Room-temperature-curable silicone rubber composition, and the use thereof
A room-temperature-curable silicone rubber composition exhibiting good adhesion to a substrate contacted during curing and capable of suppressing the occurrence of oil bleeding is disclosed. The room-temperature-curable silicone rubber composition comprises: (A) a mixture of (A1) an organopolysiloxane having at least two specified alkoxysilyl-containing groups in the molecular and (A2) an organopolysiloxane having one specified alkoxysilyl-containing group in the molecular; (B) an organopolysiloxane lacking a hydroxyl group and an alkoxy group; (C) an alkoxysilane; and (D) a condensation-reaction catalyst.
1. A room-temperature-curable silicone rubber composition comprising: (A) 100 parts by mass of a mixture containing components (A1) and (A2) in a mass ratio of from 1:10 to 10:1 below:
(A1) a straight-chain dimethylpolysiloxane having at each molecular terminal a silicon-bonded alkoxysilyl-containing group having the structure:
(A2) a straight-chain dimethylpolysiloxane having at only one molecular terminal a silicon-bonded alkoxysilyl-containing group having the structure:
(B) 1 to 100 parts by mass of a straight chain dimethylpolysiloxane having a dimethylvinylsiloxy group bonded to silicon at both molecular terminals and lacking a hydroxyl group and an alkoxy group on a silicon atom in the molecular chain;
(C) 0.5 to 30 parts by mass of methyltrimethoxysilane;
(D) a condensation-reaction catalyst;
(E) an adhesion promoter; and
(F) a reinforcing filler.
2. The room-temperature-curable silicone rubber composition according to claim 1 , wherein a viscosity at 25° C. of the component (A) as a whole is in a range of 100 to 1,000,000 mPa s.
3. The room-temperature-curable silicone rubber composition according to claim 1 , wherein a viscosity at 25° C. of the component (B) is in a range of 10 to 1,000,000 mPas.
4. The room-temperature-curable silicone rubber composition according to claim 1 , wherein component (E) is selected from the group consisting of: epoxy group-containing alkoxysilanes, acrylic group-containing alkoxysilanes, amino group-containing alkoxysilanes, and reaction mixtures of epoxy group-containing alkoxysilanes and amino group-containing alkoxysilanes.
5. The room-temperature-curable silicone rubber composition according to claim 1 , wherein component (F) is selected from the group consisting of: fumed silica fine powder, precipitated silica fine powder, baked silica fine powder, and fumed titanium oxide fine powder.
6. A silicone rubber cured product which is obtained by curing the room-temperature-curable silicone rubber composition described in claim 1 .
7. An electronic device provided with the silicone rubber cured product described in claim 6 .
8. The room-temperature-curable silicone rubber composition according to claim 1 , wherein components (A1) and (A2) each have a viscosity at 25° C. of 500 mPas, and wherein component (B) has a viscosity at 25° C. of 400 mPas.
9. The room-temperature-curable silicone rubber composition according to claim 8 , further comprising (B2) a straight-chain dimethylpolysiloxane having a trimethylsiloxy group bonded to silicon at each molecular terminal.
10. The room-temperature-curable silicone rubber composition according to claim 9 , wherein the component (B2) has a viscosity at 25° C. of 500 mPa·s.
11. The room-temperature-curable silicone rubber composition according to claim 1 , further comprising (B2) a straight-chain dimethylpolysiloxane having a trimethylsiloxy group bonded to silicon at each molecular terminal.
12. The room-temperature-curable silicone rubber composition according to claim 11 , wherein the component (B2) has a viscosity at 25° C. of 500 mPa·s.
13. A room-temperature-curable silicone rubber composition comprising: (A) a mixture containing components (A1) and (A2) below:
(A1) a straight-chain dimethylpolysiloxane having a viscosity at 25° C. of 500 mPa·s and having at each molecular terminal a silicon-bonded alkoxysilyl-containing groups represented by general formula:
(A2) a straight-chain dimethylpolysiloxane having a viscosity at 25° C. of 500 mPa·s and at one molecular terminal one of the above alkoxysilyl-containing groups;
(B) a straight chain dimethylpolysiloxane having a viscosity at 25° C. of 400 mPa·s, a dimethylvinylsiloxy group bonded to silicon at both molecular terminals and lacking a hydroxyl group and an alkoxy group on a silicon atom in the molecular chain;
(B2) a straight-chain dimethylpolysiloxane having a viscosity at 25° C. of 500 mPa·s and a trimethylsiloxy group bonded to silicon at each molecular terminal
(C) methyltrimethoxysilane;
(D) a condensation-reaction catalyst;
(E) carbasilatrane; and
(F) fumed silica.