Rubber particles, composite particles and method for producing the same

Abstract

Provided are rubber particles, composite particles having a polysiloxane structure with high dispersibility and high degradability, and a method for manufacturing the same. The rubber particles are rubber particles containing a copolymer having a polyester structure and an organopolysiloxane structure, the copolymer being a rubber particle which is a hydrosilylation crosslinking product of (A) a polyester having at least 2 aliphatic unsaturated groups in one molecule and (B) an organohydrogenpolysiloxane having at least 2 hydrogen atoms bonded to silicon atoms in one molecule, and which is a composite particle having a polyorganosilsesquioxane or silica coated on the surface of the rubber particle.

Description

Technical Field

[0001] The present invention relates to rubber particles, composite particles, and a method for producing the same. Background Art

[0002] Organosilicon rubber particles having rubber elasticity are used as a stress relaxant for resins. For example, in a thermosetting resin such as an epoxy resin used for encapsulating electronic and electrical components, rubber particles are added so that the encapsulation is not easily broken even when stress is applied due to the expansion caused by the heat generation of the electrical components. In addition, in cosmetics, it is used for the purpose of imparting a soft touch, smoothness, etc., which are the feelings of use, and stretchability.

[0003] As the organosilicon rubber particles, composite particles in which the organosilicon rubber particles are coated with a polyorganosilsesquioxane resin (Patent Document 1: Japanese Patent Laid-Open No. 7-196815), or composite particles in which the organosilicon rubber particles are coated with metal oxide fine particles such as silica (Patent Document 2: Japanese Patent Laid-Open No. 4-348143) have also been proposed. These composite particles have characteristics of low cohesiveness and high dispersibility.

[0004] In addition, as particles having good dispersibility in a thermoplastic resin or the like, Patent Document 3: Japanese Patent Laid-Open No. 2001-40214 describes organic crosslinked particles obtained by crosslinking a liquid composition containing an organic compound having an aliphatic saturated bond and a silicon-containing organic compound having a hydrogen atom bonded to a silicon atom by a hydrosilylation reaction.

[0005] Prior Art Documents

[0006] Patent Documents

[0007] [Patent Document 1] Japanese Patent Laid-Open No. 7-196815

[0008] [Patent Document 2] Japanese Patent Laid-Open No. 4-348143

[0009] [Patent Document 3] Japanese Patent Laid-Open No. 2001-40214 Summary of the Invention

[0010] Problems to be Solved by the Invention

[0011] However, when the organosilicon rubber particles are discarded into the environment such as in a resin or cosmetics, it is considered that since the particle size is very small, it is very difficult to recover, and thus it will directly flow into the ocean via inland water. Since the organosilicon rubber particles discarded into inland water or the ocean do not have a degradation structure in the particle structure and cannot be degraded by the environment, it is predicted that they will continue to remain in the environment.

[0012] In addition, microplastics in the ocean have the property of adsorbing harmful substances or pathogenic bacteria in the environment, and there is a tendency to restrict microplastics due to concerns about adverse effects on the ecosystem. Against this background, there has been a continuous pursuit of silicone rubber particles that degrade in the environment after use and do not remain as particles (solids). In order for silicone rubber particles to degrade in the environment, the crosslinked structure of the rubber particles needs to be degraded (cut) in the environment. However, since silicone rubber particles do not have degradability in terms of structure, a structure containing a degradable functional group must be introduced into the crosslinked structure.

[0013] The particles specifically shown in Patent Document 3 are particles obtained by crosslinking polyoxypropylene having allyl groups at both ends with an organopolysiloxane containing a hydrogen atom bonded to a silicon atom, and particles obtained by crosslinking hexadiene with dimethylpolysiloxane-methyl hydrogen polysiloxane. Since these particles do not contain a degradable functional group as a factor for degradation in the environment, they lack good degradability.

[0014] Accordingly, an object of the present invention is to provide rubber particles, composite particles, and a method for producing the same, which have high dispersibility and high degradability and contain a polysiloxane structure.

[0015] Means for Solving the Problem

[0016] As a result of intensive studies by the present inventors to achieve the above object, it has been found that rubber particles and composite particles containing a copolymer having a polyester structure and a polyorganosiloxane structure solve the above problem, and thus the present invention has been completed.

[0017] Therefore, the present invention is an invention for providing the following rubber particles, composite particles, and a method for producing the same. [1]

[0019] A rubber particle containing a copolymer having a polyester structure and a polyorganosiloxane structure. [2]

[0021] The rubber particle according to [1], wherein the particle shape is spherical and the volume average particle diameter is 0.1 to 50 μm. [3]

[0023] The rubber particle according to [1] or [2], wherein

[0024] the copolymer is:

[0025] (A) a polyester having at least 2 aliphatic unsaturated groups in one molecule, and

[0026] (B) An organohydrogenpolysiloxane having at least 2 hydrogen atoms bonded to silicon atoms in one molecule

[0027] Its hydrosilylation crosslinking product, provided that the case where 2 aliphatic unsaturated groups of the component (A) are present in one molecule and 2 hydrogen atoms bonded to the silicon atom of the component (B) are present in one molecule is excluded. [4]

[0029] The rubber particles according to [3], wherein the polyester having at least 2 aliphatic unsaturated groups in one molecule in the component (A) is a polyester obtained by substituting the molecular chain ends of a polyester or a polyester copolymer having a linear structure or a branched structure with aliphatic unsaturated groups. [5]

[0031] The rubber particles according to [4], wherein the polyester structure of the component (A) is poly-ε-caprolactone. [6]

[0033] The rubber particles according to any one of [3] to [5], wherein the component (B) is an organohydrogenpolysiloxane having at least 2 hydrogen atoms bonded to silicon atoms in one molecule represented by the following general formula (1).

[0034]

[0035] (R 1 Each independently represents an unsubstituted or substituted monovalent hydrocarbon group having 1 to 30 carbon atoms, R 2 Each independently represents a hydrogen atom or an unsubstituted or substituted monovalent hydrocarbon group having 1 to 30 carbon atoms, 1 ≤ m ≤ 1000, 0 ≤ n ≤ 1000, provided that when n = 0, two R 2 Together represent a hydrogen atom, and when two R 2 Do not together represent a hydrogen atom, n is 2 or more.) [7]

[0037] The rubber particles according to [6], wherein the component (B) is an organohydrogenpolysiloxane having at least 2 hydrogen atoms bonded to silicon atoms in one molecule represented by the following general formula (2).

[0038]

[0039] (R 3 Is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 30 carbon atoms other than phenyl, 0 ≤ a ≤ 500, 1 ≤ b ≤ 1000, 1 ≤ a + b ≤ 1000, 0 ≤ c ≤ 1000, provided that when c = 0, two R 2 Together represent a hydrogen atom, and when two R 2When they are not both hydrogen atoms, c is 2 or more.) [8]

[0041] A composite particle in which a polyorganosilsesquioxane or silica is coated on the surface of the rubber particle according to any one of [3] to [7]. [9]

[0043] A method for producing a rubber particle according to any one of [3] to [7], which includes the following steps (i) to (iii):

[0044] (i) A step of obtaining an O / W type emulsion by adding an aqueous phase component containing a surfactant to an oil phase component composed of a polyester (A) having at least 2 aliphatic unsaturated groups in one molecule and an organohydrogenpolysiloxane (B) having at least 2 hydrogen atoms bonded to a silicon atom in one molecule and performing emulsification;

[0045] (ii) A step of curing the oil phase component containing the component (A) and the component (B) in the emulsion by a hydrosilylation reaction in the presence of a hydrosilylation-reactive catalyst to obtain an aqueous dispersion (C) of rubber particles; and

[0046] (iii) A step of drying and removing water as a continuous phase from the aqueous dispersion (C) of rubber particles obtained in the step (ii) to obtain rubber particles.

[10]

[0048] A method for producing a composite particle as described in [8], which includes the following steps (i) to (v):

[0049] (i) A step of adding an aqueous phase component containing a surfactant to an oil phase component composed of a polyester (A) having at least 2 aliphatic unsaturated groups in one molecule and an organohydrogenpolysiloxane (B) having at least 2 hydrogen atoms bonded to a silicon atom in one molecule and stirring to obtain an O / W type emulsion;

[0050] (ii) A step of curing the oil phase component containing the component (A) and the component (B) in the emulsion by a hydrosilylation reaction in the presence of a hydrosilylation-reactive catalyst to obtain an aqueous dispersion (C) of rubber particles;

[0051] (iii’) A step of adding an alkaline substance (E) to the aqueous dispersion (C) of rubber particles obtained in the step (ii);

[0052] (iv) A step of adding one (F) selected from organic trialkoxysilanes, tetraalkoxysilanes, and their hydrolyzates represented by the following general formula (3) to the aqueous dispersion of rubber particles added with an alkaline substance obtained in step (iii’), subjecting it to a condensation reaction, and coating the surface of the rubber particles with polyorganosilsesquioxane or silica to obtain an aqueous dispersion of composite particles.

[0053]

[0054] (R 4 is a monovalent hydrocarbon group having 1 to 6 carbon atoms, and R 5 is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 20 carbon atoms or -OR 4 ); and

[0055] (v) A step of drying and removing water as the continuous phase from the aqueous dispersion of composite particles obtained in step (iv) to obtain composite particles.

[0056] Effects of the Invention

[0057] The rubber particles and composite particles of the present invention contain an ester group (polyester structure) as a degradable functional group in the particles, and have degradability because the crosslinked structure can be cleaved in an environment where moisture is present. In particular, particles having a poly-ε-caprolactone structure with a microbial recognition skeleton as the polyester structure in the particles can also be expected to have environmental degradability of the rubber particles.

[0058] Therefore, the rubber particles and composite particles of the present invention are particles with low cohesiveness, high dispersibility, and degradability, and can be expected to be materials for reducing the environmental load. Detailed Description of the Invention

[0059] Hereinafter, the present invention will be described in detail.

[0060] The rubber particles of the present invention are rubber particles containing a copolymer containing a polyester structure and an organopolysiloxane structure, and the composite particles are particles obtained by coating the surface of the rubber particles with polyorganosilsesquioxane or silica.

[0061] [Rubber Particles]

[0062] The shape of the rubber particles of the present invention is not particularly limited, and spherical shape is preferred. In the present invention, the so-called "spherical" not only means that the particle shape is a true sphere, but also means an ellipsoid with an average aspect ratio (length of the longest axis / length of the shortest axis) in the range of generally 1 to 4, preferably 1 to 2, more preferably 1 to 1.6, and further preferably 1 to 1.4. The shape of the particles can be confirmed by observing using, for example, an optical microscope or an electron microscope. The aspect ratio is the value calculated as the average of the lengths of the longest axis and the shortest axis measured for 100 particles arbitrarily selected from a micrograph.

[0063] The volume average particle diameter of the rubber particles is preferably 0.1 to 50 μm, more preferably 0.5 to 40 μm, and further preferably 1 to 20 μm. If the volume average particle diameter of the rubber particles is less than 0.1 μm, the fluidity of the particles is low and the cohesiveness becomes high. In addition, when coating with polyorganosilsesquioxane or silica, it is difficult to coat uniformly. If the volume average particle diameter of the rubber particles is greater than 50 μm, the smoothness sometimes decreases and a rough feeling is generated. In the present invention, the particle diameter is the volume average particle diameter measured by the electrical resistance method.

[0064] The rubber as the rubber particle component is preferably a non-sticky rubber. In the measurement by the Asker type C hardness meter specified in the Japanese Rubber Association standard specification (SRIS), the rubber hardness is preferably 5 to 90, more preferably 20 to 85, and further preferably 40 to 85. If the rubber hardness is less than 5, the cohesiveness becomes high and the dispersibility becomes poor.

[0065] The rubber particles of the present invention are preferably particles copolymerized by hydrosilylation reaction of the following liquid composition.

[0066] The liquid composition is:

[0067] (A) A polyester having at least 2 aliphatic unsaturated groups in one molecule, and

[0068] (B) An organohydrogenpolysiloxane having at least 2 hydrogen atoms bonded to a silicon atom in one molecule (however, excluding the case of a combination in which 2 aliphatic unsaturated groups are present in one molecule of the component (A) and 2 hydrogen atoms bonded to the silicon atom are present in one molecule of the component (B)).

[0069] The polyester having at least 2 aliphatic unsaturated groups in one molecule of the component (A) can be, for example, a polyester in which the molecular chain ends of a polyester or a polyester copolymer having a linear structure or a branched structure are substituted with aliphatic unsaturated groups.

[0070] That is, the component (A) is a polyester having a linear or branched structure, having at least one polyester structure (polyester repeating unit), and having an aliphatic unsaturated group at the molecular chain end. The component (A) can be obtained by substituting the molecular chain end of, for example, a polyester, a polyester copolymer, a polyester polyol, etc. with an aliphatic unsaturated group.

[0071] Examples of the polyester include aliphatic polyesters such as poly-ε-caprolactone, poly-β-propiolactone, γ-butyrolactone, polylactide acid, polyhydroxybutyrate, polyglycolide, ethylene glycol adipate, polyhydroxybutyric acid, ethylene succinate, butylene succinate; aromatic polyesters such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, trimethylene terephthalate. From the viewpoint of higher degradability, aliphatic polyesters are preferred.

[0072] In addition, examples of the polyester copolymer include copolymers of the polyester and other types of polymers. The other types of polymers can be selected from the polyesters, or can also be polymers other than polyesters such as polyethers or polycarbonates. For the above reasons, the polyester copolymer is preferably a copolymer of aliphatic polyesters, and examples thereof include L-lactic acid / ε-caprolactone copolymer, L-lactic acid / glycolic acid copolymer, etc.

[0073] Examples of the above polyester polyol include polyester polyols such as ethylene glycol adipate alcohol, tetramethylene adipate diol, polyethylene adipate diol; polycaprolactone polyols such as poly-ε-caprolactone diol, poly-ε-caprolactone triol, poly-ε-caprolactone tetrol. Polycaprolactone polyols are preferred, and more preferably poly-ε-caprolactone diol represented by the following formula (4), poly-ε-caprolactone triol represented by the following formula (5), and poly-ε-caprolactone tetrol represented by the following formula (6).

[0074]

[0075] Examples of the poly-ε-caprolactone polyol include addition polymers of lactones of aliphatic polyols having 2 to 20 carbon atoms, where R 6 ~R 8 is a residue of the aliphatic polyol having 2 to 20 carbon atoms, and k, l, m, and n in the formula are integers satisfying 1 ≤ k + l + m + n ≤ 100.

[0076] In the above formula (4), R 6is an aliphatic group having 2 to 20 carbon atoms, which is an aliphatic hydrocarbon group having 2 to 20 carbon atoms and may also contain heteroatoms such as oxygen atoms, specifically a residue derived from the following aliphatic diol. Examples of the aliphatic diol include straight-chain alcohols such as ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, diethylene glycol, triethylene glycol, and tetraethylene glycol; branched-chain alcohols such as 1,2-butanediol, 1,3-butanediol, or 2,3-butanediol, 2-methyl-1,4-butanediol, neopentyl glycol, 2,2-diethyl-1,3-propanediol, 2-methyl-1,5-pentanediol, 3-methyl-1,5-pentanediol, 2-methyl-1,6-hexanediol, 3-methyl-1,6-hexanediol, 2-methyl-1,7-heptanediol, 3-methyl-1,7-heptanediol, 4-methyl-1,7-heptanediol, 2-methyl-1,8-octanediol, 3-methyl-1,8-octanediol, and 4-methyloctanediol; alicyclic alcohols such as 1,4-cyclohexanediol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanediol, 1,3-cyclopentanediol, 1,4-cycloheptanediol, 2,5-bis(hydroxymethyl)-1,4-d alkane, 2,7-norbornanediol, tetrahydrofuran dimethanol, 1,4-bis(hydroxyethoxy)cyclohexane, 1,4-bis(hydroxymethyl)cyclohexane, and 2,2-bis(4-hydroxycyclohexyl)propane. Examples of commercially available poly-ε-caprolactone diols include PLACCEL 205U [manufactured by Daicel Corporation] and the like.

[0077] In R in the above formula (5) 7 is an aliphatic group having 2 to 20 carbon atoms, which is an aliphatic hydrocarbon group having 2 to 20 carbon atoms and may also contain heteroatoms such as oxygen atoms, specifically a residue derived from the following aliphatic triol. Examples of the aliphatic triol include glycerol, trimethylolethane, trimethylolpropane, etc. Examples of commercially available poly-ε-caprolactone triols include PLACCEL 305 [manufactured by Daicel Corporation] and the like.

[0078] In R in the above formula (6) 8 is an aliphatic group having 2 to 20 carbon atoms, which is an aliphatic hydrocarbon group having 2 to 20 carbon atoms and may also contain heteroatoms such as oxygen atoms, specifically a residue derived from the following aliphatic tetrol. Examples of the aliphatic tetrol include pentaerythritol, etc. Examples of commercially available poly-ε-caprolactone tetrols include PLACCEL 410 [manufactured by Daicel Corporation] and the like.

[0079] As a method for manufacturing the component (A), there can be mentioned the method of introducing a molecule having an aliphatic unsaturated group at the terminal of a molecular fragment into a polyester, a polyester copolymer, or a polyester polyol having a linear structure or a branched structure via an ester bond, an ether bond, a urethane bond, a urea bond, an amide bond, a sulfur bond, etc., as shown above. Specifically, as the molecule having an aliphatic unsaturated group that forms the above bond at the terminal of the molecular fragment, it is sufficient to react an acid halide or the like, which has excellent stability or reaction rate of the polyester during the reaction, with the above polycaprolactone polyol or the like. From the viewpoints of easy availability and cost, an acyl chloride is preferred. In addition, the aliphatic unsaturated group is preferably present at the molecular terminal site, and examples thereof include alkenyl groups such as vinyl, allyl, butenyl, pentenyl, and hexenyl; alkynyl groups such as ethynyl; and cyclic unsaturated groups such as norbornene and dicyclopentadienyl, and an alkenyl group is preferred. As the acyl chloride having an alkenyl group at the molecular terminal, examples include 4-pentenoyl chloride, 6-heptenoyl chloride, 8-nonenoyl chloride, 10-undecenoyl chloride, etc.

[0080] The component (A) is preferably in a liquid state, and the weight-average molecular weight measured by gel permeation chromatography (GPC) is more preferably 200 to 10,000, and further preferably 300 to 5,000. If the above weight-average molecular weight is less than 200, the degradability may deteriorate, and if the above weight-average molecular weight is greater than 10,000, it is difficult to prepare rubber particles.

[0081] The structure of the organohydrogenpolysiloxane having at least two hydrogen atoms bonded to a silicon atom in one molecule as the component (B) can be any of linear, cyclic, and branched structures, but a linear structure is preferred, and a structure represented by the following formula (1) is preferred.

[0082] In formula (1), R 1 are each independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 30 carbon atoms. R 2 are each independently a hydrogen atom or an unsubstituted or substituted monovalent hydrocarbon group having 1 to 30 carbon atoms. m is a number of 1 ≤ m ≤ 1000, preferably a number of 1 ≤ m ≤ 500; n is a number of 0 ≤ n ≤ 1000, preferably a number of 1 ≤ n ≤ 500. When n = 0, two R 2 are hydrogen atoms. When two R 2 are not both hydrogen atoms, n is 2 or more.

[0083]

[0084] As R 1, examples thereof include alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, decyl, undecyl, dodecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, eicosyl, heneicosyl, 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 the carbon atoms of these groups are replaced with atoms such as halogen atoms (fluorine atom, chlorine atom, bromine atom, iodine atom) and / or substituents such as acryloyloxy group, methacryloyloxy group, epoxy group, glycidyloxy group, and carboxyl group.

[0085] In formula (1), R 2 is a hydrogen atom or an unsubstituted or substituted monovalent hydrocarbon group having 1 to 30 carbon atoms. As R 2 , examples of the unsubstituted or substituted monovalent hydrocarbon group having 1 to 30 carbon atoms may be the same groups as those of the above-mentioned R 1 .

[0086] Component (B) is more preferably an organohydrogenpolysiloxane containing a diphenylsiloxy unit represented by the following formula (2). In formula (2), R 1 and R 2 represent the same groups as those in formula (1), and R 3 are each independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 30 carbon atoms other than phenyl.

[0087]

[0088] In formula (2), as R 3 , examples thereof include alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, decyl, undecyl, dodecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, eicosyl, heneicosyl, docosyl, tricosyl, tetracosyl, and triacontyl; aryl groups other than phenyl such as 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 the carbon atoms of these groups are replaced with atoms such as halogen atoms (fluorine atom, chlorine atom, bromine atom, iodine atom) and / or substituents such as acryloyloxy group, methacryloyloxy group, epoxy group, glycidyloxy group, and carboxyl group.

[0089] In formula (2), a, b, and c are in the range of 0 ≤ a ≤ 500, 1 ≤ b ≤ 1000, 1 ≤ a + b ≤ 1000, 0 ≤ c ≤ 1000, preferably in the range of 0 ≤ a ≤ 250, 1 ≤ b ≤ 500, 1 ≤ c ≤ 500. However, when c = 0, the two Rs 2 are both hydrogen atoms together. When the two Rs 2 are not both hydrogen atoms together, c is 2 or more.

[0090] (A) A polyester having at least 2 aliphatic unsaturated groups in one molecule and (B) an organohydrogenpolysiloxane having at least 2 hydrogen atoms bonded to a silicon atom in one molecule, more preferably a composition in which either the aliphatic unsaturated group of component (A) or the hydrogen atom of component (B) is at least 3. The ratio of component (A) to component (B) is preferably such that the ratio of the hydrosilyl group of component B is 0.5 to 2.0 per 1 aliphatic unsaturated group of component (A).

[0091] The hydrosilylation catalyst for crosslinking component (A) and component (B) may include platinum-based catalysts, rhodium-based catalysts, palladium-based catalysts, but platinum-based catalysts are preferred. Specific examples of platinum-based catalysts include, for example, monomers of platinum (including platinum black), platinum supported on carbon or silica, chloroplatinic acid, platinum-olefin complexes, platinum-alcohol complexes, platinum-vinyl-containing siloxane complexes, chloroplatinic acid-vinyl-containing siloxane complexes, etc. The amount of the platinum-based catalyst may be the catalytic amount as a hydrosilylation reaction catalyst. Specifically, in terms of the platinum mass in the catalyst, it is an amount of about 0.1 to 500 ppm, preferably about 0.1 to 200 ppm, more preferably about 0.5 to 100 ppm. When the amount of the platinum-based catalyst is less than 0.1 ppm, the curing becomes slow and is easily affected by catalyst toxicity. On the other hand, when the amount of the platinum-based catalyst exceeds 500 ppm, coloring of rubber particles is seen and it is not preferred in terms of economy.

[0092] [Method for manufacturing component (A)]

[0093] As a method for manufacturing component (A), for example, the following can be cited, but it is not limited to this manufacturing method. An excess of 2.2 to 8.0 moles, preferably 2.5 to 6.0 moles, of a base for capturing the generated hydrogen chloride is mixed in 1 mole of the above-mentioned polycaprolactone polyol or polyester polyol component represented by formula (4) to formula (6), and an excess of 2.0 to 7.0 moles, preferably more than 2.2 and 6.0 moles or less, of an acyl chloride having the above-mentioned aliphatic unsaturated group at the molecular end is dropped therein, and the reaction is carried out under heating for 30 minutes to 6 hours, preferably 1 hour to 2 hours. After the reaction, the reaction product can be subjected to an extraction process, a water washing process, and an adsorption process to remove by-products, and the solvent is distilled off to obtain component (A).

[0094] As the base, a base that is added to capture hydrogen chloride generated by the reaction and does not react with the polylactone polyol, or the polyester polyol or acyl chloride can be used. As such a base, a tertiary amine is preferred, and triethylamine is more preferred.

[0095] To adjust the viscosity of the reaction product in the extraction step, a hydrophobic organic solvent can also be used. The hydrophobic organic solvent is not particularly limited, and from the viewpoints of solubility and the like, toluene is preferred.

[0096] Adsorption is a step for removing the hydrochloride of the base that has not been completely removed in the water washing step, or for dehydration, decolorization, and deodorization. The adsorption material that can be used can be a known adsorption material, or a combination of multiple types can be used. As the adsorption material, desiccants such as magnesium sulfate and sodium sulfate, activated carbon, and the KYOWAAD series (manufactured by Kyowa Chemical Industry Co., Ltd.) are preferred.

[0097] [Method for manufacturing rubber particles]

[0098] The rubber particles of the present invention can be manufactured, for example, by a method including the following steps (i) to (iii).

[0099] (i)

[0100] A step of preparing an O / W type emulsion by adding an aqueous phase component containing a surfactant to an oil phase component composed of (A) a polyester having at least 2 aliphatic unsaturated groups in one molecule and (B) an organohydrogenpolysiloxane having at least 2 hydrogen atoms bonded to a silicon atom in one molecule and stirring.

[0101] (ii)

[0102] A step of obtaining an aqueous dispersion (C) of rubber particles by curing the oil phase component containing components (A) and (B) in the O / W type emulsion in the presence of the hydrosilylation catalyst.

[0103] (iii)

[0104] A step of obtaining rubber particles by drying to remove water as the continuous phase of the aqueous dispersion of the rubber particles.

[0105] Step (i)

[0106] The surfactant used in step (i) is not particularly limited, and it is a nonionic surfactant, an anionic surfactant, a cationic surfactant, or an amphoteric surfactant. They can be used alone or in appropriate combination of two or more.

[0107] Examples of the nonionic surfactant used herein include polyoxyethylene alkyl ether, polyoxyethylene polyoxypropylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyethylene glycol fatty acid ester, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene sorbitol fatty acid ester, glycerol fatty acid ester, polyoxyethylene glycerol fatty acid ester, polyglycerol fatty acid ester, propylene glycol fatty acid ester, polyoxyethylene castor oil, polyoxyethylene hydrogenated castor oil, polyoxyethylene hydrogenated castor oil fatty acid ester, polyoxyethylene alkylamine, polyoxyethylene fatty acid amide, polyoxyethylene-modified organopolysiloxane, polyoxyethylene polyoxypropylene-modified organopolysiloxane, and the like.

[0108] Examples of the anionic surfactant include alkyl sulfates such as sodium lauryl sulfate, polyoxyethylene alkyl ether sulfates, polyoxyethylene alkyl phenyl ether sulfates, sulfate salts of aliphatic alkanolamides, alkylbenzene sulfonates, polyoxyethylene alkyl phenyl ether sulfonates, alkyl diphenyl ether disulfonates, alkane sulfonates, N-acyl taurates, dialkyl sulfosuccinates, monoalkyl sulfosuccinates, polyoxyethylene alkyl ether sulfosuccinates, fatty acid salts, polyoxyethylene alkyl ether carboxylates, N-acyl amino acid salts, monoalkyl phosphate salts, dialkyl phosphate salts, polyoxyethylene alkyl ether phosphate salts, and the like.

[0109] Examples of the cationic surfactant include alkyltrimethylammonium salts, dialkyldimethylammonium salts, polyoxyethylene alkyldimethylammonium salts, dioxyethylene alkylmethylammonium salts, trioxyethylene alkylammonium salts, alkylbenzyldimethylammonium salts, alkyl pyridium salts, monoalkylamine salts, monoalkylamidoamine salts, and the like.

[0110] Examples of the zwitterionic surfactant include alkyldimethylamine oxide, alkyldimethyl carboxybetaine, alkylamidopropyldimethyl carboxybetaine, alkylhydroxy sulfobetaine, alkylcarboxymethylhydroxyethyl imidazolinium betaine, and the like.

[0111] From the viewpoint of being able to emulsify the curable liquid silicone composition with a small amount and thus form fine particles, the surfactant is preferably a nonionic surfactant.

[0112] With respect to 100 parts by mass of the emulsion, the addition amount of the surfactant is preferably 0.01 to 20 parts by mass, more preferably 0.05 to 10 parts by mass. If the addition amount of the surfactant is less than 0.01 part by mass, problems such as inability to emulsify or form fine particles may occur. If the addition amount of the surfactant is greater than 20 parts by mass, it will be difficult to coat the polyorganosilsesquioxane or silica on the rubber particles in the subsequent composite particle manufacturing process.

[0113] In addition, the content of the polyester having at least 2 aliphatic unsaturated groups in one molecule as the component (A) of the oil phase component in the emulsion and the organohydrogenpolysiloxane having at least 2 hydrogen atoms bonded to silicon atoms in one molecule as the component (B) is preferably 1 to 80 parts by mass, more preferably 10 to 60 parts by mass, based on 100 parts by mass of the emulsion. If the content of the polyester and the organohydrogenpolysiloxane is less than 1 part by mass, it is not beneficial for efficiency. If the content of the polyester and the organohydrogenpolysiloxane is greater than 80 parts by mass, it is difficult to obtain an aqueous dispersion of rubber particles.

[0114] When performing emulsification, a known emulsifying and dispersing machine can be used. As general emulsifying and dispersing machines, high-speed rotary shearing mixers such as homogenizers, high-speed centrifugal spraying mixers such as homogenizing dispersers, high-pressure jet emulsifying and dispersing machines such as homogenizers, colloid mills, ultrasonic emulsifiers, etc. can be cited.

[0115] Process (ii)

[0116] The oil phase component in the emulsion thus prepared can be cured in the presence of the above-mentioned hydrosilylation catalyst to obtain a dispersion of rubber particles. The hydrosilylation catalyst can be added to the oil phase before emulsion preparation or can be added after emulsion preparation. When added after emulsion preparation, there is a possibility that the hydrosilylation catalyst is not dispersed. However, in this case, it can be added after mixing the surfactant and the hydrosilylation catalyst. The hydrosilylation can be carried out at room temperature, and in the case where the reaction is not completed, it can also be carried out under heating conditions below 100 °C. The hydrosilylation reaction time can be appropriately selected. By this method, an aqueous dispersion of rubber particles with a volume average particle size of 0.1 to 50 μm can be obtained.

[0117] Process (iii)

[0118] By drying and removing water as the continuous phase from the obtained aqueous dispersion of rubber particles, rubber particles can be obtained. Regarding drying and removing water from the aqueous dispersion of rubber particles, it can be carried out, for example, by heating under normal pressure or reduced pressure. Specifically, methods such as allowing the dispersion to stand under heating to remove water, allowing the dispersion to flow while stirring under heating to remove water, spraying the dispersion into a hot air stream like a spray dryer to disperse it, and using a flowing heating medium can be cited. It should be noted that as a pretreatment for this operation, the dispersion can be concentrated by methods such as heating and dehydration, filtration separation, decantation, etc., and the dispersion can also be washed with water or alcohol as needed.

[0119] [Composite particles]

[0120] The polyorganosilsesquioxane or silica coated on the surface of the composite particles is not particularly limited in shape, but in the case of the manufacturing method described below, it becomes granular. Its particle size is preferably small, specifically 500 nm or less. The organosilsesquioxane or silica may coat a part or all of the surface of the rubber particles, but it is preferably coated without gaps over almost the entire surface of the rubber particles. It should be noted that the coating state, shape, and particle size can be confirmed by observing the particle surface using an electron microscope.

[0121] There is no particular limitation on the amount of polyorganosilsesquioxane or silica coated on the surface of the particles, but it is preferably in a ratio of 0.5 to 200 parts by mass, more preferably 1 to 50 parts by mass, relative to 100 parts by mass of the rubber particles.

[0122] [Manufacturing method of composite particles]

[0123] The composite particles of the present invention are obtained by adding (F) one selected from organotrialkoxysilanes, tetraalkoxysilanes, and their hydrolyzates represented by the following general formula (3) to a liquid containing (C) an aqueous dispersion of rubber particles, (D) water (optional), and (E) a basic substance, performing a hydrolysis and condensation reaction, and coating the surface of the rubber particles with polyorganosilsesquioxane or silica.

[0124]

[0125] In formula (3), R 4 are each independently a monovalent hydrocarbon group having 1 to 6 carbon atoms, and R 5 is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 20 carbon atoms or -OR 4 .

[0126] That is, the composite particles of the present invention can be manufactured by a method including the following steps (i) to (v).

[0127] (i) A step of obtaining an O / W type emulsion by adding an aqueous phase component containing a surfactant to an oil phase component composed of a polyester (A) having at least 2 aliphatic unsaturated groups in one molecule and an organohydrogenpolysiloxane (B) having at least 2 hydrogen atoms bonded to silicon atoms in one molecule and stirring.

[0128] (ii) A step of curing the oil phase component containing components (A) and (B) in the emulsion by a hydrosilylation reaction in the presence of a hydrosilylation catalyst to obtain an aqueous dispersion (C) of rubber particles.

[0129] (iii’) A step of adding a basic substance (E) to the aqueous dispersion (C) of rubber particles obtained in step (ii).

[0130] (iv) Step of adding one (F) selected from organotrialkoxysilanes represented by the general formula (3), tetraalkoxysilanes, and their hydrolyzates to the aqueous dispersion of rubber particles added with an alkaline substance obtained in step (iii'), and subjecting them to a condensation reaction to coat the surface of the rubber particles with polyorganosilsesquioxane or silica to obtain an aqueous dispersion of composite particles

[0131] (v) Step of obtaining composite particles by drying and removing water as the continuous phase from the aqueous dispersion of composite particles obtained in step (iv)

[0132] Steps (i) and (ii) of the method for producing composite particles are the same as steps (i) and (ii) of the method for producing the rubber particles. In addition, in step (iii'), (D) water may be added as an optional component

[0133] Step (iii')

[0134] (D) Water

[0135] There is no particular limitation on the water, and purified water or the like can be used, including the water contained in the aqueous dispersion of rubber particles obtained in the above step (ii) and the water added as needed

[0136] (E) Alkaline substance

[0137] The alkaline substance only needs to function as a catalyst for the hydrolysis and condensation reaction of organotrialkoxysilane or tetraalkoxysilane, and can be any substance. Specifically, for example, 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; quaternary ammonium hydroxides such as tetramethylammonium hydroxide, etc. are more preferably water-soluble, have excellent catalyst activity, and are easily removed by volatilization. Ammonia can be used, and a commercially available aqueous ammonia solution can be used

[0138] The addition amount of component (E) is preferably an amount such that the pH of the liquid containing (C) to (E) is in the range of 9.0 to 13.0 at 25°C, and more preferably in the range of 10.0 to 12.5. If the pH is lower than 10.0, the hydrolysis and condensation reaction of organotrialkoxysilane or tetraalkoxysilane cannot proceed sufficiently. If the pH is higher than 13.0, the hydrolysis rate increases, and the hydrolysis and condensation reaction occurs in parts other than the surface of the rubber particles, resulting in a lower coating property

[0139] When adding component (F), one or more (G) selected from cationic surfactants and cationic water-soluble polymer compounds can also be blended

[0140] Cationic surfactants and cationic water-soluble polymer compounds have the effect of promoting the condensation reaction of hydrolyzed organic trialkoxysilanes and tetraalkoxysilanes and generating polyorganosilsesquioxanes or silica. In addition, there are cases where the generated polyorganosilsesquioxanes or silica are adsorbed onto the surface of rubber particles.

[0141] Examples of the cationic surfactant include alkyltrimethylammonium salts, dialkyldimethylammonium salts, polyoxyethylene alkyldimethylammonium salts, dioxyethylene alkylmethylammonium salts, trioxyethylene alkylammonium salts, alkylbenzyldimethylammonium salts, alkylpyridinium salts, monoalkylamine salts, monoalkylamidoamine salts, etc. Among them, alkyltrimethylammonium salts are preferred, and lauryltrimethylammonium salt and cetyltrimethylammonium salt are more preferred.

[0142] Examples of the cationic water-soluble polymer compound include polymers of dimethyldiallylammonium chloride, polymers of vinylimidazoline, polymers of methylvinylimidazolium chloride, polymers of ethyltrimethylammonium acrylate, polymers of ethyltrimethylammonium methacrylate, polymers of acrylamidopropyltrimethylammonium chloride, polymers of methacrylamidopropyltrimethylammonium chloride, epichlorohydrin / dimethylamine polymers, polymers of ethyleneimine, quaternized products of polymers of ethyleneimine, polymers of allylamine hydrochloride, polylysine, cationic starch, cationized cellulose, chitosan, and derivatives obtained by copolymerizing monomers having nonionic groups or anionic groups with these cationic water-soluble polymer compounds. Among them, polymers of dimethyldiallylammonium chloride are preferred.

[0143] With respect to 100 parts by mass of water in the liquid containing (C) to (E), the addition amount of the component (G) is preferably in the range of 0.001 to 2 parts by mass, more preferably in the range of 0.005 to 1 part by mass. If the addition amount of the component (G) is greater than 2 parts by mass, there is a concern that polyorganosilsesquioxanes or silica that are not coated on the surface of rubber particles may be generated.

[0144] (F) is selected from one of the organic trialkoxysilanes, tetraalkoxysilanes, and their hydrolyzates represented by the above general formula (3)

[0145] The polyorganosilsesquioxane or silica coating the rubber particles is formed by adding to the rubber particles one selected from the organic trialkoxysilanes, tetraalkoxysilanes, and their hydrolyzates represented by the above-mentioned general formula (3). R in this formula 4 is a monovalent hydrocarbon group having 1 to 6 carbon atoms, and examples include methyl, ethyl, propyl, butyl, etc. R in the formula 5is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 20 carbon atoms or -OR 4 . Examples of the unsubstituted or substituted monovalent hydrocarbon group 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-phenethyl and β-phenylpropyl; monovalent halogenated hydrocarbon groups such as chloromethyl and 3,3,3-trifluoropropyl; and further groups in which these monovalent hydrocarbon groups are substituted with an epoxy group, an amino group, a mercapto group, an acryloyloxy group, a methacryloyloxy group, etc.

[0146] When R 5 is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 20 carbon atoms, the rubber particles are coated with a polyorganosilsesquioxane. When R 5 is -OR 4 , the rubber particles are coated with silica.

[0147] Examples of the organotrialkoxysilane and tetraalkoxysilane used for coating include, for example, methyltrimethoxysilane, methyltriethoxysilane, methyltripropoxysilane, methyltributoxysilane, ethyltrimethoxysilane, propyltrimethoxysilane, butyltrimethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, vinyltrimethoxysilane, phenyltrimethoxysilane, γ-methacryloyloxypropyltrimethoxysilane, 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, tetraethoxysilane, etc.

[0148] The addition amount of the component (F) is preferably 20 parts by mass or less with respect to 100 parts by mass of water in the liquid containing (C) to (E). If the addition amount of the component (F) is greater than 20 parts by mass, there is a concern about the formation of lumps.

[0149] Step (iv)

[0150] By adding (F), which is selected from an organotrialkoxysilane, a tetraalkoxysilane, and a hydrolyzate thereof, to a liquid containing (C) to (E) and (G), the organotrialkoxysilane and the tetraalkoxysilane are hydrolyzed and condensed, thereby coating the surface of the polyorganosilsesquioxane or silica-coated rubber particles. Specifically, for an aqueous solution in which (E) an alkaline substance and (G), which is one or more (optional) selected from a cationic surfactant and a cationic water-soluble polymer compound, are dissolved in (C) an aqueous dispersion of rubber particles and (D) water (optional), (F), which is selected from an organotrialkoxysilane, a tetraalkoxysilane, and a hydrolyzate thereof, is added, and hydrolysis and condensation are carried out. The surface of the rubber particles is coated with the condensate, i.e., the polyorganosilsesquioxane or silica, to form composite particles.

[0151] The addition of the organotrialkoxysilane, the tetraalkoxysilane, and the hydrolyzate thereof is preferably carried out under stirring using a conventional stirrer such as a propeller blade or a flat blade. The organotrialkoxysilane, the tetraalkoxysilane, and the hydrolyzate thereof are preferably added over time. The dropping time is preferably from 1 minute to 6 hours, more preferably from 10 minutes to 3 hours.

[0152] The temperature inside the system during dropping is preferably in the range of 0 to 60 °C, more preferably in the range of 0 to 40 °C. If within this temperature range, the polyorganosilsesquioxane and silica can be coated on the surface of the rubber particles.

[0153] Step (v)

[0154] After the hydrolysis and condensation reaction is completed, the composite particles can be obtained by drying and removing the water as the continuous phase from the aqueous dispersion of the composite particles of the present invention obtained. The removal of water can be carried out, for example, by heating the reaction aqueous dispersion under normal pressure or reduced pressure. Specifically, methods such as allowing the dispersion to stand under heating to remove water, allowing the dispersion to flow under heating while stirring to remove water, spraying the dispersion into a hot air stream as in a spray dryer, and using a flowing heating medium can be cited. It should be noted that as a pretreatment for this operation, the dispersion can be concentrated by methods such as heating dehydration, filtration separation, centrifugation, and decantation, and if necessary, the dispersion can also be washed with water or alcohol.

[0155] In the case where the product obtained by drying and removing water from the reaction aqueous dispersion agglomerates, it can be pulverized by a pulverizer such as a jet mill, a ball mill, or a hammer mill to obtain composite particles in which the surface of the rubber particles is coated with polyorganosilsesquioxane and silica.

[0156] [Examples]

[0157] Hereinafter, examples and comparative examples are shown, and the present invention will be described in more detail. However, the present invention is not limited to the following examples. In addition, in the examples, the kinematic viscosity is the value measured at 25 ° C, and "%" indicating the concentration and content is expressed as "mass%". The penetration of the rubber cured product is the value measured in accordance with the specifications of the Japan Rubber Association Standard (SRIS). The molecular weight of the component (A) is the weight average molecular weight using polystyrene as a standard substance by GPC measured under the following conditions.

[0158] [Measurement Conditions]

[0159] Elution solvent: Tetrahydrofuran (THF)

[0160] Flow rate: 0.60 mL / min

[0161] Detector: Differential refractive index detector (RI)

[0162] Column: TSK Guardcolumn SuperH-H

[0163] TSKgel SuperHM-N

[0164] TSKgel SuperH2500

[0165] (All manufactured by TOSOH Corporation)

[0166] Column temperature: 40 °C

[0167] Sample injection volume: 50 μL (THF solution with a concentration of 0.5 mass%)

[0168] [Example 1]

[0169] [Synthesis 1 of Poly-ε-caprolactone Containing Alkenyl]

[0170] In a 1 L glass flask equipped with a stirrer, a dropping funnel, a thermometer, and a condenser, 200 g of poly-ε-caprolactone diol (trade name: PLACCEL 205, manufactured by DAICEL CORPORATION, molecular weight 530, hydroxyl value 212.4 mg / g), 200 g of toluene, and 95.8 g of triethylamine were added. The temperature was adjusted to 55 °C and mixed, and 168.9 g of undecenoyl chloride (the amount added was such that the chlorine of the acyl chloride was 1.1 times that of one hydroxyl group of the poly-ε-caprolactone diol) was dropped in through the dropping funnel, and after dropping, it was aged for 2 hours. After aging, 200 g of water and 100 g of toluene were added, the aqueous phase was transferred to a separatory funnel, and extracted with 100 g of toluene. After extraction, the oil phase was washed once with 450 g of water and twice with 450 g of saturated brine, and then 10 g each of magnesium sulfate, activated carbon, and KYOWAAD 700 (manufactured by KYOWA CHEMICAL INDUSTRY CO., LTD.) were added and shaken for 2 hours. After shaking, magnesium sulfate, activated carbon, and KYOWAAD 700 were removed by pressure filtration, and the solvent was distilled off under the conditions of 60 °C and 10 mmHg or less to obtain alkenyl-containing poly-ε-caprolactone 1 (the following formula (7)).

[0171]

[0172] (R 6 represents an aliphatic group, and 2 ≤ m + n ≤ 5, weight-average molecular weight: 862)

[0173] [Preparation of rubber particles]

[0174] 171 g of the synthesized alkenyl-containing poly-ε-caprolactone 1 and 83.46 g of phenylhydrogenpolysiloxane having a kinematic viscosity of 23 mm 2 / s represented by the following formula (8) (the compounding amount was such that the hydrosilyl group was 1.1 times that of one vinyl group) were charged into a 1 L container and stirred and dissolved at 1500 rpm using a homogenizer. Then, 1.35 of polyoxyethylene lauryl ether and 31.5 g of water were added, and stirred at 5000 rpm using a homogenizer. As a result, it became an O / W type emulsion, thickening was observed, and stirring was continued for a further 10 minutes. Then, while stirring at 1500 rpm, it was diluted with 258.54 g of water to obtain a white emulsion.

[0175]

[0176] The emulsion was transferred to a 1-L glass flask of a stirring device equipped with an anchor-shaped stirring blade. After adjusting the temperature to 15 - 20°C, a mixed solution of 1 g of an isododecane solution of a platinum-containing vinyl group-containing disiloxane complex (platinum content 0.5%) and 0.68 g of polyoxyethylene lauryl ether was added dropwise with stirring, and stirring was continued for 30 minutes to 1 hour. Subsequently, the temperature was adjusted to 40°C and stirring was continued for 2 days to obtain an aqueous dispersion of rubber particles.

[0177] The shape of the rubber particles in the obtained aqueous dispersion was observed with an optical microscope, and the result was spherical. When the volume average particle diameter was measured using an electrical resistance method particle size distribution measuring device (Multisizer 3, manufactured by Beckman Coulter, Inc.), the volume average particle diameter was 5 μm.

[0178] The obtained aqueous dispersion of rubber particles was dried using a spray dryer with an inlet temperature set at 150°C and an outlet temperature set at 80°C to obtain powdery rubber particles in white to pale yellow color.

[0179] In addition, the hardness of the rubber constituting the rubber particles was measured in the following manner. An alkenyl group-containing poly-ε-caprolactone 1, a phenylhydrogenpolysiloxane represented by the above formula (8), and an isododecane solution of a platinum-containing vinyl group-containing disiloxane complex (platinum content 0.5%) were mixed in the above ratio and poured into an aluminum petri dish to a thickness of 10 mm. After standing at 40°C for 2 days, a non-tacky flat rubber was obtained. The hardness was measured with an Asker C hardness meter, and the result was 63.

[0180] [Example 2]

[0181] [Preparation of Composite Particles]

[0182] In the same manner as in Example 1, an aqueous dispersion of rubber particles was obtained. 357 g of the obtained aqueous dispersion of rubber particles was transferred to a 2-L glass flask of a stirring device equipped with an anchor-shaped stirring blade, and 602.5 g of water, 19 g of a 28% aqueous ammonia solution, and 1 g of a 40% aqueous solution of dimethyldiallylammonium chloride polymer (trade name: ME Polymer H40W, manufactured by Toho Chemical Industry Co., Ltd., Japan) were further added. The pH of the solution at this time was 11.3. After adjusting the temperature to 5 - 10°C, 20.5 g of methyltrimethoxysilane (an amount corresponding to 6.7 parts by mass of polymethylsilsesquioxane after hydrolysis and condensation reaction relative to 100 parts by mass of rubber particles) was added dropwise over 25 minutes, and the liquid temperature during this period was maintained at 5 - 10°C, and stirring was further continued for 1 hour. Subsequently, the temperature was raised to 55 - 60°C and this temperature was maintained while stirring for 1 hour to complete the hydrolysis and condensation reaction of methyltrimethoxysilane.

[0183] Using a pressure filter, the liquid in which hydrolysis and condensation reactions of methyltrimethoxysilane occur in an aqueous dispersion of rubber particles is dehydrated to a water content of about 30%. The dehydrated product is transferred to a 2 L glass flask of a stirring device equipped with an anchor-shaped stirring blade, 1000 g of water is added, and after stirring for 30 minutes, dehydration is carried out using a pressure filter. The dehydrated product is transferred again to a 2 L glass flask of a stirring device equipped with an anchor-shaped stirring blade, 1000 g of water is added, and after stirring for 30 minutes, dehydration is carried out using a pressure filter. The dehydrated product is dried in a hot air flow dryer at a temperature of 105 °C, and the dried product is pulverized with a jet mill to obtain particles with fluidity.

[0184] The obtained particles were observed with an electron microscope, and as a result, it was confirmed that composite particles (organopolysiloxane-coated rubber particles) in which the entire surface of the rubber particles was coated with granular organopolysiloxane were formed.

[0185] The obtained composite particles were dispersed in water using a surfactant, and measurement was carried out using a resistance method particle size distribution measuring device (Multisizer 3, manufactured by Beckman Coulter, Inc.). As a result, the particle size distribution was the same as that of the above-mentioned aqueous dispersion of rubber particles, and the volume average particle diameter was 5 μm.

[0186] [Example 3]

[0187] In the same manner as in Example 1, an aqueous dispersion of rubber particles was obtained. 265 g of the obtained aqueous dispersion of rubber particles was transferred to a 2 L glass flask of a stirring device equipped with an anchor-shaped stirring blade, 651.1 g of water, 2.2 g of a 2.8% aqueous ammonia solution, and 12 g of a 30% aqueous solution of lauryltrimethylammonium chloride (trade name: CATION BB, manufactured by NOF Corporation) (an amount of 0.44 parts of lauryltrimethylammonium chloride relative to 100 parts by mass of water) were added. At this time, the pH of the solution was 10.4. After adjusting the temperature to 5 - 10 °C, 70.7 g of tetramethoxysilane (an amount of 27 parts by mass of silica after hydrolysis and condensation reaction relative to 100 parts by mass of rubber particles) was dropped over 60 minutes, and at this time, the liquid temperature was maintained at 5 - 10 °C, and stirring was further continued for 3 hours. Then, it was heated to 70 - 75 °C, and stirring was carried out at this temperature for 1 hour while maintaining it, and the hydrolysis and condensation reaction of tetramethoxysilane was completed.

[0188] The obtained composite particles were dispersed in water using a surfactant, and the particle size distribution was measured using a resistive particle size distribution analyzer (Multisizer 3, manufactured by Beckman Coulter, Inc.). As a result, the particle size distribution was equivalent to that of the aqueous dispersion of the rubber particles, and the volume average particle size was 5 μm. Observation of these particles with an electron microscope confirmed that the composite particles were rubber particles coated with silica in a granular shape.

[0189] [Example 4]

[0190] [Synthesis of alkenyl-containing poly-ε-caprolactone 2]

[0191] In Example 1, 200 g of poly-ε-caprolactone tetraol (trade name: PLACCEL 410, manufactured by DAICEL Corporation, molecular weight 1030, hydroxyl value 216.7 mg / g) was used in place of 200 g of poly-ε-caprolactone diol (trade name: PLACCEL205U, manufactured by DAICEL Corporation). Triethylamine was changed from 95.8 g to 98.4 g, and undecylenoyl chloride was changed from 168.9 g to 173.5 g (the addition amount of acyl chloride was 1.1 times relative to 1 hydroxyl group). The synthesis was carried out in the same manner as in Example 1 to obtain alkenyl-containing poly-ε-caprolactone 2 (weight average molecular weight: 1698).

[0192]

[0193] (R 9 represents an aliphatic group, 4 ≤ k + l + m + n ≤ 9, weight average molecular weight: 1698)

[0194] [Preparation of rubber particles]

[0195] In Example 1, 170 g of alkenyl-containing poly-ε-caprolactone 2 was used in place of 171 g of the synthesized alkenyl-containing poly-ε-caprolactone 1 described above, and it was combined with the formula (8) shown above and had a kinematic viscosity of 23 mm 285.32 g of phenylhydrogenpolysiloxane with a viscosity of / s (the compounding amount with 1.1 silicon hydride groups relative to 1 vinyl group), and the others were obtained in the same manner as in Example 1 to obtain an aqueous dispersion of rubber particles. When observing the shape of the rubber particles in the obtained aqueous dispersion with an optical microscope, the result was spherical, and when measuring the volume average particle diameter using a resistance method particle size distribution measuring device (Multisizer 3, manufactured by Beckman Coulter, Inc.), the volume average particle diameter was 5 μm. This aqueous dispersion was dehydrated in the same manner as in Example 1 using a spray dryer, and as a result, a white to light yellow powder was obtained. In addition, the hardness of the rubber constituting the rubber particles was measured in the same manner as in Example 1, and the hardness of this rubber was 82.

[0196] [Example 5]

[0197] From the aqueous dispersion of rubber particles obtained in Example 4, composite particles coated with polyorganosilsesquioxane were obtained in the same manner as in Example 2. Using a surfactant, the obtained composite particles were dispersed in water, and measured using a resistance method particle size distribution measuring device (Multisizer 3, manufactured by Beckman Coulter, Inc.). As a result, the particle size distribution was the same as that of the above-mentioned aqueous dispersion of rubber particles, and the volume average particle diameter was 5 μm.

[0198] [Example 6]

[0199] Using the aqueous dispersion of rubber particles obtained in Example 4, composite particles coated with silica were obtained in the same manner as in Example 3. Using a surfactant, the obtained composite particles were dispersed in water, and measured using a resistance method particle size distribution measuring device (Multisizer 3, manufactured by Beckman Coulter, Inc.). As a result, the particle size distribution was the same as that of the aqueous dispersion of the rubber particles, and the volume average particle diameter was 5 μm. The particles were observed with an electron microscope, and as a result, it was confirmed that the composite particles were formed by coating the surface of the rubber particles with silica in a granular shape.

[0200] [Comparative Example 1]

[0201] [Preparation of Flat Organosilicon Rubber]

[0202] 25 g of methylvinylpolysiloxane represented by the following formula (10) and having a kinematic viscosity of 600 mm 2 / s, and methylvinylpolysiloxane represented by the following formula (11) and having a kinematic viscosity of 27 mm 21 g of methylhydrogenpolysiloxane per second (a compounding amount such that the hydrosilylation groups are 1.1 relative to 1 vinyl group) was placed in a 100 mL container and stirred until dissolved. Next, 0.06 g of an isododecane solution of a platinum - vinyl - containing disiloxane complex (platinum content 0.5%) was added and stirred, and it was poured into an aluminum petri dish so as to have a thickness of 10 mm. It was left at 40°C for 2 days to prepare a flat rubber of a rubber composition of silicone particles. The hardness of the rubber was measured in the same manner as in Example 1, and the hardness of this rubber was 60.

[0203]

[0204] [Evaluation of hydrolysis of rubber (measurement of change in hardness of flat rubber over time)]

[0205] For the flat rubbers composed of the alkenyl - containing poly - ε - caprolactone 1 obtained in Example 1 above and the phenylhydrogenpolysiloxane represented by the above formula (8) (rubber hardness: 63), the flat rubbers composed of the alkenyl - containing poly - ε - caprolactone 2 obtained in Example 4 above and the phenylhydrogenpolysiloxane represented by the above formula (8) (rubber hardness: 82), and the flat rubbers composed of the methylvinylpolysiloxane represented by the above formula (10) and the methylhydrogenpolysiloxane represented by the above formula (11) obtained in Comparative Example 1 (rubber hardness: 60), the hydrolysis was evaluated by the following method.

[0206] The three above - mentioned flat rubber specimens were placed in a thermo - hygrostat (Model IW222, manufactured by Yamato Scientific Co., Ltd., Japan) at a temperature of 70°C and a humidity of 90% and left standing, and the change in rubber hardness was measured in days.

[0207] In addition, the flat rubber (rubber hardness: 63) obtained in Example 1 was left standing in a dryer (Model DNE601, manufactured by Yamato Scientific Co., Ltd., Japan) at a temperature of 70°C and in an environment at room temperature and humidity of ~65% (assuming the use environment), and the change in rubber hardness was measured in days.

[0208] [Table 1]

[0209]

[0210] Regarding the flat rubber specimens of Examples 1 and 4 that have been placed in a thermo-hygrostat, since they have a structure crosslinked with poly-ε-caprolactone having an alkenyl group and organohydropolysiloxane having a hydrogen atom bonded to a silicon atom in the presence of a hydrosilylation catalyst, the rubber hardness decreases in a high-temperature and high-humidity environment of 70 °C and 90% humidity, and thus it is presumed to have degradability. On the other hand, regarding the flat rubber specimen of Comparative Example 1, in the components constituting the rubber, a structure having a hydrolyzable functional group such as polyester is not used, and even in a high-temperature and high-humidity environment, the rubber hardness remains unchanged, and thus it is presumed not to have degradability. Regarding the flat rubber specimen of Example 1 that has been placed in a dryer at 70 °C, although it is presumed that the heat slightly causes curing and an increase in rubber hardness is confirmed, since the rubber hardness does not decrease, it is presumed that degradation does not occur unless moisture is present. Regarding the flat rubber specimen of Example 1 placed in an environment of room temperature and humidity of ~65% in a hypothetical usage environment, since the rubber hardness does not decrease during the 95-day measurement period, it is presumed to be stable in the actual usage environment during this measurement period.

Claims

1. A rubber particle, which is (A) a polyester in which the molecular chain ends of poly-ε-caprolactone are substituted with aliphatic unsaturated groups and which has at least 2 aliphatic unsaturated groups in one molecule, and (B) a hydrosilylation crosslinking product of an organohydrogenpolysiloxane having at least 2 hydrogen atoms bonded to a silicon atom in one molecule, provided that a combination in which 2 of the (A) component has 2 of the aliphatic unsaturated groups in one molecule and 2 of the (B) component has 2 hydrogen atoms bonded to the silicon atom in one molecule is excluded, The particle shape is spherical and the volume average particle diameter is 0.1 to 50 μm.

2. The rubber particle according to claim 1, wherein, (B) component is an organohydrogenpolysiloxane having at least 2 hydrogen atoms bonded to a silicon atom in one molecule represented by the following general formula (1), Among them, R 1 is independently a monovalent hydrocarbon group with 1 to 30 carbon atoms, which may be unsubstituted or substituted. R 2 is independently a hydrogen atom or a monovalent hydrocarbon group with 1 to 30 carbon atoms, which may be unsubstituted or substituted. 1 ≤ m ≤ 1000, 0 ≤ n ≤ 1000. However, when n = 0, two R 2 are jointly a hydrogen atom. When two R 2 are not jointly a hydrogen atom, n is 2 or more.

3. The rubber particle according to claim 2, wherein, (B) component is an organohydrogenpolysiloxane having at least 2 hydrogen atoms bonded to a silicon atom in one molecule represented by the following general formula (2), R 3 is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 30 carbon atoms other than phenyl, 0 ≤ a ≤ 500, 1 ≤ b ≤ 1000, 1 ≤ a + b ≤ 1000, 0 ≤ c ≤ 1000, provided that when c = 0, two Rs 2 are jointly hydrogen atoms, and when two Rs 2 are not jointly hydrogen atoms, c is 2 or more.

4. A composite particle, wherein, The surface of the rubber particle according to any one of claims 1 to 3 is coated with polyorganosilsesquioxane or silica.

5. A method for producing a rubber particle according to any one of claims 1 to 3, which comprises the following steps (i) to (iii): (i) A step of adding an aqueous phase component containing a surfactant to an oil phase component composed of a polyester (A) in which the molecular chain ends of poly-ε-caprolactone are substituted with aliphatic unsaturated groups and which has at least 2 aliphatic unsaturated groups in one molecule and an organohydrogenpolysiloxane (B) having at least 2 hydrogen atoms bonded to a silicon atom in one molecule and emulsifying to obtain an O / W type emulsion; (ii) A step of curing the oil phase component containing the (A) component and the (B) component in the emulsion by a hydrosilylation reaction in the presence of a hydrosilylation reactive catalyst to obtain an aqueous dispersion (C) of rubber particles; and (iii) A step of drying and removing water as a continuous phase from the aqueous dispersion (C) of rubber particles obtained in step (ii) to obtain rubber particles.

6. A method for producing a composite particle according to claim 4, which comprises the following steps (i) to (v): (i) A step of adding an aqueous phase component containing a surfactant to an oil phase component composed of a polyester (A) in which the molecular chain ends of poly-ε-caprolactone are substituted with aliphatic unsaturated groups and which has at least 2 aliphatic unsaturated groups in one molecule and an organohydrogenpolysiloxane (B) having at least 2 hydrogen atoms bonded to a silicon atom in one molecule and stirring to obtain an O / W type emulsion; (ii) A step of curing the oil phase component containing the (A) component and the (B) component in the emulsion by a hydrosilylation reaction in the presence of a hydrosilylation reactive catalyst to obtain an aqueous dispersion (C) of rubber particles; (iii’) A step of adding an alkaline substance (E) to the aqueous dispersion (C) of rubber particles obtained in step (ii); (iv) A step of adding one (F) selected from organotrialkoxysilanes represented by the following general formula (3), tetraalkoxysilanes, and their hydrolyzates to the aqueous dispersion of rubber particles added with an alkaline substance obtained in step (iii’) to cause a condensation reaction, and coating the surface of the rubber particles with polyorganosilsesquioxane or silica to obtain an aqueous dispersion of composite particles. R 4 is a monovalent hydrocarbon group having 1 to 6 carbon atoms, R 5 is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 20 carbon atoms or -OR 4 ; and (v) A step of drying and removing water as the continuous phase from the aqueous dispersion of composite particles obtained in step (iv) to obtain composite particles.

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