Patent ID: 7563854

Claim:
A method of producing a high molecular weight organopolysiloxane with a polystyrene equivalent weight average molecular weight of at least 5 ×10 4 , represented by an average composition formula (1) shown below: R 1 a (OX) b SiO (4-a-b)/2 (1) (wherein, each R 1 represents, independently, an alkyl group, alkenyl group or aryl group of 1 to 6 carbon atoms, each X represents, independently, a hydrogen atom, or an alkyl group, alkenyl group, alkoxyalkyl group or acyl group of 1 to 6 carbon atoms, a represents a number within a range from 1.00 to 1.5, and b represents a number that satisfies 0<b<2, provided that a+b satisfies 1.00<a+b <2), comprising the steps of producing an organopolysiloxane by subjecting a silane compound having a hydrolyzable group to a first hydrolysis and condensation, and subjecting said organopolysiloxane to an additional second hydrolysis and condensation.