Patent ID: 8889809

Claim:
A silicone resin composition comprising (A) an organopolysiloxane having at least two alkenyl groups per molecule, and is represented by the following average compositional formula (1): R 1 a R 2 b R 3 c SiO (4-a-b-c)/2 (1) wherein R 1 is a cycloalkyl group having 4 to 8 carbon atoms, R 2 is a substituted or unsubstituted monovalent hydrocarbon group which has 1 to 10 carbon atoms and is not an alkenyl group nor a cycloalkyl group, R 3 is an alkenyl group having 2 to 8 carbon atoms, a is the number of 0.3 to 1.0, b is the number of 0.05 to 1.5, and c is the number of 0.05 to 0.8, provided that a+b+c is 0.5 to 2.0, wherein component A is a mixture of an organopolysiloxane having a linear structure whose main chain is composed of R 2 SiO 2/2 units and which has R 3 SiO 1/2 units at both terminals, wherein R is a group selected from the groups defined for R 1 , R 2 , or R 3 set forth above, and an organopolysiloxane having a three dimensional network structure which comprises R 6 SiO 3/2 units and R 5 q R 6 r SiO 1/2 units, wherein R 5 is a vinyl or allyl group, R 6 is a group selected from the groups defined for R 1 and R 2 set forth above, q is 1, 2, or 3, and r is 0, 1, or 2, provided that a total of q and r is 3, wherein an amount of the organopolysiloxane having a three dimensional network structure is 20 to 95% by mass based on a total mass of component (A), (B) an organohydrogenpolysiloxane having at least two hydrogen atoms bonded to a silicon atom, that is, SiH groups, and is represented by the following average compositional formula (2): R 1 a R 2 b H d SiO (4-a-b-d)/2 (2) wherein R 1 is a cycloalkyl group having 4 to 8 carbon atoms, R 2 is a substituted or unsubstituted, monovalent hydrocarbon groups which has 1 to 10 carbon atoms and is not an alkenyl group nor a cycloalkyl group, a is the number of 0 to 1.4, b is the number of 0.6 to 1.5, and d is the number of 0.05 to 1.0, provided that a+b+d is 1.0 to 2.5, (C) a catalytic amount of a curing catalyst, and (D) 0.001 to 3 parts by mass of an antioxidant, relative to a total 100 parts by mass of components (A) and (B), wherein an amount of the cycloalkyl groups is 20 to 80 mass %, based on the total mass of components (A) and (B).