Patent ID: 8895678

Claim:
A cross-linkable silicone composition comprising at least the following components: (A) an organopolysiloxane represented by the following average unit formula: (R 1 3 SiO 1/2 ) a (R 1 2 SiO 2/2 ) b (R 1 SiO 3/2 ) c (SiO 4/2 ) d (R 2 O 1/2 ) e where R 1 are phenyl groups, alkyl or cycloalkyl groups having 1 to 6 carbon atoms, or alkenyl groups having 2 to 6 carbon atoms, and where 60 to 80 mole % of R 1 are phenyl groups and 10 to 20 mole % of R 1 are alkenyl groups; R 2 is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms; and “a”, “b”, “c”, “d”, and “e” are numbers that satisfy the following conditions: 0≦a≦0.2; 0.2≦b≦0.7; 0.2≦c≦0.6; 0≦d≦0.2; 0≦e≦0.1; and a+b+c+d=1; (B) an organopolysiloxane represented by the following general formula: R 3 3 SiO(R 3 2 SiO) m SiR 3 3 where R 3 are phenyl groups, alkyl or cycloalkyl groups having 1 to 6 carbon atoms, or alkenyl groups having 2 to 6 carbon atoms, and where 40 to 70 mole % of R 3 are phenyl groups and at least one R 3 is an alkenyl group; and “m” is an integer in the range of 5 to 100, wherein component (B) is used in an amount of 0 to 20 parts by weight per 100 parts by weight of component (A); (C) an organopolysiloxane having in one molecule two silicon-bonded hydrogen atoms and where phenyl groups constitute 30 to 70 mole % of silicon-bonded organic groups and where the mole ratio of silicon-bonded hydrogen atoms contained in this component to the total sum of alkenyl groups contained in components (A) and (B) is in the range of 0.5 to 2; and (D) a hydrosilylation catalyst in an amount sufficient to promote a hydrosilylation reaction between the alkenyl groups contained in components (A) and (B) and silicon-bonded hydrogen atoms contained in component (C).