Room temperature vulcanizable organopolysiloxane composition

Claim 1

A room temperature vulcanizable composition which comprises: (A) 100 parts by weight of a diorganopolysiloxane blocked with a silanol group at both ends of the molecular chain, said diorganopolysiloxane being of the following formula HO[(R 1 )(R 2 )SiO] n H wherein each of R 1 and R 2 independently represents an unsubstituted or substituted monovalent hydrocarbon group selected from a C 1-8 alkyl group, a C 2-3 alkenyl group, a C 6-8 aryl group, a C 5-7 cycloalkyl group or those groups defined above substituted with a halogen atom or cyano group for one to all of the hydrogen atoms bonded to the carbon atoms thereof, and n is an integer of 5 or more; (B) from 0.01 to 10 parts by weight of an organopolysiloxane having at least three silanol groups in the molecule, and is of the following formula R 3 O[(R) 2 SiO] m [(R/(OH)SiO] k [(R) 2 SiO]R 3 wherein each R independently represents an unsubstituted or substituted monovalent hydrocarbon group selected from a C 1-8 alkyl group, a C 2-3 alkenyl group, a C 6-8 aryl group or those groups defined above substituted with a halogen or cyano group for one to all of the hydrogen atoms bonded to the carbon atoms thereof, both R 3 are hydrogen atoms or the group (R) 3 Si, k is an integer of 3 or over, and m is an integer of 1 or over; and (C) from 0.5 to 30 parts by weight of at least one member selected from the group consisting of organosilanes and organopolysiloxanes each having two hydrolyzable groups in one molecule, the at least one member serving to crosslink said diorganopolysiloxane and said organopolysiloxane therethrough.