Polymer particle, polymer particle composition and optical film

Abstract

This invention provides polymer particles that can be uniformly dispersed in dispersion media such as organic solvents and adhesive resins, and can maintain a uniform dispersion even in coatings obtained from polymer particle compositions prepared in organic solvents. The polymer particles of this invention contain 55 to 98% by mass of an acrylic polymer with acrylic monomer units represented by a predetermined structural formula, and therefore can be uniformly dispersed in dispersion media such as organic solvents and adhesive resins.

Description

Polymer particles, polymer particle compositions and optical films This invention relates to polymer particles, polymer particle compositions, and optical films. Polymer particles manufactured by suspension polymerization or seed polymerization are widely used as matting agents in coatings, additives to improve the physical properties of resins, and light diffusing agents. Generally speaking, when polymer particles obtained by suspension polymerization or seed polymerization are contained in coatings or the like, the polymer particles form unevenness on the coating surface, giving the coating surface a matte effect or imparting light diffusivity to the coating. Patent Document 1 discloses a polysiloxane composition containing polymer particles, which contains polymer particles and an addition-reaction-curable polysiloxane. The polymer particles contain cross-linked polymer particles of a polymeric composition, which includes one or more ester compounds selected from the group consisting of (meth)acrylates and vinyl carboxylate esters having 4 or more carbon atoms, styrene compounds, and a cross-linking agent. Patent Document 1 also describes forming a polysiloxane layer on the surface of the polymer particles. Patent document 2 discloses an organic particle obtained by polymerizing monomer components, with a particle size variation coefficient of less than 20% and a hydrophobicity index of 35 to 65. Patent document 3 discloses a (meth)acrylic acid microparticle, which is obtained by polymerizing a monomer composition containing 50 to 90% by weight of a monofunctional (meth)acrylic acid monomer (A) having 8 or more or less carbon atoms in a straight chain or branched chain, and 10 to 50% by weight of a monomer (B) having 2 or more (meth)acrylic acid groups, and the 10% compressive strength of the micro compression tester is 1 to 5 MPa. Patent document 4 discloses a resin particle containing a polymer containing structural units represented by a predetermined structural formula. [Previous Technical Documents] [Patent Literature] [Patent Document 1] WO2018 / 180739 Publication No. [Patent Document 2] Japanese Patent Application Publication No. 2012-57177 [Patent Document 3] Japanese Patent Application Publication No. 2018-24786 [Patent Document 4] Japanese Patent Application Publication No. 2020-15857 In the polysiloxane composition containing polymer particles in Patent Document 1, a polysiloxane layer is formed on the surface of the cross-linked polymer particles in order to improve the dispersibility with organic solvents. However, sometimes the formation of the polysiloxane layer becomes uneven due to the surface state of the polymer particles, which raises concerns about the uneven dispersibility of the polymer particles with organic solvents. Furthermore, the polymer particles in the aforementioned polysiloxane composition containing polymer particles are (meth)acrylate units with four or more carbon atoms. However, due to the high hydrophobicity of (meth)acrylate monomers with four or more carbon atoms, the absorption of seed particles is reduced during seed polymerization, resulting in absorption residues and the formation of small particles. Since the composition of these small particles differs from that of the polymer particles obtained from the absorption of seed particles, their dispersibility with organic solvents will also differ from that of the polymer particles. This results in an uneven dispersion of the overall particles in organic solvents. In Patent Document 2, when organic solvents evaporate from a composition containing organic particles prepared by mixing with solvents, the organic particles will aggregate through interaction with the organic particles, even without the addition of coagulants or other additives. However, the degree of aggregation is difficult to adjust, and the particle size of the secondary particles obtained from the aggregation of organic particles is prone to dispersion. As a result, uneven coating of the composition containing organic particles may occur, or particles may easily detach from the surface of the coating film formed by the composition containing organic particles. Patent Document 3 contains a monofunctional (meth)acrylic acid monomer (A) unit with a straight-chain or branched alkyl group having 8 to 18 carbon atoms. Because this monofunctional (meth)acrylic acid monomer is highly hydrophobic, it produces small particles during seed polymerization, similar to the polymer particles in Patent Document 1. This small particle size causes the particle as a whole to become unevenly dispersed in organic solvents. The resin particles in Patent Document 4 contain a specific monomer with a dioxolane ring skeleton. However, the dioxolane ring is highly hydrolyzable, so ring-opening of the dioxolane ring occurs as a side reaction during the manufacture of the resin particles. As a result, the resin particles cannot be endowed with the desired hydrophobicity. Furthermore, the hydrolysis of the dioxolane ring also occurs unevenly, so the hydrophobicity of the resin particles becomes uneven, the dispersibility of the resin particles with organic solvents becomes uneven, and there is also the problem of uneven coating. This invention provides polymer particles that can be uniformly dispersed in dispersion media such as organic solvents and adhesive resins, and can maintain a uniform dispersion state and reduce peeling from the coating film even in coating films formed from polymer particle compositions prepared from dispersion media. This invention also provides polymer particle compositions and optical films using polymer particles. [Polymer particles] The polymer particles of the present invention comprise: an acrylic polymer containing 55 to 98% by mass of an acrylic monomer unit represented by formula (1). In equation (1), R 1 To R 3 Each of the following independently represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, R 4 This indicates a monovalent substituent with 5 to 8 carbon atoms, a heterocycle, and a heteroatom ratio (number of heteroatoms n / number of constituent atoms N) greater than 0 but less than 0.4. Because the polymer particles contain acrylic monomer units represented by formula (1), they exhibit excellent affinity for dispersion media such as organic solvents and adhesive resins, and can impart moderate interaction between polymer particles. Therefore, they can be uniformly dispersed in dispersion media such as organic solvents or adhesive resins, and the dispersion stability in the dispersion media is also excellent. Furthermore, due to the acrylic monomer unit represented by formula (1), the polymer particles exhibit excellent affinity with the dispersion medium and moderate interaction between the polymer particles. Therefore, when forming a coating film from a polymer particle composition obtained by dispersing polymer particles in a dispersion medium, the coating film is formed while maintaining the uniform dispersion of the polymer particles even as the viscosity of the polymer particle composition increases during the formation process. Thus, the polymer particles are uniformly dispersed in the resulting coating film. In addition, the polymer particles are reliably held in the coating film by the adhesive resin, thereby reducing the shedding of polymer particles from the coating film surface. During the process of forming a coating film from polymer particle composition, even when polymer particles aggregate with each other, as mentioned above, due to the excellent affinity with the dispersion medium and the moderate strength of the interaction between polymer particles, the polymer particles do not aggregate excessively. They can aggregate to a moderate size while forming aggregated particles of uniform size. Therefore, the aggregated particles of uniform size are uniformly dispersed in the coating film. Furthermore, polymer particles can be appropriately incorporated into the adhesive resin while forming aggregated particles of appropriate size. Therefore, the aggregated particles are reliably retained in the adhesive resin within the coating film, thus reducing the shedding of aggregated particles from the coating surface. In equation (1), R 1 To R 3 Each is independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. Due to R 1 To R 3 Each is independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and therefore also related to the substituent R. 4 The interactions of heterocyclic compounds complement each other, thereby imparting appropriate interactions between polymer particles. In equation (1), at R 1 To R 3 When the alkyl group has 1 to 3 carbon atoms, there is no particular limitation on the alkyl group, and examples include methyl, ethyl, n-propyl, isopropyl, etc. In equation (1), due to the substituent R, 4 The interactions between heterocyclic polymer particles are complementary, and can impart appropriate interactions between polymer particles, so R 1 and R 2 The preferred atom is hydrogen. Due to the cause of substituent R 4 The interactions between heterocyclic polymer particles are complementary, and can impart appropriate interactions between polymer particles, so R 3 Preferably, it is a hydrogen atom, a methyl group, or an ethyl group; more preferably, it is a hydrogen atom or a methyl group. R 4 It consists of a 5- to 8-carbon group and a heterocyclic monovalent substituent. This is achieved by introducing the substituent R... 4 The polymer particles, which have an overall carbon number of 5 to 8 and contain heterocyclic structures, and contain a predetermined amount of acrylic monomer units represented by formula (1), exhibit moderate interactions between the polymer particles. Therefore, the polymer particles exhibit excellent dispersibility and dispersion stability in dispersion media such as organic solvents or adhesive resins, and maintain excellent dispersibility even in coatings. R 4 The carbon number is 5 or more, preferably 6 or more. R 4 The number of carbon atoms is 8 or less, preferably 7 or less. R 4 When the carbon number is within the above range, the polymer particles exhibit excellent affinity with the dispersion medium and can impart moderate interaction between the polymer particles. Therefore, the polymer particles have excellent dispersibility and dispersion stability in dispersion media such as organic solvents or adhesive resins, and can maintain excellent dispersibility even in coatings. R 4 It has heterocyclic rings. By making R 4 Possessing heterocyclic structures, the polymer particles exhibit excellent affinity for the dispersion medium and can impart moderate interactions between the polymer particles. Therefore, the polymer particles demonstrate excellent dispersibility and dispersion stability with dispersion media such as organic solvents or adhesive resins. A heterocycle refers to a ring structure in which the atoms constituting the ring include carbon atoms and atoms other than carbon atoms (heteroatoms). R 4 The heteroatom in the heterocycle is preferably an oxygen atom. When the heteroatom is an oxygen atom, the polymer particles exhibit excellent affinity with the dispersion medium and can impart moderate interaction between the polymer particles. Therefore, the polymer particles exhibit excellent dispersibility and dispersion stability in the dispersion medium, and can maintain excellent dispersibility even in coatings. At R 4 In this process, the heteroatom ratio (number of heteroatoms n / number of constituent atoms N) in the heterocycle is greater than 0 and less than 0.4, preferably greater than 0 and less than 0.35, and even more preferably greater than 0 and less than 0.25. When the heteroatom ratio of the heterocycle is within the above range, the polymer particles exhibit excellent affinity with the dispersion medium and can impart appropriate interactions between the polymer particles. Therefore, the polymer particles exhibit excellent dispersibility and dispersion stability in the dispersion medium, and can maintain excellent dispersibility even in coatings. The number of constituent atoms N of the heterocycle refers to the number of atoms that directly constitute the heterocycle, excluding atoms that constitute substituents and are bonded to the heterocycle (including hydrogen atoms). Substituent R 4 Preferred to be a monovalent substituent as represented by the following formulas (2) and (3). In equation (2), R 5 R represents an alkyl group having 1 to 3 carbon atoms. 7 and R 8Each independently represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, R 6 and R 9 Each of them is independent, and either one represents an oxygen atom, while the other represents a divalent hydrocarbon group produced by removing (extracting) two hydrogen atoms from the same carbon atom at the end of an aliphatic saturated hydrocarbon with 1 to 4 carbon atoms; *1 means a bonded bond and is a single bond. R 5 The term refers to alkyl groups having 1 to 3 carbon atoms. In this invention, an alkyl group refers to a divalent group formed by removing (extracting) two hydrogen atoms bonded to two different carbon atoms in an aliphatic saturated hydrocarbon, and includes both linear and branched groups. Examples of alkyl groups having 1 to 3 carbon atoms include: methylene (-CH4). 2-) Ethyl, propenyl[-CH(CH 3)-CH 2-], Trimethylene [-CH 2-CH 2-CH [2-] etc., because the polymer particles have excellent affinity with the dispersion medium and can impart appropriate interaction between polymer particles, methylene is preferred. R 7 and R 8 Each atom is independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. Hydrogen atoms are preferred because they exhibit excellent affinity between the polymer particles and the dispersion medium and can impart moderate interaction between the polymer particles. (Regarding R) 7 and R 8 When the alkyl group has 1 to 3 carbon atoms, there is no particular limitation on the alkyl group, and examples include methyl, ethyl, n-propyl, isopropyl, etc. R 6 and R 9 Each of the two groups is an oxygen atom, and the other is a divalent hydrocarbon group formed by removing (extracting) two hydrogen atoms from the same terminal carbon atom in an aliphatic saturated hydrocarbon having 1 to 4 carbon atoms; preferably, one of the groups is an oxygen atom and the other is a methylene group. By making R... 6 and R 9One of them is an oxygen atom and the other is the aforementioned divalent hydrocarbon group. The polymer particles have excellent affinity with the dispersion medium and can impart appropriate interactions between the polymer particles. Furthermore, it can prevent the heterocyclic ring from opening due to hydrolysis, homogenize the interactions between polymer particles in the polymer particle whole, and uniformly disperse the polymer particles in the dispersion medium and coating film. There are no particular limitations on the divalent hydrocarbon group produced by removing (extracting) two hydrogen atoms from the same terminal carbon atom in aliphatic saturated hydrocarbons with 1 to 4 carbon atoms. Examples include: methylene (-CH4). 2-), =CH-CH 3[Equation (10)], =C(CH) 3) 2[Equation (11)], =CH-CH 2-CH 3[Equation (12)], =CH-CH 2-CH 2-CH 3[Equation (13)], =CH-CH 2(CH 3)-CH 2[Formula (13)] etc., preferably methylene. In formulas (10) to (14), *2 to *11 indicate bonded and single bond. In equation (3), R 10 R represents an alkyl group having 1 to 3 carbon atoms. 11 To R 13 Each independently represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, R 14 and R 15 Each of the above independently represents an oxygen atom or a methylene group, and at least one of them is an oxygen atom; *12 indicates a bonded bond and is a single bond. R 10 This refers to alkyl groups having 1 to 3 carbon atoms. Examples of alkyl groups having 1 to 3 carbon atoms include: methylene (-CH4). 2-) Ethyl, propenyl[-CH(CH 3)-CH 2-], Trimethylene [-CH 2-CH 2-CH [2-] etc., because the polymer particles have excellent affinity with the dispersion medium and can impart appropriate interaction between polymer particles, methylene is preferred. R 11 To R 13 Each is independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. Due to the excellent affinity of the polymer particles for the dispersion medium and the ability to impart moderate interactions between the polymer particles, R... 11 Preferably methyl and ethyl, more preferably ethyl. This is because it reduces bulkiness and effectively utilizes the interparticle interactions of polymers facilitated by the oxygen atoms of the heterocycle, therefore R... 12 and R 13 Preferably, it is a hydrogen atom. (Regarding R) 11 To R 13 When the alkyl group has 1 to 3 carbon atoms, there is no particular limitation on the alkyl group, and examples include methyl, ethyl, n-propyl, isopropyl, etc. R 14 and R 15 Each can be independently represented by an oxygen atom or a methylene group. R 14 and R 15 Ideally, all should be oxygen atoms. By making R... 14 and R 15 Each component is an oxygen atom or a methylene group, which independently contributes to the affinity of the polymer particles for the dispersion medium and can impart appropriate interactions between the polymer particles. Therefore, the acrylic monomer represented by formula (1) is preferably the acrylic monomer represented by formulas (4) and (5) below, and more preferably the acrylic monomer represented by formulas (6), (7) and (8) below. In formulas (4) and (5), R 1 To R 13 As above, the explanation is omitted. The acrylic monomer units represented by formula (1) in the acrylic polymer contained in the polymer particles are 55% by mass or more, preferably 61% by mass or more, and more preferably 65% ​​by mass or more. The acrylic monomer units represented by formula (1) in the polymer particles are 98% by mass or less, preferably 90% by mass or less, more preferably 85% by mass or less, and more preferably 80% by mass or less. When the content of acrylic monomer units is within the above range, the polymer particles have excellent affinity with the dispersion medium and can impart appropriate interaction between the polymer particles. Therefore, the polymer particles can be uniformly dispersed in dispersion media such as organic solvents or adhesive resins, and the dispersion stability in the dispersion medium is also excellent. Furthermore, even in the coating film formed from the polymer particle composition obtained by dispersing the polymer particles in the dispersion medium, the polymer particles are reliably retained by the adhesive resin, which can reduce the shedding of polymer particles from the coating film surface. Furthermore, during the process of forming a coating film from polymer particle components, even when polymer particles aggregate, they do not aggregate excessively, forming aggregated particles of a uniform size while maintaining an appropriate size. Therefore, uniformly sized aggregated particles are evenly dispersed within the coating film, and the shedding of aggregated particles from the coating surface is also reduced. The acrylic polymer contained in the polymer particles preferably contains multifunctional monomer units, and is cross-linked through these multifunctional monomer units. When the acrylic polymer contains multifunctional monomer units, the changes in the interaction between polymer particles caused by the absorption of the dispersion medium by the polymer particles can be reduced, thereby improving the homogeneity and dispersion stability of the polymer particles in the dispersion medium. Furthermore, it can reduce the viscosity non-uniformity of the polymer particle composition caused by "partial changes in the viscosity of the polymer particle composition obtained by dispersing polymer particles in the dispersion medium due to the absorption of the dispersion medium by the polymer particles", thereby reducing the occurrence of uneven coating of the polymer particle composition. Multifunctional monomers are monomers having a plurality of polymerizable functional groups (e.g., vinyl, epoxy, isocyanate groups, etc.). Preferably, multifunctional monomers have a plurality of vinyl groups as functional groups. Examples of multifunctional monomers include: 1,10-decanediol dimethacrylate, polyethylene glycol dimethacrylate, trimethylolpropane tri(meth)acrylate, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, decaethylene glycol di(meth)acrylate, pentadecylethylene glycol di(meth)acrylate, 150% ethylene glycol di(meth)acrylate, neopentyl tert-tetra(meth)acrylate, 1,3-di(meth)acrylate, allyl (meth)acrylate, and other acrylic multifunctional monomers, divinylbenzene, divinylnaphthalene, or their derivatives, and aromatic divinyl compounds. In this invention, (meth)acrylate means acrylate or methacrylate. Multifunctional monomers can be used alone or in combination of two or more. The content of multifunctional monomer units in acrylic polymers is preferably 5% by mass or more, more preferably 10% by mass or more, and more preferably 15% by mass or more. The content of multifunctional monomer units in acrylic polymers is preferably 45% by mass or less, more preferably 40% by mass or less, more preferably 35% by mass or less, and more preferably 30% by mass or less. When the content of multifunctional monomer units is 5% by mass or more, the variation in the interaction between polymer particles caused by the absorption of the dispersion medium by polymer particles can be reduced, thereby improving the homogeneity and dispersion stability of the polymer particles in the dispersion medium. Furthermore, reducing the absorption of the dispersion medium by polymer particles can reduce the viscosity non-uniformity of the polymer particle composition caused by "partial changes in the viscosity of the polymer particle composition obtained by dispersing polymer particles in the dispersion medium," thus reducing the occurrence of uneven coating of the polymer particle composition. When the content of multifunctional monomer units is 45% by mass or less, the polymer particles exhibit excellent affinity with the dispersion medium and can impart appropriate interactions between the polymer particles. Therefore, the homogenization and dispersion stability of the polymer particles in the dispersion medium can be improved, and the polymer particles can be uniformly dispersed in the coating film formed from the polymer particle composition obtained by dispersing polymer particles in the dispersion medium. The gel fraction of the polymer particles is preferably 90% by mass or higher, more preferably 91% by mass or higher, and even more preferably 95% by mass or higher. A gel fraction of 90% by mass or higher improves the solvent resistance of the polymer particles. For example, when preparing a polymer particle composition by dispersing the polymer particles in a dispersion medium, the swelling of the polymer particles due to absorption of the dispersion medium is reduced, thereby improving the dispersibility and dispersion stability of the polymer particles in the dispersion medium. Furthermore, even in coatings formed from polymer particle compositions prepared by dispersing polymer particles in a dispersion medium, a more uniform dispersion can be maintained, and the shedding of polymer particles from the coating film can be more effectively reduced. The gel fraction of polymer particles refers to the value determined by the following procedure. First, 1.0 g of polymer particles and 0.03 g of zeolite as the sample are precisely weighed and added to a 200 mL round-bottom flask. Then, 100 mL of toluene is added, a cooling tube is installed in the round-bottom flask, and the flask is immersed in an oil bath maintained at 130°C for 24 hours under reflux. After reflux, use glass fiber filter paper manufactured by ADVANTEC (GB-140). 37mm) and GA-200 The TOP company's Büchner Funnel type filter paper 3G (glass particle pore diameter 20 to 30 mm) was weighed and tested. The contents (solution) of the above-mentioned eggplant-shaped flask were filtered using a filter paper (μm, capacity 30mL), and the solid components were recovered within the above-mentioned Buchner funnel-shaped filter paper 3G. Then, the solid components recovered within the above-mentioned Buchner funnel-shaped filter paper 3G, together with the above-mentioned Buchner funnel-shaped filter paper 3G, were dried in a vacuum oven at 130°C for 1 hour, and then dried at a gauge pressure of 0.06MPa for 2 hours to remove toluene, and then cooled to room temperature. After cooling, the total mass of the Buchner funnel-shaped filter paper 3G, the glass fiber filter paper, and the solid components was measured while the solid components were contained within the Buchner funnel-shaped filter paper 3G. Then, the mass (g) of the dried powder was obtained by subtracting the mass of the Buchner funnel-shaped filter paper 3G, the glass fiber filter paper, and the zeolite from the measured total mass. Then, the gel fraction was calculated using the mass (g) of the dried powder and the mass (g) of the sample added to the flask, and by the following formula. Gel fraction (mass %) = [mass of dried powder (g) / mass of sample (g)] × 100 The acrylic polymer contained in the polymer particles preferably contains styrene monomer units. By including styrene monomer units in the acrylic polymer, the polymer particles exhibit excellent affinity with the dispersion medium and provide appropriate interaction between the polymer particles. Therefore, the polymer particles can be uniformly dispersed in dispersion media such as organic solvents or adhesive resins, and the dispersion stability in the dispersion medium is also excellent. Furthermore, in the coating film formed from the polymer particle composition obtained by dispersing polymer particles in the dispersion medium, the polymer particles can be uniformly dispersed, and the detachment of polymer particles from the coating film surface can be reduced. In addition, during the process of forming the coating film from the polymer particle composition, even when the polymer particles aggregate with each other, they do not aggregate excessively, and can aggregate to an appropriate size while forming aggregated particles of uniform size. Therefore, uniformly sized aggregated particles can be uniformly dispersed in the coating film, and the detachment of aggregated particles from the coating film surface can be reduced. There are no particular limitations on styrene monomers; examples include styrene, α-methylstyrene, vinyltoluene, chlorostyrene, ethylstyrene, isopropylstyrene, dimethylstyrene, and bromostyrene. Styrene monomers can be used alone or in combination of two or more. Acrylic polymers may also be free of styrene monomer units. When acrylic polymers contain styrene monomer units, the content of these units is preferably 40% by mass or less, more preferably 30% by mass or less, and even more preferably 20% by mass or less. When the content of styrene monomer units is 40% by mass or less, during the process of forming a coating film from the polymer particle composition, excessive aggregation of polymer particles is reduced, allowing the polymer particles to aggregate into appropriately sized aggregates with uniform size. Therefore, uniformly sized aggregates can be evenly dispersed in the coating film, and the shedding of aggregates from the coating film surface can be reduced. Without impairing the physical properties of the polymer particles, the acrylic polymer contained in the polymer particles may also contain other monomer units. Examples of such monomers include acrylates and methacrylates. There are no particular limitations on acrylates; examples include methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, isobutyl acrylate, and other alkyl acrylates. Examples of methacrylates include methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, and other alkyl methacrylates. The content of monomer units contained in polymer particles refers to the value determined by the following method. A sample of polymer particles of approximately 0.1 to 0.5 mg is weighed precisely. The test specimen is prepared by coating the sample with a strongly magnetic metal (product name "Pyrofoil" manufactured by Japan Analysis Industries Co., Ltd.) with a Curie Point of 590°C. The test system was constructed by pressing the sample against a strongly magnetic metal body. The sample was decomposed by heating it using a Curie point pyrolysis apparatus (JPS-700 model, manufactured by Nippon Analytical Industries, Ltd.). A gas chromatography system (GC7820, detector = FID, manufactured by Agilent Technologies, Ltd.) was used to determine the monomer components generated during decomposition, and the peak area of ​​the monomers to be measured was calculated. For the monomers to be measured, a calibration curve showing the relationship between monomer quantity and peak area was pre-constructed. Based on the calibration curve, the amount of monomers contained in the sample was calculated from the measured peak area. (Measurement conditions) Heating = 590℃ - 5 seconds Oven temperature = 300℃ Needle temperature = 300℃ Tube column = Agilent Technologies "DB-5" (0.25) μm×0.25mm ×30m) (GC oven heating conditions) Initial temperature = 50℃ (hold for 0.5 min) The heating rate in the first stage is 10℃ / min (until reaching 200℃, then holding for 0 min). The second stage heating rate is 20℃ / min (until reaching 320℃). Final temperature = 320℃ (hold for 0.5 min) Carrier gas = He He flow rate = 1.275 mL / min Inlet pressure = 100 kPa Tube inlet pressure = 100 kPa Inlet temperature = 300℃ Detector temperature = 300℃ Flow split ratio = 1 / 50 The optimal amount of surfactant contained in 1g of polymer particles is 45. Below μg / g, preferably 40 Below μg / g, preferably 35 μg / g Below μg / g, preferably 30 μg / g Below μg / g, preferably 25 μg / g Below μg / g. The surfactant concentration is 45 μg / g. At concentrations below μg / g, moderate interactions between polymer particles are achieved, resulting in excellent dispersibility and dispersion stability of the polymer particles in the dispersion medium. Furthermore, in coatings formed from polymer particle compositions obtained by dispersing polymer particles in a dispersion medium, the polymer particles are uniformly dispersed, and particle detachment from the coating surface is reduced. Moreover, even when polymer particles aggregate during coating formation, they do not excessively aggregate, forming uniformly sized aggregated particles at an appropriate size. Therefore, uniformly sized aggregated particles can be uniformly dispersed in the coating, and particle detachment from the coating surface is reduced. The surfactant concentration in the polymer particles was determined using the following method. Approximately 0.10 g of polymer particles (as the sample) was precisely weighed into a centrifuge tube, and 5 mL of methanol (as the extraction solution) was added using a full-volume pipette. The polymer particles and extraction solution were then thoroughly mixed. After ultrasonic extraction for 15 minutes, the mixture was centrifuged at 3500 rpm for 15 minutes, and the resulting supernatant was used as the test solution. The surfactant concentration in this test solution was measured. The surfactant concentration in the measured test solution was then calculated using the following formula (…). The surfactant content (μg / g) in the polymer particles was calculated using the following parameters: the mass of the polymer particles used as the sample [sample mass (g)], and the volume of the extract (extract volume (mL)). The extract volume was 5 mL. The content of surfactants ( μg / g) = [concentration of surfactant in the test solution (μg / g)] [μg / mL) × Extraction solution volume (mL) / Sample mass (g) The arithmetic mean particle size in the particle size distribution based on the number of polymer particles is preferably 0.5. Above μm, preferably 1 Above μm, 1.5 is preferred. The arithmetic mean particle size in the particle size distribution based on the number of polymer particles is preferably 10 μm or larger. Below μm, 8 μm is preferred. Below μm, 6 is preferred. Below μm, 4 is preferred. Below μm. The arithmetic mean particle size in the particle size distribution based on the number of polymer particles is 0.5. When the polymer particles are larger than μm, they exhibit excellent optical properties such as light diffusion when used in optical applications such as light diffusing agents, thus being superior. The arithmetic mean particle size in the particle size distribution based on the number of polymer particles is 10. When the thickness is below μm, the coating thickness can be made uniform on the surface of polymer particles protruding from the coating film. Therefore, the homogenization of the coating film can be achieved, and the shedding of polymer particles from the coating film surface can be reduced. In the polymer particles, the content of small particles having a particle size of less than 50% of the arithmetic mean particle size in the particle size distribution based on quantity is preferably 6% or less, and more preferably 5% or less. When the content of small particles is less than 6%, the interaction between polymer particles can be more uniformly and holistically achieved in the overall polymer particle composition. Therefore, the uniformity and dispersion stability of polymer particles in the dispersion medium can be improved. Furthermore, in the coating film formed from the polymer particle composition, the polymer particles can be more uniformly dispersed and the peeling off from the coating surface can be reduced. The coefficient of variation (CV) of the particle size obtained from the particle size distribution based on the number of polymer particles is preferably 15% or less, and more preferably 14% or less. When the coefficient of variation of polymer particles is 15% or less, the interaction between polymer particles can be more uniformly and holistically achieved throughout the polymer particle assembly. Therefore, the uniformity and dispersion stability of polymer particles in the dispersion medium can be improved. Furthermore, in the coating film formed from the polymer particle composition, the polymer particles can be more uniformly dispersed and the shedding from the coating surface can be reduced. The arithmetic mean particle size and coefficient of variation (CV) of the particle size distribution based on the number of polymer particles, as well as the content of small particles in the polymer particles, are determined by the following methods. The arithmetic mean particle size in the particle size distribution based on the number of polymer particles is obtained using a Coulter Multisizer. TM The measurement was performed using a 4e (a measuring device manufactured by Beckman Coulter, Inc.). The measurement was conducted using the aperture calibrated according to the Beckman Coulter, Inc. Multisizer 4 user manual. In addition, the pore size used for measurement is appropriately selected according to the size of the polymer particles being measured. Current (pore current) and Gain are appropriately set according to the selected pore size. The sample used for the determination was prepared by dispersing 0.1 g of polymer particles in 10 mL of a 0.1% (w / w) nonionic surfactant aqueous solution using a touch mixer (Yamato Scientific, Inc., trade name "TOUCHMIXER MT-31") and an ultrasonic cleaner (Velvo-Clear, Inc., trade name "ULTRASONIC CLEANER VS-150") to form a dispersion. During the determination, the beaker was stirred slowly to a level that prevented air bubbles from entering, and the determination was stopped when 100,000 polymer particles were measured. The particle size of the polymer particles is the spherical equivalent diameter. That is, the particle size of the polymer particles is the diameter of a true sphere with the same volume as the polymer particles. The arithmetic mean particle size of the polymer particles is the arithmetic mean of the particle size distribution based on the number of 100,000 particles. The content of polymer particles with a particle size of less than 50% of the arithmetic mean particle size (small particles) is the percentage of small particles calculated based on the particle size distribution of 100,000 particles. The coefficient of variation (CV) of polymer particle size is calculated using the following mathematical formula. The coefficient of variation (CV) of polymer particle size = 100 × (standard deviation of particle size in the particle size distribution based on the number of polymer particles) / (arithmetic mean particle size in the particle size distribution based on the number of polymer particles) The dispersion coefficient of the polymer particles is preferably less than 0.20, and more preferably less than 0.15. When the dispersion coefficient of the polymer particles is less than 0.20, the uniformity and dispersion stability of the polymer particles in the dispersion medium can be improved. Furthermore, in the coating film formed from the polymer particle composition, the polymer particles can be more uniformly dispersed and the shedding from the coating surface can be reduced. The dispersion displacement of polymer particles is preferably less than 0.02, and more preferably less than 0.015. When the dispersion displacement of polymer particles is less than 0.02, the uniformity and dispersion stability of polymer particles in the dispersion medium can be improved. Furthermore, in the coating film formed from the polymer particle composition, the polymer particles can be more uniformly dispersed and the shedding from the coating surface can be reduced. The dispersion coefficient and dispersion displacement of polymer particles are determined by the following methods. [Methods for preparing dispersions] 0.10 g of polymer particles and 5.00 g of butyl acetate as the dispersion medium were added to a 10 mL sample tube, and the mixture was stirred for 1 minute using an ultrasonic cleaner (Velvo-Clear Co., Ltd., trade name "ULTRASONIC CLEANER VS-150") to disperse the polymer particles in the butyl acetate and obtain a dispersion. Then, 0.50 g of acrylic resin (DIC Co., Ltd., trade name "ACRYDIC (registered trademark) A-817-Ba") was added to this dispersion, and the mixture was stirred for about 10 minutes using the same ultrasonic cleaner to prepare a dispersion in which the polymer particles were dispersed in butyl acetate and acrylic resin. [Determination Method] The viscosity of the dispersion was determined using a viscometer (m-VROC microsample viscometer manufactured by Nihon Rufuto Co., Ltd.) and by the method described below. The viscometer was placed in the measurement environment for at least 30 minutes before the viscosity was measured. Using the viscometer described above, the prepared dispersion was allowed to stand at room temperature (laboratory temperature 23°C to 27°C) for 5 hours. Then, the dispersion was stirred for 5 minutes using an ultrasonic cleaner (redispersed) and the viscosity (mPa·s) of the dispersion was measured. Then, using the measured viscosity (mPa·s) and the measured temperature (K), the viscosity value V (mPa·s / K) per unit temperature (K) is calculated using the following formula. The viscosity measurement is repeated 10 times, and the average viscosity value, the maximum viscosity value, and the minimum viscosity value are calculated. Viscosity value V (mPa·s / K) = Measured value (mPa·s) / Measured temperature (K) [Calculation method for dispersed motion displacement] The maximum, minimum, and average viscosity values ​​from 10 measurements are used to calculate the displacement of the viscosity value, i.e., the dispersion displacement, using the following formula. <Formula for Dispersed Motion Displacement> Distributed motion displacement = (VMAX - VMIN) / VAVE VMAX: The maximum viscosity value (mPa·s / K) from 10 measurements. VMIN: The minimum viscosity value (mPa·s / K) among 10 measurements. VAVE: The average viscosity value (mPa·s / K) from 10 measurements. [Methods for calculating the dispersion coefficient] The dispersion was prepared using the same method as for determining the dispersion displacement. Using the viscometer described above, the prepared dispersion was allowed to stand at room temperature (laboratory temperature 23°C to 27°C) for 4, 5, or 6 hours. Then, the dispersion was stirred for 5 minutes using an ultrasonic cleaner (redispersion). The viscosity V (mPa·s / K) of the dispersion after standing for 4, 5, or 6 hours was measured using the same method as for determining the dispersion displacement. The dispersion coefficient was calculated using the following formula. <Formula for the dispersion factor> Dispersion coefficient = |V6hr.AVE - V4hr.AVE| / V5hr.AVE V4hr. AVE: The average viscosity value of 10 measurements taken in the dispersion after standing for 4 hours. V5hr. AVE: The average viscosity value of 10 measurements taken in the dispersion after standing for 5 hours. V6hr. AVE: The average viscosity value of 10 measurements taken in the dispersion after standing for 6 hours. [Methods for manufacturing polymer particles] Next, the method for manufacturing polymer particles will be described. There is no particular limitation on the method for manufacturing polymer particles. They can be manufactured by polymerizing raw material monomers containing acrylic monomers represented by formula (1) in the presence of a polymerization initiator as needed, using a general approach. There are no particular limitations on the polymerization method; general polymerization methods such as suspension polymerization, seed polymerization, bulk polymerization, and solution polymerization can be used, with seed polymerization being preferred. Emulsion polymerization is a polymerization method in which the raw material monomers are dispersed in an aqueous medium (described later) and polymerization is carried out in the presence of a polymerization initiator and an emulsifier, and it is included in suspension polymerization. Seed polymerization is a method in which seed particles, consisting of polymers of separately manufactured vinyl monomers, are introduced to polymerize a raw material monomer containing an acrylic monomer represented by formula (1) at the beginning of polymerization. In detail, seed polymerization uses polymer particles composed of vinyl monomers as seed particles, and polymerizes the raw material monomers containing acrylic monomers represented by formula (1) within the seed particles in an aqueous medium. In this method, by allowing the seed particles to grow, polymer particles with a larger particle size than the original seed particles can be obtained. The following describes a general method of seed polymerization, but the polymerization method is not limited to this method. The weight-average molecular weight of the polymer constituting the seed particles used in seed polymerization is preferably 40,000 or less, more preferably 35,000 or less. The weight-average molecular weight of the polymer constituting the seed particles used in seed polymerization is preferably 6,000 or more, more preferably 8,000 or more. When the raw material monomer is absorbed into the swollen state of the seed particles, the polymer constituting the seed particles is dispersed within the raw material monomer. When the weight-average molecular weight of the polymer constituting the seed particles is 6,000 or more, in the aforementioned swollen state, the viscosity of the raw material monomer is moderately increased, which can inhibit the aggregation of the raw material monomers. When the weight-average molecular weight of the polymer constituting the seed particles is 40,000 or less, the absorbability of the raw material monomer is improved, the particle size dispersion of the polymer particles is reduced, and the interaction between polymer particles in the overall polymer particle structure becomes more uniform, thereby improving the dispersibility and dispersion stability of the polymer particles in the dispersion medium. In this invention, the weight-average molecular weight of the polymer refers to the value determined by the following methods. Specifically, it is determined by the following methods. The weight-average molecular weight of a polymer can be determined using GPC (gel permeation chromatography). The weight-average molecular weight refers to the weight-average molecular weight converted from polystyrene. Specifically, 0.003 g of polymer particles used as the sample is dissolved in 10 mL of tetrahydrofuran (THF) at room temperature for at least 24 hours, and then dissolved using a non-aqueous 0.45 mL gel permeation chromatography system. The solution obtained by filtration through a chromatography disc with a particle size of μm was used as the assay solution. The weight-average molecular weight of the polymer particles was then determined from a pre-prepared calibration curve of standard polystyrene. The chromatography conditions are as described below. Equipment: High-speed GPC device Product Name: Tosoh HLC-8320GPC EcoSEC-WorkStation (with built-in RI detector) Analysis conditions Column: TSKgel SuperHZM-H x 2 (4.6mm I.D x 15cm L x 2) Protective tubing: TSKguardcolumn SuperHZ-H × 1 piece (4.6mm ID × 2cm L) Flow rate: 0.175 mL / min for sample side, 0.175 mL / min for reference side Detector: Built-in RI detector Concentration: 0.3 g / L Injection volume: 50 μL Column temperature: 40℃ System temperature: 40℃ Solution: THF In seed polymerization, firstly, a mixture comprising a raw material monomer containing an acrylic monomer represented by formula (1) and an aqueous medium, and seed particles are mixed. A surfactant may also be included in the mixture as needed. The mixture can be prepared by commonly known methods. For example, a raw material monomer containing an acrylic monomer represented by formula (1) and a surfactant as needed can be added to an aqueous medium and mixed using a homogenizer, an ultrasonic processor, a nanomizer (registered trademark), or other microemulsifiers. The aqueous medium can be water or a mixture of water and an organic solvent [e.g., lower alcohols (alcohols with 5 or fewer carbon atoms)], preferably water. The amount of surfactant used in seed polymerization is preferably 1.5 parts by mass or less, relative to 100 parts by mass of the raw material monomer containing the acrylic monomer represented by formula (1). When the amount of surfactant is 1.5 parts by mass or less, the side reaction of the raw material monomer absorbed by the seed particles flowing out of the seed particles and undergoing polymerization outside the seed particles can be reduced, thereby reducing the particle size dispersion of the resulting polymer particles. By reducing the particle size dispersion of the polymer particles, the interaction between polymer particles can be made uniform in the polymer particles as a whole. Therefore, the dispersibility and dispersion stability of polymer particles in the dispersion medium can be improved, and the polymer particles can be uniformly dispersed in the coating obtained from the polymer particle composition. After the mixture and seed particles are mixed, the raw material monomer containing the acrylic monomer represented by formula (1) is absorbed into the seed particles. This absorption can usually be carried out by stirring the mixture at room temperature (20 to 50°C) for 1 to 12 hours. Acrylic monomers represented by formula (1) are only slightly soluble in water, thus exhibiting excellent absorption by seed particles. In aqueous media, they reduce polymerization as a side reaction and promote polymerization within the seed particles, enabling the production of polymer particles with small particle size dispersion. The small particle size dispersion of polymer particles allows for uniform interaction between polymer particles, resulting in excellent dispersibility and dispersion stability in the dispersion medium. Furthermore, in coatings formed from polymer particle compositions, the polymer particles can be uniformly dispersed, reducing the shedding of polymer particles from the coating surface. The seed particles swell by absorbing a raw material monomer containing an acrylic monomer represented by formula (1). Regarding the mixing ratio of the raw material monomer containing the acrylic monomer represented by formula (1) to the seed particles, the raw material monomer is preferably in the range of 9 to 110 parts by mass relative to 1 part by mass of the seed particles. When the amount of raw material monomer is 9 parts by mass or more, the manufacturing efficiency of the polymer particles is improved. When the amount of raw material monomer is 110 parts by mass or less, the polymerization of the raw material monomer as a side reaction outside the seed particles can be reduced, thereby reducing the particle size dispersion of the polymer particles. Next, polymer particles can be obtained by polymerizing the raw material monomers absorbed by the seed particles. Alternatively, polymer particles can be manufactured by repeating the steps of absorbing raw material monomers and polymerizing them multiple times. Polymerization initiators may also be added to the raw monomers as needed. There are no particular limitations on polymerization initiators, but examples include: benzyl peroxide, lauryl peroxide, o-chlorobenzyl peroxide, o-methoxybenzyl peroxide, 3,5,5-trimethylhexyl peroxide, tert-butylperoxy-2-ethylhexanoate, di(tert-butyl) peroxide, and other organic peroxides; 2,2'-azobisisobutyronitrile, 2,2'-azobis(2,4-dimethylpentanonitrile), 2,2'-azobis(2,3-dimethylbutyronitrile), 2,2 Azo compounds such as '-azobis(2-methylbutyronitrile), 2,2'-azobis(2,3,3-trimethylbutyronitrile), 2,2'-azobis(2-isopropylbutyronitrile), 1,1'-azobis(cyclohexane-1-formonitrile), 2,2'-azobis(4-methoxy-2,4-dimethylpentanonitrile), (2-aminomethoxyazo)isobutyronitrile, 4,4'-azobis(4-cyanopentanoic acid), and dimethyl-2,2'-azobisisobutyrate are used. The polymerization initiator is preferably used in the range of 0.1 to 1.0 parts by weight relative to 100 parts by weight of the raw monomer. The polymerization temperature of seed polymerization can be appropriately selected according to the type of raw material monomer or the type of polymerization initiator used as needed. Specifically, the preferred polymerization temperature for seed polymerization is 25 to 110°C, more preferably 50 to 100°C. The preferred polymerization time for seed polymerization is 1 to 12 hours. In seed polymerization, to improve the dispersion stability of polymer particles, a polymeric dispersion stabilizer can be added to the polymerization reaction system. Examples of polymeric dispersion stabilizers include: polyvinyl alcohol, polycarboxylic acids, cellulose derivatives (hydroxyethyl cellulose, carboxymethyl cellulose, etc.), and polyvinylpyrrolidone, with polyvinyl alcohol and polyvinylpyrrolidone being preferred. The amount of polymeric dispersion stabilizer added relative to 100 parts by weight of the raw monomer is preferably 0.5 to 15 parts by weight, more preferably 1 to 10 parts by weight. In addition, in order to reduce the polymerization of raw material monomers in the aqueous medium outside the seed particles in the above polymerization reaction, water-soluble polymerization inhibitors such as sodium nitrite, nitrites, hydroquinones, ascorbic acid, water-soluble B vitamins, citric acid, and polyphenols can be added to the aqueous medium. In addition, the polymerization method used to polymerize vinyl monomers to obtain seed particles can be a general polymerization method, although there are no particular limitations. However, it can be, for example, dispersion polymerization, emulsion polymerization, emulsion polymerization without emulsifier (emulsion polymerization without the use of surfactants as emulsifiers), seed polymerization, suspension polymerization, etc. The reaction solution containing polymer particles obtained by polymerization using the above-described method is supplied to a general-purpose filter to separate the polymer particles contained in the reaction solution from the aqueous medium. After washing the separated polymer particles with a washing solution, drying is performed using a general-purpose method to almost completely remove the washing solution. Fractionation (preferably air-separation) can also be performed as needed to obtain polymer particles. Other examples of cleaning solutions include: water; lower alcohols (alcohols with 5 or fewer carbon atoms) such as methanol and ethanol; and mixtures of water and lower alcohols. [Applications of polymer particles] Polymer particles are suitable for use as optical films such as anti-glare films or light diffusion films, or as optical components such as light diffusers, and are particularly suitable for use as anti-glare components. Polymer particles can also be used as matting agents in coatings and as additives to improve the physical properties of resins. [Polymer Particle Composition] Polymer particle compositions can be prepared by dispersing polymer particles in a dispersion medium. This polymer particle composition is then coated onto a substrate and dried, thereby creating a coating film containing polymer particles on the substrate. Examples of substrates include films and other molded bodies. Since the polymer particles contain an acrylic polymer containing an acrylic monomer unit represented by formula (1) in a predetermined amount, and have excellent dispersibility and dispersion stability in the dispersion medium, the polymer particles are stably and uniformly dispersed in the polymer particle composition, and no uneven coating will occur, so the polymer particle composition can be easily coated on the substrate. Furthermore, in the coating film formed by drying the polymer particle composition, the polymer particles are maintained in a uniformly dispersed state, resulting in a coating film with homogeneous physical properties. Moreover, because the polymer particles are firmly held within the coating film, the shedding of polymer particles from the coating surface is reduced. Furthermore, even when polymer particles aggregate to form aggregated particles during the formation of the coating film, the polymer particles will not aggregate excessively but will form aggregated particles of moderate and uniform size. The coating film has homogeneous physical properties, and the shedding of aggregated particles from the coating film surface is also reduced. There are no particular limitations on the dispersion medium; examples include adhesive resins and organic solvents. Adhesive resins can be appropriately selected according to the intended use of the coating. Examples of adhesive resins include: (meth)acrylic resins; (meth)acrylic-amine ester resins; amine ester resins; polyvinyl chloride resins; polydichloroethylene resins; melamine resins; styrene resins; alkyd resins; phenolic resins; epoxy resins; polyester resins; polysiloxane resins such as alkyl polysiloxane resins; modified polysiloxane resins such as (meth)acrylic-polysiloxane resins, polysiloxane-alkyd resins, polysiloxane-amine ester resins, and polysiloxane-polyester resins; fluorinated resins such as polydifluoroethylene and fluoroolefin vinyl ether polymers. Note that (meth)acrylic acid refers to acrylic acid or methacrylic acid. Adhesive resins can also be curable resins that can form a cross-linked structure through a cross-linking reaction. Curable resins are classified according to the type of curing, such as ultraviolet-cured resins, electron-beam-cured resins, ionizing radiation-cured resins, thermosetting resins, and hot-gas-cured resins. Curable resins also include those that generate adhesive components through curing. Curable resins also include compositions containing monomers before curing. Examples of thermosetting resins include: thermosetting amine resins containing acrylic polyols and isocyanate prepolymers, phenolic resins, urea melamine resins, epoxy resins, unsaturated polyester resins, and polysiloxane resins. Examples of resins that can be cured by ionizing radiation include: trimethylolpropane tri(meth)acrylate, trimethylolethane tri(meth)acrylate, 1,2,4-cyclohexane tri(meth)acrylate, and other polyol polyfunctional (meth)acrylate resins; polyfunctional amine acrylate resins synthesized from diisocyanates, polyols, and (meth)acrylates containing hydroxyl groups; polyether resins with acrylate functional groups; polyester resins; epoxy resins; alkyd resins; spiroacetal resins; polybutadiene resins; and polythiol polyene resins. To adjust the viscosity of the polymer particle composition, organic solvents may also be included. Examples of organic solvents include: aromatic solvents such as toluene and xylene; alcohol solvents such as methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, and propylene glycol monomethyl ether; ester solvents such as ethyl acetate and butyl acetate; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclopentanone, and cyclohexanone; and solvents such as 2-methoxyethanol, 2-ethoxyethanol, 2-butoxyethanol, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, and propylene glycol methyl ether. Glycol ethers; glycol ether esters such as 2-methoxyethyl acetate, 2-ethoxyethyl acetate (Celuzo acetate), 2-butoxyethyl acetate, and propylene glycol methyl ether acetate; chlorinated solvents such as chloroform, dichloromethane, trichloromethane, and methylene chloride; ether solvents such as tetrahydrofuran, diethyl ether, 1,4-dioxane, and 1,3-dioxane; and amide solvents such as N-methylpyrrolidone, dimethylformamide, dimethyl sulfoxide, and dimethylacetamide. In addition, organic solvents can be used alone or in combination of two or more. The amount of polymer particles in the polymer particle composition is preferably 2 parts by mass or more, more preferably 4 parts by mass or more, and more preferably 6 parts by mass or more, relative to 100 parts by mass of the adhesive resin. The amount of polymer particles in the polymer particle composition is preferably 300 parts by mass or less, more preferably 200 parts by mass or less, and more preferably 100 parts by mass or less, relative to 100 parts by mass of the adhesive resin. There are no particular limitations on the material of the substrate to which the polymer particle composition is coated. Examples include: polyester polymers such as polyethylene terephthalate (PET) and polyethylene naphthalate; cellulose polymers such as cellulose diacetate and cellulose triacetate (TAC); synthetic resins such as polycarbonate polymers and (meth)acrylic polymers such as polymethyl methacrylate; cement, ceramic tiles, metals, and glass. There are no particular limitations on the method of coating polymer particle composition onto a substrate. Examples include: rod coating, doctor blade coating, spin coating, reverse coating, die coating, spray coating, roller coating, gravure coating, microgravure coating, lip coating, air knife coating, and impregnation. The thickness of the coating film formed from the polymer particle composition is not particularly limited, but is appropriately determined according to the particle size of the polymer particles, preferably 1 to 20 mm. μm, preferably 2 to 10 μm. μm. The polymer particles of this invention can be uniformly dispersed in dispersion media such as organic solvents and adhesive resins. Even in coatings obtained from polymer particle compositions prepared by dispersing in organic solvents, the polymer particles of this invention can maintain a uniform dispersion. The polymer particles of this invention can easily form a coating with reduced polymer particle shedding from the surface. The following series of examples illustrate the present invention in more detail, but are not limited to these examples. [Example] In the examples and comparative examples, the following compounds were used. [Acrylic monomers] . Tetrahydrofuran methyl acrylate [Formula (6), THFA, R 4 Carbon number: 5, heteroatom ratio: 0.2 . Tetrahydrofuran methyl methacrylate [Formula (7), THFMA, R] 4 Carbon number: 5, heteroatom ratio: 0.2 . Trimethylolpropane acetal acrylate [Formula (8), CTFA, R 4 Carbon number: 7, heteroatom ratio: 0.33 Cyclohexyl methacrylate [CHMA, R] 4 Carbon number: 6, heteroatom ratio: 0] Benzyl methacrylate [BzMA, R] 4 Carbon number: 7, heteroatom ratio: 0] . Phenoxyethyl methacrylate [FEMA, R] 4 Carbon number: 8, heteroatom ratio: 0] Lauryl methacrylate [LMA, R] 4 Carbon number: 12, heteroatom ratio: 0] . Methacrylate (2-methyl-2-ethyl-1,3-dioxacyclopentane-4-yl) ester [as shown in formula (9) below], MEOMA, R 4 Carbon number: 7, heteroatom ratio: 0.4 Hydroxyethyl methacrylate [HEMA, R] 4 Carbon number: 2, heteroatom ratio: 0] In Table 1, R is listed sequentially below the column for the types of acrylic monomers. 4 The ratio of carbon number to heteroatom number. [Styrene-based monomers] Styrene monomer [St] [Multifunctional monomer] Ethylene glycol dimethacrylate [EGDMA] Trimethylolpropane triacrylate [TMPTA] Divinylbenzene [DVB] (Examples 1 to 12, 14 and 15, Comparative Examples 1 to 7) [Seed Particle Manufacturing] 2900 parts by mass of water, 500 parts by mass of ethyl methacrylate, and a predetermined amount of n-octylthiol as shown in Table 1, used as an aqueous medium, were supplied to a 5L reactor equipped with a stirrer and a thermometer. While stirring the contents, nitrogen was substituted into the reactor, and the internal temperature was raised to 55°C. Then, while maintaining the internal temperature at 55°C, an aqueous solution prepared by dissolving 3.0 parts by mass of potassium persulfate (used as a polymerization initiator) in 100 parts by mass of water was supplied to the reactor contents, and the polymerization reaction was carried out for 12 hours. Using 400 mesh (32 aperture) A metal mesh (μm) was used to filter the polymerized reaction solution, producing a slurry containing 15% by mass of seed particles composed of polyethyl methacrylate as the solid component. The seed particles in this slurry are true spherical. The arithmetic mean particle size in the particle size distribution based on the number of seed particles is 0.70 μm. μm. The weight-average molecular weight (Mw) of the polyethyl methacrylate that constitutes the seed particles is shown in Table 1. [Example of polymer particle manufacturing] Six parts by mass of benzyl peroxide, which serves as a polymerization initiator, are dissolved in a raw material monomer containing predetermined amounts of acrylic monomers, multifunctional monomers, and styrene monomers (St) as shown in Table 1 to prepare a monomer mixture. A surfactant solution was prepared by adding 10 parts by mass of sodium dodecylbenzenesulfonate (trade name "Neogen (registered trademark) S-20D" of Daiichi Industrial Pharmaceutical Co., Ltd.) as a surfactant to 1000 parts by mass of ion-exchanged water as an aqueous medium. The monomer mixture and surfactant solution were mixed and placed in a homogenizer (Primix Inc.'s "TKHomomixer MARKII 2.5") and processed at 8000 rpm for 10 minutes to obtain an emulsion (mixture). A slurry of seed particles was added to this emulsion at a ratio of 20 parts by mass of seed particles, and the mixture was stirred at 30°C for 3 hours to obtain a dispersion. Ten parts by weight of polyvinyl alcohol (trade name "Gohsenol GM-14L" manufactured by Nippon Synthetic Chemicals Co., Ltd.) as a dispersant and 0.60 parts by weight of sodium nitrite as a polymerization inhibitor were dissolved in 1989.4 parts by weight of deionized water to obtain 2000 parts by weight of an aqueous solution, which was then supplied to the dispersion. The dispersion was then heated to 75°C and maintained at 75°C for 5 hours with stirring. The dispersion was then heated to 100°C and maintained at 100°C for 3 hours with stirring to obtain a slurry containing polymer particles. The slurry containing polymer particles is dehydrated using a pressure filter and washed with warm water until the surfactant concentration is less than 40 mg / 1g of polymer particles. After reaching a concentration of μg / g, the polymer particles were vacuum dried at 70°C for 24 hours to obtain polymer particles. The obtained polymer particles were processed using an air classifier (Nisshin Engineering Co., Ltd.'s "Turbo Classifier (registered trademark) TC-15") to remove coarse particles with a diameter greater than 2.5 times the arithmetic mean diameter of the particle size distribution based on the number of particles before classification, and to remove particles with a diameter less than 0.5 times the arithmetic mean diameter of the particle size distribution based on the number of particles before classification, thus obtaining the desired polymer particles. (Example 13) The stirring time at 30°C after adding the seed particle slurry to the emulsion was set to 1.5 hours, and the particles were graded in such a way that the content of small particles with a particle size of less than 50% of the arithmetic mean particle size was 6.4%. Otherwise, the desired polymer particles were obtained in the same manner as in Example 1. (Example 16) The slurry containing polymer particles is dehydrated using a pressure filter and washed with warm water until the surfactant concentration is 43% relative to 1g of polymer particles. After reaching a concentration of μg / g, the polymer particles were vacuum dried at 70°C for 24 hours. Otherwise, the desired polymer particles were obtained in the same manner as in Example 1. For the obtained polymer particles, the arithmetic mean particle size, coefficient of variation (CV) of particle size, content of small particles with a particle size of less than 50% of the arithmetic mean particle size, content of surfactant, dispersion displacement and dispersion coefficient were determined by the above-mentioned method, and the results are shown in Table 1. By using the above-mentioned methods to determine the content (mass%) of monomer units contained in the obtained polymer particles, the result is that the content (mass%) of the monomers used to manufacture the polymer particles is the same as that of the monomers used to manufacture the polymer particles. The coating properties and particle shedding properties of the obtained polymer particles were determined by the following methods, and the results are shown in Table 1. [Copyability] [Manufacturing of optical films] 0.20 g of polymer particles and 1.00 g of butyl acetate as an organic solvent were fed into a 10 mL sample tube and stirred for 1 minute using an ultrasonic cleaner (Velvo-Clear Co., Ltd., trade name "ULTRASONIC CLEANER VS-150") to disperse the polymer particles in butyl acetate and obtain a dispersion. 1.50g of acrylic resin (product name "ACRYDIC (registered trademark) A-817-BA" manufactured by DIC Corporation) used as adhesive resin was added to the obtained dispersion and stirred for about 2 minutes using the ultrasonic cleaner mentioned above. After the dispersion was allowed to stand for 4 hours, 5.50 g of butyl acetate, an organic solvent, was added to the dispersion and stirred for 1 minute using the ultrasonic cleaner to obtain the polymer particle composition. Use 75 A coating machine with a slit width of μm is used to coat the obtained polymer particle composition onto a 100 μm thick substrate. The coating is applied to a polyethylene terephthalate (PET) film (manufactured by Fujifilm Co., Ltd., trade name "FUJIX (registered trademark) OHP film for photocopiers") with a diameter of μm. After coating, the film is placed in a dryer maintained at 70°C for 1 hour to evaporate and remove the organic solvent from the polymer particle composition, thereby obtaining an optical film with a coating on the PET film. In the coating, the polymer particles are contained in a state of dispersion in an acrylic resin. Evaluation of optical properties (the degree of haze dispersion) The optical film was cut into a square shape with one side of 6cm to make a test piece. For the coating of the test piece, according to JIS K7136, the haze of each of the four corners and the center (a total of 5 points) was measured using a measuring device manufactured by Nippon Denshoku Kogyo Co., Ltd. and sold under the trade name "NDH-4000". The fog difference (%) is calculated using the maximum, minimum, and arithmetic mean of the fog (%) measured at the five locations, and evaluated according to the following criteria. Haze difference (%) = 100 × [(maximum haze value - minimum haze value) / arithmetic mean of haze] A: The haze difference did not reach 0.5%. B: The haze difference is greater than 0.5% but less than 1.0%. C: Haze difference is greater than 1.0% but less than 3.0%. D: Haze difference is 3.0% or more. [Particle shedding] The optical film was prepared using the same methods as those used for coating performance testing. An RT-200 vibration-type friction testing machine (sold by Daiei Scientific Instruments Co., Ltd.) was used. A 20mm x 20mm flat friction piece with a 300g load was slid across the coating surface 10 times. The results were then observed using a digital microscope (sold by Keyence under the trade name "VHX"). The number of polymer particle detachments was measured at arbitrary test points on the coating surface, each with 1mm sides, and evaluated according to the following criteria. A: Less than 10. B: 10 or more but less than 20. C: More than 20 but less than 30. D: More than 30. [Table 1] (Cross-reference to related applications) This application asserts priority based on Japanese Patent Application No. 2022-20484 filed on February 14, 2022 and Japanese Patent Application No. 2022-137108 filed on August 30, 2022, the disclosure of which is incorporated herein by reference to the entire contents of these applications. [Industry applicability] This invention provides particles that can be uniformly dispersed in dispersion media such as organic solvents and adhesive resins. This invention also provides polymer particles that can maintain a uniform dispersion in coatings obtained from polymer particle compositions prepared by dispersing in organic solvents. The polymer particles of the present invention can provide a polymer particle composition that can easily form a coating with reduced shedding of polymer particles from the surface.

Claims

1. A polymer particle comprising: an acrylic polymer containing 55 to 98% by mass of an acrylic monomer unit represented by formula (1), wherein the polymer particle has a gel fraction of 90% by mass or more, and the acrylic polymer comprises a multifunctional monomer unit.

1. In formula (1), R1 to R3 independently represent hydrogen atoms or alkyl groups having 1 to 3 carbon atoms, and R4 represents a monovalent substituent having 5 to 8 carbon atoms and having a heterocycle with a heteroatom ratio (heteroatom number n / constituting atom number N) exceeding 0 and not reaching 0.

4.

2. The polymer particles as described in claim 1, wherein, In equation (1), R4 is a monovalent substituent having the structure described in equation (2) or (3).

2. In formula (2), R5 represents an alkyl group with 1 to 3 carbon atoms, R7 and R8 independently represent hydrogen atoms or alkyl groups with 1 to 3 carbon atoms, R6 and R9 independently represent either an oxygen atom or a divalent hydrocarbon group formed by removing two hydrogen atoms from the same carbon atom at the end of an aliphatic saturated hydrocarbon with 1 to 4 carbon atoms; *1 means that the bond is a single bond; 2. In formula (3), R10 represents an alkyl group with 1 to 3 carbon atoms, R11 to R13 represent hydrogen atoms or alkyl groups with 1 to 3 carbon atoms, R14 and R15 represent oxygen atoms or methylene groups, and at least one of them is an oxygen atom; *12 means a bonded bond and is a single bond.

3. The polymer particles as described in claim 1 or 2, wherein, The coefficient of variation (CV) of the particle size obtained from the particle size distribution based on the number of polymer particles is less than 15%.

4. The polymer particles as described in claim 1 or 2, wherein, In the particle size distribution based on the number of polymer particles, the content of small particles with a particle size of less than 50% of the arithmetic mean particle size is less than 6%.

5. The polymer particles as described in claim 1 or 2, wherein, The dispersion factor did not reach 0.

20.

6. The polymer particles as described in claim 1 or 2 are used in optical components.

7. The polymer particles as described in claim 1 or 2 are used in anti-glare components.

8. The polymer particles as described in claim 1 or 2, wherein, The gel fraction is over 91% by mass.

9. The polymer particles as described in claim 1 or 2, wherein, The amount of surfactant contained in 1g of polymer particles is less than 40μg / g.

10. A polymer particle composition comprising: a dispersion medium and polymer particles as described in claim 1 or 2 dispersed in the dispersion medium.

11. An optical film, comprising a film and a coating; wherein, The coating is formed on the aforementioned film and is formed from a polymer particle composition containing an adhesive resin and polymer particles as described in claim 1 or 2 dispersed in the aforementioned adhesive resin.

12. The optical film as described in claim 11 is an anti-glare component.