JP6919593B2 - Silicone rubber composition and silicone rubber - Google Patents

Description

The present invention relates to a silicone rubber composition that provides a cured product having excellent transparency and excellent flame retardancy, and a cured product (silicone rubber) of the composition.

Silicone rubber is widely used in various fields because it has excellent transparency, weather resistance, electrical properties, low compression permanent strain resistance, heat resistance, cold resistance, and the like. In particular, materials used in home appliances are required to have excellent flame retardancy. Further, transparency is required for materials that transmit light, such as lamp holders and liquid crystal blankets.

Silicone rubber has a main skeleton made of siloxane bonds, has a lower proportion of organic components (hydrocarbon components) than ordinary organic rubber, and has the property of being hard to burn. However, under harsh conditions such as direct contact with flames, the silicone rubber ignites and burns. In order to solve the above problems, it is known that a triazole compound is added to a silicone rubber composition as a flame retardant-imparting agent in a platinum compound or a reaction product of a platinum compound and a compound having an alkynyl group and an alcoholic hydroxyl group. (Patent Documents 1 and 2).

Further, a method of adding titanium dioxide having an average particle size of 0.10 to 0.50 μm (Patent Document 3) has also been proposed, but in either case, the transparency of the obtained cured silicone rubber is impaired, which is difficult. The flammability is also not enough.

Further, in the epoxy resin composition, there is a description that silicone powder is effective as a flame retardant imparting agent and a flame retardant aid (Patent Documents 4 and 5), but for silicone rubber having the same molecular structure. , It was not clear whether it had the effect of improving flame retardancy.

Japanese Unexamined Patent Publication No. 10-168317 Japanese Unexamined Patent Publication No. 11-14325 Japanese Unexamined Patent Publication No. 9-194730 International Publication No. 2012/029690 International Publication No. 2017/0227221

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a silicone rubber composition and a silicone rubber which are silicone rubbers (cured products) having excellent light transmission and flame retardancy.

As a result of diligent studies to achieve the above object, the present inventors have made titanium oxide with respect to a silicone rubber composition containing an organopolysiloxane having at least two alkenyl groups in one molecule and reinforcing silica. A mixed solution of an organic solvent sol of inorganic particles having a core-shell structure having a silicon oxide shell on the outside of a core composed of metal fine particles containing silanol and a silanol group-containing siloxane, a silicone resin powder and a triazole-based compound. By blending, it was found that the cured product of this silicone rubber composition is excellent in light transmission and flame retardancy, and the present invention has been achieved.

Therefore, the present invention provides the following silicone rubber composition and a silicone rubber obtained by curing the composition.
1. 1. (A) The following average composition formula (1)
R _n SiO _{(4-n) / 2} (1)
(In the formula, R is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 12 carbon atoms, and n is a positive number of 1.95 to 2.05.)
Organopolysiloxane represented by and having at least two alkenyl groups in one molecule
100 parts by mass,
(B) Reinforcing silica with a specific surface area of 50 m ² / g or more 5 to 100 parts by mass,
(C) It has a core-shell structure having a silicon oxide shell on the outside of a nucleus composed of metal fine particles containing titanium oxide, and has a 50% cumulative distribution diameter of 1 to 200 nm in a volume-based particle size distribution by a dynamic light scattering method. 0.01 to 50 parts by mass of a mixed solution of inorganic particles, an organic solvent sol of the inorganic particles, and a silanol group-containing siloxane having a degree of polymerization of 1 to 20.
(D) Silicone resin powder 1 to 50 parts by mass,
(E) Triazole-based compound 0.001 to 0.1 parts by mass,
(F) Platinum-based compound Contains 0.5 to 1,000 ppm with respect to the total mass of the components (A) to (E), and an effective amount for curing the (G) curing agent (A) component , as described above (C). ) A silicone rubber composition, wherein the content of the inorganic particles having a core-shell structure of the component is 0.68 to 1.7 parts by mass with respect to 100 parts by mass of the component (A).
2. The surface of the inorganic particles having the core-shell structure of the component (C) is the following general formula (2).
R ¹⁹ Si (Y) ₃ (2)
(In the formula, R ¹⁹ may be the same or different, and may be substituted with a (meth) acrylic group, an oxylanyl group, an amino group, a mercapto group, an isocyanate group or a fluorine atom. Substituent or hydrogen selected from the group consisting of the following alkyl groups, alkenyl groups having 2 or more and 20 or less carbon atoms, aryl groups having 6 or more and 20 or less carbon atoms, and (poly) dimethylsiloxy groups having 50 or less silicon atoms. It is an atom, and Y is a substituent selected from the group consisting of an alkoxy group, an acetoxy group, an enol group, and a chlorine atom.)
The silicone rubber composition according to 1 above, which is surface-modified with an organosilicon compound represented by (1) and / or a (partial) hydrolyzed condensate thereof.
3. 3. The silicone rubber composition according to 1 or 2 above, wherein the triazole-based compound of the component (E) is benzotriazole.
4. The silicone rubber composition according to any one of 1 to 3 above, wherein the curing agent for the component (G) is an addition reaction curing type comprising a combination of an organohydrogenpolysiloxane and a hydrosilylation catalyst.
5. The silicone rubber composition according to any one of 1 to 3 above, wherein the curing agent for the component (G) is an organic peroxide.
6. A silicone rubber made of a cured product of the silicone rubber composition according to any one of 1 to 5 above.

The silicone rubber composition of the present invention can provide a silicone rubber (cured product) having excellent light transmission and flame retardancy.

Hereinafter, the present invention will be described in detail.
The silicone rubber composition of the present invention comprises an organopolysiloxane (A) having at least two alkenyl groups in one molecule as a base polymer, an addition reaction curing agent (G-1) and / or as a curing agent (G). An organic peroxide curing agent (G-2) is used. The shape of this silicone rubber composition is preferably a mirrorable type that can be extruded. The mirabable silicone rubber composition is a non-liquid (solid or highly viscous paste) having high viscosity and no self-fluidity at room temperature, and is uniformly kneaded under high shear stress by a kneading means such as a roll mill. It means a raw rubber-like composition that can be mixed.

-(A) component-
In the present invention, the component (A) is an organopolysiloxane represented by the following average composition formula (1).
R _n SiO _{(4-n) / 2} (1)
(In the formula, R is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 12 carbon atoms, and n is a positive number of 1.95 to 2.05.)

In the above average composition formula (1), R is a monovalent hydrocarbon group having the same or different substituents or substituents having 1 to 12 carbon atoms, and those having 1 to 8 carbon atoms are particularly preferable. Specifically, an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, a hexyl group or an octyl group, a cycloalkyl group such as a cyclopentyl group or a cyclohexyl group, an alkenyl group such as a vinyl group, an allyl group or a propenyl group. , Cycloalkenyl group, phenyl group, aryl group such as tolyl group, aralkyl group such as benzyl group and 2-phenylethyl group and the like. Further, a part or all of the hydrogen atoms of these groups may be replaced with a halogen atom such as fluorine or chlorine or a cyano group. Of these, a methyl group, a vinyl group, a phenyl group and a trifluoropropyl group are preferable, and a methyl group and a vinyl group are particularly preferable.

In particular, the organopolysiloxane as the component (A) has two or more, usually 2 to 50, particularly about 2 to 20 alkenyl groups, cycloalkenyl groups and other aliphatic unsaturated groups in one molecule. Those having a vinyl group are preferable, and those having a vinyl group are particularly preferable. In this case, 0.01 to 20 mol%, particularly 0.02 to 10 mol% of the total R is preferably an aliphatic unsaturated group. The aliphatic unsaturated group may be bonded to a silicon atom at the end of the molecular chain, to a silicon atom in the middle of the molecular chain (non-terminal of the molecular chain), or both. However, it is preferable that it is bonded to at least a silicon atom at the end of the molecular chain.
Further, 80 mol% or more, preferably 90 mol% or more, more preferably 95 mol% or more, still more preferably all Rs except the aliphatic unsaturated group in the total R are alkyl groups, particularly methyl groups. Is desirable.

In the above formula (1), n is a positive number of 1.95 to 2.05, preferably 1.98 to 2.02, and more preferably 1.99 to 2.01.

The molecular structure of the organopolysiloxane as the component (A) is preferably linear or linear with a partially branched structure. _{Specifically, the repeating structure of the diorganosiloxane unit (R 2} SiO _2/2 , R is the same as above, the same applies hereinafter) constituting the main chain of the organopolysiloxane consists of repeating only the dimethylsiloxane unit. , Or a diphenylsiloxane unit having a phenyl group, a vinyl group, a 3,3,3-trifluoropropyl group or the like as a substituent as a part of a dimethylpolysiloxane structure composed of repeating dimethylsiloxane units constituting the main chain. Those introduced with diorganosiloxane units such as methylphenylsiloxane unit, methylvinylsiloxane unit, and methyl-3,3,3-trifluoropropylsiloxane unit are suitable.

_{Further, both ends of the molecular chain are, for example, a triorganosyloxy group (R 3} SiO _1/2 ) such as a trimethylsiloxy group, a dimethylphenylsiloxy group, a vinyldimethylsiloxy group, a divinylmethylsiloxy group, a trivinylsiloxy group, or hydroxydimethyl. It is preferably sealed with a hydroxydiorganosiloxy group (R ₂ (HO) SiO _{1/2) such as a siloxy group.}

As described above, the organopolysiloxane of the component (A) has a triorganosyloxy group (R ₃ SiO _1/2 ) or a hydroxydiorganosyloxy group (R ₂ (HO) SiO _1/2 ) at both ends of the molecular chain. A linear one in which the main chain is closed and the main chain _{consists of repeating diorganosiloxane units (R 2} SiO _2/2 ) can be preferably mentioned. Particularly preferred are methylvinylpolysiloxane, methylphenylvinylpolysiloxane, and methyltrifluoropropylvinyl as the type of substituent in the molecule (ie, an unsubstituted or substituted monovalent hydrocarbon group attached to a silicon atom). Examples thereof include polysiloxane and dimethylpolysiloxane.

Such an organopolysiloxane can be obtained, for example, by (co) hydrolyzing and condensing one or more of organohalogenosilanes, or by making cyclic polysiloxanes (trimers of siloxanes, tetramers, etc.) alkaline or It can be obtained by ring-opening polymerization using an acidic catalyst.

The degree of polymerization of the organopolysiloxane is preferably 100 or more (usually 100 to 100,000), preferably 150 to 100,000. This degree of polymerization can be measured as a polystyrene-equivalent weight average degree of polymerization by gel permeation chromatography (GPC) analysis.

The component (A) may be used alone or as a mixture of two or three or more having different molecular weights (degrees of polymerization) and molecular structures.

-(B) component-
The reinforcing silica of the component (B) is a filler added to obtain a silicone rubber composition having excellent mechanical strength, and for this purpose, the specific surface area by the BET adsorption method is 50 m ² / g or more. It is necessary that the amount ^{is 100 to 450 m 2} / g, more preferably 100 to 300 m ² / g. If the specific surface area is ^{less than 50 m 2} / g, the mechanical strength of the cured product will be low.

Examples of such reinforcing silica include fuming silica (fumed silica), precipitated silica (wet silica), and the like, and the surfaces thereof are an organosilane compound such as methylchlorosilane, hexamethyldisilazane, and the like. A product which has been hydrophobized with a silazane compound or the like is also preferably used. Of these, aerosol silica, which has excellent transparency, is preferable.

The component (B) may be used alone or in combination of two or more.

The blending amount of the reinforcing silica of the component (B) is 5 to 100 parts by mass, preferably 10 to 100 parts by mass, and 20 to 60 parts by mass with respect to 100 parts by mass of the organopolysiloxane of the component (A). Is more preferable. If the amount of the component (B) is too small, the reinforcing effect cannot be obtained, and if it is too large, the workability is deteriorated, the mechanical strength is lowered, and the dynamic fatigue durability is also deteriorated. It ends up.

In the present invention, (B) a dispersant (wetter) of reinforcing silica can be blended as an optional component, if necessary. Examples of this wetter include a silanol group (that is, a silicon atom-bonded hydroxyl group) -containing silane compound such as diphenylsilanediol, and a linear dimethylsiloxane oligomer having a silanol group block at both ends of the molecular chain (for example, the degree of polymerization or in the molecule). One or more selected from silanol group-containing organosiloxane oligomers (low-polymerized polymers having 2 to 30 silicon atoms, particularly 3 to 20 silicon atoms) and the like are used.

The blending amount of the wetter is preferably 0 to 25 parts by mass, more preferably 3 to 20 parts by mass with respect to 100 parts by mass of the base polymer (component (A)). ..

-(C) component-
The component (C) is an organic solvent sol of inorganic particles having a core-shell structure having a silicon oxide shell on the outside of a nucleus composed of metal fine particles containing titanium oxide, and a silanol group-containing siloxane having a degree of polymerization of 1 to 20. It is a mixed solution. The above-mentioned inorganic particles may be referred to as "core-shell titanium oxide particles" in the following description.

The content of the core-shell titanium oxide particles in the organic solvent sol is preferably 1 to 50% by mass, more preferably 10 to 40% by mass. If the content is less than 1% by mass, the amount added increases, and it takes time to remove the organic solvent from the silicone rubber composition of the present invention, which is uneconomical. On the contrary, if the content is more than 50% by mass, it is difficult to disperse the core-shell titanium oxide particles.

Examples of the metal fine particles containing titanium oxide used as a core include those containing titanium oxide as essential and tin oxide and indium tin oxide, and a solid solution of titanium oxide and tin and / or manganese is used. May be good.

The particle size of the metal fine particles containing titanium oxide is 50% cumulative distribution diameter (D ₅₀ ) based on the volume measured by a dynamic light scattering method using a laser beam. For example, as the dynamic light scattering method, an apparatus such as Nanotrack UPA-EX150 (manufactured by Nikkiso Co., Ltd.) can be used. Since transparency of the core-shell titanium oxide particles used in the present invention is important in the visible region, the D ₅₀ of the raw material titanium oxide fine particles needs to be 1 to 200 nm, preferably 1 to 100 nm. , 1 to 80 nm, more preferably 1 to 50 nm. When the average cumulative particle size of the titanium oxide fine particles exceeds 200 nm, the particle size of the core-shell titanium oxide particles becomes larger than the light wavelength in the visible region, and scattering may become remarkable. On the other hand, if it is less than 1 nm, the total surface area of the dispersoid in the system becomes extremely large, which may make it difficult to handle as a dispersion liquid, for example, agglomeration is likely to occur.

_{The D 50} of the core-shell titanium oxide particles is preferably 1 to 200 nm, more preferably 1 to 100 nm, and further preferably 5 to 50 nm.

[(Α) step]
In the first step (α) in the method for producing the organic solvent sol of the core-shell titanium oxide particles of the component (C), the volume-based 50% cumulative particle size (D ₅₀ ) measured by the dynamic light scattering method is 1 to 200 nm. This is a step of preparing a dispersion liquid in which the core-shell titanium oxide particles are dispersed in a polar organic solvent.

In the present invention, as described above, the dispersion liquid refers to a state in which the particles are stably dispersed (colloidal dispersion) in which the particles do not settle at the time of passage unless otherwise specified. The stable dispersion state occurs when the Brownian motion velocity of the particles becomes faster than the sedimentation velocity due to its own weight. On the other hand, in a viscous liquid such as silicone, the sedimentation rate of the particles is slow, so it is difficult to determine whether or not the particles are stably dispersed. In such a case, the presence or absence of particle sedimentation can be determined by applying a centrifugal force using a centrifuge to promote the sedimentation of the particles.

The core-shell titanium oxide particles prepared in the present invention are as described above, but the titanium oxide fine particle raw material in the present invention may be a synthetic one or a commercially available general-purpose product. As a specific example of using a commercially available product, in titanium oxide fine particles dispersed in water such as Tynoc M-6 (titanium oxide aqueous dispersion, manufactured by Taki Chemical Co., Ltd.), water as a dispersion medium is replaced with a polar organic solvent. May be used. Further, the aqueous dispersion may be one in which the surface of the core-shell titanium oxide particles is treated with a general-purpose silane coupling agent or dispersant before solvent replacement.

<Raw material colloidal dispersion>
In the above step (α), it is preferable to use a colloidal dispersion of core-shell titanium oxide particles using water as a dispersion medium. As the water, fresh water such as tap water, industrial water, well water, natural water, rainwater, distilled water, and ion-exchanged water can be used, but ion-exchanged water is particularly preferable. Ion-exchanged water can be produced using a pure water producer (for example, manufactured by Organo Corporation, product name "FW-10", manufactured by Merck Millipore Co., Ltd., product name "Direct-QUV3", etc.). .. Further, the dispersion medium may contain a monohydric alcohol that can be arbitrarily mixed with water in the step of producing the aqueous dispersion colloidal solution as described below. A monohydric alcohol that is optionally mismixable with water may be contained as a co-solvent in the production of core-shell particles and as a hydrolysis by-product of the metal alkoxide in the sol-gel reaction. The dispersoid concentration of the raw material colloidal dispersion prepared in the present invention is preferably 1% by mass or more and 35% by mass or less, more preferably 5% by mass or more and 30% by mass or less, and further preferably 10% by mass or more and 25% by mass or less. be. If the dispersoid concentration is lower than 1% by mass, the production efficiency may not be good. If the dispersoid concentration is higher than 35% by mass, gelation may easily occur depending on conditions such as pH and temperature.

The step (α) is a step of modifying the surface of the core-shell titanium oxide particles with an organosilicon compound and / or a (partial) hydrolysis condensate of the organosilicon compound when the surface of the core-shell titanium oxide particles has a siloxane coating layer (α-). It consists of 1) and a step (α-2) of solvent substitution with a polar organic solvent. Details will be described below.

[Step (α-1)]
The step (α-1) is a step of modifying the surface of the core-shell titanium oxide particles by adding an organosilicon compound represented by the following general formula (2) and / or a (partial) hydrolyzed condensate of the organosilicon compound. ..
R ¹⁹ Si (Y) ₃ (2)
(In the formula, R ¹⁹ may be the same or different, and may be substituted with a (meth) acrylic group, an oxylanyl group, an amino group, a mercapto group, an isocyanate group or a fluorine atom. Substituent or hydrogen selected from the group consisting of the following alkyl groups, alkenyl groups having 2 or more and 20 or less carbon atoms, aryl groups having 6 or more and 20 or less carbon atoms, and (poly) dimethylsiloxy groups having 50 or less silicon atoms. It is an atom, and Y is a substituent selected from the group consisting of an alkoxy group, an acetoxy group, an enol group, and a chlorine atom.)

In this case, the alkyl group preferably includes an alkyl group having 1 to 6 carbon atoms, particularly a methyl group and an ethyl group, and the aryl group includes an aryl group having 6 to 10 carbon atoms, particularly a phenyl group. Further, the number of silicon of the (poly) dimethylsiloxy group is preferably 1 to 50, particularly preferably 1 to 30.

Specific examples of the organic silicon compound represented by the general formula (2) include hydrogen trimethoxysilane, hydrogen triethoxysilane, methyl trimethoxy silane, methyl triethoxysilane, methyl triisopropoxysilane, ethyl trimethoxysilane, and ethyl tri. Ethoxysilane, ethyltriisopropoxysilane, propyltrimethoxysilane, propyltriethoxysilane, propyltriisopropoxysilane, phenyltrimethoxysilane, vinyltrimethoxysilane, allyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ − Methacryloxypropyltriethoxysilane, γ-acryloxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxy Silane, γ-chloropropyltrimethoxysilane, 3,3,3-trifluoropropyltrimethoxysilane, 3,3,3-trifluoropropyltriethoxysilane, perfluorooctylethyltrimethoxysilane, γ-mercaptopropyltrimethoxy Silane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N- (2-aminoethyl) aminopropyltrimethoxysilane, γ-isocyanabotrimethoxysilane, γ-isocyanabotriethoxysilane, phenyltri Partial hydrolysis condensate of methoxysilane, phenyltriethoxysilane, tris (3-trimethoxysilylpropyl) isocyanurate in which isocyanate groups are bonded, tris (3-triethoxysilylpropyl) isocyanurate, and methyltrimethoxysilane (commodity) Names "KC-89S", "X-40-9220" manufactured by Shin-Etsu Chemical Industry Co., Ltd., partial hydrolysis condensate of methyltrimethoxysilane and γ-glycidoxypropyltrimethoxysilane (trade name "X-41") -1056 ”alkoxysilanes such as Shin-Etsu Chemical Industry Co., Ltd .; allylsilanes such as triallylmethylsilane, triallylethylsilane, and triallylisopropylsilane; triacetoxymethylsilane, triacetoxyethylsilane, and triacetoxypropylsilane. , Acetoxysilanes such as triacetoxyphenylsilane; trichloromethylsilane, trichloroethylsilane, trichloropropylsilane, tri Chlorosilanes such as chlorophenylsilane; enolsilanes such as triisopropenyloxymethylsilane, ethyltriisopropenyloxysilane, triisopropenyloxypropylsilane, and phenyltriisopropenyloxysilane can be mentioned.

In the organosilicon compound represented by the general formula (2), ^{as a specific example when R 19} is (poly) dimethylsiloxane, a compound represented by the following general formula (3) can be mentioned. In the general formula (3), r is preferably an integer of 0 or more and 49 or less, more preferably r is an integer of 5 or more and 40 or less, and further preferably r is an integer of 10 or more and 30 or less. When r is larger than 49, the property as a silicone oil becomes stronger, and the solubility of the surface-treated organosol in various resins may be limited, which is not preferable. In the following general formula (3), the compound having an average structure of r = 30 can be obtained under the trade name “X-24-9822” (manufactured by Shin-Etsu Chemical Co., Ltd.). Me represents a methyl group.

The amount of the organosilicon compound to be added is preferably 0.5 times or more and 50 times or less, and more preferably 1 time or more and 25 times or less with respect to the dispersoid weight of the raw material colloidal aqueous dispersion. More preferably, it is 2 times or more and 10 times or less. If the amount added is more than 50 times the dispersoid weight of the raw material colloidal aqueous dispersion, gelation may occur. If the amount added is less than 0.5 times, the coating may not be sufficiently performed and agglutination may occur.

The method for adding the organosilicon compound can be carried out by dropping in liquid, dropping outside the liquid, adding a portion, and the like, and it is preferable that the organic silicon compound is dropped in liquid.

In the step (α-1), an acid or a base catalyst for accelerating the surface treatment can be added, if necessary. Specific examples of the base catalyst include potassium hydroxide, sodium hydroxide, potassium carbonate, sodium carbonate, a basic ion exchange resin, and the like. Examples of the acid catalyst include hydrochloric acid, sulfuric acid, methanesulfonic acid, trifluoromethanesulfonic acid, acetic acid, and a cationic ion exchange resin. Further, examples of the cationic ion exchange resin include Amberlite (manufactured by Organo Corporation), Levacit (manufactured by Lanxess Co., Ltd.), Purolite (manufactured by Purolite Co., Ltd.), Muromac (manufactured by Muromachi Chemical Co., Ltd.) and the like. The amount of the catalyst used is preferably 0.01% by mass or more and 20% by mass or less, more preferably 0.1% by mass or more and 10% by mass or less, still more preferably 1% by mass or more, based on the inorganic particles. It is 5% by mass or less. If the addition amount is more than 20% by mass, the reaction may proceed rapidly and control may be difficult, which is not preferable. If the addition amount is less than 0.01% by mass, the reaction may not proceed.

The liquid temperature at the time of adding the organosilicon compound is preferably 0 ° C. or higher and 45 ° C. or lower, more preferably 5 ° C. or higher and 40 ° C. or lower, and further preferably 10 ° C. or higher and 35 ° C. or lower. If the liquid temperature is lower than 0 ° C., the colloidal aqueous dispersion may change its state due to freezing, which is not preferable. If the liquid temperature is higher than 45 ° C., the added organosilicon compound may cause an unexpected hydrolysis / condensation reaction, which is not preferable. As a result of hydrolysis condensation, the temperature of the reaction solution may reach a degree not exceeding 70 ° C.

In the step (α-1), the above reaction solution may be diluted with an organic solvent if necessary, and the diluting solvent is preferably monohydric alcohols such as methanol, ethanol, isopropyl alcohol and butanol; ethylene glycol and propylene. Polyhydric alcohols such as glycol and glycerin; ethers such as propylene glycol monomethyl ether, ethylene glycol monomethyl ether, glyme and jigrim; ketones such as acetone and methyl isobutyl ketone; esters such as ethyl acetate and propylene glycol monomethyl ether acetate Reactive esters such as hexanediol diacrylate, trimethylpropantriacrylate, pentaerythritol tetraacrylate, and dipentaerythritol hexaacrylate can be used, and ethanol and isopropyl alcohol are particularly preferable. Dilution is preferably carried out to avoid solvent shock in the next step (α-2), but is not always essential. The dilution ratio is preferably 1 to 20 times, more preferably 2 to 15 times, still more preferably 3 to 10 times. The effect of solvent shock mitigation intended to be less than 1 may not be sufficient. If it is larger than 20, it may take a lot of processing time in the next process.

[Step (α-2)]
The step (α-2) is a step of replacing the dispersion medium in the reaction solution with a polar organic solvent, and concentration can be performed as necessary by exuding the dispersion medium of the dispersion solution by ultrafiltration. .. The dispersion medium is water contained in the aqueous dispersion produced in the step (α-1), a hydrolyzed condensate of the added organic silicon compound and / or the organic silicon compound, and / or a silicic acid ester produced by the hydrolyzed condensation. Derived alcohols and organic solvents can be included. By exuding the dispersion liquid of such a complex system, the dispersoid concentration of the dispersion liquid in the filtration chamber is preferably 1 to 30% by mass, more preferably 5 to 25% by mass, and further preferably 10 to 20% by mass. Concentrate to. Although the dispersion medium exuded in this system is a complicated mixture, a porous ceramic filter can be preferably used. In the conventional method, a hollow fiber membrane was preferably used for removing salts in water, but there was a risk of clogging in a particle dispersion system. Organic polymer ultrafiltration membranes are often used in areas such as particle removal, concentration, and solid-liquid separation, but if organic solvents are contained, the filtration membranes may swell and become unusable. Inorganic ceramic filters are useful for solid-liquid separation and concentration of samples containing organic solvents.

In ultrafiltration, it is preferable to use a filter plate having an inorganic ceramic film having an average pore diameter of 5 nm or more and less than 20 nm, more preferably 6 nm or more and less than 18 nm, and most preferably 7 nm. The filter plate is preferably in the shape of a disk that can rotate. The porous inorganic ceramic film can be produced by a known method. Examples of the material of the porous inorganic ceramic film include spinel-based, alumina-based, titania-based, and zirconia-based materials. For example, if it is a spinel system, a known method (Ueno, S et al., Journal of Physics: Conference Series 2009, Vol. 165, No. 1, Fabrication of porosity magnesium magnesium or It can be synthesized in 2000, 2000, No. 03, MgAl ₂ O Ultrafiltration Ceramic Membrane Delivered from Mg-Al Double Alkoxide, etc.). It is preferable to control the pore size by controlling the synthesis conditions and the crystal growth of spinel. It is preferable that the filter plate is formed by epitaxial growth of a surface layer having a uniform pore diameter on a porous disk-shaped unglazed plate made of alumina or the like by a sol-gel method. As a porous disk made of alumina or the like, it is preferable to use a porous disk having a pore diameter of 0.05 μm or more and 1 μm or less as a base material. The surface layer preferably has an average pore diameter of 5 nm or more and less than 20 nm, more preferably 6 nm or more and less than 18 nm, and most preferably 7 nm. The size of the disk-shaped filter plate is preferably 100 mm or more and less than 500 mm in diameter, more preferably 120 mm or more and less than 300 mm, and further preferably 140 mm or more and 200 mm. If this diameter is less than 100 mm, shear stress is less likely to be applied when rotating, and it is also difficult to secure an area, which may be unfavorable. On the contrary, if the diameter is 500 mm or more, the torque required for rotation may increase. Further, if the diameter is too large, it may be easily cracked and may be difficult to handle. The thickness of the filter plate is preferably 1 mm or more and less than 10 mm, and more preferably 3 mm or more and less than 5 mm. If the filter plate is less than 1 mm, mechanical strength may not be ensured. If the filter plate is 10 mm or more, it may not be preferable in terms of securing the volume of the filtration chamber. Such a filter may be manufactured by a known method, or a commercially available filter may be used.
The pore size of the filter used in the solvent replacement step is preferably determined by electron microscopy. Examples of electron microscopes that can be used for such purposes include scanning electron microscopes, transmission electron microscopes, and atomic force microscopes.

In the solvent replacement step, the dispersion medium is exuded by a static pressure of preferably less than 0.5 MPa, more preferably less than 0.4 MPa, further preferably less than 0.3 MPa, and most preferably less than 0.2 MPa and 0.03 MPa or more. At a static pressure of 0.5 MPa or more, the interface selection of the filtration device may be limited. If it is less than 0.03 MPa, it may not exude efficiently. The static pressure is preferably a head tube or closed system whose surface is in contact with the atmosphere and is achieved by hydraulic and compressed air pressure. In particular, the compressed air pressure method is preferable because the device can be made compact. Compressed air can be easily produced by using a known method or a commercially available compressor.

In the solvent replacement step, a shear stress of preferably 0.1 Pa or more and 10 Pa or less, more preferably 0.5 Pa or more and 5 Pa or less, still more preferably 1 Pa or more and 5 Pa or less is applied to the filter plate. Shear stress may be achieved by the flow of the dispersion or by the rotation of the disc-shaped filter plate. In particular, when shear stress is applied by rotation of the filter plate, the shear rate on the surface of the filter plate increases, which is preferable. Shear stress can be calculated from the distance between walls and the rotational speed in the filter chamber. In addition, an appropriate baffle (obstruct plate) can be provided in the filter chamber as needed. The baffle is preferably installed for the purpose of reducing the distance between walls in the filter chamber. Increasing shear stress by rotation and baffle is a known means. The maximum shear stress (τ) acting on the circumference is the diameter of the disc-shaped filter plate (φ [m]), the rotation speed of the filter plate (ω [rps]), and the distance between the filter plate and the wall of the filtration chamber. Is (L [m]), the circumference ratio is (π), and the viscosity of the dispersion liquid is (η [Pa · s]).
τ = (η ・ π ・ φ ・ ω) / L [Pa] …… Formula (1)
For example, diameter φ = 0.15 [m], filter plate rotation speed ω = 16.7 [rps] (≈1,000 [rpm]), pi = 3.14, viscosity of dispersion η = When 0.001 [Pa · s] and the inter-wall distance L = 0.003 [m], τ = (0.001 × 3.14 × 0.15 × 16.7) /0.003≈2. It is 6 [Pa]. The shear stress can be given by changing the respective parameters of φ, ω, and L so as to be within the above preferable range.

The rotational energy given to the dispersion in the solvent replacement step is preferably defined by the shear stress, but can also be defined by the fluid state. The state of the fluid can also be defined by the Reynolds number. The stirring Reynolds number is preferably 3,000 or more and 5,000,000 or less, more preferably 5,000 or more and 1,000,000 or less, and further preferably 10,000 or more and 500,000 or less. If it is smaller than 3,000, laminar flow stirring may occur and efficient dispersion may be difficult. If it is larger than 5,000,000, the energy required for stirring becomes unnecessarily large, which is preferable from the viewpoint of industrial efficiency. Sometimes not. The Reynolds number (Re) can be obtained from the mathematical formula (2). In formula (2), ρ represents density (kg / m ³ ), ω represents rotation speed (rps), φ filter plate diameter (m), and η represents viscosity (Pa · s).
Re ＝ ρ ・ ω ・ φ ² / η …… Formula (2)

The core-shell titanium oxide particle dispersion treated in the present invention has ρ of 900 to 2,000 (kg / m ³ ), preferably 1,000 to 1,500 (kg / m ³ ), and η of 0.001 to 0. It is 05 (Pa · s), preferably 0.002 to 0.01 (Pa · s). For example, a 0.15 (m) disk-shaped filter plate ^{is treated with a titanium oxide dispersion having a ρ of 1,000 (kg / m 3} ) and an η of 0.001 (Pa · s) at 16.7 (rps). Re in the case of is about 3.8 × 10 ^5. By appropriately selecting ω and φ, it can be adjusted so as to be within the above desired Re range. Further, for stirring, a method for improving stirring efficiency by using a reactor equipped with a baffle may be implemented.

The solvent replacement step is preferably carried out at 5 to 80 ° C., more preferably 10 to 60 ° C., still more preferably 15 to 50 ° C., and most preferably 20 to 40 ° C. If it is lower than 5 ° C., the dispersion may freeze. If the temperature is higher than 80 ° C., there may be a problem in the working environment due to the volatilization of the dispersion medium and / or reaction energy when reactive esters are used and gelation may occur. The viscosity of the dispersion is generally temperature dependent. Since the viscosity affects the rotational torque, it may be carried out by adjusting the temperature so that the electromagnetic rotor and / or the engine is not overloaded. In the solvent replacement step, unreacted compounds and by-products can be removed as needed by continuous ultrafiltration.

Here, specific examples of the organic solvent used in the solvent replacement step include methanol, ethanol, 1-propanol, 2-propanol, cyclopentanol, ethylene glycol, propylene glycol, β-thiadiglycol, butylene glycol, glycerin and the like. Unit price and polyhydric alcohols can be mentioned.

Among these, methanol, ethanol, isopropyl alcohol, n-propyl alcohol and the like are particularly preferable from the viewpoint of dispersibility of the core-shell titanium oxide particles and the ease of distillation of the dispersion medium.
The amount of the organic solvent used in the solvent replacement step is preferably 1 to 20 times by volume, more preferably 2 to 10 times by volume, and further preferably 3 to 8 times by volume of the filtration chamber capacity. If it is less than 1 volume times, the solvent substitution may not be sufficient. If it is more than 20 times by volume, it may not be preferable in terms of industrial efficiency.

In the above formula (2), when the surface of the core-shell titanium oxide particles ^{does not have a siloxane coating layer composed of SiR 1} O _3/2 units, the step (α-1) is not carried out and only the step (α-2) is performed. In this case, when the core-shell titanium oxide particles dispersed in water are used, the solvent is replaced as described above. However, if the core-shell titanium oxide particles are in the form of powder, they may be dispersed in the organic solvent, and if the core-shell titanium oxide particles are dispersed in the organic solvent in advance, the step (α-2) may be omitted. Can be done.

[(Β) step]
This step is a step of preparing a mixed solution of the organic solvent sol of the core-shell titanium oxide particles and the silanol group-containing siloxane in the component (C). As the organic solvent sol of the core-shell titanium oxide particles, those prepared through the above (α-1) and (α-2) may be used, or commercially available ones may be used. Preferred embodiments of the organic solvent sol, such as dispersoid concentration, are as described above. The silanol group-containing siloxane is an organo (poly) siloxane having at least 2, preferably 2 to 10 silanol groups in one molecule. If the number of silanol groups is less than two, the particles may aggregate or the transparency of the sol may decrease when mixed with the organic solvent sol of the core-shell titanium oxide particles, which is not preferable. Examples of the group other than the hydroxyl group bonded to the silicon atom of the organo (poly) siloxane include a monovalent hydrocarbon group having 1 to 10 carbon atoms, particularly 1 to 6 carbon atoms, and an alkyl group, particularly a methyl group. The degree of polymerization of the silanol group-containing siloxane needs to be 1 to 20, preferably 1 to 10. If the degree of polymerization is greater than 20, the core-shell titanium oxide particles will settle when mixed with the organic solvent sol of the core-shell titanium oxide particles, and the transparency of the silicone rubber composition and its cured product will deteriorate. When the organic solvent sol of the core-shell titanium oxide particles and the silanol group-containing siloxane are mixed, their ratio is 1/10 to 5/1 by mass ratio. The mixing ratio of the organic solvent sol of the core-shell titanium oxide particles and the silanol group-containing siloxane is not particularly limited, but is preferably 1/10 to 5/1 in terms of mass ratio, and more preferably 1/5 to 2 /. It is 1. When the ratio of the organic solvent sol to the silanol group-containing siloxane is less than 1/10, the dispersion of titanium oxide particles in the mixed solution becomes insufficient, and the transparency of the silicone rubber composition and its cured product deteriorates. There is a risk. If the mixing ratio is larger than 5/1, the dispersion of titanium oxide particles in the compound may be insufficient, and the transparency of the silicone rubber composition and its cured product may be deteriorated. The mixture of the organic solvent sol of the core-shell titanium oxide particles and the silanol group-containing siloxane is preferably uniformly dispersed, and particularly preferably has no sediment.

-(D) component-
As the component (D), a silicone resin powder which is a fine powder of polyorganosylsesquioxane, for example, those described in JP-A-2-209927 are used.
_{The silicone resin powder has a particle size (d 50} ) having a cumulative frequency of 50% measured by a laser diffraction method of 1 to 50 μm, preferably 3 to 40 μm. If d ₅₀ is less than 1 μm, no flame retardant effect is observed, and if d 50 is 50 μm or more, the transparency deteriorates.

The blending amount of the silicone resin powder of the component (D) is 1 to 50 parts by mass, preferably 20 to 40 parts by mass with respect to 100 parts by mass of the organopolysiloxane of the component (A). If this blending amount is small, the flame retardant effect is insufficient, and if the blending amount is large, not only is it uneconomical, but transparency may deteriorate.

-(E) component-
Examples of the triazole-based compound of the component (E) include 1,2,3-triazole, 1,2,4-triazole and derivatives thereof. Specifically, the 1,2,3-triazole derivatives include benzotriazole, 4-hydroxy-1,2,3-triazole, 1,2,3-triazole-4-aldehyde, 4-cyano-1,2, Examples include 3-triazole. Derivatives of 1,2,4-triazole include 5-amino-3-methyl-1,2,4-triazole, 3-mercapto-1,2,4-triazole and the like. The most suitable of these are benzotriazole, 1,2,3-triazole and 1,2,4-triazole. These may be used alone or in combination of two or more.

The blending amount of the component (E) is 0.001 to 0.1 parts by mass, preferably 0.005 to 0.05 parts by mass with respect to 100 parts by mass of the organopolysiloxane of the component (A). If it is less than 0.001 part by mass, the flame retardancy is not improved, and if it is more than 0.1 part by mass, it is not economical and the cured product may turn yellow.

-(F) component-
Examples of the platinum-based compound of the component (F) include platinum black, second platinum chloride, platinum chloride acid, a reaction product of platinum chloride acid and a monovalent alcohol, a complex of platinum chloride acid and olefins, platinum bisacetoacetate and the like. Platinum-based compounds can be mentioned.

The blending amount of this platinum-based compound is 0.5 to 1,000 ppm, particularly about 1 to 500 ppm, based on the total mass of the components (A) to (E) in terms of platinum (mass conversion). If it is less than 0.5 ppm, the flame retardancy is insufficient, and if it is 1,000 ppm or more, it is not economical and the flame retardancy may decrease.

-(G) component-
The curing agent is not particularly limited as long as it can cure the component (A), and examples thereof include the following (G-1) addition reaction curing agent and (G-2) organic peroxide curing agent.

(G-1) Addition reaction curing agent (G-1) As the addition reaction curing agent, an organohydrogenpolysiloxane and a hydrosilylation catalyst are used in combination.

As the organohydrogenpolysiloxane, hydrogen atoms bonded to 2 or more, preferably 3 or more, more preferably 3 to 200, and further preferably about 4 to 100 silicon atoms in one molecule (that is, SiH). As long as it contains a group), it may have a linear, cyclic, branched, or three-dimensional network structure, and an organohydrogenpolysiloxane known as a cross-linking agent for an addition reaction-curable silicone rubber composition is used. For example, an organohydrogenpolysiloxane represented by the following average composition formula (5) can be used.
R ²⁰ _p H _q SiO _{(4-pq) / 2} (5)

In the above average composition formula (5), R ²⁰ represents an unsubstituted or substituted monovalent hydrocarbon group, which may be the same or different, and preferably excludes an aliphatic unsaturated bond. .. Usually, those having 1 to 12 carbon atoms, particularly 1 to 8 carbon atoms are preferable, and specific examples thereof include an alkyl group such as a methyl group, an ethyl group and a propyl group, a cycloalkyl group such as a cyclohexyl group, a phenyl group and a trill group. Aralkyl groups such as aryl groups, benzyl groups, 2-phenylethyl groups and 2-phenylpropyl groups, and groups in which some or all of the hydrogen atoms of these groups are substituted with halogen atoms or the like, for example, 3,3,3- Examples thereof include a trifluoropropyl group.

In addition, p, q is 0 <p <3, preferably 0.5 ≦ p ≦ 2.2, more preferably 1.0 ≦ p ≦ 2.0, 0 <q ≦ 3, preferably 0.002 ≦ q. It is a positive number satisfying ≦ 1.1, more preferably 0.005 ≦ q ≦ 1, 0 <p + q ≦ 3, preferably 1 ≦ p + q ≦ 3, and more preferably 1.002 ≦ p + q ≦ 2.7.

Organohydrogenpolysiloxane has two or more, preferably three or more SiH groups in one molecule, both at the end of the molecular chain and in the middle of the molecular chain. May be good. Further, the organohydrogenpolysiloxane preferably has a viscosity at 25 ° C. of 0.5 to 10,000 mPa · s, particularly preferably 1 to 300 mPa · s.

Specific examples of such organohydrogenpolysiloxane include 1,1,3,3-tetramethyldisiloxane, 1,3,5,7-tetramethylcyclotetrasiloxane, and tris (hydrogendimethylsiloxy). ) Methylsilane, Tris (hydrogendimethylsiloxy) phenylsilane, methylhydrogencyclopolysiloxane, methylhydrogensiloxane / dimethylsiloxane cyclic copolymer, both-terminal trimethylsiloxy group blockage methylhydrogenpolysiloxane, both-terminal trimethylsiloxy group blockade Dimethylsiloxane / methylhydrogensiloxane copolymer, both-terminal dimethylhydrogensiloxy group-blocking dimethylpolysiloxane, both-terminal dimethylhydrogensiloxy group-blocking dimethylsiloxane / methylhydrogensiloxane copolymer, both-terminal trimethylsiloxy group-blocking methylhydro Gensiloxane / diphenylsiloxane copolymer, both-terminal trimethylsiloxy group-blocked methylhydrogensiloxane / diphenylsiloxane / dimethylsiloxane copolymer, both-terminal trimethylsiloxy group-blocked methylhydrogensiloxane / methylphenylsiloxane / dimethylsiloxane copolymer, Both-terminal dimethylhydrogensiloxy group-blocked methylhydrogensiloxane / dimethylsiloxane / diphenylsiloxane copolymer, both-terminal dimethylhydrogensiloxy group-blocked methylhydrogensiloxane / dimethylsiloxane / methylphenylsiloxane copolymer, (CH ₃ ) ₂ HSiO _1/2 unit and (CH ₃ ) ₃ Siloxane _1/2 unit and SiO _4/2 unit, (CH ₃ ) ₂ HSiO _1/2 unit and SiO _4/2 unit Combined, a _{copolymer consisting of (CH 3} ) ₂ HSiO _1/2 units, SiO _4/2 units and (C ₆ H ₅ ) ₃ SiO _1/2 units, etc., and some of the methyl groups in the above-exemplified compounds. Alternatively, those in which all of them are replaced with other alkyl groups, phenyl groups, or the like can be mentioned.

The blending amount of the organohydrogenpolysiloxane is preferably 0.1 to 40 parts by mass with respect to 100 parts by mass of the component (A). Further, it is appropriate that the ratio of hydrogen atoms (≡SiH groups) bonded to silicon atoms to one aliphatic unsaturated bond (alkenyl group, diene group, etc.) of component (A) is in the range of 0.5 to 10. Yes, preferably a range of 0.7 to 5 is suitable. If it is less than 0.5, the cross-linking may not be sufficient and sufficient mechanical strength may not be obtained, and if it exceeds 10, the physical characteristics after curing will deteriorate, especially the heat resistance will deteriorate or compression will occur. Permanent distortion may increase.

The hydrosilylation catalyst is a catalyst in which the alkenyl group of the component (A) and the silicon atom-bonded hydrogen atom (SiH group) of the organohydrogenpolysiloxane are hydrosilylated and added. Examples of the hydrosilylation catalyst include platinum group metal-based catalysts, which include a single platinum group metal and a compound thereof, and conventionally known catalysts for addition reaction curable silicone rubber compositions can be used. For example, a platinum catalyst such as a particulate platinum metal adsorbed on a carrier such as silica gel, alumina or silica gel, a second platinum chloride, a platinum chloride acid, an alcohol solution of a hexahydrate of platinum chloride acid, a palladium catalyst, a rhodium catalyst and the like can be used. Although mentioned, platinum or a platinum compound (platinum catalyst) is preferable.

The amount of the catalyst added is sufficient as long as the addition reaction can be promoted, and is usually used in the range of 1% by mass to 1% by mass with respect to the organopolysiloxane of the component (A) in terms of the amount of platinum group metal. The range of ~ 500 mass ppm is preferable. If the addition amount is less than 1% by mass, the addition reaction may not be sufficiently promoted and the curing may be insufficient, while if it exceeds 1% by mass, even if a larger amount is added, the effect on the reactivity is small. , May be uneconomical.

The platinum group metal catalyst used as the hydrosilylation catalyst of the component (G-1) may be the same as or different from the platinum compound used in the component (F), but when the same catalyst is used, it may be different. , It is necessary to set the desired compounding amount for each, and be careful not to make it too much or too little as a whole.

(G-2) Organic Peroxide Hardener (G-2) Examples of the organic peroxide curing agent include benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, p-methylbenzoyl peroxide, and o-methyl. Benzoyl peroxide, 2,4-dicumyl peroxide, 2,5-dimethyl-2,5-bis (t-butylperoxy) hexane, di-t-butyl peroxide, t-butylperbenzoate, 1,6 -Hexanediol-bis-t-butylperoxycarbonate and the like can be mentioned. The amount of the organic peroxide added is preferably 0.1 to 10 parts by mass, particularly 0.2 to 5 parts by mass, based on 100 parts by mass of the component (A). If the blending amount is too small, the curing may be insufficient, and if the blending amount is too large, the cured silicone rubber may turn yellow due to the decomposition residue of the organic peroxide. In addition, addition reaction curing and organic peroxide curing, in which the component (G-1) and the component (G-2) were combined and blended in the above-mentioned blending amount, were used in combination with the component (A). It can also be a co-vulcanized type silicone rubber composition.

[Other ingredients]
In addition to the above components, the silicone rubber composition of the present invention contains, if necessary, a filler such as pulverized quartz, crystalline silica, diatomaceous earth, calcium carbonate, a colorant, and tear strength. Various alkoxysilanes as improvers, acid receivers, thermal conductivity improvers such as alumina and boron nitride, mold release agents, and dispersants for fillers, especially phenyl group-containing alkoxysilanes and their hydrolysates, diphenylsilanediol, and carbon. It is optional to add known fillers and additives in thermocurable silicone rubber compositions such as functional silanes and silanol group-containing low molecular weight siloxanes.

The silicone rubber composition and other optional components can be obtained by mixing each of the above components with a known kneader such as a kneader, a Banbury mixer, or a double roll, but usually, the silicone rubber composition and other optional components are mixed with the organopolysiloxane of the component (A). After mixing a mixed solution of the reinforcing silica of the component (B), the organic solvent sol of the core-shell inorganic particles of the component (C), and the silanol group-containing siloxane, the silicone resin powder of the component (D) and the triazole of the component (E) are mixed. It is preferable to add the system compound, the platinum compound of the component (F), and the curing agent of the component (G).

The silicone rubber composition of the present invention thus obtained is heat-cured to become a silicone rubber having excellent physical properties of both light transmission and flame retardancy. As the molding method, a known molding method may be selected according to the shape and size of the target molded product. For example, methods such as injection molding, compression molding, injection molding, calendar molding, extrusion molding, coating, and screen printing are exemplified. The curing conditions may be those known in the molding method, and are generally 60 to 450 ° C., particularly 80 to 400 ° C., and further 120 to 200 ° C. for several seconds to one day. Further, for the purpose of reducing the compressive permanent strain property of the cured product, reducing the low molecular weight siloxane component remaining in the silicone rubber, removing the decomposed product of the organic peroxide, etc., 150 to 150 to Post-curing (secondary vulcanization) may be carried out in an oven at 250 ° C., preferably 200 to 240 ° C. for 1 hour or longer, preferably about 1 to 70 hours, and more preferably about 1 to 10 hours.

The silicone rubber thus obtained has high transparency, and the total light transmittance of the 2 mm thick silicone rubber (cured product) measured by the method described in JIS K 7361-1: 1997 is 75% or more (75 to 100). %), More preferably 85% or more (85-100%). Further, the silicone rubber thus obtained is excellent in flame retardancy and excellent in transparency.

Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples. The degree of polymerization of siloxane is the polystyrene-equivalent weight average degree of polymerization obtained by gel permeation chromatography analysis using toluene as a developing solvent.

[Preparation of component (C)]
Inorganic particle-polysiloxane complex (polysiloxane grafted inorganic particles) as a component (C) is shown in Preparation Examples 1 to 11 below.

[Preparation Examples 1 to 5: Preparation of Metal Oxide Particles]
(Preparation Example 1A: Preparation of aqueous dispersion of core-shell particles (1))
An aqueous dispersion of a metal oxide was prepared using a titanium oxide-tin oxide composite oxide as a nucleus, core-shell particles having silicon oxide as a shell as a dispersoid, and water as a dispersion medium. Specifically, the core shell is first produced by producing a composite oxide dispersion liquid (i) containing titanium oxide-tin oxide particles as a core, and then hydrolyzed and condensed with tetraethoxysilane by the following procedure. The aqueous dispersion containing particles (1) was used.

(Preparation of composite oxide dispersion liquid (i))
36% by mass of titanium (IV) chloride aqueous solution (manufactured by Ishihara Sangyo Co., Ltd., product name: TC-36) to 66.0 g of tin (IV) chloride pentahydrate (manufactured by Wako Pure Chemical Industries, Ltd.) 1. After adding 8 g and mixing well, this was diluted with 1,000 g of ion-exchanged water. A precipitate of titanium hydroxide containing tin was obtained by gradually adding 300 g of 5% by mass aqueous ammonia (manufactured by Wako Pure Chemical Industries, Ltd.) to this metal salt aqueous solution mixture to neutralize and hydrolyze it. .. The pH of the titanium hydroxide slurry at this time was 8. The obtained titanium hydroxide precipitate was deionized by repeating addition of ion-exchanged water and decantation. To the tin-containing titanium hydroxide precipitate after the deionization treatment, 100 g of 30% by mass hydrogen peroxide solution (manufactured by Wako Pure Chemical Industries, Ltd.) is gradually added, and then the mixture is sufficiently stirred at 60 ° C. for 3 hours. Reacted to. Then, pure water was added to adjust the concentration to obtain a translucent tin-containing peroxotitanic acid solution (solid content concentration: 1% by mass). In an autoclave with a volume of 500 mL (manufactured by Pressure-Resistant Glass Industry Co., Ltd., product name: TEM-D500), 350 mL of the peroxotitanic acid solution synthesized as described above was charged, and this was charged under the conditions of 200 ° C. and 1.5 MPa for 240 minutes. Hydro-heat treated. Then, the reaction mixture in the autoclave is discharged to a container held in a water bath at 25 ° C. via a sampling tube, and the reaction is stopped by rapid cooling to obtain a composite oxide dispersion liquid (i). rice field.

(Preparation of aqueous dispersion of core-shell particles (1))
To a separable flask equipped with a magnetic rotor and a thermometer, 1,000 parts by mass of the composite oxide dispersion (i), 100 parts by mass of ethanol, and 2.0 parts by mass of ammonia were added at room temperature (25 ° C.). Magnetic stirring was performed. The separable flask was immersed in an ice bath and cooled to a content temperature of 5 ° C. After adding 18 parts by mass of tetraethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name "KBE-04"), a separable flask was installed in μReactorEx (manufactured by Shikoku Measurement Industry Co., Ltd.). Magnetic stirring was performed while irradiating a microwave having a frequency of 2.45 GHz and an output of 1,000 W for 1 minute. During that time, the thermometer was observed to confirm that the content temperature reached 85 ° C. The obtained mixture was filtered through a qualitative filter paper (Advantec 2B) to obtain a dilute colloidal solution. This dilute dispersion Dyna filter (Mitsubishikakoki Co., Ltd., product name "DyF152 / S", average pore diameter 7nm of MgAl ₂ O-made disk [ANDRITZ KMPT GmbH, Ltd., part number 2065181, type φ152 / 7nm]) the The ultrafiltration used was concentrated to a dispersoid concentration of 10% by mass to obtain an aqueous dispersion (1) of core-shell particles having a titanium oxide-tin oxide composite oxide as a nucleus and silicon oxide as a shell. The solid content concentration of the aqueous dispersion (1) of the core-shell particles was 15.9% by mass, and the particle size was 19.5 nm. _{At this time, the particle size is a value of 50% cumulative distribution diameter (D 50} ) based on the volume measured by the dynamic light scattering method, and was measured using Nanotrack UPA-EX150 (manufactured by Nikkiso Co., Ltd.).

(Preparation Example 1B: Synthesis of Ethanol Dispersion Solution (1) of Surface-Modified Core-Shell Particles)
In a 4-port 2L separable flask equipped with a Dimroth condenser, a nitrogen introduction tube, a thermometer, and a mechanical stirring blade, as an aqueous dispersion of metal oxide particles, an aqueous dispersion of core shell particles (1) (300 g, solid content) The concentration was 15.9% by mass) and 3 g of a sulfonic acid-based cationic ion exchange resin was added as a catalyst. Methyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., product name "KBM-13", 230 g) was added thereto as a surface modifier, and the mixture was vigorously stirred (250 rpm). It was observed that the dispersion liquid and the alkoxysilane reacted with each other by stirring and became uniform. At that time, it was observed that the temperature of the dispersion liquid increased from 25 ° C. to 52 ° C. After heating and stirring for 2 hours so that the temperature of the dispersion was 50 ° C., ethanol (750 g) was added to the dispersion while stirring (250 rpm) to dilute the dispersion. Introduced to the diluted dispersion Dyna filter (Mitsubishikakoki Co., Ltd., product name "DyF152 / S", average pore diameter 7nm of MgAl ₂ O-made disk [ANDRITZ KMPT GmbH, Ltd., part number 2065181, type φ152 / 7nm]) bottom. The rotating shaft connected to the filter was rotated (1,000 rpm) while applying a static pressure of 0.2 MPa with compressed air. It was observed that the dispersion liquid exuded through the ceramic filter. A receiver (5,000 mL) was provided at the filter outlet, and 800 g of exudate was collected. An organic solvent (ethanol) was continuously pressurized and supplied (0.2 MPa) to the concentrated dispersion. The rotating shaft connected to the filter was rotated (1,000 rpm) while applying a static pressure of 0.2 MPa with compressed air. It was observed that the dispersion liquid exuded through the ceramic filter. A receiver (5,000 mL) was provided at the filter outlet, and ethanol was pressurized and supplied until the exudate reached 800 g. The dispersion was taken out from the filtration chamber to obtain an ethanol dispersion (1) of surface-modified core-shell particles. The surface-modified core-shell particles in the ethanol dispersion (1) had a solid content concentration of 17% by mass and a particle size of 19.2 nm. _{At this time, the particle size is a value of 50% cumulative distribution diameter (D 50} ) based on the volume measured by the dynamic light scattering method, and was measured using Nanotrack UPA-EX150 (manufactured by Nikkiso Co., Ltd.).

(Preparation Example 2: Synthesis of Ethanol Dispersion Solution (2) of Surface-Modified Core-Shell Particles)
36% by mass of titanium (IV) chloride aqueous solution (manufactured by Ishihara Sangyo Co., Ltd., product name: TC-36) to 66.0 g of tin (IV) chloride pentahydrate (manufactured by Wako Pure Chemical Industries, Ltd.) 1. Instead of adding 8 g, tin (IV) chloride pentahydrate (Wako Pure Chemical Industries, Ltd.) to 66.0 g of a 36 mass% titanium (IV) chloride aqueous solution (manufactured by Ishihara Sangyo Co., Ltd., product name: TC-36) Ethanol dispersion of core-shell particles surface-modified in the same manner as in Preparation Example 1 except that 1.8 g (manufactured by Co., Ltd.) and 0.09 g of manganese oxide (II) (High Purity Chemical Laboratory Co., Ltd.) were added. (2) was obtained. The surface-modified core-shell particles in the ethanol dispersion (2) had a solid content concentration of 14.5% by mass and a particle size of 19.2 nm.

(Preparation Example 3: Synthesis of Ethanol Dispersion Solution (3) of Surface-Modified Core-Shell Particles)
An ethanol dispersion (3) of surface-modified core-shell particles was obtained in the same manner as in Preparation Example 1 except that tin (IV) chloride pentahydrate was not added. The surface-modified core-shell particles in the ethanol dispersion (3) had a solid content concentration of 13% by mass and a particle size of 17.2 nm.

(Preparation Example 4: Synthesis of Ethanol Dispersion Solution (4) of Surface-Modified Core-Shell Particles)
As a surface modifier, not methyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., product name "KBM-13", 230 g), but γ-glycidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., product name) An ethanol dispersion (4) of core-shell particles surface-modified in the same manner as in Preparation Example 1 was obtained except that "KBM-403" (230 g) was used. The surface-modified core-shell particles in the ethanol dispersion (4) had a solid content concentration of 16% by mass and a particle size of 18.5 nm.

(Preparation Example 5: Synthesis of Ethanol Dispersion Solution (5) of Surface-Modified Core-Shell Particles)
As a surface modifier, not methyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., product name "KBM-13", 230 g), but γ-acryloxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., product name " An ethanol dispersion (5) of core-shell particles surface-modified in the same manner as in Preparation Example 1 was obtained except that KBM-5103 ”, 230 g) was used. The surface-modified core-shell particles in the ethanol dispersion (5) had a solid content concentration of 15% by mass and a particle size of 19.5 nm.

(Preparation Example 6: Preparation of a mixed solution 1 of an aqueous dispersion of core-shell particles and a silanol group-containing siloxane)
[Β process]
4.3 g of the aqueous dispersion of core-shell particles (1) prepared in Preparation Example 1A, 23.7 g of dimethyldimethoxysilane, and 7.9 g of hydrochloric acid water having a pH of 3.5 were mixed, and the aqueous dispersion of core-shell particles and a silanol group were contained. A "mixture 1" with siloxane was prepared.

(Preparation Example 7: Preparation of mixed solution 2 of ethanol dispersion of core-shell particles and silanol group-containing siloxane)
[Β process]
10 g of the ethanol dispersion of core-shell particles (1) prepared in Preparation Example 1B and 4 g of dimethylpolysiloxane having both terminal silanol groups and a viscosity of 15 mPa · s at an average degree of polymerization of 3, 25 ° C. were mixed. A "mixture 2" of an ethanol dispersion of core-shell particles and a silanol group-containing siloxane was prepared.

(Preparation Example 8: Preparation of mixed solution 3 of ethanol dispersion of core-shell particles and silanol group-containing siloxane)
[Β process]
Core shell in the same manner as in Preparation Example 7 except that the ethanol dispersion of core-shell particles (2) prepared in Preparation Example 2 was used instead of the ethanol dispersion (1) of core-shell particles prepared in Preparation Example 1B. A "mixture 3" of the ethanol dispersion of the particles and the silanol group-containing siloxane was prepared.

(Preparation Example 9: Preparation of mixed solution 4 of ethanol dispersion of core-shell particles and silanol group-containing siloxane)
[Β process]
Core shell in the same manner as in Preparation Example 7 except that the ethanol dispersion of core-shell particles (3) prepared in Preparation Example 3 was used instead of the ethanol dispersion (3) of core-shell particles prepared in Preparation Example 1B. A mixed solution (4) of the ethanol dispersion of the particles and the silanol group-containing siloxane was prepared.

(Preparation Example 10: Preparation of mixed solution 5 of ethanol dispersion of core-shell particles and silanol group-containing siloxane)
[Β process]
Core shell in the same manner as in Preparation Example 7 except that the ethanol dispersion of core-shell particles (4) prepared in Preparation Example 4 was used instead of the ethanol dispersion (1) of core-shell particles prepared in Preparation Example 1B. A mixed solution (5) of the ethanol dispersion of the particles and the silanol group-containing siloxane was prepared.

(Preparation Example 11: Preparation of mixed solution 6 of ethanol dispersion of core-shell particles and silanol group-containing siloxane)
[Β process]
Core shell in the same manner as in Preparation Example 7 except that the ethanol dispersion of core-shell particles (5) prepared in Preparation Example 5 was used instead of the ethanol dispersion (1) of core-shell particles prepared in Preparation Example 1B. A mixed solution (6) of the ethanol dispersion of the particles and the silanol group-containing siloxane was prepared.

[Example 1]
The component (A) is an organopolysiloxane having 99.850 mol% of dimethylsiloxane unit, 0.125 mol% of methylvinylsiloxane unit, and 0.025 mol% of dimethylvinylsiloxy unit, and having an average degree of polymerization of about 6,000. Raw rubber (however, referred to as "organopolysiloxane raw rubber I" in the table) 50 parts by mass, dimethylsiloxane unit 99.500 mol%, methylvinylsiloxane unit 0.475 mol%, dimethylvinylsiloxy unit 0.025 mol% Organopolysiloxane raw rubber having an average degree of polymerization of about 6,000 (however, referred to as "organopolysiloxane raw rubber II" in the table) is 50 parts by mass, and as a component (B), the BET method specific surface area is 230 m. ^{50 parts by mass of 2} / g surface-hydrophosated fumed silica (Leoloseal DM30S, manufactured by Tokuyama Co., Ltd.) contains an aqueous dispersion of core-shell particles prepared in Preparation Example 6 and a silanol group as the component (C). 35.8 parts by mass of the mixed solution (1) with siloxane was added, kneaded with a kneader, and heat-treated at 170 ° C. for 2 hours to prepare a composition (base compound 1).

With respect to 100 parts by mass of this composition (base compound 1), a structure in which 0.025 parts by mass of benzotriazole as a component (E) and a three-dimensional network having an average particle size of 2.0 μm as a component (D) are cross-linked. 20 parts by mass of silicone resin powder (KMP-590, manufactured by Shin-Etsu Chemical Industry Co., Ltd.), 0.1 mass by mass of 2-ethylhexanol solution of hexahydrate chloroplatinic acid (platinum concentration 2% by mass) as component (F) C25A (platinum group metal-based hydrosilylation catalyst, 0.09% by mass as platinum atom, manufactured by Shin-Etsu Chemical Industry Co., Ltd.) 0.5 parts by mass and C25B (organohydrogenpoly) 2.4 parts by mass of organohydrogenpolysiloxane (containing 40% by mass of siloxane, manufactured by Shin-Etsu Chemical Industry Co., Ltd.) was added, and the composition was press-cured at ^{120 ° C. and 70 kgf / cm 2 for 10 minutes.} Sheets with a thickness of 2 mm and a thickness of 1 mm were prepared. Post-cure was then performed in an oven at 200 ° C. for 4 hours. These silicone rubber sheets were returned to room temperature (25 ° C.), and various physical properties, light transmittance and flame retardancy were measured.

[Example 2]
As the component (C), not the mixed solution (1) of the aqueous dispersion of the core-shell particles and the silanol group-containing siloxane, but the mixed solution (2) of the ethanol dispersion of the core-shell particles and the silanol group-containing siloxane prepared in Preparation Example 7. ) Was 14 parts by mass, but the base compound (2) was prepared in the same manner as in Example 1, and various physical properties, light transmittance and flame retardancy were measured.

[Example 3]
As the component (C), not the mixed solution (1) of the aqueous dispersion of the core-shell particles and the silanol group-containing siloxane, but the mixed solution (3) of the ethanol dispersion of the core-shell particles and the silanol group-containing siloxane prepared in Preparation Example 8. ) Was 14.7 parts by mass, a base compound (3) was prepared in the same manner as in Example 1, and various physical properties, light transmittance and flame retardancy were measured.

[Example 4]
As the component (C), not the mixed solution (1) of the aqueous dispersion of the core-shell particles and the silanol group-containing siloxane, but the mixed solution (4) of the ethanol dispersion of the core-shell particles and the silanol group-containing siloxane prepared in Preparation Example 9. ) Was 15.2 parts by mass, and the base compound (4) was prepared in the same manner as in Example 1, and various physical properties, light transmittance and flame retardancy were measured.

[Example 5]
As the component (B), not fumed silica (Leoloseal DM30S, manufactured by Tokuyama Co., Ltd.) that has been surface-hydrophobicized with a ^{specific surface area of 230 m 2} / g by the BET method, but surface hydrophobic with a ^{specific surface area of 240 m 2 / g by the BET method.} Fumed silica (Aerosil R976S, manufactured by Nippon Aerosil Co., Ltd.) was prepared, and the component (C) was not a mixture of an aqueous dispersion of core-shell particles and a silanol group-containing siloxane (1), but Preparation Example 10. The base compound (5) was prepared in the same manner as in Example 1 except that the mixed solution (5) of the ethanol dispersion of the core-shell particles prepared in 1 and the silanol group-containing siloxane was adjusted to 14.2 parts by mass, and various physical characteristics were prepared. , Light transmission and flame retardancy were measured.

[Example 6]
As the component (C), not the mixed solution (4) of the aqueous dispersion of the core-shell particles and the silanol group-containing siloxane, but the mixed solution (6) of the ethanol dispersion of the core-shell particles and the silanol group-containing siloxane prepared in Preparation Example 11. ) Was 14.5 parts by mass, and the base compound (6) was prepared in the same manner as in Example 5.

With respect to 100 parts by mass of this composition (base compound 6), a structure in which 0.025 parts by mass of benzotriazole as a component (E) and a three-dimensional network having an average particle size of 2.0 μm as a component (D) are cross-linked. 30 parts by mass of silicone resin powder (KMP-590, manufactured by Shin-Etsu Chemical Industry Co., Ltd.), as a component (F), a toluene solution of a complex of divinyltetramethyldisiloxane of platinum chloride acid (containing 1% by mass as a platinum atom) ) 0.1 parts by mass, C25A (platinum group metal-based hydrosilylation catalyst, 0.09% by mass as platinum atom) as component (G-1) 0.5 parts by mass and C25B (organohydrogenpolysiloxane 40% by mass) Organohydrogenpolysiloxane (containing, manufactured by Shin-Etsu Chemical Industry Co., Ltd.) 2.4 parts by mass was added, and the composition was ^{press-cured at 120 ° C. and 70 kgf / cm 2} for 10 minutes to have a thickness of 2 mm and 1 mm. A thick sheet was created. Post-cure was then performed in an oven at 200 ° C. for 4 hours. These silicone rubber sheets were returned to room temperature (25 ° C.), and various physical properties, light transmittance and flame retardancy were measured.

[Example 7]
Base compound (2) A silicone resin having a structure crosslinked in a three-dimensional network with an average particle size of 2.0 μm as a component (D) and 0.025 parts by mass of benzotriazole as a component (E) with respect to 100 parts by mass of the base compound. Powder (KMP-590, manufactured by Shin-Etsu Chemical Industry Co., Ltd.) 20 parts by mass, as component (F), toluene solution of complex of divinyltetramethyldisiloxane of chloroplatinic acid (containing 1% by mass as platinum atom) 0. 1 part by mass and 0.3 part by mass of dicumyl peroxide as a component (G-2) were added, and the composition was ^{press-cured at 170 ° C. and 70 kgf / cm 2} for 10 minutes to have a thickness of 2 mm and 1 mm. A thick sheet was created. Post-cure was then performed in an oven at 200 ° C. for 4 hours. These silicone rubber sheets were returned to room temperature (25 ° C.), and various physical properties, light transmittance and flame retardancy were measured.

[Example 8]
The component (D) is not a silicone resin powder (KMP-590, manufactured by Shin-Etsu Chemical Co., Ltd.) having a structure crosslinked in a three-dimensional network with an average particle size of 2.0 μm, but a tertiary having an average particle size of 0.7 μm. Various physical characteristics, light transmittance and flame retardancy in the same manner as in Example 2 except that the silicone resin powder (X-52-854, manufactured by Shin-Etsu Chemical Co., Ltd.) having a structure crosslinked in the original mesh shape was used. Was measured.

[Comparative Example 1]
Examples of the component (C) were not the mixed solution (2) prepared in Preparation Example 7, but 10 parts by mass of dimethylpolysiloxane having a viscosity of 15 mPa · s at an average degree of polymerization of 3 and 25 ° C. was added. A base compound (7) was prepared in the same manner as in 2, and various physical properties, light transmittance and flame retardancy were measured.

[Comparative Example 2]
As the component (C), it has 4 parts by mass of the ethanol dispersion (1) of the core-shell particles prepared in Preparation Example 1B and silanol groups at both ends instead of the mixed solution (2) prepared in Preparation Example 7, and average polymerization. The base compound (8) was prepared in the same manner as in Example 1 except that the viscosity was 10 parts by mass of dimethylpolysiloxane having a viscosity of 15 mPa · s at 3 and 25 ° C., and various physical properties, light transmittance and difficulty were prepared. The flammability was measured.

[Comparative Example 3]
Various physical properties, light transmittance and flame retardancy are the same as in Example 2 except that a silicone resin powder having a structure crosslinked in a three-dimensional network having an average particle size of 2.0 μm is not added as the component (D). Was measured.

[Comparative Example 4]
Various physical characteristics, light transmittance and flame retardancy were measured in the same manner as in Example 2 except that benzotriazole was not added as the component (E).

[Comparative Example 5]
Various physical characteristics, light transmittance and flame retardancy were measured in the same manner as in Example 7 except that a toluene solution of a complex of divinyltetramethyldisiloxane of chloroplatinic acid was not added as a component (F).

[Comparative Example 6]
In 100 parts by mass of the base compound (7) prepared in Comparative Example 1, 5 parts by mass of titanium oxide (AEROXIDE TiO2 P25, manufactured by Nippon Aerodil Co., Ltd.) instead of the component (C), and benzotriazole 0 as the component (E). .025 parts by mass, 0.1 parts by mass of 2-ethylhexanol solution of hexahydrate chloroplatinic acid (platinum concentration 2% by mass) as component (F), C25A (platinum group metal-based hydrosilyl) as component (G-1) Chemical catalyst, containing 0.09% by mass as platinum atom, 0.5 parts by mass of Shin-Etsu Chemical Industry Co., Ltd. and C25B (containing 40% by mass of organohydrogen polysiloxane, manufactured by Shin-Etsu Chemical Industry Co., Ltd., Organohydrogen 2.4 parts by mass of polysiloxane) was added, and the composition was ^{press-cured at 120 ° C. and 70 kgf / cm 2} for 10 minutes to prepare sheets having a thickness of 2 mm and a thickness of 1 mm. Post-cure was then performed in an oven at 200 ° C. for 4 hours. These silicone rubber sheets were returned to room temperature (25 ° C.), and various physical properties, light transmittance and flame retardancy were measured.

[Measurement of various physical properties]
Various physical characteristics [hardness (durometer A), tensile strength, elongation at cutting] were measured by a method according to JIS K 6249: 2003 using a test sheet prepared according to JIS K 6249: 2003. .. The results are shown in Table 1 (each example) and Table 2 (each comparative example) below.

[Measurement of light transmittance]
Light from a 2 mm thick silicone rubber sheet after post-curing at 200 ° C. for 4 hours using a haze meter (manufactured by Suga Test Instruments Co., Ltd., model: HGM-2) by the method described in JIS K 7361-1: 1997. The transmittance was measured. The results are shown in Table 1 (each example) and Table 2 (each comparative example) below.

[Measurement of flame retardancy]
The flame retardancy is measured by using five 1 mm thick silicone rubber sheets according to the method specified in the UL94 20 mm vertical combustion test, the residual flame period T1 and T2, and the residual flame time of each set by all treatments. (The total of T1 + T2 of 5 silicone rubber sheets) was measured, and the flame-retardant classification of the material was performed based on the result. T1 represents the after-flame time after the first contact with flame, and T2 represents the after-flame time after the second contact with flame.

Claims (6)

(A) The following average composition formula (1)
R _n SiO _{(4-n) / 2} (1)
(In the formula, R is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 12 carbon atoms, and n is a positive number of 1.95 to 2.05.)
Organopolysiloxane represented by and having at least two alkenyl groups in one molecule
100 parts by mass,
(B) Reinforcing silica with a specific surface area of 50 m ² / g or more 5 to 100 parts by mass,
(C) It has a core-shell structure having a silicon oxide shell on the outside of a nucleus composed of metal fine particles containing titanium oxide, and has a 50% cumulative distribution diameter of 1 to 200 nm in a volume-based particle size distribution by a dynamic light scattering method. 0.01 to 50 parts by mass of a mixed solution of inorganic particles, an organic solvent sol of the inorganic particles, and a silanol group-containing siloxane having a degree of polymerization of 1 to 20.
(D) Silicone resin powder 1 to 50 parts by mass,
(E) Triazole-based compound 0.001 to 0.1 parts by mass,
(F) Platinum-based compound Contains 0.5 to 1,000 ppm with respect to the total mass of the components (A) to (E), and an effective amount for curing the (G) curing agent (A) component , as described above (C). ) A silicone rubber composition, wherein the content of the inorganic particles having a core-shell structure of the component is 0.68 to 1.7 parts by mass with respect to 100 parts by mass of the component (A). The surface of the inorganic particles having the core-shell structure of the component (C) is the following general formula (2).
R ¹⁹ Si (Y) ₃ (2)
(In the formula, R ¹⁹ may be the same or different, and may be substituted with a (meth) acrylic group, an oxylanyl group, an amino group, a mercapto group, an isocyanate group or a fluorine atom. Substituent or hydrogen selected from the group consisting of the following alkyl groups, alkenyl groups having 2 or more and 20 or less carbon atoms, aryl groups having 6 or more and 20 or less carbon atoms, and (poly) dimethylsiloxy groups having 50 or less silicon atoms. It is an atom, and Y is a substituent selected from the group consisting of an alkoxy group, an acetoxy group, an enol group, and a chlorine atom.)
The silicone rubber composition according to claim 1, wherein the surface is modified with an organosilicon compound represented by (1) and / or a (partial) hydrolyzed condensate thereof. The silicone rubber composition according to claim 1 or 2, wherein the triazole-based compound of the component (E) is benzotriazole. The silicone rubber composition according to any one of claims 1 to 3 , wherein the curing agent for the component (G) is an addition reaction curing type comprising a combination of an organohydrogenpolysiloxane and a hydrosilylation catalyst. The silicone rubber composition according to any one of claims 1 to 3 , wherein the curing agent for the component (G) is an organic peroxide. A silicone rubber comprising a cured product of the silicone rubber composition according to any one of claims 1 to 5.