Abstract: A silicon-containing polymer which is represented by general formula (5) below and has a weight-average molecular weight in the range from 500 to 500,000: (In the formula, A2 is an organic group of 2-10 carbons, having a carbon-carbon unsaturated group; R3 is an alkylene group of 1-20 carbons, a bivalent aromatic group of 6-20 carbons, or a bivalent alicyclic group of 3-20 carbons; n is 0 or 1; R4 is a hydrogen atom or an alkyl group of 1-10 carbons (R4 in one molecule may be the same type or a combination of two or more different types.); each of x and y is a positive number; each of w and z is 0 or a positive number; 0?z/(w+x+y)?2; and 0.01?y/(w+x)?5), and the heat-resistant resin composition comprising the silicon-containing polymer.

Abstract: The alkali-soluble silicon-containing polymer of the present invention is represented by the general formula (1) below and has a weight-average molecular weight in the range from 500 to 500,000: (In the formula, A1 is a phenyl group having either a hydroxyl group or an alkoxy group; R1 is an alkylene group of 1-4 carbons; m is 0 or 1; R2 is an alkyl group of 1-4 carbons; each of s and u is a positive number; t is 0 or a positive number; 0?t/(s+u)?1; and 0<u/s?5).

Abstract: A silicon-containing polymer which is represented by general formula (5) below and has a weight-average molecular weight in the range from 500 to 500,000: (In the formula, A2 is an organic group of 2-10 carbons, having a carbon-carbon unsaturated group; R3 is an alkylene group of 1-20 carbons, a bivalent aromatic group of 6-20 carbons, or a bivalent alicyclic group of 3-20 carbons; n is 0 or 1; R4 is a hydrogen atom or an alkyl group of 1-10 carbons (R4 in one molecule may be the same type or a combination of two or more different types.); each of x and y is a positive number; each of w and z is 0 or a positive number; 0?z/(w+x+y)?2; and 0.01?y/(w+x)?5), and the heat-resistant resin composition comprising the silicon-containing polymer.

Abstract: The object of the present invention is to provide a polyorganosiloxane that has a specific structure and is superior to curability and a curable composition which is high in workability during curing, which leads to a cured product excellent in ultraviolet-ray transparency and heat resistance, and further wherein toughness thereof and occurrence of a crack by cyclic heat-cool are improved. The present polyorganosiloxane is one obtained by conducting hydrolysis and condensation of a silicon-containing organic compound represented by the general formula (1) below in the presence of an organic polyol compound having two or more hydroxyl groups and has an oxetanyl group.

Abstract: The object of the present invention is to provide a polyorganosiloxane that has a specific structure and is superior to curability and a curable composition which is high in workability during curing, which leads to a cured product excellent in ultraviolet-ray transparency and heat resistance, and further wherein toughness thereof and occurrence of a crack by cyclic heat-cool are improved. The present polyorganosiloxane is one obtained by conducting hydrolysis and condensation of a silicon-containing organic compound represented by the general formula (1) below in the presence of an organic polyol compound having two or more hydroxyl groups and has an oxetanyl group.

Abstract: The alkali-soluble silicon-containing polymer of the present invention is represented by the general formula (1) below and has a weight-average molecular weight in the range from 500 to 500,000: (In the formula, A1 is a phenyl group having either a hydroxyl group or an alkoxy group; R1 is an alkylene group of 1-4 carbons; m is 0 or 1; R2 is an alkyl group of 1-4 carbons; each of s and u is a positive number; t is 0 or a positive number; 0?t/(s+u)?1; and 0<u/s?5).