Thermally-conductive silicone gel composition, thermally-conductive member, and heat dissipation structure

1. A thermally conductive silicone gel composition comprising:

(A) 100 parts by mass of an alkenyl group-containing organopolysiloxane having a viscosity of from 10 to 100,000 mPa·s at 25° C.;

(B1) a straight-chain organohydrogenpolysiloxane containing an average of 2 silicon-bonded hydrogen atoms only in the side chain of the molecular chain and having a viscosity of from 1 to 1,000 mPa·s at 25° C.;

(non-B) an organohydrogenpolysiloxane other than component (B1);

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

(D) 400 to 3,500 parts by mass of a thermally conductive filler;

(E) 0.1 to 2.0 mass % of an alkoxysilane having an alkyl group with 6 or more carbon atoms per molecule with respect to component (D); and

(F) a heat resistance imparting agent;

wherein the total amount of silicon-bonded hydrogen atoms in components (B1) and (non-B) is from 0.2 to 5 mol per 1 mol of an alkenyl group contained in component (A);

wherein component (non-B) is an organohydrogenpolysiloxane selected from the group consisting of:

i) copolymers of methylhydrogensiloxane and dimethylsiloxane capped at both ends of the molecular chain by trimethylsiloxy groups, having on average more than 4 silicon-bonded hydrogen atoms per molecule; and

ii) copolymers of methylhydrogensiloxane and dimethylsiloxane capped at both ends of the molecular chain by dimethylhydrogensiloxy groups, having on average more than 4 silicon-bonded hydrogen atoms per molecule;

wherein the content of silicon-bonded hydrogen atoms in component (B1) ([H B ]) and the content of silicon-bonded hydrogen atoms in organohydrogenpolysiloxane(s) other than component (B1) ([H non-B ]) in the composition, that is the value of [H non-B ]/([H B ]+[H non-B ]), is in the range of greater than 0.0 to 0.70; and

wherein component (D) is: (D1) a lamellar boron nitride powder having an average particle size of 0.1 to 30 μm; (D2) a granular boron nitride powder having an average particle size of 0.1 to 50 μm; (D3) a spherical and/or crushed aluminum oxide powder having an average particle size of 0.01 to 50 μm; (D4) a graphite having an average particle size of 0.01 to 50 μm; or a mixture of two or more of these.

2. The thermally conductive silicone gel composition according to claim 1 , wherein component (E) is an alkoxysilane represented by the following structural formula:

Y n Si(OR) 4-n

wherein Y is an alkyl group having 6 to 18 carbon atoms, R is an alkyl group having 1 to 5 carbon atoms, and n is 1 or 2.

3. The thermally conductive silicone gel composition according to claim 1 , wherein component (E) is a trialkoxysilane having an alkyl group having 6 to 18 carbon atoms.

4. The thermally conductive silicone gel composition according to claim 1 , wherein component (D) is surface treated with component (E).

5. The thermally conductive silicone gel composition according to claim 1 , wherein component (F) is a phthalocyanine compound.

6. The thermally conductive silicone composition according to claim 1 , wherein component (D3) is present and comprises a mixture of two or more spherical and/or crushed aluminum oxide powders having different average particle sizes of from 0.01 to 50 μm.

7. The thermally conductive silicone composition according to claim 1 , wherein the value of [H non-B ]/([H B ]+[H non-B ]) is in the range of greater than 0.0 to 0.50.

8. The thermally conductive silicone composition according to claim 7 , wherein the value of [H non-B ]/([H B ]+[H non-B ]) is in the range of greater than 0.0 to 0.25.

9. A thermally conductive member comprising the thermally conductive silicone gel composition according to claim 1 .

10. A thermally conductive member obtained by curing the thermally conductive silicone gel composition according to claim 1 .

11. A heat dissipation structure comprising the thermally conductive member according to claim 9 .

12. The heat dissipation structure according to claim 11 , which is an electric/electronic device.

13. The heat dissipation structure according to claim 11 , which is an electric/electronic component or a secondary battery.

14. A heat dissipation structure comprising the thermally conductive member according to claim 10 .

15. The heat dissipation structure according to claim 14 , which is an electric/electronic device.

16. The heat dissipation structure according to claim 14 , which is an electric/electronic component or a secondary battery.

17. The thermally conductive silicone composition according to claim 6 , wherein component (D3) comprises a mixture of three different spherical and/or crushed aluminum oxide powders having different average particle sizes of from 0.01 to 50 μm.

18. The thermally conductive silicone composition according to claim 1 , wherein component (non-B) comprises:

ia) a copolymer of methylhydrogensiloxane and dimethylsiloxane capped at both ends of the molecular chain by trimethylsiloxy groups, having an average of 5 silicon-bonded hydrogen atoms per molecule and only present in the side chain of the molecular chain, optionally with a viscosity of 5 mPa·s, and optionally with a Si—H content of 0.75 mass %.

19. The thermally conductive silicone gel composition according to claim 5 , wherein component (F) is a copper phthalocyanine compound, or optionally is 29H, 31H-phthalocyaninato (2-)-N29, N30, N31, N32 copper.

20. The thermally conductive silicone gel composition according to claim 5 , wherein component (F) is present in an amount of from 0.01 to 5.0 mass %, or optionally of from 0.05 to 0.2 mass %, of the total composition.