Silicone grease composition
AssigneeShin-Etsu Chemical Co., Ltd.
InventorsShigeru Mori, Takayuki Takahashi
Life of this patent
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Abstract
The silicone grease composition is highly light-transmitting and very stable with little oil separation. The grease composition is compounded with (a) a methyl phenyl polysiloxane having a specific phenyl content, (b) a fumed silica filler having a specific surface area of at least 130 m.sup.2 /g and (c) an alkoxy-containing organosilane compound such as vinyl trimethoxy silane, 3-methacryloxypropyl trimethoxy silane, dimethyl dimethoxy silane and the like in a specified proportion.
Claims6
A light-transmitting silicone grease composition which comprises:
- (a) 100 parts by weight of a methyl phenyl polysiloxane having a viscosity in the range from 100 to 500,000 centistokes at 25.degree. C. and containing from 5 to 20 % by moles of phenyl groups based on the overall amount of the organic groups bonded to the silicon atoms;
- (b) from 1 to 30 parts by weight of a fumed silica filler having a specific surface area of at least 130 m.sup.2 /g;
- and
- (c) from 0.1 to 20 parts by weight of an alkoxy-containing organosilane compound represented by the general formula
- X.sub.a SiMe.sub.b R.sub.c,
- in which Me is a methyl group, R is an alkoxy group, X is a monovalent group selected from the class consisting of a vinyl group, 3-methacryloxypropyl group and 3-glycidyloxypropyl group, the subscript a is zero or 1, b is zero, 1 or 2 and c is 2 or 3 with the proviso that a+b+c is equal to 4.
A method for the preparation of a light-transmitting silicone grease composition which comprises the steps of:
- (a) mixing a fumed silica filler having a specific surface area of at least 130 m.sup.2 /g and an alkoxy-containing organosilane compound represented by the general formula
- X.sub.a SiMe.sub.b R.sub.c,
- in which Me is a methyl group, R is an alkoxy group, X is a monovalent group selected from the class consisting of a vinyl group, 3-methacryloxyporpyl group and 3-glycidyloxypropyl group, the subscript a is zero or 1, b is zero, 1 or 2 and c is 2 or 3 with the proviso that a+b+c is equal to 4;
- (b) subjecting the mixture of the fumed silica filler and the alkoxy-containing organosilane compound to a heat treatment at a temperature in the range from 50 to 200.degree. C.;
- and
- (c) admixing the thus heat-treated mixture with a methyl phenyl polysiloxane having a viscosity in the range from 100 to 500,000 centistokes at 25.degree. C. and containing from 5 to 20 % by moles of phenyl groups based on the overall amount of the organic groups bonded to the silicon atoms, the amounts of the fumed silica filler and the alkoxy-containing organosilane compound being in the ranges from 1 to 30 parts by weight and from 0.1 to 20 parts by weight, respectively, per 100 parts by weight of the methyl phenyl polysiloxane.
Dependencies are inferred from the claim text.