Rubber particles, composite particles, and methods for producing the same

Abstract

Provided are: rubber particles having high degradability and containing a polyorgano-siloxane structure; composite particles; and manufacturing methods for these particles.　The rubber particles are made of a polymer containing a structural unit derived from a silicone-polyester copolymer (A) having, in one molecule, at least two radically polymerizable unsaturated groups. In the composite particles, the surface of the rubber particles is coated with polyorgano-silsesquioxane and / or silica.

Description

[Technical Field]

[0001] The present invention relates to rubber particles, composite particles, and methods for producing the same. [Background technology]

[0002] Silicone rubber particles with rubber elasticity are used as a stress relaxation agent for resins.For example, in thermosetting resins such as epoxy resins used in packaging electronic and electrical components, rubber particles are blended to prevent the package from cracking even when stress is applied to the package due to the expansion caused by the heat generated by the electrical components.In addition, silicone rubber particles are used in cosmetics to impart a soft feel, smoothness, and other usability and extensibility.

[0003] Proposed silicone rubber particles include composite particles in which silicone rubber particles are coated with polyorganosilsesquioxane resin (Patent Document 1: JP-A-7-196815), and composite particles in which silicone rubber particles are coated with metal oxide particles such as silica (Patent Document 2: JP-A-4-348143). These composite particles are characterized by low coagulation and high dispersibility.

[0004] As particles having good dispersibility in thermoplastic resins and the like, Patent Document 3 (JP 2001-40214 A) describes organic crosslinked rubber particles obtained by crosslinking a liquid composition consisting of an organic compound having an aliphatic saturated bond and a silicon-containing organic compound having silicon-bonded hydrogen atoms through a hydrosilylation reaction.

[0005] Furthermore, Patent Document 4 (JP-A-10-182987) describes a method for preparing silicone-containing rubber particles by copolymerizing, in an emulsion system, a (meth)acrylic acid ester and a diorganopolysiloxane (silicone macromonomer) having a radically polymerizable functional group-containing organic group at one end. These particles are used to impart slip properties to thermoplastic resins. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 7-196815 [Patent Document 2] Japanese Patent Application Publication No. 4-348143 [Patent Document 3] Japanese Patent Application Laid-Open No. 2001-40214 [Patent Document 4] Japanese Patent Application Publication No. 10-182987 Summary of the Invention [Problem to be solved by the invention]

[0007] However, when such silicone particles blended into resins, cosmetics, etc. are discarded into the environment, their extremely small particle size makes recovery extremely difficult, and they are likely to end up in land waters and then end up in the ocean.Since the silicone particles that end up in land waters or the ocean do not have a decomposition structure within their particle structure, they are not decomposed in the environment and are therefore expected to continue to remain in the environment.

[0008] In addition, marine microplastics have the ability to adsorb harmful substances and pathogens in the environment, raising concerns that they could have a negative impact on ecosystems, and efforts to regulate microplastics are underway. Against this backdrop, there is a growing demand for silicone rubber particles that decompose in the environment after use and do not persist as particles (solids). For silicone rubber particles to decompose in the environment, the cross-linked structure of the rubber particles must be broken down (cleaved) in the environment. However, because silicone rubber particles are not structurally degradable, a structure containing degradable functional groups must be introduced into the cross-linked structure.

[0009] Patent Document 3 specifically discloses particles in which polypropylene oxide containing allyl groups at both ends is crosslinked with organopolysiloxane containing silicon-bonded hydrogen atoms, and particles in which hexadiene is crosslinked with dimethylpolysiloxane-methylhydrogenpolysiloxane. These particles are poorly degradable because they do not contain degradable functional groups that are factors for decomposition in the environment. Therefore, an object of the present invention is to provide rubber particles and composite particles containing a polyorganosiloxane structure, which have high degradability, and methods for producing the same. [Means for solving the problem]

[0010] As a result of intensive research to achieve the above object, the present inventors have discovered that rubber particles and composite particles containing a specific polyester structure and a polyorganosiloxane structure can solve the above-mentioned problems, and have thus completed the present invention.

[0011] Therefore, the present invention provides the following rubber particles, composite particles, and methods for producing them. [1] Rubber particles made of a polymer containing structural units derived from a silicone-polyester copolymer (A) having at least two radically polymerizable unsaturated groups in one molecule. [2] The rubber particles according to [1], wherein the silicone-polyester copolymer (A) having at least two radically polymerizable unsaturated groups in one molecule is represented by the general formula (1): [ka] (In formula (1), R 1 are each independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 30 carbon atoms, and each X is independently a polyester structure-containing group represented by general formula (2), (2') or (3), m is a number in the range of 0≦m≦1000, and n is a number in the range of 0≦n≦1000. [ka] (In formulas (2) and (2'), R 2 is a substituted or unsubstituted aliphatic group having 1 to 10 carbon atoms which may have a heteroatom, a is a number satisfying 1≦a≦30, l is a number satisfying 1≦l≦10, and R 3 is a radically polymerizable functional group-containing organic group represented by general formula (4a), (4b), (4c) or (4d). [ka] (In formula (3), R 4 is a substituted or unsubstituted aliphatic group having 1 to 10 carbon atoms which may have a heteroatom, b is a number satisfying 1≦b≦30, k is a number satisfying 1≦k≦10, and R 5 is a radical polymerizable functional group-containing organic group represented by general formula (5a) or (5b). [ka] (In formulas (4a), (4b), (4c), (4d), (5a) and (5b), R 6 are each independently an unsubstituted or substituted hydrocarbon group having 1 to 20 carbon atoms which may have a heteroatom, and R 7 is a hydrogen atom or a hydrocarbon group having 1 to 3 carbon atoms, and Y is a hydrocarbon group having 1 to 40 carbon atoms which may have a heteroatom. [3] The rubber particles according to [1] or [2], wherein the silicone-polyester copolymer (A) having at least two radically polymerizable unsaturated groups in one molecule is represented by general formula (6): [ka] (In formula (6), R 5 are each independently a radical polymerizable functional group-containing organic group represented by formula (5a) or (5b), and R 8 are each independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 30 carbon atoms, o is a number in the range of 0≦o≦10, p is a number in the range of 0≦p≦1000, and q is a number in the range of 1≦q≦30. [ka] [4] The rubber particles according to any one of [1] to [3], which have a spherical particle shape and a volume average particle size of 0.1 to 50 μm. [5] Composite particles, in which the surface of the rubber particle according to any one of [1] to [4] is coated with polyorganosilsesquioxane and / or silica. [6] A method for producing rubber particles according to any one of [1] to [4], comprising the following steps (i) to (iii): (i) A step of adding an aqueous phase component containing a surfactant to an oil phase component containing a silicone-polyester copolymer (A) having at least two radically polymerizable unsaturated groups per molecule, and emulsifying the mixture to obtain an O / W emulsion. (ii) A step of curing component (A) in the oil phase of the emulsion by radical polymerization in the presence of a radical polymerization initiator (B) to obtain an aqueous dispersion of rubber particles (C). (iii) A step of obtaining rubber particles by drying and removing the water, which is the continuous phase, from the aqueous dispersion (C) of rubber particles obtained in step (ii). [7] A method for producing composite particles according to [5], comprising the following steps (i) to (v): (i) A step of adding an aqueous phase component containing a surfactant to an oil phase component containing a silicone-polyester copolymer (A) having at least two radically polymerizable unsaturated groups per molecule, and emulsifying the mixture to obtain an O / W emulsion. (ii) A step of curing component (A) in the oil phase of the emulsion by radical polymerization in the presence of a radical polymerization initiator (B) to obtain an aqueous dispersion of rubber particles (C). (iii') A step of adding an alkaline substance (E) to the aqueous dispersion (C) of rubber particles obtained in the step (ii). (iv) adding the alkaline substance to the aqueous dispersion of rubber particles obtained in step (iii'); The following general formula (7): [ka] (In formula (7), R 9 are each independently an alkyl group having 1 to 6 carbon atoms, and R 10 is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 20 carbon atoms. Organotrialkoxysilanes represented by the formula: General formula (8): Si(OR 11 )4-(8) (In formula (8), R 11 are each independently a monovalent hydrocarbon group having 1 to 6 carbon atoms. Tetraalkoxysilane represented by the formula: and one or more hydrolyzates thereof (F) are added and a condensation reaction is carried out to coat the surfaces of the rubber particles with polyorganosilsesquioxane and / or silica, thereby obtaining an aqueous dispersion of composite particles. (v) A step of obtaining composite particles by drying and removing the water, which is the continuous phase, from the aqueous dispersion of composite particles obtained in step (iv). [Effects of the Invention]

[0012] The rubber particles and composite particles of the present invention contain a polyester structure, which is a degradable functional group, and the crosslinked structure is cleaved in a moisture-containing environment, making them degradable. In particular, particles containing a poly-ε-caprolactone structure, which is a microorganism-recognition skeleton, as the polyester structure in the particles can be expected to be environmentally degradable. Therefore, the rubber particles and composite particles of the present invention are degradable particles and are expected to be environmentally friendly materials. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is an electron microscope photograph of rubber particles obtained in Example 5. [Figure 2] 1 is an electron microscope photograph of the composite particles obtained in Example 6. DETAILED DESCRIPTION OF THE INVENTION

[0014] The present invention will be described in detail below. The rubber particles of the present invention are rubber particles made of a polymer containing structural units derived from a silicone-polyester copolymer (A) having at least two radically polymerizable unsaturated groups in one molecule, and the composite particles of the present invention are particles whose surfaces are coated with polyorganosilsesquioxane and / or silica. In this specification, "a silicone-polyester copolymer (A) having at least two radically polymerizable unsaturated groups in one molecule" may be simply referred to as "component (A)".

[0015] [Rubber particles] The shape of the rubber particles of the present invention is not particularly limited, but is preferably spherical. In the present invention, "spherical" does not only refer to a particle shape that is a perfect sphere, but also includes deformed ellipsoids having an aspect ratio (length of longest axis / length of shortest axis) that is, on average, usually in the range of 1 to 4, preferably 1 to 2, more preferably 1 to 1.6, and even more preferably 1 to 1.4. The particle shape can be confirmed by observation using, for example, an optical microscope or an electron microscope, and the aspect ratio is calculated as the average value by measuring the lengths of the longest axis and the shortest axis of 100 particles selected from a micrograph.

[0016] The volume average particle size of the rubber particles is preferably 0.1 to 50 μm, more preferably 0.5 to 40 μm, and even more preferably 1 to 20 μm. If the volume average particle size of the rubber particles is less than 0.1 μm, the particles will have low fluidity and will be more likely to aggregate. Furthermore, when coating with polyorganosilsesquioxane and / or silica, it will be difficult to achieve a uniform coating. If the volume average particle size of the rubber particles is greater than 50 μm, smoothness will decrease and a rough feeling may occur. In the present invention, the particle size is the volume average particle size measured by an electrical resistance method.

[0017] The rubber that constitutes the rubber particles is preferably tack-free, and its rubber hardness, as measured using an Asker Type C rubber hardness tester as specified in the Society of Rubber Industry Standards of Japan (SRIS), is preferably 5 to 90, more preferably 20 to 85, and even more preferably 40 to 85. If the rubber hardness is less than 5, cohesion increases and dispersibility deteriorates. If the rubber hardness exceeds 90, the soft feel may decrease.

[0018] The rubber particles of the present invention are preferably particles obtained by radically polymerizing a liquid composition containing a silicone-polyester copolymer (A) having at least two radically polymerizable unsaturated groups in one molecule in the presence of a radical polymerization initiator (B).

[0019] The polyester structure of the silicone-polyester copolymer (A) having at least two radically polymerizable unsaturated groups per molecule is preferably an aliphatic polyester, which is considered to be highly degradable. Examples of aliphatic polyesters include poly-ε-caprolactone, poly-β-propiolactone, γ-butyrolactone, polylactic acid, polyhydroxybutyrate, polyglycolic acid, polyethylene adipate, polyhydroxybutyric acid, polyethylene succinate, and polybutylene succinate. In terms of degradability and ease of handling, poly-ε-caprolactone structures are particularly preferred.

[0020] The structure of the silicone-polyester copolymer (A) having at least two radically polymerizable unsaturated groups in one molecule is preferably a structure represented by the following general formula (1): 1 are each independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 30 carbon atoms. X is each independently a polyester structure-containing group represented by general formula (2), (2') or (3), and m and n are numbers 0≦m≦1000 and 0≦n≦1000, respectively. [ka]

[0021] R1 Examples of the alkyl group include alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, decyl, undecyl, dodecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, icosyl, henicosyl, docosyl, tricosyl, tetracosyl, and triacontyl; aryl groups such as phenyl, tolyl, and naphthyl; aralkyl groups such as benzyl and phenethyl; cycloalkyl groups such as cyclopentyl, cyclohexyl, and cycloheptyl; and hydrocarbon groups in which some or all of the hydrogen atoms bonded to carbon atoms of these groups have been substituted with atoms such as halogen atoms (fluorine, chlorine, bromine, and iodine) and / or substituents such as acryloyloxy, methacryloyloxy, epoxy, glycidoxy, and carboxyl.

[0022] X is a polyester structure-containing group represented by the following formula (2), (2') or (3).

[0023] [ka] In formulas (2) and (2'), R 2 R is a substituted or unsubstituted aliphatic group having 1 to 10 carbon atoms, which may contain a heteroatom, and is specifically a residue of a modified silicone containing active hydrogen, which is the starting material for producing component (A), which will be described later. 2 The aliphatic group having 1 to 10 carbon atoms represented by the formula (I) is preferably an aliphatic hydrocarbon group having 1 to 10 carbon atoms, more preferably -(CH2) x - (x is an integer of 1 to 10), and when these aliphatic groups have hetero atoms, examples include groups in which some of the carbon atoms in the aliphatic hydrocarbon group have been substituted with at least one hetero atom such as an oxygen atom or a nitrogen atom. In formulas (2) and (2'), R 3 is a radically polymerizable functional group-containing organic group represented by the following formula (4a), (4b), (4c) or (4d). In addition, in the formulas (2) and (2'), a is 1≦a≦30, preferably 2≦a≦10. In the formulas (2) and (2'), l is 1≦l≦10, preferably 1≦l≦6.

[0024] [ka] In formula (3), R 4 R is a substituted or unsubstituted aliphatic group having 1 to 10 carbon atoms, which may contain a heteroatom, and is specifically a residue of a modified silicone containing active hydrogen, which is the starting material for producing component (A), which will be described later. 4 The aliphatic group having 1 to 10 carbon atoms represented by the formula (I) is preferably an aliphatic hydrocarbon group having 1 to 10 carbon atoms, more preferably -(CH2) x - (x is an integer of 1 to 10), and when these aliphatic groups have hetero atoms, examples include groups in which some carbon atoms of the aliphatic hydrocarbon group are substituted with at least one hetero atom such as an oxygen atom or a nitrogen atom. In formula (3), R 5 is a radically polymerizable functional group-containing organic group represented by the following formula (5a) or (5b). In addition, in formula (3), b is 1≦b≦30, and preferably 2≦b≦10. In formula (3), k is 1≦k≦10, and preferably 1≦k≦6.

[0025] [ka] R in formulas (4a), (4b), (4c), (4d), (5a) and (5b) 6 are each independently an unsubstituted or substituted hydrocarbon group having 1 to 20 carbon atoms which may have a heteroatom, and specifically a residue derived from the polymerizable monomer shown below. Examples of the polymerizable monomer include the hydroxyl group-containing (meth)acrylic acid ester and isocyanate group-containing (meth)acrylic acid ester shown below.

[0026] Examples of hydroxyl group-containing (meth)acrylic acid esters include hydroxyalkyl esters of (meth)acrylic acid having 2 to 8 carbon atoms, such as hydroxyethyl (meth)acrylic acid ester and hydroxypropyl (meth)acrylic acid ester; and carboxy(meth)acrylates, such as carboxyethyl acrylate, (meth)acryloyloxyethyl succinate, and (meth)acryloyloxyethyl phthalate. Examples of the isocyanate group-containing monomer include isocyanate ethyl (meth)acrylate, isocyanate propyl (meth)acrylate, isocyanate butyl (meth)acrylate, and isocyanate hexyl (meth)acrylate. R 6 The hydrocarbon group having 1 to 20 carbon atoms represented by the formula (I) is preferably an aliphatic hydrocarbon group having 1 to 8 carbon atoms, more preferably -(CH2) y - (y is an integer of 1 to 8), and when these aliphatic groups have hetero atoms, examples include groups in which some carbon atoms of the hydrocarbon group are substituted with at least one hetero atom such as an oxygen atom or a nitrogen atom.

[0027] In formulas (4a), (4b), (4c), (4d), (5a) and (5b), R 7 is a hydrogen atom or a hydrocarbon group having 1 to 3 carbon atoms. Examples of the hydrocarbon group having 1 to 3 carbon atoms include a methyl group, an ethyl group, and a propyl group. 7 is preferably a hydrogen atom or a methyl group.

[0028] In formulae (4a), (4b), (4c), (4d), (5a), and (5b), Y represents a hydrocarbon group having 1 to 40 carbon atoms which may have a heteroatom. The aliphatic group is preferably an aliphatic hydrocarbon group having 1 to 30 carbon atoms, and specifically, a residue derived from the following dicarboxylic acid: Examples of dicarboxylic acids include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, tridecanedioic acid, tetradecanedioic acid, hexadecanedioic acid, octadecanedioic acid, eicosanedioic acid, methylsuccinic acid, dimethylmalonic acid, 3-methylglutaric acid, ethylsuccinic acid, isopropylmalonic acid, 1,3-cyclopentanedicarboxylic acid, 1,2-cyclopentanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 1,3- Examples of suitable dicarboxylic acids include aliphatic dicarboxylic acids such as cyclohexanedicarboxylic acid, 1,4-cyclohexanediacetic acid, 1,3-cyclohexanediacetic acid, 1,2-cyclohexanediacetic acid, 1,1-cyclohexanediacetic acid, dimer acid, maleic acid, and fumaric acid; and aromatic dicarboxylic acids such as phthalic acid, terephthalic acid, isophthalic acid, phenylmalonic acid, homophthalic acid, phenylsuccinic acid, β-phenylglutaric acid, α-phenyladipic acid, β-phenyladipic acid, biphenyl-2,2'-dicarboxylic acid, biphenyl-4,4'-dicarboxylic acid, and naphthalenedicarboxylic acid.

[0029] [Method of producing component (A)] Examples of methods for producing component (A) include using a modified silicone containing active hydrogen, such as a carbinol-modified silicone, a carboxy-modified silicone, or an amino-modified silicone, as a starting material. This is done by ring-opening polymerization of cyclic ε-caprolactone to obtain a poly-ε-caprolactone-modified silicone. To this is then introduced a polymerizable monomer having a radically polymerizable unsaturated group via an ester bond, ether bond, urethane bond, urea bond, or amide bond. The polymerizable monomer having a radically polymerizable unsaturated group is preferably a hydroxyalkyl ester of (meth)acrylic acid, due to its ease of availability, cost, reaction stability, and excellent reactivity. Reaction conditions for this production method include, but are not limited to, the following: A poly-ε-caprolactone-modified silicone is obtained by adding, for example, 4 equivalents of ε-caprolactone to 1 equivalent of a modified silicone containing active hydrogen, such as a carbinol-modified silicone, and reacting at 110°C for 2 hours in the presence of a known ring-opening polymerization catalyst. One mole of carboxyl groups from the resulting poly-ε-caprolactone-modified silicone is mixed with 1.0 to 1.25 moles of hydroxyl groups from a hydroxyalkyl ester of (meth)acrylic acid having 2 to 8 carbon atoms and 0.1 to 5.0 moles of an esterification catalyst, and the mixture is stirred at 5 to 150°C for 10 to 30 minutes (the temperature is selected depending on the catalyst used). Optionally, 1.0 to 1.25 moles of a dehydration condensation agent is added, and the mixture is reacted at 15 to 150°C for 5 to 30 hours. After the reaction, the reaction product is filtered, washed with water, and / or subjected to an adsorption process to remove by-products, and the solvent is distilled off to obtain component (A).

[0030] When a carbinol-modified silicone is used as the starting material, examples of component (A) include those shown in the following formulas (9a) to (9c) (only one end is shown due to the symmetrical structure). [ka]

[0031] In formulas (9a) to (9c), R 8 are each independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 30 carbon atoms. Specific examples of the monovalent hydrocarbon group having 1 to 30 carbon atoms include R1 Examples of Y are the same as those in formula (4d), preferably a methyl group. Y is a hydrocarbon group having 1 to 40 carbon atoms which may have a heteroatom, and specific examples are the same as those in formula (4d) above. p and q are 0≦p≦1000 and 1≦q≦30, respectively, and preferably 1≦p≦500 and 2≦q≦10.

[0032] When a carboxy-modified silicone is used as the starting material, the component (A) may be, for example, one of the following formula (10) (only one end is shown due to the symmetrical structure): [ka]

[0033] In formula (10), R 8 are each independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 30 carbon atoms. Specific examples of the monovalent hydrocarbon group having 1 to 30 carbon atoms include R 1 Examples of o, p, and q are the same as those shown in the above, and a methyl group is preferred. o, p, and q are each 0≦o≦10, 0≦p≦1000, and 1≦q≦30, and preferably 1≦o≦10, 1≦p≦500, and 2≦q≦10.

[0034] When an amino-modified silicone is used as the starting material, examples of the component (A) include those shown in the following formulas (11a) to (11f) (only one end is shown due to the symmetrical structure). [ka]

[0035] In formulas (11a) to (11f), R 8 are each independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 30 carbon atoms. Specific examples of the monovalent hydrocarbon group having 1 to 30 carbon atoms include R 1Examples of Y are the same as those in formula (4d), preferably a methyl group. Y is a hydrocarbon group having 1 to 40 carbon atoms which may have a heteroatom, and specific examples are the same as those in formula (4d) above. p and q are 0≦p≦1000, 1≦q≦30, preferably 1≦p≦500, 2≦q≦10.

[0036] Another method for producing component (A) is to subject a poly-ε-caprolactone-modified (meth)acrylate represented by the following formula (12) to an esterification reaction with the above-mentioned carboxy-modified silicone. Commercially available poly-ε-caprolactone-modified (meth)acrylates include PLACCEL FA2D, PLACCEL FA4DT, PLACCEL FA10L, PLACCEL FM2D, and PLACCEL FM4 (all manufactured by Daicel Corporation). [ka] (r is a number between 1 and 10.)

[0037] Examples of methods for producing component (A) using this poly-ε-caprolactone-modified (meth)acrylate include, but are not limited to, the following. 1 mole of carboxy groups from the carboxy-modified silicone component is mixed with 1.0 to 1.25 moles of hydroxyl groups from the poly-ε-caprolactone-modified (meth)acrylate (formula (12) above) and 0.1 to 5.0 moles of an esterification catalyst, and the mixture is stirred at 5 to 150°C for 10 to 30 minutes (the temperature is selected depending on the catalyst used). Optionally, 1.0 to 1.25 moles of a dehydration condensation agent is added, and the mixture is reacted at 15 to 150°C for 5 to 30 hours. After the reaction, the reaction product is filtered, washed with water, and / or subjected to an adsorption step to remove by-products, and the solvent is then distilled off to obtain component (A).

[0038] Any esterification catalyst can be used in the esterification reaction without any particular limitation. Examples of the esterification catalyst include alcoholates, carboxylates, or chelate compounds of titanium, zirconium, tin, aluminum, and zinc, Lewis acid catalysts such as boron trifluoride and boron trifluoride etherate, acid catalysts such as hydrochloric acid, sulfuric acid, hydrogen bromide, acetic acid, trifluoroacetic acid, methanesulfonic acid, and p-toluenesulfonic acid, and amine catalysts such as pentamethyldiethylenetriamine (PMDETA), trimethyltriazacyclononane (TMTACN), triethylamine (TEA), 4-(N,N-dimethylamino)pyridine (DMAP), 1,4-diazabicyclo(2,2,2)octane (DABCO), and tetramethylethylenediamine (TMEDA). Among these, amine catalysts are preferred from the standpoint of the stability of the product obtained by the esterification reaction and economical aspects.

[0039] When using an amine catalyst, a dehydration condensation agent may be added to improve the reaction efficiency. Known dehydration condensation agents can be used, such as 1,1'-carbonyldiimidazole (CDI), N,N'-dicyclohexylcarbodiimide (DCC), N,N'-diisopropylcarbodiimide (DIC), 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC), 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide hydrochloride (EDC·HCl), and 1-[bis(dimethylamino)methylene]-1H-1,2,3-triazolo[4,5-b]pyridinium 3-oxide hexafluorophosphate (HATU).

[0040] The reaction product may be filtered, washed with water, and / or subjected to an adsorption step to remove by-products, and the solvent may be distilled off in a conventional manner, and a hydrophobic organic solvent may be used in the filtration step to adjust the viscosity of the reaction product. The hydrophobic organic solvent is not particularly limited, but toluene, hexane, and ethyl acetate are preferred from the viewpoint of solubility, etc. The adsorption step is a step for adsorbing, dehydrating, decolorizing, and deodorizing the hydrochloride salt of the base that cannot be completely removed in the water washing step. Any known adsorbent can be used, and a combination of several adsorbents may be used. Preferable adsorbents include desiccants such as magnesium sulfate and sodium sulfate, activated carbon, and Kyoward series (manufactured by Kyowa Chemical Industry Co., Ltd.).

[0041] Component (A) is preferably liquid, and has a weight average molecular weight measured by gel permeation chromatography (GPC) of preferably 200 to 10,000, more preferably 300 to 5,000. If the molecular weight is less than 200, decomposition may be impaired, and if it is more than 10,000, preparation of rubber particles may be difficult. The silicone-polyester copolymer (A) having at least two radically polymerizable unsaturated groups in one molecule is preferably one represented by general formula (6) because of ease of production. [ka] In formula (6), R 5 R are each independently an organic group containing a radical polymerizable functional group represented by the formula (5a) or (5b). 8 are each independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 30 carbon atoms. Specific examples of the monovalent hydrocarbon group having 1 to 30 carbon atoms include R 1 Examples of o, p, and q are the same as those shown in the above, and a methyl group is preferred. o, p, and q are each within the ranges of 0≦o≦10, 0≦p≦1000, and 1≦q≦30, preferably 1≦o≦10, 1≦p≦500, and 2≦q≦10.

[0042] [Method of manufacturing rubber particles] The rubber particles of the present invention can be produced, for example, by a method including the following steps (i) to (iii). (i) An O / W emulsion is prepared by adding an aqueous phase component containing a surfactant to an oil phase component containing a silicone-polyester copolymer (A) having at least two radically polymerizable unsaturated groups in one molecule and stirring the mixture. (ii) Component (A) is cured in the oil phase of the O / W emulsion by radical polymerization in the presence of a radical polymerization initiator (B), to obtain an aqueous dispersion of rubber particles (C). (iii) The water, which is the continuous phase of the aqueous dispersion (C) of rubber particles obtained in step (ii), is dried and removed to obtain rubber particles.

[0043] First, each component used in steps (i) to (iii) will be described. A silicone-polyester copolymer (A) having at least two radically polymerizable unsaturated groups in one molecule. As the silicone-polyester copolymer (A) having at least two radically polymerizable unsaturated groups in one molecule, specifically, the same as those mentioned above can be used.

[0044] Surfactants The surfactant used in step (i) is not particularly limited and may be a nonionic surfactant, anionic surfactant, cationic surfactant, or amphoteric surfactant, which may be used alone or in appropriate combination of two or more.

[0045] Examples of the nonionic surfactant used herein include polyoxyethylene alkyl ethers, polyoxyethylene polyoxypropylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyethylene glycol fatty acid esters, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene sorbit fatty acid esters, glycerin fatty acid esters, polyoxyethylene glycerin fatty acid esters, polyglycerin fatty acid esters, propylene glycol fatty acid esters, polyoxyethylene castor oil, polyoxyethylene hydrogenated castor oil, polyoxyethylene hydrogenated castor oil fatty acid esters, polyoxyethylene alkylamines, polyoxyethylene fatty acid amides, polyoxyethylene-modified organopolysiloxanes, and polyoxyethylene polyoxypropylene-modified organopolysiloxanes.

[0046] Examples of anionic surfactants include alkyl sulfate salts such as sodium lauryl sulfate, polyoxyethylene alkyl ether sulfate salts, polyoxyethylene alkyl phenyl ether sulfate salts, alkyl benzene sulfonates, polyoxyethylene alkyl phenyl ether sulfonates, alkyl diphenyl ether disulfonates, alkanesulfonates, N-acyltaurate salts, dialkyl sulfosuccinates, monoalkyl sulfosuccinates, polyoxyethylene alkyl ether sulfosuccinates, fatty acid salts, polyoxyethylene alkyl ether carboxylate salts, N-acylamino acid salts, monoalkyl phosphate salts, dialkyl phosphate salts, and polyoxyethylene alkyl ether phosphate salts.

[0047] Examples of cationic surfactants include alkyltrimethylammonium salts, dialkyldimethylammonium salts, polyoxyethylenealkyldimethylammonium salts, dipolyoxyethylenealkylmethylammonium salts, tripolyoxyethylenealkylammonium salts, alkylbenzyldimethylammonium salts, alkylpyridinium salts, monoalkylamine salts, and monoalkylamidoamine salts.

[0048] Examples of the amphoteric surfactant include alkyldimethylamine oxide, alkyldimethylcarboxybetaine, alkylamidopropyldimethylcarboxybetaine, alkylhydroxysulfobetaine, and alkylcarboxymethylhydroxyethylimidazolinium betaine.

[0049] As the surfactant, a nonionic surfactant is preferred, since a small amount of the surfactant can emulsify the oil phase components and form fine particles.

[0050] The amount of surfactant added is preferably 0.01 to 20 parts by mass, more preferably 0.05 to 10 parts by mass, per 100 parts by mass of emulsion. If the amount is less than 0.01 part by mass, problems such as failure to emulsify or failure to form fine particles may occur. If the amount is more than 20 parts by mass, the particle size cannot be reduced, and the dispersibility of the rubber particles cannot be improved. Furthermore, if the amount is more than 20 parts by mass, it becomes difficult to coat the rubber particles with polyorganosilsesquioxane and / or silica in the composite particle production process described below.

[0051] The content of the silicone-polyester copolymer (A) having at least two radically polymerizable unsaturated groups per molecule in this emulsion is preferably 1 to 80 parts by mass, more preferably 10 to 60 parts by mass, per 100 parts by mass of emulsion. If it is less than 1 part by mass, it will be inefficient, and if it is more than 80 parts by mass, it will be difficult to obtain an aqueous dispersion of rubber particles.

[0052] Radical polymerization initiator (B) When radically polymerizing component (A), a conventional radical polymerization initiator can be used as the radical polymerization initiator for component (B), and depending on the polymerization method, a thermal polymerization initiator, photopolymerization initiator, or redox polymerization initiator can be used. However, even with photopolymerization, a certain amount of heat is generated by ultraviolet irradiation, etc., and also as the polymerization reaction, which is an exothermic reaction, progresses. Therefore, even when using photopolymerization, a thermal polymerization initiator can be additionally used.

[0053] Thermal polymerization initiators include 2,2'-azobis-(2-methylbutyronitrile), 2,2'-azobis-(2,4-dimethylvaleronitrile), 2,2'-azobisisobutyronitrile, t-butylperoxy-2-ethylhexanoate, 2,2-azobis-(2-amidinopropane) dihydrochloride, 2,2-azobis-(N,N-dimethylene)isobutylamidine dihydrochloride, 2-(carbamoylazo azo-based compounds such as isobutyronitrile, 2,2-azobis[2-(2-imidazolin-2-yl)propane]dihydrochloride, and 4,4-azobis-(4-cyanovaleric acid); persulfates such as sodium persulfate, potassium persulfate, and ammonium persulfate; peroxides such as hydrogen peroxide, t-butyl peroxide, and methyl ethyl ketone peroxide; and perchlorates such as potassium perchlorate and sodium perchlorate.

[0054] Photopolymerization initiators include diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, and benzyl dimethyl Ke Tar, acetophenone derivatives such as 4-(2-hydroxyethoxy)phenyl-(2-hydroxy)-2-propyl ketone, 1-hydroxycyclohexyl phenyl ketone; benzoin methyl ether, benzoin hmm Examples include benzoin alkyl ethers such as ethyl ether, benzoin isopropyl ether, and benzoin isobutyl ether; benzophenone derivatives such as methyl o-benzoylbenzoate, 4-phenylbenzophenone, 4-benzoyl-4'-methyl-diphenyl sulfide, and (4-benzoylbenzyl)trimethylammonium chloride; thioxanthone compounds; acylphosphine oxide derivatives such as bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide and diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide; and azo compounds such as 2-hydroxymethylpropionitrile and 2,2'-{azobis(2-methyl-N-[1,1'-bis(hydroxymethyl)-2-hydroxyethyl)propionamide].

[0055] Examples of redox polymerization initiators include a combination of the above-mentioned persulfates or peroxides with reducing compounds such as sulfites, L-ascorbic acid, and ferrous salts. A thermal polymerization initiator and a photopolymerization initiator can also be used in combination. As the polymerization method for component (A), thermal polymerization or photopolymerization is preferred for the reason of emulsion stability, which will be described later.

[0056] The amount of component (B) added is preferably 0.1 to 10 mass %, and more preferably 0.5 to 5 mass %, based on the total amount of component (A).

[0057] Process (i) In step (i), an O / W emulsion is prepared by adding an aqueous phase component containing a surfactant to an oil phase component containing component (A) in the above-mentioned ratio and stirring. The surfactant may be added to the oil phase component in the form of a solution in which it has been dissolved in water in advance, or water and the surfactant may be added separately to the oil phase component. Furthermore, the radical polymerization initiator of component (B) may be blended with the oil phase component in step (i), or may be added to the O / W emulsion obtained in step (i) before step (ii) described below. To carry out the emulsification, a known emulsifying disperser may be used. Common emulsifying dispersers include high-speed rotary shear type agitators such as a homomixer, high-speed centrifugal radiation type agitators such as a homodisper, high-pressure jet type emulsifying dispersers such as a homogenizer, colloid mills, ultrasonic emulsifiers, etc.

[0058] Process (ii) In step (ii), component (A) is radically polymerized in the O / W emulsion obtained in step (i) in the presence of a radical polymerization initiator (B) to obtain an aqueous dispersion of rubber particles (C). When component (B) is not blended into the emulsion in step (i), the above-mentioned amount of component (B) is blended into the emulsion before subjecting it to step (ii). Component (A) in the oil phase of the emulsion thus prepared can be cured by the polymerization method described above to obtain a dispersion of rubber particles. For example, polymerization of the silicone-polyester copolymer can be carried out through redox polymerization, which involves polymerization at a temperature of 30 to 70°C for 2 to 24 hours, thermal polymerization, which involves polymerization at a temperature of 30 to 80°C for 10 to 24 hours, or photopolymerization (UV). In the case of photopolymerization, the light source and wavelength range used for UV irradiation can be those well known in the art. This method can produce an aqueous dispersion of rubber particles (C) with a volume average particle size of 0.1 to 50 μm.

[0059] Process (iii) In step (iii), rubber particles can be obtained by drying and removing the water, which is the continuous phase, from the resulting aqueous dispersion (C) of rubber particles. Drying and removing water from the aqueous dispersion (C) of rubber particles can be carried out, for example, by heating under normal or reduced pressure. Specific examples include a method of removing water by leaving the dispersion to stand under heating, a method of removing water while stirring and fluidizing the dispersion under heating, a method of spraying and dispersing the dispersion in a hot air stream using a spray dryer, and a method using a fluidized heat medium. As a pretreatment for this operation, the dispersion may be concentrated by methods such as thermal dehydration, filtration separation, and decantation, and, if necessary, the dispersion may be washed with water or alcohol.

[0060] [Composite particles] The shape of the polyorganosilsesquioxane and / or silica coating the surface of the composite particles is not particularly limited, but in the manufacturing method described below, it will be granular. The particle size is preferably small, specifically 500 nm or less. The organosilsesquioxane and / or silica may cover part or all of the surface of the rubber particles, but it is preferable that they cover the entire surface of the rubber particles with almost no gaps. The coating state, shape, and particle size can be confirmed by observing the particle surface with an electron microscope.

[0061] [Method of manufacturing composite particles] The composite particles of the present invention can be produced, for example, by a method comprising the following steps (i) to (v). (i) An O / W emulsion is prepared by adding an aqueous phase component containing a surfactant to an oil phase component containing a silicone-polyester copolymer (A) having at least two radically polymerizable unsaturated groups in one molecule and emulsifying the mixture. (ii) The component (A) in the oil phase of the O / W emulsion is cured by radical polymerization in the presence of a radical polymerization initiator (B), to obtain an aqueous dispersion of rubber particles (C). (iii') An alkaline substance (E) is added to the aqueous dispersion (C) of rubber particles obtained in step (ii). (iv) To the aqueous dispersion of rubber particles to which the alkaline substance obtained in step (iii') has been added, one or more (F) selected from organotrialkoxysilanes represented by the following general formula (7), tetraalkoxysilanes represented by the following general formula (8), and hydrolysates thereof are added, and a condensation reaction is carried out to coat the surfaces of the rubber particles with polyorganosilsesquioxane and / or silica, thereby obtaining an aqueous dispersion of composite particles. (v) The water, which is the continuous phase, is dried and removed from the aqueous dispersion of composite particles obtained in step (iv) to obtain composite particles.

[0062] The steps (i) and (ii) of the method for producing composite particles are the same as the steps (i) and (ii) of the method for producing rubber particles. In step (iii'), water (D) may be added as an optional component, and in step (iv), one or more compounds selected from a cationic surfactant and a cationic water-soluble polymer compound may be further blended.

[0063] First, each component used in steps (i) to (v) will be described. ·(D)Water The water that can be added in step (iii') is not particularly limited, and purified water or the like can be used, including the water in the aqueous dispersion of rubber particles obtained in step (ii) above and water added as needed. The amount of water in component (D) is preferably blended so that the rubber particle concentration in the aqueous dispersion of rubber particles obtained in step (iii') is 1% by mass to 60% by mass.

[0064] (E) Alkaline substances The alkaline substance added in step (iii') may be any substance that acts as a catalyst for the hydrolysis and condensation reaction of component (F), which will be described later. Specific examples of the alkaline substance that can be used include alkali metal hydroxides such as potassium hydroxide, sodium hydroxide, and lithium hydroxide; alkaline earth metal hydroxides such as calcium hydroxide and barium hydroxide; alkali metal carbonates such as potassium carbonate and sodium carbonate; amines such as ammonia, monomethylamine, and dimethylamine; and quaternary ammonium hydroxides such as tetramethylammonium hydroxide. Ammonia is more preferred because it has excellent water solubility and catalytic activity and is easily removed by evaporation, and a commercially available aqueous ammonia solution may be used for this purpose.

[0065] The amount of component (E) added is preferably an amount such that the pH of the aqueous dispersion obtained in step (iii') is in the range of 9.0 to 13.0 at 25° C., more preferably 10.0 to 12.5. If the pH is lower than 10.0, the hydrolysis and condensation reaction of component (F), which will be described later, does not proceed sufficiently. If the pH is higher than 13.0, the hydrolysis rate of component (F), which will be described later, increases, and the hydrolysis and condensation reaction occurs in areas other than the surfaces of the rubber particles, which may result in reduced coverage.

[0066] (F) at least one selected from organotrialkoxysilanes represented by general formula (7), tetraalkoxysilanes represented by general formula (8), and hydrolysates thereof The component (F) added in step (iv) is at least one selected from organotrialkoxysilanes represented by general formula (7), tetraalkoxysilanes represented by general formula (8), and hydrolysates thereof. [ka] In formula (7), R 9 are each independently an alkyl group having 1 to 6 carbon atoms, and R 10 is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 20 carbon atoms. Si(OR 11 )4-(8) In formula (8), R 11 are each independently a monovalent hydrocarbon group having 1 to 6 carbon atoms. The polyorganosilsesquioxane and / or silica that coats the rubber particles is formed by adding to the rubber particles one or more compounds selected from the group consisting of organotrialkoxysilanes represented by the general formula (7), tetraalkoxysilanes represented by the general formula (8), and hydrolysates thereof.

[0067] In formula (7), R 9 is an alkyl group having 1 to 6 carbon atoms, such as a methyl group, an ethyl group, a propyl group, or a butyl group. 10 is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 20 carbon atoms. Examples of unsubstituted or substituted monovalent hydrocarbon groups having 1 to 20 carbon atoms include alkyl groups such as methyl, ethyl, propyl, and butyl; aryl groups such as phenyl and tolyl; alkenyl groups such as vinyl and allyl; aralkyl groups such as β-phenylethyl and β-phenylpropyl; monovalent halogenated hydrocarbon groups such as chloromethyl and 3,3,3-trifluoropropyl; and groups in which these monovalent hydrocarbon groups are substituted with an epoxy group, amino group, mercapto group, acryloxy group, methacryloxy group, or the like.

[0068] In formula (8), R 11 is a monovalent hydrocarbon group having 1 to 6 carbon atoms, specifically R 9 The same can be exemplified.

[0069] Specific examples of organotrialkoxysilanes and tetraalkoxysilanes used for coating include methyltrimethoxysilane, methyltriethoxysilane, methyltripropoxysilane, methyltributoxysilane, ethyltrimethoxysilane, propyltrimethoxysilane, butyltrimethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, vinyltrimethoxysilane, phenyltrimethoxysilane, γ-methacrylic propyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, 3,3,3-trifluoropropyltrimethoxysilane, 3,3,4,4,5,5,6,6,6-nonafluorohexyltrimethoxysilane, 3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-heptadecafluorodecyltrimethoxysilane, tetramethoxysilane, and tetraethoxysilane.

[0070] The amount of component (F) added is preferably 0.5 to 200 parts by mass, and more preferably 1 to 50 parts by mass, per 100 parts by mass of the rubber particles in component (C).

[0071] (G) one or more selected from cationic surfactants and cationic water-soluble polymer compounds In step (iv), one or more components selected from cationic surfactants and cationic water-soluble polymer compounds may be blended as component (G) together with the component (F). Component (G) promotes the condensation reaction of the hydrolyzed component (F) to produce polyorganosilsesquioxane and / or silica, and also has the effect of adsorbing the produced polyorganosilsesquioxane and / or silica onto the surface of the rubber particles.

[0072] Examples of cationic surfactants include alkyltrimethylammonium salts, dialkyldimethylammonium salts, polyoxyethylene alkyldimethylammonium salts, dipolyoxyethylene alkylmethylammonium salts, tripolyoxyethylene alkylammonium salts, alkylbenzyldimethylammonium salts, alkylpyridinium salts, monoalkylamine salts, monoalkylamidoamine salts, etc. Among these, alkyltrimethylammonium salts are preferred, and lauryltrimethylammonium salts and cetyltrimethylammonium salts are more preferred.

[0073] Examples of cationic water-soluble polymer compounds include polymers of dimethyldiallylammonium chloride, polymers of vinylimidazoline, polymers of methylvinylimidazolium chloride, polymers of ethyl acrylate trimethylammonium chloride, polymers of ethyl methacrylate trimethylammonium chloride, polymers of acrylamidopropyl trimethylammonium chloride, polymers of methacrylamidopropyl trimethylammonium chloride, epichlorohydrin / dimethylamine polymers, polymers of ethyleneimine, quaternized polymers of ethyleneimine, polymers of allylamine hydrochloride, polylysine, cationic starch, cationized cellulose, chitosan, and derivatives thereof obtained by copolymerizing monomers having nonionic or anionic groups with these, etc. Among these, polymers of dimethyldiallylammonium chloride are preferred.

[0074] The amount of component (G) added is preferably 0.001 to 2 parts by mass, more preferably 0.005 to 1 part by mass, per 100 parts by mass of water in the aqueous dispersion obtained in step (iii'). If the amount added is more than 2 parts by mass, there is a risk that polyorganosilsesquioxane and / or silica will not be coated on the surfaces of the rubber particles.

[0075] Process (iii') In step (iii'), the alkaline substance (E) is added in the amount described above to the aqueous dispersion (C) of rubber particles obtained in step (ii). The method for adding component (E) is not particularly limited, and component (E) may be added by mixing it into the aqueous dispersion (C) of rubber particles obtained in step (ii) so that the component (E) is uniformly dissolved.

[0076] Process (iv) In step (iv), one or more of the aforementioned (F) organotrialkoxysilanes, tetraalkoxysilanes, and their hydrolyzates are added to the aqueous rubber particle dispersion obtained in step (iii') to which the alkaline substance has been added. The organotrialkoxysilanes and / or tetraalkoxysilanes are hydrolyzed and condensed to coat the surfaces of the rubber particles with polyorganosilsesquioxane and / or silica. Specifically, one or more of the (F) organotrialkoxysilanes, tetraalkoxysilanes, and their hydrolyzates are added to an aqueous solution containing (C) the aqueous rubber particle dispersion and (D) water (optional), (E) an alkaline substance, and (G) one or more (optional) selected from cationic surfactants and cationic water-soluble polymers, followed by hydrolysis and condensation. The condensate, i.e., polyorganosilsesquioxane and / or silica, coats the surfaces of the rubber particles, forming composite particles.

[0077] The addition of the organotrialkoxysilane, tetraalkoxysilane, and hydrolysates thereof as component (F) is preferably carried out under stirring using a conventional stirrer such as a propeller blade, flat blade, etc. The organotrialkoxysilane, tetraalkoxysilane, and hydrolysates thereof are preferably added over a period of time, with the dropwise addition time preferably being 1 minute to 6 hours, more preferably 10 minutes to 3 hours.

[0078] The temperature in the system during the dropping is preferably 0 to 60° C., more preferably 0 to 40° C. At a temperature in this range, the surfaces of the rubber particles can be coated with polyorganosilsesquioxane and / or silica.

[0079] Process (v) After the hydrolysis and condensation reaction in step (iv) is completed, the composite particles can be obtained by drying and removing the water, which is the continuous phase, from the aqueous dispersion of the composite particles of the present invention obtained. Water removal can be carried out, for example, by heating the aqueous dispersion after the reaction under normal pressure or reduced pressure. Specific examples include a method of removing water by leaving the dispersion to stand under heating, a method of removing water while stirring and fluidizing the dispersion under heating, a method of spraying and dispersing the dispersion in a hot air stream using a spray dryer, and a method using a fluidized heat medium. As a pretreatment for this operation, the dispersion can be concentrated by methods such as thermal dehydration, filtration separation, centrifugation, and decantation, and, if necessary, the dispersion can be washed with water or alcohol.

[0080] If the product obtained by drying and removing water from the aqueous dispersion after the reaction is aggregated, it can be crushed using a grinder such as a jet mill, ball mill, or hammer mill to obtain composite particles in which the surfaces of the rubber particles are coated with polyorganosilsesquioxane and / or silica. [Example]

[0081] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples. In the examples, the kinematic viscosity is a value measured at 25°C, and the "%" indicating concentration and content indicates "% by mass." The penetration of the cured rubber was measured in accordance with the Standards and Regulations of the Society of Rubber Industry, Japan (SRIS). The molecular weight of component (A) is a weight-average molecular weight measured by GPC under the following conditions using polystyrene as the standard. [Measurement conditions] Developing solvent: tetrahydrofuran (THF) Flow rate: 0.60mL / min Detector: Refractive index detector (RI) Column: TSK Guardcolumn SuperH-H TSKgel SuperHM-N TSKgel SuperH2500 (All manufactured by Tosoh Corporation) Column temperature: 40℃ Sample injection volume: 50 μL (0.5% by mass THF solution) [Example]

[0082] [Synthesis of poly-ε-caprolactone acrylate modified silicone 1] A 1-liter glass flask equipped with a stirrer, a dropping funnel, a thermometer, and a condenser was charged with 300 g of carboxy-modified silicone (molecular weight 1200, carboxy equivalent: 0.187 mol / 100 g), 202.75 g of poly-ε-caprolactone monoacrylate (trade name: Placcel FA2D, manufactured by Daicel Corporation, molecular weight 344, hydroxyl value: 0.291 mol / 100 g), 200 g of dehydrated toluene, and 6.85 g of 4-dimethylaminopyridine (DMAP). The mixture was mixed in an ice bath for 10 minutes, and a solution of 168.9 g of N,N′-dicyclohexylcarbodiimide (DCC) dissolved in 173.63 g of dehydrated toluene was added dropwise to the flask using the dropping funnel. After the dropwise addition, the mixture was aged at room temperature (20°C ± 10°C, the same applies hereinafter) for 20 hours. After aging, the mixture was washed with 200 g of toluene and 300 g of 0.5 M hydrochloric acid, followed by sequential washing with aqueous sodium bicarbonate and 10% saline. After washing with water, 10 g each of magnesium sulfate, activated carbon, and Kyoward 700 (Kyowa Chemical Industry Co., Ltd.) were added, and the mixture was shaken for 2 hours. After shaking, the magnesium sulfate, activated carbon, and Kyoward 700 were removed by pressure filtration, 0.09 g of dibutylhydroxytoluene (BHT) was added as a polymerization inhibitor, and the solvent was distilled off at 65°C and 10 mmHg or less to obtain poly-ε-caprolactone acrylate-modified silicone 1 (formula (13) below, weight-average molecular weight: 1672). [ka]

[0083] [Preparation of rubber particles] 120 g of the synthesized poly-ε-caprolactone acrylate-modified silicone 1 and 0.9 g of the radical polymerization initiator 2,2'-azobis-(2,4-dimethylvaleronitrile) were placed in a 500 mL container and stirred at 1500 rpm using a homomixer to dissolve. Next, 1.8 g of polyoxyethylene lauryl ether and 42 g of water were added, and the mixture was stirred at 5000 rpm using a homomixer. An O / W emulsion was formed, and thickening was observed. Stirring was continued for another 10 minutes. The mixture was then diluted with 77.1 g of water while stirring at 1500 rpm, yielding a white emulsion.

[0084] This emulsion was transferred to a 1 L glass flask equipped with an anchor-type stirring blade stirrer, and 158.2 g of water was added. The temperature was adjusted to 52°C and the mixture was stirred for 20 hours to obtain an aqueous dispersion of rubber particles.

[0085] The shape of the rubber particles in the resulting aqueous dispersion was observed under an optical microscope and found to be spherical. The volume average particle size was measured using an electrical resistance particle size distribution analyzer (Multisizer 3, manufactured by Beckman Coulter, Inc.) and found to be 8.3 μm.

[0086] The water in the obtained aqueous dispersion of rubber particles was dried using a spray dryer set at an inlet temperature of 150°C and an outlet temperature of 80°C, yielding white to pale yellow powdery rubber particles.

[0087] The hardness of the rubber constituting the rubber particles was measured as follows. Poly-ε-caprolactone acrylate-modified silicone 1 and 2,2'-azobis-(2,4-dimethylvaleronitrile) were mixed in the above ratio and poured into an aluminum petri dish to a thickness of 10 mm. After leaving at 70°C for 30 minutes, a flat rubber with no stickiness (tack) was obtained. The hardness of this flat rubber was measured using an Asker C hardness tester and was found to be 71. [Example]

[0088] [Preparation of composite particles] An aqueous dispersion of rubber particles was obtained in the same manner as in Example 1. 357 g of the obtained aqueous dispersion of rubber particles was transferred to a 1 L glass flask equipped with a stirrer using an anchor-shaped stirring blade, and 489.6 g of water, 15.92 g of 28% aqueous ammonia solution, and 0.344 g of 40% aqueous dimethyldiallylammonium chloride polymer solution (trade name: ME Polymer H40W, manufactured by Toho Chemical Industry Co., Ltd.) were added. The pH of the solution at this time was 11.3. After adjusting the temperature to 5 to 10°C, 15.28 g of methyltrimethoxysilane (an amount such that the amount of polymethylsilsesquioxane after hydrolysis and condensation reaction would be 8.7 parts by mass per 100 parts by mass of rubber particles) was added dropwise over 20 minutes. The liquid temperature was maintained at 5 to 10°C during this period, and stirring was continued for another hour. Next, the solution was heated to 55 to 60°C, and stirring was continued for 1 hour while maintaining that temperature, completing the hydrolysis and condensation reaction of methyltrimethoxysilane.

[0089] The liquid obtained by hydrolysis and condensation reaction of methyltrimethoxysilane in an aqueous dispersion of rubber particles was dehydrated to approximately 30% water using a pressure filter. The dehydrated product was transferred to a 2 L glass flask equipped with an anchor-type impeller stirrer, 1000 g of water was added, and the mixture was stirred for 30 minutes, after which it was dehydrated using a pressure filter. The dehydrated product was again transferred to a 2 L glass flask equipped with an anchor-type impeller stirrer, 1000 g of water was added, and the mixture was stirred for 30 minutes, after which it was dehydrated using a pressure filter. The dehydrated product was dried at 105°C in a hot air fluidized dryer, and the dried product was crushed using a jet mill to obtain flowable particles.

[0090] When the obtained particles were observed under an electron microscope, it was confirmed that the rubber particle surfaces were entirely coated with granular polyorganosilsesquioxane (polyorganosilsesquioxane-coated rubber particles).

[0091] The obtained composite particles were dispersed in water using a surfactant, and the particle size distribution was measured using an electrical resistance particle size distribution analyzer (Multisizer 3, manufactured by Beckman Coulter, Inc.). The particle size distribution was found to be the same as that of the water dispersion of the rubber particles, and the volume average particle size was 8 μm. Comparative Example 1

[0092] [Making flat silicone rubber] The kinematic viscosity shown by the following formula (14) is 600 mm 2 25 g of methylvinylpolysiloxane having a kinematic viscosity of 27 mm / s and 2 1 g of methylhydrogenpolysiloxane (amount equivalent to 1.1 hydrosilyl groups per vinyl group) was placed in a 100 mL container and stirred to dissolve. Next, 0.06 g of an isododecane solution of a platinum-vinyl group-containing disiloxane complex (platinum content 0.5%) was added and stirred, and the mixture was poured into an aluminum dish to a thickness of 10 mm and left at 40°C for 2 days to produce a flat rubber with a rubber composition of silicone particles. The hardness of the rubber was measured in the same manner as in Example 1, and was found to be 60. [ka] [Example]

[0093] [Evaluation of rubber hydrolysis (measurement of flat rubber hardness over time)] The hydrolysis resistance of a flat rubber (rubber hardness: 71) composed of poly-ε-caprolactone acrylate-modified silicone 1 obtained in Example 1 above, and a flat rubber (rubber hardness: 60) composed of methylvinylpolysiloxane shown in formula (14) above and methylhydrogenpolysiloxane shown in formula (15) above obtained in Comparative Example 1 was evaluated by the following method. The two flat rubber samples were placed in a thermo-hygrostat (IW222 model, manufactured by Yamato Scientific Co., Ltd.) at a temperature of 70°C and a humidity of 90%, and the change in rubber hardness was measured daily. In addition, the flat rubber (rubber hardness: 71) obtained in Example 1 was left standing in a dryer (DNE601 type, manufactured by Yamato Scientific Co., Ltd.) at a temperature of 70°C and in an environment at room temperature and humidity of 65% (estimated usage environment), and the change in rubber hardness was measured on a daily basis.

[0094] [Table 1]

[0095] The flat rubber sample in Example 1 that had been placed in a thermo-hygrostat had a poly-ε-caprolactone structure, and its rubber hardness decreased in a high-temperature, high-humidity environment at 70°C and 90% humidity, suggesting that it is hydrolyzable. On the other hand, the flat rubber sample in Comparative Example 1 does not contain a component with a hydrolyzable functional group, such as polyester, and its rubber hardness remains constant even in a high-temperature, high-humidity environment, suggesting that it is not degradable. The flat rubber sample in Example 1 that had been placed in a 70°C dryer did not experience a decrease in rubber hardness, suggesting that it does not decompose unless moisture is present. The flat rubber sample that had been placed in a room temperature, 65% humidity environment, which simulates the usage environment of Example 1, did not experience a decrease in rubber hardness over a measurement period of 160 days, suggesting that it is stable in the actual usage environment during this measurement period. [Example]

[0096] [Biodegradability evaluation of poly-ε-caprolactone acrylate modified silicone 1] Biodegradability was evaluated by the degree of biodegradation. The degree of biodegradation was measured using a method using activated sludge in accordance with OECD 301F. The activated sludge used was from a municipal sewage treatment plant, and the suspended solids concentration was 2400 mg / L. Sodium benzoate was used as the reference substance, and the degree of biodegradation was calculated based on the following formula.

number

[0097] When measured using the above method at an incubation temperature of 22±1°C for 28 days, the biodegradability of poly-ε-caprolactone acrylate-modified silicone 1 was an average of 26% after 28 days. Therefore, it is presumed that if the particles are used and then released directly into the ocean via land waters, they will eventually decompose without remaining in the environment as particles. [Example]

[0098] [Synthesis of poly-ε-caprolactone acrylate modified silicone 2] In Example 1, instead of poly-ε-caprolactone monoacrylate (trade name: PLACCEL FA2D, manufactured by Daicel Corporation), 224.57 g of poly-ε-caprolactone monoacrylate (trade name: PLACCEL FA4DT, manufactured by Daicel Corporation, molecular weight 572, hydroxyl value 0.175 mol / 100 g) was used, the amount of carboxy-modified silicone was changed from 300 g to 200 g, the amount of 4-dimethylaminopyridine (DMAP) was changed from 6.85 g to 4.52 g, the amount of N,N′-dicyclohexylcarbodiimide (DCC) was changed from 168.9 g to 77.17 g, and the amount of dehydrated toluene in which DCC was dissolved was changed from 173.63 g to 77.17 g. Synthesis was performed in the same manner as in Example 1, and poly-ε-caprolactone acrylate-modified silicone 2 (formula (17) below, weight average molecular weight: 2130) was obtained. [ka]

[0099] [Preparation of rubber particles] An aqueous dispersion of rubber particles was obtained in the same manner as in Example 1, except that poly-ε-caprolactone acrylate-modified silicone 1 used in Example 1 was replaced with poly-ε-caprolactone acrylate-modified silicone 2. Observation of the shape of the rubber particles in the obtained aqueous dispersion using an optical microscope revealed that they were spherical. Measurement of the volume average particle size using an electrical resistance particle size distribution analyzer (Multisizer 3, manufactured by Beckman Coulter, Inc.) revealed that the volume average particle size was 4.2 μm. Water was removed from this aqueous dispersion using a spray dryer in the same manner as in Example 1, yielding a white to pale yellow powder ( FIG. 1 ). Furthermore, measurement of the hardness of the rubber constituting the rubber particles in the same manner as in Example 1 revealed a hardness of 75. [Example]

[0100] Composite particles coated with polyorganosilsesquioxane were obtained from the aqueous dispersion of rubber particles obtained in Example 5 in the same manner as in Example 2. The obtained composite particles were dispersed in water using a surfactant, and the particle size distribution was measured using an electrical resistance particle size distribution analyzer (Multisizer 3, manufactured by Beckman Coulter, Inc.). The particle size distribution was the same as that of the aqueous dispersion of rubber particles, and the volume average particle size was 5.0 μm.

[0101] When the obtained particles were observed under an electron microscope, it was confirmed that the entire surface of the rubber particles was coated with granular polyorganosilsesquioxane (polyorganosilsesquioxane-coated rubber particles) (Figure 2). [Industrial Applicability]

[0102] Due to their characteristic structural composition and structure, the rubber particles and composite particles of the present invention are expected to be particularly useful in cosmetics, etc. The particles produced in Example 6 have more poly-ε-caprolactone structures in their molecules than the particles produced in Example 2, and are therefore expected to exhibit better decomposition properties.

Claims

1. Rubber particles made of a polymer containing structural units derived from a silicone-polyester copolymer (A) having at least two radically polymerizable unsaturated groups in one molecule, as represented by general formula (1). 【Chemical 1】 (In formula (1), R 1 are each independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 30 carbon atoms, each X is independently a polyester structure-containing group represented by general formula (2), (2') or (3), m is a number in the range of 0≦m≦1000, and n is a number in the range of 0≦n≦1000. 【Chemistry 2】 (In formulas (2) and (2′), R 2 is an alkylene group having 1 to 10 carbon atoms, a is a number satisfying 1≦a≦30, l is a number satisfying 1≦l≦10, and R 3 is a radical polymerizable functional group-containing organic group represented by general formula (4a), (4b), (4c) or (4d). 【Chemistry 3】 (In formula (3), R 4 is an alkylene group having 1 to 10 carbon atoms, b is a number satisfying 1≦b≦30, k is a number satisfying 1≦k≦10, and R 5 is a radical polymerizable functional group-containing organic group represented by general formula (5a) or (5b). 【Chemistry 4】 (In formulas (4a), (4b), (4c), (4d), (5a) and (5b), R 6 are each independently an unsubstituted or substituted hydrocarbon group having 1 to 20 carbon atoms which may have a heteroatom, and R 7 is a hydrogen atom or a hydrocarbon group having 1 to 3 carbon atoms, and Y is a hydrocarbon group having 1 to 40 carbon atoms which may have a heteroatom.

2. 2. The rubber particles according to claim 1, wherein the silicone-polyester copolymer (A) having at least two radically polymerizable unsaturated groups in one molecule is represented by general formula (6): 【Chemistry 5】 (In formula (6), R 5 are each independently an organic group containing a radical polymerizable functional group represented by formula (5a) or (5b), and R 8 are each independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 30 carbon atoms, o is a number in the range of 0≦o≦10, p is a number in the range of 0≦p≦1000, and q is a number in the range of 1≦q≦30. 【Chemistry 6】 (In formulas (5a) and (5b), R 6 is independently an unsubstituted or substituted hydrocarbon group having 1 to 20 carbon atoms which may have a heteroatom, and R 7 is a hydrogen atom or a hydrocarbon group having 1 to 3 carbon atoms.)

3. The rubber particles according to claim 1, wherein the particle shape is spherical and the volume average particle size is 0.1 to 50 μm.

4. Composite particles in which the surface of the rubber particle according to any one of claims 1 to 3 is coated with polyorganosilsesquioxane and / or silica.

5. A method for producing the rubber particles according to any one of claims 1 to 3, comprising the following steps (i) to (iii): (i) A step of adding an aqueous phase component containing a surfactant to an oil phase component containing a silicone-polyester copolymer (A) having at least two radically polymerizable unsaturated groups per molecule, and emulsifying the mixture to obtain an O / W emulsion. (ii) A step of curing the component (A) in the oil phase of the emulsion by radical polymerization in the presence of a radical polymerization initiator (B) to obtain an aqueous dispersion of rubber particles (C). (iii) A step of obtaining rubber particles by drying and removing the water, which is the continuous phase, from the aqueous dispersion (C) of rubber particles obtained in step (ii).

6. A method for producing the composite particles according to claim 4, comprising the following steps (i) to (v): (i) A step of adding an aqueous phase component containing a surfactant to an oil phase component containing a silicone-polyester copolymer (A) having at least two radically polymerizable unsaturated groups per molecule, and emulsifying the mixture to obtain an O / W emulsion. (ii) A step of curing the component (A) in the oil phase of the emulsion by radical polymerization in the presence of a radical polymerization initiator (B) to obtain an aqueous dispersion of rubber particles (C). (iii') A step of adding an alkaline substance (E) to the aqueous dispersion (C) of rubber particles obtained in the step (ii). (iv) adding the alkaline substance to the aqueous dispersion of rubber particles obtained in step (iii'); The following general formula (7): 【Chemistry 7】 (In formula (7), R 9 are each independently an alkyl group having 1 to 6 carbon atoms, and R 10 is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 20 carbon atoms. Organotrialkoxysilanes represented by the formula: General formula (8): Si(OR 11 ) 4 -(8) (In formula (8), R 11 are each independently a monovalent hydrocarbon group having 1 to 6 carbon atoms. Tetraalkoxysilane represented by the formula: and one or more hydrolyzates thereof (F) are added and subjected to a condensation reaction to coat the surfaces of the rubber particles with polyorganosilsesquioxane and / or silica, thereby obtaining an aqueous dispersion of composite particles. (v) A step of obtaining composite particles by drying and removing the water, which is the continuous phase, from the aqueous dispersion of composite particles obtained in step (iv).

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