Patent ID: 8716362

Claim:
An ultraviolet-curable silicone resin composition comprising (A) a polyorganosiloxane having a mercaptoalkyl group bonded to a silicon atom and a viscosity at 25° C. of 20 to 25000 cP; (B) an organopolysiloxane having aliphatic unsaturated groups which comprises (B1) a linear polyorganosiloxane having aliphatic unsaturated groups represented by the formula (I): wherein each R 1 independently represents an aliphatic unsaturated group, each R independently represents a C 1 -C 6 alkyl group or a C 6 -C 12 group, and among Rs, 1 to 60 mol % is a C 6 -C 12 aryl group, n is a number which results in a viscosity at 23° C. of 100 to 25000 cP, and (B2) a branched organopolysiloxane which comprises an SiO 4/2 unit, an R′ 3 SiO 1/2 unit and an R′ 2 SiO 2/2 unit, and optionally further comprises an R′SiO 3/2 unit, wherein each R′ independently represents a C 1 -C 6 alkyl group or an aliphatic unsaturated group, and at least three of R′ per one molecule are aliphatic unsaturated groups, provided that an amount of (B2) is an amount where a number of the aliphatic unsaturated group in (B2) based on a total number of the aliphatic unsaturated groups in (B) is 50% or less; (C) a photoinitiator; and (D) one or more silane compounds containing an aliphatic unsaturated group selected from the group of 3-methacryloxypropyltriethoxysilane, 3-methacryloxypropyltrimethoxysilane, vinyltrimethoxysilane and vinyltriethoxysilane, wherein a ratio of a number of the mercaptoalkyl groups present in (A) based on a total number of the aliphatic unsaturated groups in (B) and (D) is 0.5 to 1.05, a ratio of a number of the mercaptoalkyl groups present in (A) based on a number of the aliphatic unsaturated groups in (B) is 0.95 to 3, and a ratio of a number of the mercaptoalkyl groups present in (A) based on a number of the aliphatic unsaturated groups in (D) is 1.5 to 3.