Polymer particle, polymer particle composition and optical film

Abstract

To provide polymer particles that enable uniform dispersion in dispersion media such as an organic solvent and synthetic resin, and are capable of sustaining a uniform dispersion state even in a molded product derived from a polymer particle composition created through dispersion in a dispersion solvent.SOLUTION: A polymer particle of the present invention comprises an acrylic polymer containing an acrylic monomer unit represented by a predetermined structural formula, with its surface being coated with a surfactant with an SP value of 9.0-12.0 in an amount of 0.5×10-3 to 5.0×10-3 g / m2.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to polymer particles, a polymer particle composition, and an optical film. [Background technology]

[0002] Polymer particles produced by suspension polymerization or seed polymerization are used in a wide range of fields as antiblocking agents, matting agents for paints, additives for improving the physical properties of resins, light diffusing agents, and the like.

[0003] Generally, when polymer particles obtained by the suspension polymerization method or the seed polymerization method are used by being contained in a paint, the polymer particles form unevenness on the coating film surface, imparting a matte effect to the coating film surface or light diffusion properties to the coating film. In addition, the polymer particles are contained in a synthetic resin film to form fine unevenness on the surface of the synthetic resin film, and are used as an antiblocking agent that prevents adhesion between synthetic resin films.

[0004] Patent Document 1 discloses organic particles obtained by polymerizing a monomer composition, the organic particles having a particle size variation coefficient of 20% or less and a hydrophobicity index of 35-65.

[0005] Patent Document 2 discloses polymer particles containing a vinyl polymer, the polymer particles having a particle size variation coefficient of 20% or less and a hydrophobicity index of 15-35.

[0006] Patent Document 3 discloses resin particles that contain a polymer that includes a structural unit represented by a specific structural formula. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2012-57177 A [Patent Document 2] JP 2010-248275 A [Patent Document 3] JP 2020-158573 A Summary of the Invention [Problem to be solved by the invention]

[0008] The organic particles of Patent Document 1 are aggregated by the interaction of the organic particles without adding additives such as aggregating agents when the organic solvent is evaporated from the organic particle-containing composition prepared by mixing with a solvent, but it is difficult to adjust the degree of aggregation, and the particle size of the secondary particles obtained by the aggregation of the organic particles is likely to vary. Therefore, there is a problem that unevenness occurs in the coating of the organic particle-containing composition, or particles are likely to fall off from the surface of the coating film formed from the organic particle-containing composition.

[0009] Furthermore, when a hydrophobic monomer is used, the absorption into the seed particles is reduced during seed polymerization, resulting in the generation of unabsorbed small particles. Since the small particles have a different composition from the organic particles obtained by absorbing the small particles into the seed particles, the dispersibility of the small particles in organic solvents is different from that of the organic particles, resulting in a problem that the dispersibility of the whole particles in organic solvents is non-uniform.

[0010] The polymer particles of Patent Document 2 are characterized by having a low hydrophobicity index and being uniformly dispersed in a dispersion medium. However, since the obtained cake is washed with methanol, there is almost no surfactant on the surface of the obtained polymer particles, and the polymer particles absorb the dispersion medium in the dispersion medium, changing the dispersibility of the polymer particles in the dispersion medium and causing the dispersibility of the polymer particles in the dispersion medium to become non-uniform.

[0011] Even if a surfactant is present on the surface of the polymer particles, the surfactant will dissolve into the dispersion medium, changing the dispersibility of the polymer particles in the dispersion medium and causing another problem in that the dispersibility of the polymer particles in the dispersion medium becomes non-uniform.

[0012] The resin particles of Patent Document 3 contain a specific monomer having a dioxolane ring skeleton. However, since the dioxolane ring is highly hydrolyzable, the dioxolane ring opens as a side reaction during the production of the resin particles, making it impossible to impart the desired hydrophobicity to the resin particles. In addition, the hydrolysis of the dioxolane ring occurs unevenly, which results in uneven hydrophobicity of the resin particles, resulting in uneven dispersibility of the resin particles in organic solvents and the occurrence of coating unevenness.

[0013] The present invention provides polymer particles which can be uniformly dispersed in a dispersion medium such as a synthetic resin, e.g., a binder resin, and an organic solvent, and which can maintain a uniformly dispersed state even in a molded article, such as a coating film or a sheet, formed from a polymer particle composition prepared by dispersing the polymer particles in a dispersion medium, and which are reduced in falling off from the surface of the molded article. The present invention provides a polymer particle composition and an optical film using the polymer particles. [Means for solving the problem]

[0014] [Acrylic polymer] The polymer particles of the present invention contain an acrylic polymer containing an acrylic monomer unit represented by formula (1) and have a surfactant having an SP value of 9.0 to 12.0 in an amount of 0.5×10 -3 ~5.0×10 -3 g / m 2 is attached.

[0015] [ka] [In formula (1), R 1 ~R 3 each independently represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms; R 4 represents a monovalent substituent having 5 to 8 carbon atoms, having a heterocycle, and having a heteroatom ratio in the heterocycle (number of heteroatoms n / number of constituent atoms N) exceeding 0 and less than 0.4.]

[0016] Since the polymer particles contain the acrylic monomer unit represented by formula (1), they have excellent affinity with dispersion media such as synthetic resins such as binder resins and organic solvents, and can impart appropriate interactions between the polymer particles. Therefore, they can be uniformly dispersed in dispersion media such as organic solvents and binder resins, and also have excellent dispersion stability in the dispersion media.

[0017] The polymer particles have excellent affinity with the dispersion medium and moderate interaction between the polymer particles due to the acrylic monomer unit represented by formula (1). Therefore, when forming a molded body such as a coating film or a sheet from a polymer particle composition obtained by dispersing polymer particles in a dispersion medium, the molded body is formed while maintaining the state in which the polymer particles are uniformly dispersed even when the viscosity of the polymer particle composition increases during the process of forming the molded body from the polymer particle composition. Therefore, the polymer particles are uniformly dispersed in the obtained molded body. In addition, the polymer particles are reliably held by the binder resin in the molded body, and the falling off of the polymer particles from the surface of the molded body is reduced.

[0018] In the process of forming a molded article from the polymer particle composition, even if the polymer particles aggregate together, as described above, the polymer particles have excellent affinity with the dispersion medium and the interaction between the polymer particles is of appropriate strength, so that the polymer particles do not aggregate excessively but can aggregate to an appropriate size to form aggregated particles having a uniform size, and therefore, the aggregated particles of a uniform size are uniformly dispersed in the molded article.

[0019] In addition, the polymer particles can form aggregated particles of an appropriate size while incorporating a suitable amount of synthetic resin such as a binder resin between the polymer particles, and therefore the aggregated particles are securely held by the synthetic resin in the molded product, reducing the likelihood of the aggregated particles falling off from the surface of the molded product.

[0020] Further, the polymer particles have a predetermined amount of surfactant with an SP value of 9.0 to 12.0 attached to their surfaces. Since a surfactant with a specific SP value is attached to the surfaces of the polymer particles, the polymer particles can be reduced from absorbing the dispersion medium while maintaining the compatibility between the polymer particles and the dispersion medium. By the polymer particles absorbing the dispersion medium, the viscosity of the polymer particle composition obtained by dispersing the polymer particles in the dispersion medium can be reduced from becoming non-uniform, which is caused by the viscosity of the polymer particle composition partially varying, and the occurrence of coating unevenness of the polymer particle composition can be reduced. Furthermore, the dispersibility of the polymer particles in the dispersion medium can be prevented from changing over time, and the polymer particles can be uniformly dispersed in the dispersion medium. In addition, in the process of forming a molded body such as a coating film and a sheet from the polymer particle composition formed by dispersing the polymer particles in the dispersion medium, when the polymer particles aggregate with each other, the polymer particles can be reduced from excessively agglomerating with each other, and the polymer particles can be agglomerated to a suitable size to form aggregated particles having a uniform size. Therefore, it is possible to uniformly disperse agglomerated particles of uniform size in the green body, and to reduce the falling off of the agglomerated particles from the surface of the green body.

[0021] A surfactant having an SP value of 9.0 to 12.0 has good compatibility with the acrylic polymer containing the acrylic monomer unit represented by formula (1) constituting the polymer particles, and is present stably attached to the surface of the polymer particles, and is hardly dissolved in the dispersion medium. Therefore, it is possible to prevent the dispersibility of the polymer particles in the dispersion medium from changing over time, and to uniformly disperse the polymer particles in the dispersion medium.

[0022] In this way, the polymer particles contain an acrylic polymer containing an acrylic monomer unit represented by formula (1), and have a predetermined amount of a surfactant having a specific SP value attached to the surface, and due to the synergistic effect of these, the compatibility between the polymer particles and the dispersion medium and the appropriate interaction between the polymer particles in the dispersion medium are stably maintained over time, so that the polymer particles can be uniformly dispersed in the dispersion medium and the state in which the polymer particles are uniformly dispersed can be maintained even in the molded product.

[0023] In particular, submicron-sized polymer particles having an arithmetic mean particle diameter of less than 1 μm in a particle size distribution based on the number (hereinafter sometimes referred to as "submicron-sized polymer particles") are generally difficult to disperse uniformly in a dispersion medium and tend to aggregate unevenly, but with the above-mentioned polymer particles, even submicron-sized polymer particles can be uniformly dispersed in a dispersion medium, and the state in which the polymer particles are uniformly dispersed can be maintained even in a molded product. Furthermore, even if the polymer particles aggregate during the process of forming the molded product, excessive aggregation of the polymer particles can be reduced, and the polymer particles can be aggregated to a moderate size to form aggregated particles having a uniform size, and the aggregated particles can be uniformly dispersed in the molded product.

[0024] In formula (1), R 1 ~R 3 R are each independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. 1 ~R 3 are each independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, 4 This, together with the interaction due to the hetero ring, can provide an appropriate interaction between the polymer particles.

[0025] In formula (1), R 1 ~R 3When R is an alkyl group having 1 to 3 carbon atoms, the alkyl group is not particularly limited, and examples thereof include a methyl group, an ethyl group, an n-propyl group, and an isopropyl group. In the present invention, an alkyl group is a monovalent atomic group obtained by removing (pulling out) one hydrogen atom from an aliphatic saturated hydrocarbon. 1 ~R 3 When is an alkyl group having 1 to 3 carbon atoms, it is preferable that the hydrogen atoms of the alkyl group are not substituted.

[0026] In formula (1), the substituent R 4 In addition to the interaction between polymer particles due to the heterocycle of R, it is possible to impart a more appropriate interaction between polymer particles. 1 and R 2 is preferably a hydrogen atom.

[0027] R 3 is a substituent R 4 In addition to the interaction between the polymer particles due to the heterocycle, a more appropriate interaction can be imparted between the polymer particles. Therefore, a hydrogen atom, a methyl group, or an ethyl group is preferable, and a hydrogen atom or a methyl group is more preferable.

[0028] R 4 is a monovalent substituent having 5 to 8 carbon atoms and having a heterocycle. 4 However, since the total number of carbon atoms is 5 to 8 and the polymer particles containing the acrylic monomer unit represented by formula (1) have a suitable degree of interaction between the polymer particles, the polymer particles have excellent dispersibility and dispersion stability in a dispersion medium such as an organic solvent or a binder resin, and can maintain excellent dispersibility even in a molded product.

[0029] Furthermore, the polymer particles contain an acrylic polymer containing an acrylic monomer unit represented by formula (1) and have a predetermined amount of a specific surfactant on the surface. This surfactant has a predetermined SP value, so that the acrylic polymer constituting the polymer particles and the surfactant have excellent affinity, and the surfactant is hardly dissolved into the dispersion medium. The polymer particles can exhibit excellent affinity with the dispersion medium and moderate interaction between the polymer particles, and the polymer particles can be uniformly dispersed in the dispersion medium.

[0030] R 4 The carbon number of R is 5 or more, and preferably 6 or more. 4 The carbon number of R is 8 or less, and preferably 7 or less. 4 When the number of carbon atoms is within the above range, the polymer particles have better affinity with the dispersion medium and can impart more appropriate interaction between the polymer particles. Therefore, the polymer particles have excellent dispersibility and dispersion stability in dispersion media such as synthetic resins such as binder resins and organic solvents, and can maintain excellent dispersibility even in molded articles such as coating films and sheets.

[0031] R 4 R has a heterocycle. 4 By having a hetero ring, the polymer particles have excellent affinity with a dispersion medium and can impart appropriate interaction between the polymer particles, and therefore the polymer particles have excellent dispersibility and dispersion stability in a dispersion medium such as an organic solvent or a binder resin.

[0032] A heterocycle is a cyclic structure that contains both carbon atoms and atoms other than carbon atoms (heteroatoms). 4 Preferably, the heteroatom in the hetero ring is an oxygen atom. When the heteroatom is an oxygen atom, the polymer particles have better affinity with the dispersion medium and can impart more appropriate interaction between the polymer particles. Therefore, the polymer particles have better dispersibility and dispersion stability in the dispersion medium, and can maintain better dispersibility in a coating film, a sheet, or other molded article.

[0033] R 4 In the above, the heteroatom ratio in the heterocycle (heteroatom number n / constituent atom number N) is more than 0 and less than 0.4, preferably more than 0 and 0.35 or less, more preferably more than 0 and 0.25 or less. When the heteroatom ratio in the heterocycle is within the above range, the polymer particles have better affinity with the dispersion medium and can impart more appropriate interaction between the polymer particles. Therefore, the polymer particles have better dispersibility and dispersion stability in the dispersion medium, and can maintain better dispersibility in the coating film. The number of constituent atoms N of the heterocycle is the number of atoms directly constituting the heterocycle, and does not include atoms constituting the atomic group (including hydrogen atoms) bonded to the heterocycle as a substituent.

[0034] Substituent R 4 As the substituent, the monovalent substituents represented by the following formulas (2) and (3) are preferable.

[0035] [ka] [In formula (2), R 5 represents an alkylene group having 1 to 3 carbon atoms, and R 7 and R 8 each independently represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms; R 6 and R 9 each independently represents a divalent hydrocarbon group, one of which is an oxygen atom and the other of which is a divalent hydrocarbon group formed by removing (removing) two hydrogen atoms bonded to the same carbon atom in an aliphatic saturated hydrocarbon having 1 to 4 carbon atoms. *1 is a bond and means a single bond.]

[0036] R 5represents an alkylene group having 1 to 3 carbon atoms. In the present invention, the alkylene group is a divalent atomic group obtained by removing (pulling out) one hydrogen atom bonded to each different carbon atom in an aliphatic saturated hydrocarbon, or a divalent atomic group obtained by removing (pulling out) two hydrogen atoms from methane, and includes both linear and branched atomic groups. Examples of the alkylene group having 1 to 3 carbon atoms include a methylene group [-CH2-], an ethylene group [-CH2-CH2-], a propylene group [-CH(CH3)-CH2-], and a trimethylene group [-CH2-CH2-CH2-], and the like. The methylene group is preferred because it provides the polymer particles with better affinity to the dispersion medium and can provide more appropriate interaction between the polymer particles.

[0037] R 7 and R 8 R are each independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and are preferably hydrogen atoms because the polymer particles have better affinity with the dispersion medium and can provide more appropriate interaction between the polymer particles. 7 and R 8 When R is an alkyl group having 1 to 3 carbon atoms, the alkyl group is not particularly limited, and examples thereof include a methyl group, an ethyl group, an n-propyl group, and an isopropyl group. 7 and R 8 When is an alkyl group having 1 to 3 carbon atoms, it is preferable that the hydrogen atoms of the alkyl group are not substituted.

[0038] R 6 and R 9 are each independently one of which is an oxygen atom and the other of which is a divalent hydrocarbon group formed by removing (abtracting) two hydrogen atoms bonded to the same carbon atom in an aliphatic saturated hydrocarbon having 1 to 4 carbon atoms, and it is preferable that one of which is an oxygen atom and the other of which is a methylene group. 6 and R 9When either one of the groups is an oxygen atom and the other is the divalent hydrocarbon group, the polymer particles have better affinity with the dispersion medium and can impart more appropriate interaction between the polymer particles. Furthermore, the heterocycle is prevented from being opened by hydrolysis, and the interaction between the polymer particles is made more uniform throughout the polymer particles, so that the polymer particles can be more uniformly dispersed in the dispersion medium and in molded articles such as coatings and sheets.

[0039] The divalent hydrocarbon group obtained by removing (abtracting) two hydrogen atoms bonded to the same carbon atom in an aliphatic saturated hydrocarbon having 1 to 4 carbon atoms is not particularly limited, and examples thereof include a methylene group [-CH2-], =CH-CH3 [formula (10)], =C(CH3)2 [formula (11)], =CH-CH2-CH3 [formula (12)], =CH-CH2-CH2-CH3 [formula (13)], and =CH-CH2(CH3)-CH2 [formula (14)], with a methylene group being preferred. In formulas (10) to (14), *2 to *11 are bonds and represent single bonds.

[0040] [ka]

[0041] [ka] [In formula (3), R 10 represents an alkylene group having 1 to 3 carbon atoms, and R 11 ~R 13 each independently represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms; R 14 and R 15 are each independently an oxygen atom or a methylene group, and at least one of them represents an oxygen atom. *12 is a bond and represents a single bond.]

[0042] R 10represents an alkylene group having 1 to 3 carbon atoms. Examples of the alkylene group having 1 to 3 carbon atoms include a methylene group [-CH2-], an ethylene group [-CH2-CH2-], a propylene group [-CH(CH3)-CH2-], and a trimethylene group [-CH2-CH2-CH2-], and the like. The methylene group is preferred because it provides the polymer particles with better affinity to the dispersion medium and can impart more appropriate interaction between the polymer particles.

[0043] R 11 ~R 13 R is independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. 11 R is preferably a methyl group or an ethyl group, more preferably an ethyl group, because the polymer particles have better affinity with the dispersion medium and can provide more appropriate interaction between the polymer particles. 12 and R 13 R is preferably a hydrogen atom, since it reduces the bulkiness and can more effectively exert the interaction between the polymer particles due to the oxygen atom of the hetero ring. 11 ~R 13 When R is an alkyl group having 1 to 3 carbon atoms, the alkyl group is not particularly limited, and examples thereof include a methyl group, an ethyl group, an n-propyl group, and an isopropyl group. 11 ~R 13 When is an alkyl group having 1 to 3 carbon atoms, it is preferable that the hydrogen atoms of the alkyl group are not substituted.

[0044] R 14 and R 15 R is each independently an oxygen atom or a methylene group. 14 and R 15 Preferably, both R are oxygen atoms. 14 and R 15 When each of the groups is independently an oxygen atom or a methylene group, the polymer particles have better affinity with the dispersion medium and more appropriate interaction can be imparted between the polymer particles.

[0045] Therefore, as the acrylic monomer represented by formula (1), the acrylic monomer represented by the following formulas (4) and (5) is preferable, and the acrylic monomer represented by the following formulas (6), (7) and (8) is more preferable. 1 ~R 13 is the same as above, so the explanation will be omitted.

[0046] [ka]

[0047] [ka]

[0048] [ka]

[0049] [ka]

[0050] [ka]

[0051] The content of the acrylic monomer unit represented by formula (1) in the acrylic polymer contained in the polymer particles is preferably 55% by mass or more, more preferably 60% by mass or more, more preferably 65% ​​by mass or more, and more preferably 70% by mass or more. The content of the acrylic monomer unit represented by formula (1) in the polymer particles is preferably 98% by mass or less, more 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 the acrylic monomer unit is within the above range, the polymer particles have excellent affinity with the dispersion medium and can impart moderate interaction between the polymer particles. Furthermore, it is possible to generally prevent the surfactant present on the surface of the polymer particles from dissolving into the dispersion medium. Therefore, the polymer particles can be uniformly dispersed in a dispersion medium such as a synthetic resin such as a binder resin and an organic solvent, and also have excellent dispersion stability in the dispersion medium. Furthermore, the polymer particles are reliably held by the synthetic resin even in a molded body such as a coating film and a sheet formed from a polymer particle composition obtained by dispersing the polymer particles in a dispersion medium, and the falling off of the polymer particles from the surface of the molded body can be reduced. In addition, even when the polymer particles aggregate together during the process of forming a molded article such as a coating film or a sheet from the polymer particle composition, the polymer particles can form aggregated particles having a uniform size while aggregating to an appropriate size without excessive aggregation. Therefore, aggregated particles of a uniform size are uniformly dispersed in the molded article such as the coating film or the sheet, and the falling off of the aggregated particles from the surface of the molded article can be reduced.

[0052] In the acrylic polymer contained in the polymer particles, the content of acrylic monomer units other than the acrylic monomer unit represented by formula (1) is preferably 30 mass % or less, more preferably 20 mass % or less, and still more preferably 10 mass % or less.

[0053] Examples of acrylic monomers other than the acrylic monomer represented by formula (1) include alkyl acrylates such as methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, and isobutyl acrylate; and alkyl methacrylates such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, and isobutyl methacrylate.

[0054] In the present invention, the acrylic monomer refers to a monomer having a structure represented by the following formula (15): 1 ~R 3 is the same as above, so the explanation will be omitted.

[0055] [ka]

[0056] [In formula (15), R 1 ~R 3 each independently represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. *13 is a bond and means a single bond.]

[0057] The acrylic polymer contained in the polymer particles preferably contains a polyfunctional monomer unit. The acrylic polymer is preferably crosslinked by the polyfunctional monomer unit. When the acrylic polymer contains a polyfunctional monomer unit, the fluctuation of the interaction between the polymer particles caused by the polymer particles absorbing the dispersion medium can be reduced, and the uniformity of the dispersion state of the polymer particles in the dispersion medium and the dispersion stability can be further improved. Furthermore, by the polymer particles absorbing the dispersion medium, the non-uniformity of the viscosity of the polymer particle composition caused by the partial fluctuation of the viscosity of the polymer particle composition obtained by dispersing the polymer particles in the dispersion medium can be further reduced, and the occurrence of coating unevenness of the polymer particle composition can be further reduced.

[0058] The polyfunctional monomer is a monomer having a plurality of polymerizable functional groups (e.g., vinyl groups, epoxy groups, isocyanate groups, etc.). The polyfunctional monomer preferably has a plurality of vinyl groups as the functional group. Examples of the polyfunctional monomer include acrylic polyfunctional monomers such as 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, pentadecaethylene glycol di(meth)acrylate, pentacontahexaethylene glycol di(meth)acrylate, pentaerythritol tetra(meth)acrylate, 1,3-butylene di(meth)acrylate, and allyl(meth)acrylate, and aromatic divinyl compounds such as divinylbenzene, divinylnaphthalene, or derivatives thereof. In the present invention, the (meth)acrylate means an acrylate or a methacrylate. The polyfunctional monomers may be used alone or in combination of two or more kinds.

[0059] The content of the polyfunctional monomer unit in the acrylic polymer 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 the polyfunctional monomer unit in the acrylic polymer 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 the polyfunctional monomer unit is 5% by mass or more, the fluctuation of the interaction between the polymer particles due to the absorption of the dispersion medium by the polymer particles can be reduced, and the uniformity of the dispersion state of the polymer particles in the dispersion medium and the dispersion stability can be further improved. Furthermore, the absorption of the dispersion medium by the polymer particles can be reduced, and the non-uniformity of the viscosity of the polymer particle composition obtained by dispersing the polymer particles in the dispersion medium due to the partial fluctuation of the viscosity of the polymer particle composition can be further reduced, and therefore the occurrence of coating unevenness of the polymer particle composition can be further reduced. When the content of the polyfunctional monomer unit is 45% by mass or less, the polymer particles have even better affinity with the dispersion medium and can impart even more appropriate interaction between the polymer particles. Therefore, it is possible to further improve the uniformity and dispersion stability of the polymer particles in the dispersion medium, and it is also possible to make the polymer particles more uniformly dispersed in a coating film formed from a polymer particle composition obtained by dispersing the polymer particles in a dispersion medium.

[0060] The gel fraction of the polymer particles is preferably 90% by mass or more, more preferably 91% by mass or more, and more preferably 95% by mass or more. When the gel fraction of the polymer particles is 90% by mass or more, the solvent resistance of the polymer particles can be further improved. For example, when the polymer particles are dispersed in a dispersion medium to prepare a polymer particle composition, the polymer particles can be further reduced from absorbing the dispersion medium and swelling, and the dispersibility and dispersion stability of the polymer particles in the dispersion medium can be further improved. Furthermore, a more uniform dispersion state can be maintained in a molded body such as a coating film and a sheet formed from the polymer particle composition prepared by dispersing the polymer particles in a dispersion medium, and the falling off of the polymer particles from the surface of the molded body can be more effectively reduced.

[0061] The gel fraction of the polymer particles is a value measured as follows: First, 1.0 g of polymer particles as a sample and 0.03 g of boiling stones are precisely weighed and placed in a 200 mL recovery flask, and 100 mL of toluene is added. After that, a cooling tube is attached to the recovery flask, and the recovery flask is immersed in an oil bath maintained at 130°C and refluxed for 24 hours.

[0062] After refluxing, the content (dissolved solution) in the eggplant flask is filtered using a Buchner funnel filter 3G (glass particle pore diameter 20-30 μm, volume 30 mL) manufactured by TOP Co., Ltd., which is equipped with glass fiber filters "GB-140 (φ37 mm)" and "GA-200 (φ37 mm)" manufactured by ADVANTEC Co., Ltd. and weighed, and the solid content is collected in the Buchner funnel filter 3G. The solid content collected in the Buchner funnel filter 3G is then dried together with the Buchner funnel filter 3G in a vacuum oven at 130° C. for 1 hour, and then dried at a gauge pressure of 0.06 MPa for 2 hours to remove the toluene, and cooled to room temperature.

[0063] After cooling, the total mass of the Buchner funnel filter 3G, the glass fiber filter, and the solids is measured with the solids contained in the Buchner funnel filter 3G. The mass of the Buchner funnel filter 3G, the glass fiber filter, and the boiling stones is then subtracted from the measured total mass to determine the mass (g) of the dry powder.

[0064] Then, the gel fraction is calculated using the mass (g) of the dry powder and the mass (g) of the sample placed in the recovery flask according to the following formula. Gel fraction (mass%) = [mass of dry powder (g) / mass of sample (g)] x 100

[0065] The acrylic polymer contained in the polymer particles may contain a styrene-based monomer unit. By containing a styrene-based monomer unit in the acrylic polymer, the polymer particles have better affinity with the dispersion medium and can impart more appropriate interaction between the polymer particles. Therefore, the polymer particles can be more uniformly dispersed in a dispersion medium such as an organic solvent or a binder resin, and the dispersion stability in the dispersion medium is also more excellent. Furthermore, the polymer particles can be more uniformly dispersed in a molded body such as a coating film and a sheet formed from a polymer particle composition obtained by dispersing the polymer particles in a dispersion medium, and the falling off of the polymer particles from the surface of the molded body can be further reduced. In addition, even if the polymer particles aggregate with each other in the process of forming a molded body from the polymer particle composition, the polymer particles can form aggregated particles having a uniform size while aggregating to a moderate size without excessive aggregation. Therefore, aggregated particles of a more uniform size can be more uniformly dispersed in the molded body, and the falling off of the aggregated particles from the surface of the molded body can be further reduced.

[0066] The styrene-based monomer is not particularly limited, and examples thereof include styrene, α-methylstyrene, vinyltoluene, chlorostyrene, ethylstyrene, i-propylstyrene, dimethylstyrene, bromostyrene, etc. The styrene-based monomer may be used alone or in combination of two or more kinds.

[0067] The acrylic polymer may not contain a styrene monomer unit. When the acrylic polymer contains a styrene monomer unit, the content of the styrene monomer unit in the acrylic polymer is preferably 40% by mass or less, more preferably 30% by mass or less, and more preferably 20% by mass or less. When the acrylic polymer contains a styrene monomer unit, the content of the styrene monomer unit in the acrylic polymer is preferably 1% by mass or more, more preferably 5% by mass or more, and more preferably 10% by mass or more. When the content of the styrene monomer unit is 40% by mass or less, when the polymer particles aggregate with each other in the process of forming a molded body such as a coating film and a sheet from the polymer particle composition, the excessive aggregation of the polymer particles with each other can be further reduced, and the polymer particles can be aggregated to a moderate size to form aggregated particles having a uniform size. Therefore, the aggregated particles of a uniform size can be more uniformly dispersed in the molded body, and the falling off of the aggregated particles from the surface of the molded body can be further reduced. When the content of the styrene-based monomer unit is 1% by mass or more, the polymer particles can be aggregated to an appropriate size to form aggregated particles having a uniform size, which is preferable.

[0068] The acrylic polymer contained in the polymer particles may contain other monomer units within a range that does not impair the physical properties of the polymer particles. Examples of such monomers include acrylates and methacrylates. The acrylates are not particularly limited, and examples thereof include alkyl acrylates such as methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, and isobutyl acrylate. Examples of methacrylates include alkyl methacrylates such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, and isobutyl methacrylate.

[0069] In the polymer constituting the polymer particles, the content of the acrylic polymer containing the acrylic monomer unit represented by formula (1) is preferably 50% by mass or more, more preferably 60% by mass or more, more preferably 70% by mass or more, more preferably 80% by mass or more, more preferably 90% by mass or more, more preferably 95% by mass or more, more preferably 98% by mass or more, and more preferably 100% by mass.

[0070] The content of the monomer unit contained in the polymer particles is a value measured as follows. Approximately 0.1 to 0.5 mg of a sample of the polymer particles is precisely weighed. The sample is wrapped in a ferromagnetic metal body (manufactured by Japan Analytical Industry Co., Ltd., product name "Pyrofoil") with a Curie point of 590°C to prepare a test specimen.

[0071] The test specimen was prepared so that the ferromagnetic metal body was pressed against the sample. The test specimen was heated in a Curie point pyrolyzer (Japan Analytical Industry Co., Ltd., product name "JPS-700 type") to decompose the sample. The monomer components generated by the decomposition were measured using a gas chromatograph (Agilent Technologies, product name "GC7820", detector = FID) to determine the peak area of ​​the monomer to be measured. A calibration curve showing the relationship between the monomer amount and peak area for the monomer to be measured was created in advance. The amount of monomer contained in the sample was calculated from the measured peak area based on the calibration curve. (Measurement conditions) Heating=590℃-5sec Oven temperature = 300 °C Needle temperature = 300℃ Column: Agilent Technologies "DB-5" (0.25 μm × 0.25 mm φ × 30 m) (GC oven heating conditions) Initial temperature = 50℃ (held for 0.5min) First stage heating rate = 10℃ / min (up to 200℃, hold for 0 min) Second stage heating rate = 20℃ / min (up to 320℃) Final temperature = 320℃ (held for 0.5min) Carrier gas = He He flow rate=1.275mL / min Inlet pressure = 100kPa Column inlet pressure = 100kPa Inlet temperature=300℃ Detector temperature = 300℃ Split ratio = 1 / 50

[0072] [Surfactants] The surface of the polymer particles is coated with 0.5 × 10 surfactants having an SP value of 9.0 to 12.0. -3 ~5.0×10 -3 g / m 2The surfactant having an SP value of less than 9.0 or the surfactant having an SP value of more than 12.0 may be attached to the surface of the polymer particle, but it is preferable that the surfactant has an SP value of 9.0 to 12.0 so as not to inhibit the action of the surfactant. In all surfactants, the content of the surfactant having an SP value of less than 9.0 is preferably 1% by mass or less, more preferably 0.5% by mass or less, more preferably 0.01% by mass or less, and more preferably 0% by mass. In all surfactants, the content of the surfactant having an SP value of more than 12.0 is preferably 1% by mass or less, more preferably 0.5% by mass or less, more preferably 0.01% by mass or less, and more preferably 0% by mass. In all surfactants, the total content of the surfactant having an SP value of less than 9.0 and the surfactant having an SP value of more than 12.0 is preferably 2% by mass or less, more preferably 1% by mass or less, more preferably 0.02% by mass or less, more preferably 0.01% by mass or less, and more preferably 0% by mass. The surfactant is preferably attached to the surface of the polymer particle in the form of a layer. By the surfactant being attached to the surface of the polymer particle in a layer form, the surfactant can exert its action almost uniformly in all directions of the polymer particle, and the polymer particle can improve the uniform dispersibility and dispersion stability in the dispersion medium. The SP value of the surfactant is 9.0 or more, preferably 9.1 or more, more preferably 9.2 or more, more preferably 9.3 or more, and more preferably 9.4 or more. The SP value of the surfactant is 12.0 or less, preferably 11.9 or less, more preferably 11.8 or less, more preferably 11.7 or less, and more preferably 11.6 or less. Since the polymer particle contains a specific acrylic polymer and the SP value of the surfactant attached to the surface is 9.0 to 12.0, excellent affinity between the polymer particle and the dispersion medium and moderate interaction between the polymer particles are maintained, and elution from the surface of the polymer particle into the dispersion medium is generally prevented, and the uniform dispersibility and dispersion stability of the polymer particle in the dispersion medium are excellent.

[0073] On the surface of the polymer particle, a surfactant having an SP value of 9.0 to 12.0 is 0.5 × 10 -3~5.0×10 -3 g / m 2 The adhesion amount of surfactants with SP values ​​of 9.0 to 12.0 is 0.5 × 10 -3 g / m 2 More than or equal to 0.55 x 10 -3 g / m 2 More than 0.6×10 is preferable. -3 g / m 2 More preferably, 0.7×10 -3 g / m 2 More preferably, 0.8×10 -3 g / m 2 More preferably, 0.9×10 -3 g / m 2 More preferably, 1.0×10 -3 g / m 2 More preferably, 1.2×10 -3 g / m 2 More preferably, 1.3×10 -3 g / m 2 More preferably, 1.4×10 -3 g / m 2 More preferably, 1.5×10 -3 g / m 2 More preferably, 1.6×10 -3 g / m 2 More preferably, 1.7×10 -3 g / m 2 More preferably, the adhesion amount of a surfactant having an SP value of 9.0 to 12.0 is 5.0 × 10 -3 g / m 2 is less than 4.9 x 10 -3 g / m 2 Less than or equal to 4.8×10 is preferred -3 g / m 2 Less than 4.0×10 is more preferable. -3 g / m 2 Less than or equal to 3.5×10 is preferable. -3 g / m 2 Less than 3.0×10 is more preferable. -3 g / m 2 Less than or equal to 2.5×10 is preferable. -3 g / m 2 Less than 2.0×10 is more preferable.-3 g / m 2 Less than or equal to 1.9×10 is preferable. -3 g / m 2 More preferably, the amount of the surfactant having an SP value of 9.0 to 12.0 is 0.5×10 -3 g / m 2 When the amount of the surfactant having an SP value of 9.0 to 12.0 is more than 5.0×10, excellent affinity between the polymer particles and the dispersion medium and appropriate interaction between the polymer particles can be imparted, and the polymer particles can be uniformly dispersed and have excellent dispersion stability in the dispersion medium. -3 g / m 2 If the ratio is less than this, the dispersion medium can easily reach the surface of the polymer particles, imparting excellent affinity between the polymer particles and the dispersion medium, and the polymer particles can be made to have excellent uniform dispersibility and dispersion stability in the dispersion medium.

[0074] Submicron-sized polymer particles, which have an arithmetic mean particle size of less than 1 μm in a number-based particle size distribution, generally tend to aggregate non-uniformly in a dispersion medium.

[0075] On the other hand, the polymer particles contain a specific acrylic polymer and have a specific surfactant attached to the surface in a predetermined amount, and can effectively exhibit excellent affinity between the polymer particles and the dispersion medium and appropriate interaction between the polymer particles, and can reduce the absorption of the dispersion medium by the polymer particles. Therefore, even for polymer particles of submicron size, uniform dispersibility and dispersion stability of the polymer particles in the dispersion medium can be effectively imparted.

[0076] The SP value of a surfactant refers to the solubility parameter δ calculated by the following formula (A) using the ΔF and Δv values ​​of various atomic groups listed in Table 1 by Okitsu Toshinao in "Adhesion", Polymer Publishing Society, Vol. 40, No. 8 (1996), pp. 342-350. In the case of mixed solvents and copolymers, the solubility parameter δ is calculated by the following formula (B). In the case of terminal metals and ammonium salts, the calculation is performed assuming a hydrogen atom (H). δ=ΣΔF / ΣΔv (A) δ mix =φ1δ1+φ2δ2+···+φ n δ n (B) In formula (A), ΔF represents ΔF in Table 1, Δv represents the molar volume Δv in Table 1, φ represents the mole fraction, φ1+φ2+···+φ n =1. For example, the SP value of heptane as a solvent is calculated as follows: Heptane has two -CH3 and five -CH2- atomic groups. Calculate the ΔF and Δv values ​​for each atomic group from Table 1. ΣΔF=205×2+132×5=1070 ΣΔv=31.8×2+16.5×5=146.1 Therefore, from the above formula (A), the δ hep is calculated as follows: δ hep =ΣΔF / ΣΔv=1070 / 146.1=7.32 For example, the SP value of a mixed solvent of 50% by mass of heptane and 50% by mass of toluene is calculated as follows. As described above, the SP value of heptane alone is 7.32. Moreover, by using the same method as above, the SP value of toluene alone is 9.02. Since the molecular weight of heptane is 100 and the molecular weight of toluene is 92, the molar fraction of the mixed solvent is heptane:toluene = 50 / 100:50 / 92 = 0.48:0.52. Therefore, φ hep = 0.48, φ tol = 0.52. From the above formula (B), the SP value of the mixed solvent (δ mix ) is calculated as follows: δ mix =φ hep ×δ hep +φ tol ×δ tol =0.48×7.32+0.52×9.02

[0077] When multiple types of surfactants are used, the SP value (solubility parameter δ) of the entire mixture of surfactants is calculated based on the SP value (solubility parameter δ) and molar fraction of each surfactant in the manner described above. mix ) is calculated. When a mixture of multiple surfactants is used as the surfactant, the SP value of the entire mixture of surfactants is preferably 9.0 or more, more preferably 9.1 or more, more preferably 9.2 or more, more preferably 9.3 or more, and more preferably 9.4 or more, for the same reasons as above. The SP value of the entire mixture of surfactants is preferably 12.0 or less, preferably 11.9 or less, more preferably 11.8 or less, more preferably 11.7 or less, and more preferably 11.6 or less, for the same reasons as above. When a mixture of multiple surfactants is used as the surfactant, it is preferable that all of the surfactants have an SP value of 9.0 to 12.0.

[0078] The amount of surfactant adhering to the surface of the polymer particles refers to a value measured as follows. Approximately 0.10 g of polymer particles is precisely weighed into a centrifuge tube as a sample, and 5 mL of methanol is poured into the sample as an extracting solution using a whole pipette, and the polymer particles and the extracting solution are thoroughly mixed. After ultrasonic extraction for 15 minutes, the mixture is centrifuged at 3500 rpm for 15 minutes, and the resulting supernatant is used as the test solution. The surfactant concentration in this test solution is measured. Then, the surfactant content (g) in 1 g of polymer particles is calculated using the following formula from the measured surfactant concentration (g / mL) in the test solution, the mass of the polymer particles used as the sample [sample mass (g)], and the amount of the extracting solution (extracting solution volume (mL)). The amount of the extracting solution is 5 mL. Surfactant content (g / g) = [Concentration of surfactant in test solution (g / mL) × Volume of extract (mL)] / Sample mass (g)

[0079] Next, the specific surface area of ​​the polymer particles is measured by the BET method (nitrogen adsorption method) described in ISO 9277 1st Edition (JIS Z 8830:2001). For the target (sample) polymer particles, the BET nitrogen adsorption isotherm is measured using an automatic specific surface area / pore distribution measuring device Tristar 3000 manufactured by Shimadzu Corporation, and the specific surface area is calculated from the nitrogen adsorption amount using the BET multipoint method. After pretreatment by heated gas purging, nitrogen is used as the adsorbate, and the adsorbate cross-sectional area of ​​0.162 nm is calculated. 2 The measurement is carried out by a constant volume method under the conditions of: Specifically, the pretreatment is carried out by purging with nitrogen for 20 minutes while heating a container containing the polymer particles at 65°C, allowing it to cool to room temperature, and then, while heating the container at 65°C, carrying out vacuum degassing until the pressure inside the container becomes 0.05 mmHg or less.

[0080] The specific surface area (m 2 ) by the mass of the polymer particles used as a sample [sample mass (g)] to obtain the specific surface area (m 2 ) is calculated (m 2 / g).

[0081] The content (g) of the surfactant in 1 g of the polymer particles obtained above was calculated as the specific surface area (m 2 ) to obtain the amount of surfactant per unit area (g / m2) attached to the surface of the polymer particle. 2 ) is calculated.

[0082] The surfactant may have an SP value of 9.0 to 12.0, and any of anionic surfactants, cationic surfactants, nonionic surfactants, and amphoteric surfactants may be used, but anionic surfactants and cationic surfactants are preferred, and anionic surfactants are more preferred, since the electrostatic repulsion of the surfactants improves the dispersibility and dispersion stability of the polymer particles in the dispersion medium. The surfactants may be used alone or in combination of two or more.

[0083] The anionic surfactant is a known anionic surfactant such as a fatty acid salt, a higher alcohol sulfate having 8 to 20 carbon atoms, an alkylbenzenesulfonate, an alkylsulfonate, an alkyl sulfate, an alkylnaphthalenesulfonate, a naphthalenesulfonate-formaldehyde condensate, a dialkylsulfosuccinate, a polyoxyethylene sulfate, a polyoxyethylene alkyl ether phosphate, or a polyoxyethylene alkyl phenyl ether phosphate, the SP value of which is calculated in the manner described above. An anionic surfactant having an SP value of 9.0 to 12.0 may be used.

[0084] The cationic surfactant may be a cationic surfactant having an SP value of 9.0 to 12.0 calculated in the manner described above for known cationic surfactants such as dialkyldimethylammonium salts, ester-type dialkylammonium salts, amide-type dialkylammonium salts, and dialkylimidazolinium salts.

[0085] The SP value of a known nonionic surfactant such as a polyoxyalkylene alkyl ether, a polyoxyalkylene phenyl ether, or a polyoxyalkylene alkyl ester is calculated in the manner described above, and a nonionic surfactant having an SP value of 9.0 to 12.0 may be used.

[0086] The SP value of a known amphoteric surfactant such as alkyl dimethyl amino acetic acid betaine, alkyl dimethyl amine oxide, alkyl carboxymethyl hydroxyethyl imidazolinium betaine, alkyl amidopropyl betaine, or alkyl hydroxysulfobetaine is calculated in the manner described above, and an amphoteric surfactant having an SP value of 9.0 to 12.0 may be used.

[0087] [Polymer particles] The arithmetic mean particle diameter in the particle size distribution based on the number of polymer particles is preferably 0.1 μm or more, more preferably 0.2 μm or more, and more preferably 0.3 μm or more. The arithmetic mean particle diameter in the particle size distribution based on the number of polymer particles is preferably 3.0 μm or less, more preferably 2.5 μm or less, more preferably 2.0 μm or less, more preferably 1.5 μm or less, more preferably 1.2 μm or less, more preferably 1.0 μm or less, more preferably 0.9 μm or less, and more preferably 0.8 μm or less. When the arithmetic mean particle diameter in the particle size distribution based on the number of polymer particles is 0.1 μm or more, it is preferable because the polymer particles exhibit excellent optical properties such as light diffusion when used for optical purposes such as light diffusing agents. In addition, even after the polymer particle composition is stored for a long period of time, the polymer particles in the polymer particle composition can be redispersed to achieve uniform dispersion. When the arithmetic mean particle diameter in the number-based particle size distribution of the polymer particles is 3.0 μm or less, the thickness of the coating film covering the surfaces of the polymer particles protruding from the coating film surface can be made uniform, thereby making it possible to homogenize the coating film and reduce the falling off of the polymer particles from the coating film surface.

[0088] In the polymer particles, the content of small particles having a particle size of 50% or less of the arithmetic mean particle size in the particle size distribution based on the number is preferably 6% or less, more preferably 5% or less. When the content of small particles is 6% or less, the interaction between the polymer particles can be made more uniform throughout the polymer particles. Therefore, the dispersion of the polymer particles in the dispersion medium can be made more uniform and the dispersion stability can be improved. Furthermore, the polymer particles can be more uniformly dispersed in a molded body such as a coating film or a sheet formed from the polymer particle composition, and the falling off from the surface of the molded body can be further reduced.

[0089] The coefficient of variation (CV value) of particle size based on the particle size distribution based on the number of polymer particles is preferably 20% or less, more preferably 16% or less, and more preferably 15% or less. When the coefficient of variation of the polymer particles is 20% or less, the interaction between the polymer particles can be made more uniform throughout the polymer particles. Therefore, the dispersion of the polymer particles in the dispersion medium can be made more uniform and the dispersion stability can be improved. Furthermore, the polymer particles can be more uniformly dispersed in a molded body such as a coating film or a sheet formed from the polymer particle composition, and the falling off from the surface of the molded body can be further reduced.

[0090] The arithmetic mean particle size and the coefficient of variation (CV value) of particle size in the number-based particle size distribution of the polymer particles, and the content of small particles in the polymer particles are measured as follows.

[0091] When the arithmetic mean particle diameter in the number-based particle size distribution of polymer particles is 1 μm or more, it is measured as follows. The arithmetic mean particle diameter in the number-based particle size distribution of polymer particles is measured using a Coulter MultisizerTM 4e (a measuring device manufactured by Beckman Coulter, Inc.). The measurement is performed using an aperture calibrated according to the Multisizer 4 User's Manual published by Beckman Coulter, Inc.

[0092] The aperture used in the measurement is appropriately selected depending on the size of the polymer particles to be measured. Current (aperture current) and Gain are appropriately set depending on the size of the selected aperture.

[0093] The measurement sample is prepared by dispersing 0.1 g of polymer particles in 10 mL of 0.1% by mass aqueous solution of nonionic surfactant using a touch mixer (manufactured by Yamato Scientific Co., Ltd., product name "TOUCHMIXER MT-31") and an ultrasonic cleaner (manufactured by Vervoclear Co., Ltd., product name "ULTRASONIC CLEANER VS-150") to prepare a dispersion. During the measurement, the inside of the beaker is gently stirred to an extent that air bubbles are not introduced, and the measurement is terminated when 100,000 polymer particles are measured. The particle diameter of the polymer particles is the equivalent sphere diameter. In other words, the particle diameter of the polymer particles is the diameter of a true sphere having the same volume as the polymer particles. The arithmetic (number) average particle diameter of the polymer particles is the arithmetic average in the particle size distribution based on the number of 100,000 particles. The content of particles (small particles) having a particle size of 50% or less of the arithmetic (number) average particle size of the polymer particles is the number ratio (%) of small particles calculated based on the particle size distribution based on the number of 100,000 particles.

[0094] The coefficient of variation (CV value) of the particle size of the polymer particles is calculated by the following formula. Coefficient of variation (CV value) of particle size of polymer particles = 100 × (standard deviation of particle size in number-based particle size distribution of polymer particles) / (arithmetic mean particle size in number-based particle size distribution of polymer particles)

[0095] When the arithmetic mean particle diameter in the number-based particle size distribution of the polymer particles is less than 1 μm, it is measured as follows. The arithmetic mean particle diameter in the number-based particle size distribution of the polymer particles is measured using a laser diffraction scattering type particle size distribution measuring device (model number "LS230" manufactured by Beckman Coulter, Inc.). Specifically, 0.1 g of polymer particles (equivalent to 0.1 g in the case of a dispersion) and 20 mL of a 2% by mass anionic surfactant solution are placed in a test tube. Thereafter, the polymer particles are 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 prepare a dispersion. The number-average particle diameter of the polymer particles in the dispersion obtained was measured using a laser diffraction scattering type particle size distribution measuring device while irradiating the dispersion with ultrasonic waves. The optical model during the measurement was adjusted to the refractive index of the produced polymer particles. When one type of monomer was used to produce the polymer particles, the refractive index of the homopolymer of that monomer was used as the refractive index of the polymer particles. When multiple types of monomers were used to produce the polymer particles, the average value of the refractive index of the homopolymer of each monomer weighted by the amount of each monomer used was used as the refractive index of the polymer particles. <Measurement conditions for laser diffraction / scattering particle size distribution analyzer> medium = water Refractive index of medium = 1.333 Refractive index of solid = Refractive index of polymer particles PIDS relative concentration: 40-55%

[0096] The content of particles (small particles) having a particle size that is 50% or less of the arithmetic (number) average particle size of the polymer particles, and the coefficient of variation (CV value) of the particle size of the polymer particles are calculated in the same manner as the arithmetic average particle size in the number-based particle size distribution of the polymer particles.

[0097] The dispersion coefficient of the polymer particles is preferably less than 0.20, more preferably 0.15 or less. When the dispersion coefficient of the polymer particles is less than 0.20, the dispersion of the polymer particles in the dispersion medium can be made uniform and the dispersion stability can be improved. Furthermore, the polymer particles can be more uniformly dispersed in a molded article such as a coating film or a sheet formed from the polymer particle composition, and the falling off from the surface of the molded article can be further reduced.

[0098] The dispersion behavior shift of the polymer particles is preferably less than 0.03, more preferably 0.02 or less. When the dispersion behavior shift of the polymer particles is less than 0.03, the dispersion of the polymer particles in the dispersion medium can be made uniform and the dispersion stability can be improved. Furthermore, the polymer particles can be more uniformly dispersed in a molded article such as a coating film or a sheet formed from the polymer particle composition, and the falling off from the surface of the molded article can be further reduced.

[0099] The dispersion coefficient and dispersion behavior shift of the polymer particles are measured as follows. [Preparation method of dispersion liquid] 0.10 g of polymer particles and 5.00 g of butyl acetate as a dispersion medium are added to a 10 mL sample tube, and the mixture is stirred for 1 minute using an ultrasonic cleaner (manufactured by Vervoclear Co., Ltd., product name "ULTRASONIC CLEANER VS-150") to disperse the polymer particles in the butyl acetate to obtain a dispersion. 0.50 g of an acrylic resin (manufactured by DIC Corporation, product name "ACRYDIC (registered trademark) A-817-Ba") is further added to this dispersion, and the mixture is stirred for about 10 minutes using the ultrasonic cleaner to prepare a dispersion in which the polymer particles are dispersed in the butyl acetate and acrylic resin.

[0100] [Measurement method] The viscosity value of the dispersion is measured by the following method using a viscometer (a micro-sample viscometer m-VROC manufactured by Nippon Luft Co., Ltd.) Note that the viscometer is left in the measurement environment for 30 minutes or more before the viscosity value is measured.

[0101] Using the above viscometer, the prepared dispersion is left to stand for 5 hours at room temperature (laboratory temperature 23°C to 27°C), and then the dispersion is stirred for 5 minutes in an ultrasonic cleaner (re-dispersion), after which the viscosity (mPa s) of the dispersion is measured.

[0102] Then, using the measured viscosity value (mPa s) and the measured temperature (K), the viscosity value per unit temperature (K) V (mPa s / K) is calculated according to the following formula: The viscosity value measurement is repeated 10 times, and the average viscosity value, maximum viscosity value, and minimum viscosity value are calculated. Viscosity value V (mPa s / K) = measured value (mPa s) / measurement temperature (K)

[0103] [Calculation method for dispersed behavior displacement] The maximum, minimum and average viscosity values ​​from the 10 measurements are used to calculate the viscosity value deviation, i.e., the dispersion behavior deviation, according to the following formula. <Calculation formula for dispersed behavior displacement> Dispersion behavior displacement = (VMAX-VMIN) / VAVE VMAX: Maximum viscosity value of 10 measurements (mPa s / K) VMIN: Minimum viscosity value among 10 measurements (mPa s / K) VAVE: Average viscosity value of 10 measurements (mPa s / K)

[0104] [How to calculate the dispersion coefficient] Prepare a dispersion in the same manner as when measuring the dispersion behavior displacement. Using the above viscometer, leave the prepared dispersion at room temperature (23°C to 27°C) for 4, 5, or 6 hours, then stir the dispersion in an ultrasonic cleaner for 5 minutes (re-dispersion), and measure the viscosity value V (mPa s / K) of the dispersion after leaving it at rest for 4, 5, or 6 hours in the same manner as when measuring the dispersion behavior displacement. Calculate the dispersion coefficient based on the following formula: <Calculation formula for dispersion coefficient> Dispersion coefficient = |V6hr·AVE-V4hr·AVE| / V5hr·AVE V4hr AVE: Average viscosity value of 10 measurements on the dispersion after standing for 4 hours V5hr·AVE: Average viscosity value of 10 measurements of the dispersion after standing for 5 hours V6hr AVE: Average viscosity value of 10 measurements on the dispersion after standing for 6 hours

[0105] [Method of producing polymer particles] Next, the method for producing the polymer particles will be described. The method for producing the polymer particles is not particularly limited, and the polymer particles can be produced by polymerizing raw material monomers including the acrylic monomer represented by formula (1) in the presence of a polymerization initiator as necessary in a general manner.

[0106] The polymerization method is not particularly limited, and a general-purpose polymerization method such as suspension polymerization, seed polymerization, bulk polymerization, solution polymerization, etc. can be used, and seed polymerization is preferred. Emulsion polymerization is a polymerization method in which raw material monomers are dispersed in an aqueous medium described below and polymerized in the presence of a polymerization initiator and an emulsifier, and is included in suspension polymerization.

[0107] Seed polymerization is a method in which, when starting polymerization of raw material monomers including the acrylic monomer represented by formula (1), seed particles made of a polymer of a vinyl monomer that has been separately prepared are added to carry out polymerization.

[0108] In detail, seed polymerization is a method in which polymer particles made of a polymer of a vinyl monomer are used as seed particles, raw material monomers including an acrylic monomer represented by formula (1) are absorbed into the seed particles in an aqueous medium, and the raw material monomers are polymerized within the seed particles. In this method, the seed particles are grown to obtain polymer particles having a particle size larger than that of the original seed particles. A general method of seed polymerization is described below, but the polymerization method is not limited to this method.

[0109] The weight average molecular weight of the polymer constituting the seed particles used in the 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 the seed polymerization is preferably 6,000 or more, more preferably 8,000 or more. In the swollen state in which the seed particles absorb the raw material monomer, the polymer constituting the seed particles is dispersed in the raw material monomer. When the weight average molecular weight of the polymer constituting the seed particles is 6,000 or more, in the swollen state, the viscosity of the raw material monomer is moderately increased, and the raw material monomers can be prevented from coalescing with each other. When the weight average molecular weight of the polymer constituting the seed particles is 40,000 or less, the absorbency of the raw material monomer is improved, the variation in particle size of the polymer particles is reduced, the interaction between the polymer particles in the entire polymer particles is uniform, and the dispersibility and dispersion stability of the polymer particles in the dispersion medium are improved.

[0110] In the present invention, the weight average molecular weight of a polymer refers to a value measured in the following manner. More specifically, it is measured in the following manner.

[0111] The weight average molecular weight of a polymer can be measured using GPC (gel permeation chromatography). The weight average molecular weight of a polymer means the weight average molecular weight converted into polystyrene. Specifically, 0.003 g of polymer particles as a sample is dissolved in 10 mL of tetrahydrofuran (THF) at room temperature for 24 hours or more, and then filtered through a non-aqueous 0.45 μm chromatographic disk to obtain a measurement solution, and the weight average molecular weight of the entire polymer particles is obtained from a calibration curve of standard polystyrene prepared in advance. The measurement conditions of the chromatography are as follows. ·Equipment: High-speed GPC equipment Product name: Tosoh HLC-8320GPC EcoSEC-WorkStatio n (RI detector built-in) ·Analysis conditions Column: TSKgel SuperHZM-H x 2 (4.6mm I.D. x 15cm L x 2) Guard column: TSKguardcolumn SuperHZ-H x 1 (4.6mm ID x 2cm L) Flow rate: Sample side 0.175mL / min, Reference side 0.175mL / min Detector: Built-in RI detector Concentration: 0.3g / L Injection volume: 50μL Column temperature: 40℃ System temperature: 40℃ Eluent:THF

[0112] In the seed polymerization, first, a mixture containing raw material monomers including the acrylic monomer represented by formula (1), a surfactant, and an aqueous medium is mixed with seed particles.

[0113] The mixed liquid can be prepared by a known method. For example, the raw material monomers including the acrylic monomer represented by formula (1) and the surfactant are added to an aqueous medium, and the mixed liquid can be prepared by mixing with a microemulsifier such as a homogenizer, an ultrasonic processor, or a Nanomizer (registered trademark). As the aqueous medium, water or a mixture of water and an organic solvent [for example, a lower alcohol (alcohol having 5 or less carbon atoms)] can be used, with water being preferred.

[0114] The amount of the surfactant used in the seed polymerization is preferably 0.3 to 3.0 parts by mass relative to 100 parts by mass of the raw material monomers including the acrylic monomer represented by formula (1). When the amount of the surfactant used is 0.3 parts by mass or more, the resulting polymer particles have excellent affinity with the dispersion medium and have moderate interaction between the polymer particles, and the polymer particles can have excellent uniform dispersibility and dispersion stability in the dispersion medium. When the amount of the surfactant used is 3.0 parts by mass or less, the resulting polymer particles can easily reach the surface of the polymer particles when dispersed in the dispersion medium, and can exhibit excellent affinity between the polymer particles and the dispersion medium, and the polymer particles can have excellent uniform dispersibility and dispersion stability in the dispersion medium.

[0115] After the mixture is mixed with the seed particles, the raw material monomers including the acrylic monomer represented by formula (1) are absorbed into the seed particles. This absorption can usually be performed by stirring the mixture at room temperature (20 to 50° C.) for 1 to 12 hours.

[0116] The acrylic monomer represented by formula (1) is slightly soluble in water, and therefore has excellent absorption properties for seed particles, and can reduce polymerization as a side reaction in an aqueous medium and promote polymerization in the seed particles, thereby producing polymer particles with small particle size variations. Polymer particles with small particle size variations can uniformize the interactions between the polymer particles and have excellent dispersibility and dispersion stability in a dispersion medium. Furthermore, the polymer particles can be uniformly dispersed in a molded article such as a coating film or sheet formed from the polymer particle composition, and the falling off of the polymer particles from the surface of the molded article can be reduced.

[0117] The seed particles swell by absorbing raw material monomers containing an acrylic monomer represented by formula (1). The mixing ratio of the raw material monomers containing an acrylic monomer represented by formula (1) and the seed particles is preferably within a range of 9 to 110 parts by mass of the raw material monomer per part by mass of the seed particles. When the amount of the raw material monomer is 9 parts by mass or more, the production efficiency of the polymer particles is improved. When the amount of the raw material monomer is 110 parts by mass or less, polymerization of the raw material monomer as a side reaction outside the seed particles is reduced, and the variation in particle size of the polymer particles can be reduced.

[0118] Next, the raw material monomer absorbed in the seed particles is polymerized to obtain polymer particles. The polymer particles may be produced by repeating the process of absorbing the raw material monomer into the seed particles and polymerizing them multiple times.

[0119] A polymerization initiator may be added to the raw material monomer as necessary. The polymerization initiator is not particularly limited, but may be, for example, organic peroxides such as benzoyl peroxide, lauroyl peroxide, o-chlorobenzoyl peroxide, o-methoxybenzoyl peroxide, 3,5,5-trimethylhexanoyl peroxide, t-butylperoxy-2-ethylhexanoate, and di-tert-butyl peroxide; 2,2'-azobisisobutyronitrile, 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2,3-dimethylbutyronitrile); Examples of the azo compounds include 2,2'-azobis(2-methylbutyronitrile), 2,2'-azobis(2,3,3-trimethylbutyronitrile), 2,2'-azobis(2-isopropylbutyronitrile), 1,1'-azobis(cyclohexane-1-carbonitrile), 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), (2-carbamoylazo)isobutyronitrile, 4,4'-azobis(4-cyanovaleric acid), and dimethyl-2,2'-azobisisobutyrate. The polymerization initiator is preferably used in the range of 0.1 to 1.0 parts by mass relative to 100 parts by mass of the raw material monomer.

[0120] The polymerization temperature of the seed polymerization can be appropriately selected depending on the type of raw material monomer and the type of polymerization initiator used as necessary. Specifically, the polymerization temperature of the seed polymerization is preferably 25 to 110° C., more preferably 50 to 100° C. The polymerization time of the seed polymerization is preferably 1 to 12 hours.

[0121] In the seed polymerization, a polymer dispersion stabilizer may be added to the polymerization reaction system in order to improve the dispersion stability of the polymer particles. Examples of the polymer dispersion stabilizer include polyvinyl alcohol, polycarboxylic acid, celluloses (hydroxyethyl cellulose, carboxymethyl cellulose, etc.), polyvinyl pyrrolidone, etc., and polyvinyl alcohol and polyvinyl pyrrolidone are preferred. The amount of the polymer dispersion stabilizer added is preferably 0.5 to 15 parts by mass, more preferably 1 to 10 parts by mass, based on 100 parts by mass of the raw material monomer.

[0122] In addition, in the above polymerization reaction, in order to reduce polymerization of the raw material monomer in the aqueous medium outside the seed particles, a water-soluble polymerization inhibitor such as nitrites such as sodium nitrite, sulfites, hydroquinones, ascorbic acids, water-soluble vitamin B, citric acid, polyphenols, etc. may be added to the aqueous medium.

[0123] The polymerization method for obtaining seed particles by polymerizing a vinyl monomer is a general-purpose polymerization method, and is not particularly limited. For example, dispersion polymerization, emulsion polymerization, soap-free emulsion polymerization (emulsion polymerization without using a surfactant as an emulsifier), seed polymerization, suspension polymerization, etc. can be used.

[0124] The reaction liquid containing the polymer particles obtained by polymerization in the above-mentioned manner is fed to a general-purpose filter, and the polymer particles contained in the reaction liquid are separated from the aqueous medium. The separated polymer particles are washed with water, and then dried in a general-purpose manner to remove almost all water, and if necessary, classified (preferably air classification) to obtain the polymer particles.

[0125] [Applications of polymer particles] The polymer particles can be suitably used for optical members such as optical films such as antiglare films and light diffusion films, and light diffusers, and are particularly suitable for use in antiglare members. The polymer particles can also be used as a matting agent for paints, an antiblocking agent, an additive for improving the physical properties of resins, and the like.

[0126] [Polymer particle composition] A polymer particle composition can be prepared by dispersing the polymer particles in a dispersion medium. A coating film containing the polymer particles can be prepared on the substrate by applying the polymer particle composition to the substrate and drying the composition. Examples of the substrate include films and other molded products. The polymer particle composition can be molded in a general manner to produce a molded product such as a sheet.

[0127] The polymer particles contain an acrylic polymer that contains an acrylic monomer unit represented by formula (1) and have excellent dispersibility and dispersion stability in a dispersion medium. Therefore, in the polymer particle composition, the polymer particles are stably and uniformly dispersed in the dispersion medium, and the polymer particle composition can be easily applied to a substrate without causing coating unevenness.

[0128] In the coating film and sheet formed by drying the polymer particle composition, the polymer particles maintain a uniformly dispersed state, and a coating film and sheet having uniform physical properties can be obtained. Furthermore, since the polymer particles are firmly held in the coating film and sheet, the polymer particles are reduced from falling off from the surface of the coating film and sheet. In the molded product obtained by molding the polymer particle composition in a general-purpose manner, the polymer particles maintain a uniformly dispersed state. Furthermore, since the polymer particles are firmly held in the molded product, the polymer particles are reduced from falling off from the surface of the molded product.

[0129] Furthermore, even when the polymer particles aggregate to form agglomerated particles during the formation of a coating film or sheet, or during the formation of other molded products, the polymer particles do not aggregate excessively but form agglomerated particles having an appropriate and uniform size, so that the coating film, sheet, and other molded products have uniform physical properties and the shedding of agglomerated particles from the surface of the molded products is reduced.

[0130] The dispersion medium is not particularly limited, and examples thereof include synthetic resins such as binder resins, and organic solvents.

[0131] The synthetic resin may be appropriately selected depending on the application. Examples of the synthetic resin include (meth)acrylic resins; (meth)acrylic-urethane resins; urethane resins; polyvinyl chloride resins; polyvinylidene chloride resins; melamine resins; styrene resins; alkyd resins; phenolic resins; epoxy resins; polyester resins; silicone resins such as alkylpolysiloxane resins; modified silicone resins such as (meth)acrylic-silicone resins, silicone-alkyd resins, silicone-urethane resins, and silicone-polyester resins; fluorine resins such as polyvinylidene fluoride and fluoroolefin vinyl ether polymers. (Meth)acrylic means acrylic or methacrylic.

[0132] The synthetic resin may be a curable resin capable of forming a crosslinked structure by a crosslinking reaction. The curable resin is classified into ionizing radiation curable resins such as ultraviolet curable resins and electron beam curable resins, thermosetting resins, and warm air curable resins depending on the type of curing. The curable resin also includes a curable resin that produces a binder component by curing. The curable resin is a concept that includes a composition containing a monomer before curing.

[0133] Examples of the thermosetting resin include a thermosetting urethane resin containing an acrylic polyol and an isocyanate prepolymer, a phenol resin, a urea melamine resin, an epoxy resin, an unsaturated polyester resin, and a silicone resin.

[0134] Examples of ionizing radiation curable resins include polyfunctional (meth)acrylate resins such as polyhydric alcohol polyfunctional (meth)acrylates such as trimethylolpropane tri(meth)acrylate, trimethylolethane tri(meth)acrylate, and 1,2,4-cyclohexane tri(meth)acrylate; polyfunctional urethane acrylate resins synthesized from diisocyanates, polyhydric alcohols, and (meth)acrylic acid esters having hydroxyl groups, polyether resins having acrylate functional groups, polyester resins, epoxy resins, alkyd resins, spiroacetal resins, polybutadiene resins, and polythiolpolyene resins.

[0135] An organic solvent may be contained in order to adjust the viscosity of the polymer particle composition. Examples of the organic solvent include aromatic solvents such as toluene and xylene; alcohol solvents such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, 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; 2-methoxyethanol, 2-ethoxyethanol, 2-butoxyethanol, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, and diethylene glycol dimethyl ether. Examples of the organic solvent include glycol ethers such as ethyl ether and propylene glycol methyl ether; glycol ether esters such as 2-methoxyethyl acetate, 2-ethoxyethyl acetate (cellosolve acetate), 2-butoxyethyl acetate, and propylene glycol methyl ether acetate; chlorine-based solvents such as chloroform, dichloromethane, trichloromethane, and methylene chloride; ether-based solvents such as tetrahydrofuran, diethyl ether, 1,4-dioxane, and 1,3-dioxolane; and amide-based solvents such as N-methylpyrrolidone, dimethylformamide, dimethylsulfoxide, and dimethylacetamide. The organic solvent may be used alone or in combination of two or more kinds.

[0136] The amount of the 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 synthetic resin. The amount of the 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 synthetic resin.

[0137] The material of the substrate to which the polymer particle composition is applied is not particularly limited, and examples thereof include synthetic resins such as polyester polymers such as polyethylene terephthalate (PET) and polyethylene naphthalate, cellulose polymers such as diacetyl cellulose and triacetyl cellulose (TAC), polycarbonate polymers, and (meth)acrylic polymers such as polymethyl methacrylate, cement, tiles, metals, and glass.

[0138] The method for applying the polymer particle composition to a substrate is not particularly limited, and examples thereof include bar coating, blade coating, spin coating, reverse coating, die coating, spray coating, roll coating, gravure coating, microgravure coating, lip coating, air knife coating, and dipping.

[0139] The thickness of the coating film formed from the polymer particle composition is not particularly limited and is appropriately determined depending on the particle size of the polymer particles, but is preferably 1 to 20 μm, more preferably 2 to 10 μm. The thickness of the sheet formed from the polymer particle composition is not particularly limited and is appropriately determined depending on the particle size of the polymer particles, but is preferably 1 to 20 μm, more preferably 2 to 10 μm. Effect of the Invention

[0140] The polymer particles of the present invention can be uniformly dispersed in a dispersion medium such as a synthetic resin such as a binder resin, an organic solvent, etc. The polymer particles of the present invention can maintain a uniformly dispersed state even in a coating film or a molded article such as a sheet obtained from a polymer particle composition prepared by dispersing the polymer particles in an organic solvent.

[0141] The polymer particles of the present invention can easily form a molded article with reduced shedding of the polymer particles from the surface. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0142] The present invention will be described in more detail below by way of examples, but the present invention is not limited to these examples. EXAMPLES

[0143] In the examples and comparative examples, the following compounds were used. [Acrylic monomers] Tetrahydrofurfuryl methacrylate [formula (7), THFMA, R 4 Carbon number: 5, heteroatom ratio: 0.20] Tetrahydrofurfuryl acrylate [formula (6), THFA, R 4 Carbon number: 5, heteroatom ratio: 0.20] Trimethylolpropane formal acrylate [formula (8), CTFA, R 4 Carbon number: 7, heteroatom ratio: 0.33] Cyclohexyl methacrylate [CHMA,R 4 Carbon number: 6, heteroatom ratio: 0] Glycidyl methacrylate [GMA] Methyl methacrylate [MMA] (2-Methyl-2-ethyl-1,3-dioxolan-4-yl)methacrylate [formula (16), MEOMA, R 4 Carbon number: 7, heteroatom ratio: 0.40] In Table 1, R is written under the column for the type of acrylic monomer. 4 The carbon numbers and heteroatom ratios are listed in order.

[0144] [ka]

[0145] [ka]

[0146] [ka]

[0147] [ka]

[0148] [Styrene-based monomers] Styrene monomer (St)

[0149] [Multifunctional monomer] Ethylene glycol dimethacrylate [EGDMA] Divinylbenzene [DVB]

[0150] [Anionic surfactants] (1) Sodium dodecylbenzenesulfonate (SP value = 11.4, product name "Neogen (registered trademark) S-20D" manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) (2) Sodium di(2-ethylhexyl)sulfosuccinate (SP value = 9.2, product name "Rapisol A-80 (registered trademark)" manufactured by NOF Corporation) (3) Sodium polyoxyethylene nonylphenyl ether phosphate (SP value = 9.6, manufactured by Toho Chemical Industry Co., Ltd., trade name "Phosphanol LO-529 (registered trademark)") (4) Sodium lauryl sulfate (SP value = 11.9, product name "EMAL 2FG (registered trademark)" manufactured by Kao Corporation) (5) Sodium α-olefin sulfonate (SP value = 8.4, Kao Corporation, product name "Lipolan LB-440") (6) Sodium octanesulfonate (SP value = 13.0, manufactured by Fujifilm Wako Co., Ltd.) (7) Sodium lauryl sulfonate (SP value = 11.6, manufactured by Tokyo Chemical Industry Co., Ltd.) In Tables 1 and 2, the type of surfactant is indicated by the number written at the beginning of each compound. In Table 2, when multiple types of surfactants were used, the SP value of the surfactant is indicated as the SP value of the entire mixture of surfactants.

[0151] [Production of seed particle 1] In a 5L reactor equipped with a stirrer and a thermometer, an oil phase containing 700 parts by mass of methyl methacrylate and 2.0 parts by mass of n-octyl mercaptan as a molecular weight modifier was supplied to an aqueous phase containing 2800 parts by mass of water as an aqueous medium and 3.0 parts by mass of sodium styrenesulfonate as a styrene monomer, and the inside of the reactor was replaced with nitrogen while stirring the contents, and the internal temperature of the reactor was raised to 70° C. Furthermore, while maintaining the internal temperature of the reactor at 70° C., an aqueous solution prepared by dissolving 3.0 parts by mass of potassium persulfate in 100 parts by mass of water as a polymerization initiator was supplied to the contents in the reactor, and then polymerization reaction was carried out for 12 hours.

[0152] The reaction liquid after polymerization was filtered through a wire screen of 400 mesh (opening 32 μm) to prepare a slurry containing 20 mass% of seed particles mainly composed of polymethyl methacrylate as a solid content. The seed particles contained in this slurry were spherical particles. The arithmetic mean particle diameter of the seed particles in the number-based particle size distribution was 0.27 μm. The weight-average molecular weight of the polymethyl methacrylate constituting the seed particles was 14,000.

[0153] [Production of seed particle 2] An oil phase, which was a mixture of 500 parts by mass of ethyl methacrylate and 2.0 parts by mass of n-octyl mercaptan as a molecular weight regulator, was supplied to a 5 L reactor equipped with a stirrer and a thermometer, and the inside of the reactor was replaced with nitrogen while stirring the contents, and the internal temperature of the reactor was raised to 55° C. Furthermore, while maintaining the internal temperature of the reactor at 55° C., an aqueous solution prepared by dissolving 3.0 parts by mass of potassium persulfate in 100 parts by mass of water as a polymerization initiator was supplied to the contents in the reactor, and then polymerization reaction was carried out for 12 hours.

[0154] The reaction liquid after polymerization was classified using a wire screen with 400 mesh (opening 32 μm) to prepare a slurry containing 15 mass % of seed particles mainly composed of polyethyl methacrylate as a solid content. The seed particles contained in this slurry were spherical particles. The arithmetic mean particle diameter of the seed particles in the number-based particle size distribution was 0.70 μm. The weight-average molecular weight of the polyethyl methacrylate constituting the seed particles was 14,500.

[0155] (Examples 1 to 6 and 9 to 13, Comparative Examples 1 to 3 and 6 to 8) [Example of polymer particle production] A monomer mixture was prepared by dissolving 5 parts by mass of 2,2'-azobis(2,4-dimethylvaleronitrile) as a polymerization initiator in raw monomers containing the specified amounts of acrylic monomers, styrene monomers, and polyfunctional monomers shown in Table 1.

[0156] A surfactant solution was prepared by adding sodium dodecylbenzenesulfonate or sodium laurylsulfonate as an anionic surfactant in the amount shown in Table 1 in terms of pure content to 3,000 parts by mass of ion-exchanged water as an aqueous medium.

[0157] The monomer mixture and the surfactant solution were mixed, and the mixture was placed in a homomixer (manufactured by Primix Corporation, product name "TK homomixer MARKII 2.5 type") and treated at a rotation speed of 8000 rpm for 10 minutes to obtain an emulsion (mixture). To this emulsion, a slurry of seed particles of the type shown in Table 1 was added so that the seed particles amounted to 50 parts by mass, and the mixture was stirred at 30°C for 3 hours to obtain a dispersion.

[0158] Next, 0.60 parts by mass of sodium nitrite was dissolved as a polymerization inhibitor in 50 parts by mass of ion-exchanged water to prepare an aqueous polymerization inhibitor solution. After the aqueous polymerization inhibitor solution was supplied to the dispersion, the dispersion was heated to 60°C, maintained at that temperature, and polymerized for 5 hours while stirring. Further, the dispersion was heated to 100°C, maintained at that temperature, and polymerized for 3 hours while stirring to obtain a slurry containing polymer particles.

[0159] The slurry containing the polymer particles was classified using a wire screen of 400 mesh (openings: 32 μm) to obtain a slurry containing classified polymer particles.

[0160] The slurry containing the classified polymer particles was spray-dried under the following device conditions using a spray dryer (manufactured by Sakamoto Giken Co., Ltd., machine name: spray dryer, type: atomizer take-up type, model number: TRS-3WK) to obtain polymer particles.

[0161] <Equipment conditions> Slurry feed rate containing polymer particles: 25mL / min Atomizer rotation speed: 12000 rpm Air volume: 2m3 / min Inlet temperature (temperature of the polymer particle-containing slurry inlet provided in the spray dryer where the polymer particle-containing slurry is sprayed and introduced): 150°C Outlet temperature (outlet temperature of polymer particles from which the aggregate of polymer particles is discharged from the spray dryer): 70°C

[0162] Example 7 A monomer mixture was prepared by dissolving 5 parts by mass of 2,2'-azobis(2,4-dimethylvaleronitrile) as a polymerization initiator in raw monomers containing the acrylic monomer and polyfunctional monomer in the prescribed amounts shown in Table 1.

[0163] A surfactant solution was prepared by adding 10 parts by mass, in terms of pure content, of sodium di(2-ethylhexyl)sulfosuccinate as an anionic surfactant to 1000 parts by mass of ion-exchanged water as an aqueous medium.

[0164] The monomer mixture and the surfactant solution were mixed, and the mixture was placed in a homomixer (manufactured by Primix Corporation, product name "TK homomixer MARKII 2.5 type") and treated at a rotation speed of 8000 rpm for 10 minutes to obtain an emulsion (mixture). The slurry of seed particles was added to this emulsion so that the amount of seed particles 1 was 50 parts by mass, and the mixture was stirred at 30°C for 3 hours to obtain a dispersion.

[0165] Next, 0.60 parts by mass of sodium nitrite as a polymerization inhibitor and 10 parts by mass of polyoxyethylene nonylphenyl ether sodium phosphate as an anionic surfactant were added to 2000 parts by mass of ion-exchanged water to prepare an aqueous polymerization inhibitor solution. After the aqueous polymerization inhibitor solution was supplied to the dispersion, the dispersion was heated to 60°C, maintained at that temperature, and polymerized for 5 hours while stirring. Furthermore, the dispersion was heated to 100°C, maintained at that temperature, and polymerized for 3 hours while stirring to obtain a slurry containing polymer particles.

[0166] The slurry containing the polymer particles was classified using a wire screen of 400 mesh (openings: 32 μm) to obtain a slurry containing classified polymer particles.

[0167] The resulting slurry containing polymer particles was spray-dried in the same manner as in Example 1 to obtain polymer particles.

[0168] Example 8 Polymer particles were obtained in the same manner as in Example 7, except that the surfactant solution was prepared using 15 parts by mass of sodium lauryl sulfate, an anionic surfactant, instead of sodium di(2-ethylhexyl)sulfosuccinate, and the polymerization inhibitor aqueous solution was prepared using 5 parts by mass of sodium dodecylbenzenesulfonate, an anionic surfactant, instead of sodium polyoxyethylene nonylphenyl ether phosphate, as the surfactant.

[0169] Comparative Example 4 Polymer particles were obtained in the same manner as in Example 1, except that the surfactant solution was prepared using 20 parts by mass of sodium α-olefinsulfonate, an anionic surfactant, instead of sodium dodecylbenzenesulfonate, as the surfactant.

[0170] Comparative Example 5 Polymer particles were obtained in the same manner as in Example 1, except that the surfactant solution was prepared using 20 parts by mass of sodium octanesulfonate, an anionic surfactant, instead of sodium dodecylbenzenesulfonate, as the surfactant.

[0171] For the obtained polymer particles, the surfactant content (g) per 1 g of polymer particles was measured, and the “Surfactant content (×10 -3 The amount of surfactant attached to the methanol-washed particles was measured in the same manner as above, and the amount is shown in the "Amount of surfactant attached to the methanol-washed particles" column. -3 g / m 2 It was.

[0172] In Table 2, when a mixture of multiple types of surfactants was used, the SP value of the entire mixture of surfactants is shown in the column "SP value of surfactant."

[0173] The arithmetic mean particle size based on the number-based particle size distribution, the coefficient of variation of the particle size (CV value), the gel fraction, the specific surface area, the amount of surfactant attached, the dispersion behavior displacement and the dispersion coefficient of the obtained polymer particles were measured as described above, and the results are shown in Table 2.

[0174] The content (mass%) of the monomer units contained in the obtained polymer particles was measured as described above, and was found to be the same content (mass%) as the content (mass%) of the monomers used to produce the polymer particles.

[0175] The resulting polymer particles were measured for coatability and particle shedding properties in the manner described below. The results are shown in Table 2.

[0176] [Coatability] (Optical film manufacturing) 0.20 g of polymer particles and 1.00 g of butyl acetate as an organic solvent were supplied to a 10 mL sample tube and stirred for 1 minute using an ultrasonic cleaner (manufactured by Vervoclear Co., Ltd., product name "ULTRASONIC CLEANER VS-150") to disperse the polymer particles in the butyl acetate to obtain a dispersion.

[0177] To the obtained dispersion, 1.50 g of an acrylic resin (manufactured by DIC Corporation under the trade name "ACRYDIC (registered trademark) A-817-BA") was added as a binder resin, and the mixture was stirred for about 2 minutes in the ultrasonic cleaner.

[0178] After the dispersion was allowed to stand for 4 hours, 5.50 g of butyl acetate was added as an organic solvent to the dispersion, and the mixture was stirred for 1 minute in the ultrasonic cleaner to obtain a polymer particle composition.

[0179] The obtained polymer particle composition was applied onto a polyethylene terephthalate film having a thickness of 100 μm (manufactured by Fuji Film Corporation, product name "FUJIX (registered trademark) OHP film for copiers") using a coater with a 75 μm slit. After application, the film was placed in a dryer maintained at a temperature of 70° C. and left for 1 hour to evaporate and remove the organic solvent in the polymer particle composition, thereby obtaining an optical film in which a coating film was formed on the polyethylene terephthalate film. In the coating film, the polymer particles were contained in a state of being dispersed in the acrylic resin.

[0180] (Evaluation of optical properties (low haze variation)) A test specimen was prepared by cutting the optical film into a flat square shape with sides of 6 cm. The haze of the coating film of the test specimen was measured at each of the four corners and the center (a total of five locations) in accordance with JIS K7136 using a measuring device commercially available from Nippon Denshoku Industries Co., Ltd. under the product name "NDH-4000."

[0181] The haze difference (%) was calculated using the maximum value, minimum value and arithmetic average value of the haze (%) measured at the five points according to the following formula, and was evaluated based on the following criteria.

[0182] Haze difference (%) = 100 x [(maximum haze value - minimum haze value) / arithmetic mean haze value]

[0183] A: The haze difference was less than 0.5%. B: The haze difference was 0.5% or more and less than 1.0%. C: The haze difference was 1.0% or more and less than 3.0%. D: The haze difference was 3.0% or more.

[0184] [Particle shedding] An optical film was produced in the same manner as in the measurement of coatability. Using a Gakushin type friction tester RT-200 commercially available from Daiei Scientific Instruments, a 20mm x 20mm flat friction probe with a load of 300g was rubbed 10 times on the coating surface, and the film was observed using a digital microscope commercially available from Keyence Corporation under the product name "VHX". On the coating surface, random measurement points in a flat square shape with sides of 1mm were observed, the number of points where polymer particles had fallen off was counted, and the film was evaluated based on the following criteria.

[0185] A: Less than 10. B: 10 or more and less than 20. C: 20 or more and less than 30. D: More than 30.

[0186] [Table 1]

[0187] [Table 2] [Industrial Applicability]

[0188] The present invention can provide particles that can be uniformly dispersed in a dispersion medium such as an organic solvent, a synthetic resin, etc. The present invention can provide polymer particles that can maintain a uniformly dispersed state even in a coating film or a molded article such as a sheet obtained from a polymer particle composition prepared by dispersing the polymer particles in a dispersion medium.

[0189] The polymer particles of the present invention can provide a polymer particle composition that can easily form a coating film and a molded article such as a sheet with reduced shedding of polymer particles from the surface.

Claims

1. 0.5×10 surfactant containing an acrylic polymer containing an acrylic monomer unit represented by formula (1) and having an SP value of 9.0 to 12.0 on the surface -3 ~5.0 x 10 -3 g / m 2 A polymer particle having a polymeric particle having a polymeric particle attached thereto. 【Chemistry 1】 [In formula (1), R 1 ~R 3 each independently represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms; R 4 represents a monovalent substituent having 5 to 8 carbon atoms, a heterocycle, and a ratio of the number of heteroatoms in the heterocycle (number of heteroatoms n / number of constituent atoms N) exceeding 0 and less than 0.

4.

2. 2. The polymer particle according to claim 1, wherein the content of the acrylic monomer unit represented by formula (1) in the acrylic polymer is 55 to 98% by mass.

3. In formula (1), R 4 3. The polymer particle according to claim 1, wherein: 【Chemistry 2】 [In formula (2), R 5 represents an alkylene group having 1 to 3 carbon atoms; R 7 and R 8 each independently represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms; R 6 and R 9 each independently represents a divalent hydrocarbon group, one of which is an oxygen atom and the other of which is a divalent hydrocarbon group formed by removing two hydrogen atoms bonded to the same carbon atom in an aliphatic saturated hydrocarbon having 1 to 4 carbon atoms. *1 is a bond and means a single bond.] 【Chemistry 3】 [In formula (3), R 10 represents an alkylene group having 1 to 3 carbon atoms; R 11 ~R 13 each independently represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms; R 14 and R 15 are each independently an oxygen atom or a methylene group, and at least one of them represents an oxygen atom. *12 is a bond and represents a single bond.]

4. 3. The polymer particles according to claim 1, wherein the coefficient of variation (CV value) of particle diameter based on the number-based particle size distribution of the polymer particles is 20% or less.

5. 3. The polymer particles according to claim 1, having a dispersion coefficient of less than 0.

20.

6. 3. The polymer particles according to claim 1, wherein the dispersion behavior deviation is less than 0.

03.

7. 3. The polymer particle according to claim 1, which is used for an optical member.

8. 3. The polymer particle according to claim 1, which is used for an antiglare member.

9. 3. The polymer particle according to claim 1, which is used as an antiblocking agent.

10. A polymer particle composition comprising a dispersion medium and the polymer particles according to claim 1 or 2 dispersed in the dispersion medium.

11. Film and 3. An optical film comprising: a coating film formed on the film, the coating film comprising a synthetic resin and the polymer particles according to claim 1 or 2 dispersed in the synthetic resin.

12. 10. The optical film according to claim 9, which is an antiglare member.

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