Curable silicone composition and cured product thereof

1. A curable silicone composition comprising:

(A) an organopolysiloxane having at least two alkenyl groups in a molecule;

(B) an organopolysiloxane having at least two silicon-bonded hydrogen atoms in a molecule, included at a quantity whereby an amount of silicon-bonded hydrogen atoms in the component (B) is from 0.5 to 10 moles per 1 mole of the alkenyl groups in the component (A);

(C) a catalytic quantity of a hydrosilylation reaction catalyst;

(D) an approximately spherical silica fine powder having an average particle diameter of 50 μm or less, included at a quantity of 200 parts by mass or more relative to a total of 100 parts by mass of the component (A) and the component (B); and

(E) glass fibers having an average fiber length of 1,000 μm or less and an average fiber diameter of 30 μm or less, included at a quantity of 25 parts by mass or more relative to a total of 100 parts by mass of the component (A) and the component (B);

wherein the total content of the component (D) and the component (E) is 900 parts by mass or less relative to the total of 100 parts by mass of the component (A) and the component (B).

2. The curable silicone composition according to claim 1 , wherein the component (A) is an organopolysiloxane comprising:

30 to 100 mass % of (A 1 ) an organopolysiloxane comprising a siloxane block represented by the general formula:

—(R 1 R 2 SiO) m —

wherein, R 1 is an alkyl group having 1 to 6 carbon atoms or a phenyl group, R 2 is an alkenyl group having 2 to 10 carbon atoms, and m is a positive number in a range of 3 to 50; and

0 to 70 mass % of (A 2 ) an organopolysiloxane which does not have the above-mentioned siloxane block and which contains at least two alkenyl groups in a molecule.

3. The curable silicone composition according to claim 1 , wherein the component (B) is an organopolysiloxane comprising a siloxane block represented by the general formula:

—(R 3 HSiO) n —

wherein, R 3 is an alkyl group having 1 to 6 carbon atoms or a phenyl group, and n is a positive number in a range of 3 to 100.

4. The curable silicone composition according to claim 1 , wherein the component (D) is a fused silica fine powder.

5. The curable silicone composition according to claim 1 , wherein the component (E) is milled glass fibers.

6. The curable silicone composition according to claim 1 , further comprising a reaction inhibitor and (G) non-silicone monomer having two or more of polymerizable double bonds, wherein component (G) is divinylbenzene, divinylnaphthalene, allyl methacrylate, triacrylformal, triallylisocyanurate, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, polyethylene glycol (PEG#200) di(meth)acrylate with a weight average molecular weight of 200, polyethylene glycol (PEG#400) di(meth)acrylate with a weight average molecular weight of 400, 1,6-hexanediol (meth)acrylate, or trimethylolpropane trimethacrylate.

7. The curable silicone composition according to claim 6 , wherein the component (G) is a triallylisocyanurate.

8. The curable silicone composition according to claim 1 , further comprising (F) an adhesion promoter.

9. A cured product produced by curing the curable silicone composition described in claim 1 .

10. The curable silicone composition according to claim 2 , wherein the component (B) is an organopolysiloxane comprising a siloxane block represented by the general formula:

—(R 3 HSiO) n —

wherein, R 3 is an alkyl group having 1 to 6 carbon atoms or a phenyl group, and n is a positive number in a range of 3 to 100.

11. The curable silicone composition according to claim 10 , wherein the component (D) is a fused silica fine powder.

12. The curable silicone composition according to claim 11 , wherein the component (E) is milled glass fibers.

13. The curable silicone composition according to claim 12 , further comprising a reaction inhibitor and (G) non-silicone monomer having two or more of polymerizable double bonds, wherein component (G) is divinylbenzene, divinylnaphthalene, allyl methacrylate, triacrylformal, triallylisocyanurate, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, polyethylene glycol (PEG#200) di(meth)acrylate with a weight average molecular weight of 200, polyethylene glycol (PEG#400) di(meth)acrylate with a weight average molecular weight of 400, 1,6-hexanediol (meth)acrylate, or trimethylolpropane trimethacrylate.

14. The curable silicone composition according to claim 13 , wherein the component (G) is a triallylisocyanurate.

15. The curable silicone composition according to claim 13 , further comprising (F) an adhesion promoter.

16. The curable silicone composition according to claim 6 , wherein the component (G) is present in an amount of from 30 to 100 parts by mass per 100 parts total mass of the component (A) and the component (B).

17. The curable silicone composition according to claim 8 , wherein the component (F) is present in an amount of from 0.1 to 30 parts by pass per 100 parts total mass of the component (A) and the component (B).

18. The curable silicone composition according to claim 1 , having a viscosity of from 100 to 1,000,000 mPa·s at 25° C.

19. The cured product according to claim 9 , having an average coefficient of linear expansion in the temperature range of 25 to 300° C. of 100 ppm/° C. or lower, as measured in accordance with JIS K 7197-1991.

20. The cured product according to claim 9 , having an average coefficient of linear expansion in the temperature range of 25 to 300° C. of 50 ppm/° C. or lower, as measured in accordance with JIS K 7197-1991.