl butyronitrile), 2,2'-azobis(2,3-dimethylbutyronitrile), 2,2'-azobis(2,4-dimethylbutyronitrile), 2,2'-azobis(2-methylcapronitrile), 2,2'-azobis(2,3,3-trimethylbutyronitrile), 2,2'-azobis(2,4,4-trimethylvaleronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(4-methoxy-2, and 4,4'-azobis(4-dimethylvaleronitrile), 2,2'-azobis(4-ethoxy-2,4-dimethylvaleronitrile), 2,2'-azobis(4-n-butoxy-2,4-dimethylvaleronitrile), 1,1'-azobis(cyclohexane-1-carbonitrile), 2-(carbamoylazo)isobutyronitrile, 4,4'-azobis(4-cyanopentanoic acid), and other nitrile-azo compounds. In addition, a redox-based polymerization initiator may be used which is a combination of the above-mentioned persulfate and organic peroxide polymerization initiator with a reducing agent such as sodium sulfoxylate formaldehyde, sodium hydrogen sulfite, ammonium hydrogen sulfite, sodium thiosulfate, ammonium thiosulfate, hydrogen peroxide, sodium hydroxymethanesulfinate, L-ascorbic acid and its salts, cuprous salts, or ferrous salts.

[0048] Among these, one or more selected from the group consisting of 2,2'-azobisisobutyronitrile, 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), 1,1'-azobis(cyclohexane-1-carbonitrile), 4,4'-azobis(4-cyanopentanoic acid), cumene hydroperoxide, di-tert-butyl peroxide, dicumyl peroxide, benzoyl peroxide, and lauroyl peroxide are preferred. These polymerization initiators may be used alone or in combination of two or more.

[0049] The amount of the polymerization initiator used can be appropriately determined depending on the type of the polymerization initiator, and is not particularly limited. For example, the amount is 0.1 parts by mass or more, preferably 0.3 parts by mass or more, and for example, 5 parts by mass or less, preferably 3 parts by mass or less, relative to 100 parts by mass of the total amount of all monomers used in the polymerization.

[0050] <Surfactant> The surfactant that may be used in the method for producing resin fine particles of the present invention is not particularly limited, and any known surfactant can be used. The type of surfactant is appropriately selected and the amount used is appropriately adjusted taking into consideration the particle size of the resulting resin fine particles and the dispersion stability of the monomer during polymerization.

[0051] In the method for producing resin microparticles of the present invention, an anionic surfactant, for example, an anionic non-reactive surfactant or an anionic reactive surfactant, can be used. These anionic surfactants may be used alone or in combination of two or more.

[0052] Examples of anionic non-reactive surfactants include sodium oleate; fatty acid soaps such as castor oil potassium soap; alkyl sulfate esters such as sodium lauryl sulfate and ammonium lauryl sulfate; alkylbenzene sulfonates such as sodium dodecylbenzene sulfonate; alkylnaphthalene sulfonates; alkane sulfonates; dialkyl sulfosuccinates; alkyl phosphate esters; naphthalene sulfonic acid formalin condensates; polyoxyethylene alkyl phenyl ether sulfate esters; polyoxyethylene sulfonated phenyl ether phosphates; polyoxyethylene alkyl sulfate esters, etc. One or more selected from the group consisting of these may be mentioned.

[0053] Examples of anionic reactive surfactants include JS-20 and RS-3000 of Eleminol (registered trademark) manufactured by Sanyo Chemical Industries, Ltd., KH-10, KH-1025, KH-05, HS-10, HS-1025, BC-0515, BC-10, BC-1025, BC-20, BC-2020, AR-1025, AR-2025 of Aqualon (registered trademark) manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., Antox (registered trademark) MS-60 manufactured by Nippon Emulsion Co., Ltd., S-120, S-180A, S-180, PD-104 of Latemul (registered trademark) manufactured by Kao Corporation, SR-1025, SE-10N of Adeka Liasop (registered trademark) manufactured by ADEKA Corporation, etc. Among them, those having an oxyalkylene chain in the molecular chain are preferable from the viewpoint of improving the dispersibility of the particles.

[0054] In the method for producing the resin fine particles of the present invention, nonionic surfactants, for example, nonionic non-reactive surfactants and nonionic reactive surfactants can be used. These nonionic surfactants may be used alone or in combination of two or more. Examples of nonionic nonreactive surfactants include one or more selected from the group consisting of polyoxyalkylene branched decyl ethers, polyoxyethylene tridecyl ethers, polyoxyalkylene alkyl ethers, polyoxyalkylene tridecyl ethers, polyoxyethylene isodecyl ethers, polyoxyalkylene lauryl ethers, polyether polyols, polyoxyethylene styrenated phenyl ethers, polyoxyethylene naphthyl ethers, polyoxyethylene phenyl ethers, polyoxyethylene polyoxypropylene glycols, polyoxyethylene lauryl ethers, polyoxyethylene oleyl cetyl ethers, polyoxyethylene glyceryl isostearate, polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, polyoxyethylene fatty acid esters, sorbitan fatty acid esters, polyoxysorbitan fatty acid esters, polyoxyethylene alkylamines, glycerin fatty acid esters, and oxyethylene-oxypropylene block polymers.

[0055] Examples of the nonionic reactive surfactant include at least one selected from the group consisting of alkyl ether surfactants (commercially available products include, for example, Adeka Reasoap ER-10, ER-20, ER-30, ER-40, etc., manufactured by ADEKA Corporation; and Latemul PD-420, PD-430, PD-450, etc., manufactured by Kao Corporation); alkyl phenyl ether surfactants or alkyl phenyl ester surfactants (commercially available products include, for example, Aqualon RN-10, RN-20, RN-30, RN-50, AN-10, AN-20, AN-30, AN-5065, etc., manufactured by Daiichi Kogyo Seiyaku Co., Ltd.; and Adeka Reasoap NE-10, NE-20, NE-30, NE-40, etc., manufactured by ADEKA Corporation); and (meth)acrylate sulfate surfactants (commercially available products include, for example, RMA-564, RMA-568, RMA-1114, etc., manufactured by Nippon Nyukazai Co., Ltd.). Among these, those having an oxyalkylene chain in the molecular chain are preferred from the viewpoint of dispersion stability of the particles.

[0056] In the method for producing resin microparticles of the present invention, a cationic surfactant or an amphoteric surfactant can be used. These cationic surfactants and amphoteric surfactants may be used alone or in combination of two or more.

[0057] Examples of the cationic surfactant include one or more selected from the group consisting of alkylamine salts such as laurylamine acetate and stearylamine acetate; and quaternary ammonium salts such as lauryltrimethylammonium chloride. The amphoteric surfactant may be, for example, one or more selected from the group consisting of lauryl dimethylamine oxide, lauryl aminoacetate betaine, and the like.

[0058] In the present invention, a reactive surfactant, particularly one or more selected from the group consisting of anionic reactive surfactants and nonionic reactive surfactants, can be used, whereby the resin microparticles contain (f) reactive surfactant units. The amount of the surfactant used can be appropriately determined depending on the type thereof, and is not particularly limited. For example, the amount is 0.1 parts by mass or more, preferably 0.3 parts by mass or more, and for example, 5 parts by mass or less, preferably 3 parts by mass or less, relative to 100 parts by mass of the total amount of all monomers used in polymerization.

[0059] <Liquid medium> The liquid medium used in the method for producing resin microparticles of the present invention is not particularly limited. For example, any of water, organic solvents, and mixtures thereof can be used. In the present invention, an aqueous medium is preferred, and for example, water, lower alcohols having 5 or less carbon atoms such as methyl alcohol and ethyl alcohol, and mixtures of water and lower alcohols can be used.

[0060] <Preferable method for producing resin fine particles> The method for producing resin microparticles of the present invention preferably includes a method in which in a first step, a monomer component containing a monofunctional (meth)acrylic monomer is subjected to emulsion polymerization or soap-free polymerization to produce seed particles, and in a second step, a monomer mixture containing a hydrolyzable silicon compound unit having a reactive group copolymerizable with a vinyl monomer, a monofunctional (meth)acrylic monomer unit, a polyfunctional (meth)acrylic monomer unit, and a thiol compound unit is absorbed into the seed particles and polymerized. In the method for producing resin fine particles of the present invention, it is preferable that the monomer mixture in the second step further contains a monofunctional vinyl monomer unit having an aromatic ring in the molecular structure.

[0061] In the method for producing resin fine particles of the present invention, it is preferable to classify the resin fine particles using a filter having a desired absolute filtration accuracy, for example, an absolute filtration accuracy of 5 μm or less. In the method for producing resin fine particles of the present invention, the resin fine particles may be granulated and dried to form resin fine particle granules. EXAMPLES

[0062] The present invention will be described in more detail below with reference to Production Examples, Examples, and Comparative Examples. However, the present invention is not limited thereto. In each example, "parts" means "parts by mass" and "%" means "% by mass".

[0063] [Measurement method] The measurements of "content of silicon element in resin microparticles measured by X-ray fluorescence analysis," "weight loss rate when heated for 1 hour at 280°C in a nitrogen atmosphere," "3% thermal decomposition temperature in a nitrogen atmosphere," "volume average particle diameter," "coefficient of variation of volume average particle diameter," and "number of particles 5 μm or larger out of 300,000 resin microparticles" were performed as follows.

[0064] <Silicon content in resin particles measured by fluorescent X-ray> The silicon content in the resin microparticles was measured by measuring the peak height of the silicon element by X-ray fluorescence spectroscopy, and the amount of silicon element contained was determined by order analysis (FP bulk method). Specifically, using an X-ray fluorescence analyzer (ZSX Primus IV, manufactured by Rigaku Corporation), the Si-Kα intensity was measured under the following device conditions and qualitative element conditions, and the silicon content in the resin microparticles was measured by order analysis. First, a conductive carbon double-sided tape (manufactured by Nisshin EM Co., Ltd.) was attached to a carbon sample stage (manufactured by Nisshin EM Co., Ltd.). 20 mg of the sample (resin microparticles manufactured in each Example and Comparative Example) was weighed out on the attached conductive carbon double-sided tape, and the sample was adjusted so that it did not spread more than 10 mmφ. Then, it was covered with a PP film (polypropylene film) and set in a 10 mmφ sample case attached to the device, and used as a measurement sample. Next, the peak height of silicon element was measured under the following conditions, and the amount of silicon element contained was determined by order analysis.

[0065] <Equipment conditions> ·Device:ZSX Primus IV X-ray tube target: Rh ·Analysis method: Order analysis method (FP bulk method) Measuring diameter: 10mm Spin: Yes Atmosphere: Vacuum Sample type: Metal Balanced ingredient: CHO - Sample protection film correction: Yes (PP film) Smoothing: 11 points Flux composition, dilution rate, impurity removal: None

[0066] <Qualitative elemental conditions> ·Si-Kα ·Tube:Rh(30kV-100mA) · Primary filter: OUT Attenuator: 1 / 1 Slit: Std. Analyzing crystal: Ge 2θ: 110.820deg (measurement range: 107~114deg) ·Detector: PC ·PHA L.L.: 150 U.L.: 300 ·Step: 0.05 deg ·Time: 0.4 sec

[0067] <Weight loss ratio during heat treatment at 280 °C for 1 hour under nitrogen atmosphere> The "weight loss ratio during heat treatment at 280 °C for 1 hour under nitrogen atmosphere" of the resin microparticles was measured using a differential thermal and thermogravimetric simultaneous measurement device (TG / DTA6200, manufactured by SII NanoTechnology Inc.). The sample preparation method and measurement conditions are as follows. (Sample preparation method) Approximately 15 mg of resin microparticles (measurement sample) was filled into the bottom of a platinum measurement container so that no gaps were formed to prepare a sample. (Measurement conditions) The nitrogen gas flow rate was set to 230 mL / min, and alumina was used as the reference substance. The temperature was raised from 40 °C to 100 °C at 10 °C / min, held at 100 °C for 10 minutes, raised from 100 °C to 280 °C at 10 °C / min, held at 280 °C for 1 hour to obtain a TG / DTA curve. From the obtained TG / DTA curve, the weight loss ratio at the end of the measurement was determined using the analysis software attached to the device and was defined as the "weight loss ratio during heat treatment at 280 °C for 1 hour under nitrogen atmosphere".

[0068] <3% Thermal decomposition temperature under nitrogen atmosphere> The "3% thermal decomposition temperature under nitrogen atmosphere" of the resin microparticles was measured using a differential thermal and thermogravimetric simultaneous measurement device (TG / DTA6200, manufactured by SII NanoTechnology Inc.). The sample preparation method and measurement conditions are as follows. (Sample preparation method) Approximately 15 mg of resin microparticles (measurement sample) was filled into the bottom of a platinum measurement container so that no gaps were formed to prepare a sample. (Measurement conditions) The nitrogen gas flow rate was 230 mL / min, and alumina was used as the reference material. The temperature was raised from 300 to 500°C at 10°C / min to obtain a TG / DTA curve. From the obtained TG / DTA curve, the temperature at which the mass of the sample decreased by 3% from the start of the measurement was calculated using the analysis software attached to the device, and this was defined as the "3% thermal decomposition temperature under a nitrogen atmosphere."

[0069] <Volume average particle size> 0.1 g of the resin microparticle water dispersion (20% solid content) and 20 ml of 2% by mass anionic surfactant solution were placed in a test tube. Then, the mixture was dispersed for 5 minutes using a test tube mixer (manufactured by AS ONE Corporation, "Test Tube Mixer TRIO HM-1N") and an ultrasonic cleaner (manufactured by AS ONE Corporation, "ULTRASONIC CLEANER VS-150") to obtain a dispersion. The obtained dispersion was irradiated with ultrasonic waves, and a laser diffraction scattering type particle size distribution measuring device (manufactured by Beckman Coulter, Inc., "LS230") was used to obtain the volume-based particle size distribution and its standard deviation of the resin microparticles. The arithmetic mean of the volume-based particle size distribution was taken as the volume average particle size of the resin microparticles.

[0070] The measurement conditions for the laser diffraction scattering type particle size distribution analyzer are as follows. medium = water Refractive index of medium = 1.333 Refractive index of solid = Refractive index of resin particles PIDS relative concentration: 40-55% The optical model used in the measurement was adjusted to the refractive index of the resin microparticles produced. When one type of monomer was used to produce the resin microparticles, the refractive index of the homopolymer of that monomer was used as the refractive index of the resin microparticles. When multiple types of monomers were used to produce the resin microparticles, the average value obtained by weighting the refractive index of the homopolymer of each monomer by the amount of each monomer used was used as the refractive index of the resin microparticles.

[0071] <Variation coefficient of volume average particle size> The coefficient of variation (CV value) of the volume average particle diameter of the resin fine particles was calculated by the following formula. Coefficient of variation of volume average particle diameter of resin microparticles = [(Standard deviation of volume-based particle size distribution of resin microparticles) / (Volume average particle diameter of resin microparticles)] x 100

[0072] <Number of particles 5μm or larger out of 300,000 resin particles> A surfactant aqueous solution was prepared by adding 0.01 part of a surfactant (dodecylbenzenesulfonate) to 4.94 parts of ion-exchanged water. 0.06 parts of resin fine particles were added to the surfactant aqueous solution, and the resin fine particles were dispersed in the surfactant aqueous solution using a dispersing machine (ultrasonic cleaner (VS-150, manufactured by Vervoclear Co., Ltd.) for 10 minutes to obtain a resin fine particle aqueous dispersion. The obtained resin microparticle aqueous dispersion was introduced into a flow type particle image analyzer (Sysmex Corporation, FPIA-3000S; equipped with a standard objective lens (10x), using a particle sheath (Sysmex Corporation, PSE-900A) as the sheath liquid) and measured under the following measurement conditions. Measurement mode: HPF measurement mode Particle size measurement range: 0.5 to 200 μm Particle circularity measurement range: 0.97 ~1.0 Number of particles measured: 100,000

[0073] Before starting the measurement, the flow particle image analyzer was automatically focused using a suspension of standard polymer particles (for example, Thermo Fisher Scientific 5200A (standard polystyrene particles diluted with ion-exchanged water)). The circularity is a value obtained by dividing the perimeter calculated from the diameter of a perfect circle having the same projected area as the image of the resin fine particle by the perimeter of the image of the resin fine particle. From the particle diameters of the resin fine particles obtained by measurement, the number of resin fine particles having a volume average particle diameter of 5 μm or more was counted. These operations were carried out three times, and the total number of resin microparticles having a volume average particle size of 5 μm or more was counted. This total was defined as the "number of particles having a size of 5 μm or more out of 300,000 resin microparticles."

[0074] [Production Example] <Production Example 1> In a polymerization reactor equipped with a stirring device, a thermometer, and a cooling mechanism, 270 parts of ion-exchanged water and 0.84 part of sodium styrenesulfonate were mixed so as to have the ratio, and an aqueous phase was prepared. In another container, a monomer mixture obtained by mixing monomer components so as to have the ratio of 114 parts of methyl methacrylate, 6 parts of 2-hydroxyethyl methacrylate, and 2.4 parts of 1-octanethiol was charged into the aqueous phase in the polymerization reactor. After purging the polymerization reactor with nitrogen for 5 minutes, the temperature was raised to 80°C. When 80°C was reached, a solution prepared by dissolving 0.6 part of potassium persulfate in 10 parts of ion-exchanged water was charged. Thereafter, after purging the polymerization reactor with nitrogen again for 5 minutes, an emulsion polymerization reaction was carried out by stirring at 80°C for 5 hours. Next, the temperature was raised to 100°C, held for 3 hours, and then cooled to prepare a slurry containing seed particles A. The volume average particle diameter of the seed particles A was 176 nm.

[0075] <Production Example 2> A slurry containing seed particles B was obtained in the same manner as in Production Example 1, except that a monomer mixture obtained by mixing monomer components so as to have the ratio of 120 parts of methyl methacrylate, 1.2 parts of 3-mercaptopropyltrimethoxysilane, and 2.4 parts of 1-octanethiol was used as the monomer mixture. The volume average particle diameter of the seed particles B was 177 nm.

[0076] <Production Example 3> A slurry containing seed particles C was obtained in the same manner as in Production Example 1, except that a monomer mixture obtained by mixing monomer components so as to have the ratio of 120 parts of methyl methacrylate and 2.4 parts of 1-octanethiol was used as the monomer mixture. The volume average particle diameter of the seed particles C was 175 nm.

[0077] [Examples and Comparative Examples] <Example 1> In a polymerization vessel equipped with a stirrer, a thermometer, and a cooling mechanism, 280 parts of ion-exchanged water, 2.8 parts of a 20% solution of sodium dodecylbenzenesulfonate (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., Neogen S-20D), 0.7 parts of polyoxyethylene styrenated phenyl ether (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., Noigen EA-167), and 0.014 parts of sodium nitrite were mixed to prepare an aqueous phase. In a separate vessel, monomer components were mixed in a ratio of 35.00 parts of butyl acrylate, 21.00 parts of styrene, 14.00 parts of ethylene glycol dimethacrylate, 0.35 parts of pentaerythritol tetrakisthioglycolate, 1.33 parts of 3-methacryloxypropyltriethoxysilane, 0.35 parts of 2,2'-azobisisobutyronitrile, and 0.18 parts of benzoyl peroxide (purity 74.2%) to prepare a monomer composition, which was used as the oil phase.

[0078] The oil phase was added to the aqueous phase in the polymerization vessel, and the mixture was stirred at 8000 rpm for 10 minutes using a TK homomixer (manufactured by Primix Corporation) to obtain a monomer mixture. 33.3 parts of seed particles A prepared in Production Example 1 were added to this monomer mixture, and the mixture was swollen by stirring for 3 hours. After that, the mixture was purged with nitrogen for 5 minutes, and then heated to 65°C, and polymerized by stirring at 65°C for 6 hours. After adding 0.021 parts of sulfamic acid, the mixture was heated to 100°C, held for 3 hours, and then cooled to produce a resin fine particle-containing slurry. The obtained slurry containing resin particles was passed through a 500 Mesh SUS mesh and then through a filter with an absolute filtration accuracy of 3 μm (KDGF-030, manufactured by Asahi Kasei Corporation) to wet classify the resin particles, thereby obtaining a classified resin particle slurry.

[0079] The classified resin fine particle slurry was spray-dried using an atomizer take-up type spray dryer (TRS-3WK, manufactured by Sakamoto Giken Co., Ltd.) under the following spray drying conditions to obtain resin fine particles. (Spray drying conditions) Resin particle-containing slurry supply rate: 25mL / min Atomizer rotation speed: 12000 rpm Air volume: 2m 3 / min Inlet temperature (temperature of the inlet where the sprayed resin fine particle-containing slurry is introduced): 150°C Outlet temperature (powder outlet temperature where resin particles are discharged): 70℃

[0080] The resulting resin particles exhibited the following properties: Silicon content in resin particles measured by X-ray fluorescence analysis: 0.17% by mass Weight loss when heated for 1 hour at 280℃ in a nitrogen atmosphere: 1.8% 3% pyrolysis temperature in nitrogen atmosphere: 356℃ Volume average particle size: 350 nm Coefficient of variation of volume average particle size: 14.5% Number of particles 5μm or larger out of 300,000 resin particles: 0

[0081] <Examples 2 to 5> Resin fine particles were obtained in the same manner as in Example 1, except that a monomer composition having the composition shown in Table 1 was used as the monomer composition. The properties of the obtained resin fine particles are also shown in Table 1.

[0082] <Example 6> Resin microparticles were obtained in the same manner as in Example 4, except that, as the surfactant component, "5 parts of Aqualon KH-1025 (main component 25%) manufactured by Daiichi Kogyo Seiyaku Co., Ltd." was used instead of "2.8 parts of 20% solution of sodium dodecylbenzenesulfonate (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., Neogen S-20D) and 0.7 parts of polyoxyethylene styrenated phenyl ether (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., Noigen EA-167)." The properties of the obtained resin microparticles are also shown in Table 1.

[0083] <Comparative Example 1> A slurry containing resin fine particles was obtained in the same manner as in Example 1, except that a monomer composition having the composition shown in Table 1 was used as the monomer composition. The obtained slurry containing resin fine particles was passed through a 500 Mesh SUS net, and then spray-dried in the same manner as in Example 1 to obtain resin fine particles. The properties of the obtained resin fine particles are also shown in Table 1.

[0084] <Comparative Examples 2 to 3> Resin fine particles were obtained in the same manner as in Comparative Example 1, except that a monomer composition having the composition shown in Table 1 was used as the monomer composition. The properties of the obtained resin fine particles are also shown in Table 1.

[0085] [Table 1]

[0086] The descriptions in the column of monomer composition in the table indicate the following. BA: Butyl acrylate St: styrene EGDMA: Ethylene glycol dimethacrylate PETG: Pentaerythritol tetrakisthioglycolate MPTESi: 3-methacryloxypropyltriethoxysilane MPTMSi: 3-methacryloxypropyltrimethoxysilane KH1025: Reactive surfactant (Aqualon KH-1025)

[0087] The present invention can be embodied in various other forms without departing from its spirit or main characteristics. Therefore, the above-described embodiments are merely illustrative in all respects and should not be interpreted as being limiting. The scope of the present invention is defined by the claims and is not limited to the text of the specification. Furthermore, all modifications and changes within the scope of the claims are within the scope of the present invention.

Claims

1. (a) a hydrolyzable silicon compound unit having a hydrolyzable silyl group and a group reactive with a radically polymerizable unsaturated group, (b) a monofunctional (meth)acrylic monomer unit, (c) a polyfunctional (meth)acrylic monomer unit, and (d) a polyfunctional thiol compound unit having two or more thiol groups in the molecule, Resin particles comprising:

2. 2. The resin fine particles according to claim 1, wherein the content of silicon element in the resin fine particles as measured by fluorescent X-ray analysis is 0.03% by mass or more and 1% by mass or less.

3. The resin fine particles according to claim 1 or 2, further comprising (e) a monofunctional vinyl monomer unit having an aromatic ring in the molecular structure.

4. 3. The resin fine particles according to claim 1, wherein the (b) monofunctional (meth)acrylic monomer unit contains a (meth)acrylic acid alkyl ester unit having an alkyl group carbon number of 2 or more.

5. 3. The resin fine particles according to claim 1, which have a weight loss of 2.5% or less when heat-treated at 280° C. for 1 hour in a nitrogen atmosphere.

6. 3. The resin fine particles according to claim 1, which have a 3% thermal decomposition temperature of 350° C. or higher in a nitrogen atmosphere.

7. 3. The resin fine particles according to claim 1, having a volume average particle size of 0.05 μm or more and 3 μm or less.

8. 3. The resin fine particles according to claim 1, wherein the coefficient of variation of the volume average particle size is 25% or less.

9. Measurement range: (Measurement range) Particle size measurement range: 0.5 μm to 200 μm, Measurement range of particle circularity: 0.97 to 1.00, 3. The resin fine particles according to claim 1, wherein the number of particles having a diameter of 5 μm or more among 300,000 resin fine particles is 1 or less.

10. The resin fine particles according to claim 1 or 2, further comprising (f) a reactive surfactant unit.

11. A resin microparticle granule formed by agglomerating a plurality of the resin microparticles according to claim 1 or 2.

12. The resin fine particles according to claim 1 or 2, which are used as an anti-sticking agent for a resin film.

13. The resin fine particles according to claim 12, wherein the resin film is a resin film for optical applications.

14. A first step of preparing seed particles by emulsion polymerization or soap-free polymerization of a monomer component containing a monofunctional (meth)acrylic monomer; and a second step of absorbing a mixture containing a hydrolyzable silicon compound having a hydrolyzable silyl group and a group reactive with a radically polymerizable unsaturated group, a monofunctional (meth)acrylic monomer, a polyfunctional (meth)acrylic monomer, and a polyfunctional thiol compound having two or more thiol groups in the molecule into the seed particles, and polymerizing the mixture; A method for producing resin fine particles having the above structure.

15. The method for producing resin microparticles according to claim 14, wherein the mixture used in the second step further contains a monofunctional vinyl monomer having an aromatic ring in its molecular structure.

16. The method for producing resin fine particles according to claim 14 or 15, further comprising a step of classifying the obtained resin fine particles using a filter having an absolute filtration accuracy of 5 μm or less.

17. A method for producing a resin microparticle granule, comprising granulating and drying the resin microparticles obtained by the method for producing resin microparticles according to claim 14 or 15.

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