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1. A curable composition, comprising:
(A) an organopolysiloxane having an average composition formula of Formula 1; and (B) a crosslinked organopolysiloxane comprising an alkenyl group and an epoxy group:
(R1R22SiO1/2)a(R3R4SiO2/2)b(R5SiO3/2)c(SiO2)d [Formula 1] wherein R1 is a monovalent hydrocarbon group having at least 2 carbon atoms, R2 is an alkyl group having 1 to 4 carbon atoms, R3 and R4 are each independently an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms or an aryl group having 6 to 25 carbon atoms, R5 is an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 25 carbon atoms, with the proviso that at least one of R1, R3 and R4 is an alkenyl group; a is a positive number, b is a positive number, c is a positive number, d is 0 or a positive number, b/a is 5 or more, and b/c is 5 or more, wherein the organopolysiloxane (B) has an average composition formula of Formula 9:
(R3SiO1/2)l(R2SiO2/2)m(RSiO3/2)r(SiO4/2)s [Formula 9] wherein R's are each independently a monovalent hydrocarbon group or an epoxy group, with the proviso that at least one of R's is an alkenyl group, at least one of R's is an aryl group and at least one of R's is an epoxy group; 1 is a positive number, m is 0 or a positive number, r is a positive number, s is 0 or a positive number, (l+m)/(l+m+r+s) is 0.2 to 0.7, m/(m+r+s) is 0.3 or less, and r/(r+s) is 0.8 or more, and wherein a molar ratio (Ep/Si) of epoxy groups (Ep) in the organopolysiloxane (B) with respect to silicon atoms in the organopolysiloxane (B) is 0.15 or less. |
