Patent ID: 6875795

Claim:
A silicone composition curable by irradiation with ultraviolet light which comprises, as a uniform blend: (A) a first organopolysiloxane compound represented by the unit formula in which the subscripts a, b and c are each a positive number satisfying the relationship that the ratio of a:(b+c) is in the range from 0.5 to 2.0, R is a monovalent hydrocarbon group having 1 to 10 carbon atoms or a monovalent hydrocarbon group substituted for a part or all of the hydrogen atoms by substituent groups selected from hydroxyl groups, cyano groups, amino groups and halogen atoms, X is a hydrogen atom or a monovalent group represented by the formula the subscripts p, q, r, s and t each being 0 or a positive integer, the subscript u being a positive integer, the subscripts x and y being each 0, 1, 2 or 3, with the proviso that the sums of the subscripts q+x and s+y are each a positive integer, p+q is in the range from 1 to 40, r+s is in the range from 1 to 40 and t+u is in the range from 2 to 7, and R 1 being a monovalent group having an epoxy group; (B) a second organopolysiloxane compound represented by the formula in which R and R 1 each have the same meaning as defined above, the subscript z is 0, 1, 2 or 3 and the subscripts d, e, f and g are each 0 or a positive integer with the proviso that d+e is in the range from 3 to 45 and f+g is in the range from 3 to 8; (C) a third organopolysiloxane compound represented by the formula in which R and R 1 each have the same meaning as defined above, the subscript k is an integer of 0, 1, 2 or 3 and the subscripts h, j and m are each a positive number with the proviso that the number given by the formula h+k(m+2)+j+2 is in the range from 50 to 300; and (D) a catalytic amount of an onium salt compound as a photoreaction initiator, the relative amounts of the components (A), (B) and (C) satisfying the relationship that the weight ratio of (A):(B) is in the range from 0.1 to 1.5 and the weight ratio of [(A)+(B)]:(C) is in the range from 1.0 to 9.0.