Photocurable silicone composition and cured product thereof

A photocurable silicone composition comprising:

• (A) an organopolysiloxane represented by the following average composition formula:
• R1aR2bSiO(4-a-b)/2
• wherein, R1 is a C2-12 alkenyl group;
• R2 is a C1-12 alkyl group, a C6-12 aryl group, or a C7-12 aralkyl group;
• provided that at least one R2 in a molecule is the aryl group or the aralkyl group;
• and “a” and “b” are positive numbers satisfying:
• 1≤a+b≤2.5 and 0.001≤a/(a+b)≤0.2;
• (B) a polysiloxane block copolymer comprising:
• (i) a polysiloxane block represented by the general formula:
• (R32SiO)n, wherein each R3 is independently a C1-12 alkyl group, a C6-12 aryl group, or a C7-12 aralkyl group;
• and “n” is a positive number of at least about 5;
• and
• (ii) an organo block containing at least three sulfur atoms and free of silicon atom in a chemical structure thereof,
• wherein the polysiloxane block (i) is bonded to the organo block (ii) via a linkage represented by the general formula:
• (Si)-R4-(S), wherein Si is an atom in a chemical structure of the polysiloxane block (i);
• S is an atom in a chemical structure of the organo block (ii);
• and R4 is a C2-6 alkylene group, and
• wherein the polysiloxane block copolymer has at least two thiol (HS-) groups in a molecule, in an amount such that the thiol groups in component (B) is in a range of from 0.2 to 2.0 moles per 1 mole of the total alkenyl groups in component (A);
• (C) a photoinitiator, in an amount of from 0.01 to 5 parts by mass of per 100 parts by mass of a total mass of components (A) and (B);
• and
• (D) an inorganic filler, in an amount of from about 0.01 to about 40 parts by mass per 100 parts by mass of a total mass of components (A) and (B).