Curable composition

A curable composition, comprising:

• (A) an organopolysiloxane having an average composition formula of Formula 1, which has an acid value obtained by KOH titration of 0.05 mgKOH/g or less, which has a ratio (OR/Ak) of an area (OR) of a peak derived from an alkoxy group binding to a silicon atom to an area (Ak) derived from an alkenyl group binding to a silicon atom in a 1H-NMR spectrum of 0.05 or less, and which is a reaction product of a mixture including a compound of Formula 5 and an organopolysiloxane represented as an average composition formula of Formula 6 or 7;
• and
• (B) an organopolysiloxane comprising an alkenyl group, an epoxy group and an aryl group:
• (R1R22SiO1/2)a(R3R4SiO2/2)b(R5SiO3/2)c(SiO2)d [Formula 1]
• where R1 is a monovalent hydrocarbon group having at least two 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,
• [ReSiO3/2] [Formula 6]
• [RaRb2SiO1/2]p[ReSiO3/2]q [Formula 7]
• where Ra is a monovalent hydrocarbon group having at least two carbon atoms, Rb is an alkyl group having 1 to 4 carbon atoms, Rc to Re are each independently an aryl group having 6 to 25 carbon atoms, an alkyl group having 1 to 20 carbon atoms or a monovalent hydrocarbon group having at least two carbon atoms, o is 3 to 6, p is 1 to 3, and q is 1 to 10.