Curing agent, preparation thereof and curable composition comprising the same

Claim 1

A curable composition which comprises (C) an organic curing agent obtained by reacting (A) an organic compound of the formula: ##STR45## wherein R 8 is hydrogen or a methyl group, R 5 is a di-, tri- or tetra-valent hydrocarbon group having 2 to 50 carbon atoms, and a is an integer of 2 to 4, with (B) a polyvalent hydrogensilicon compound of the formula: ##STR46## in the presence of a hydrosilylation catalyst so that at least two hydrosilyl groups remain after the reaction, the organic curing agent being non-polymeric and having 2 to 4 cyclic residual groups derived from the polyvalent hydrogensilicon compound (B), the at least two hyrosilyl groups being present in the residual groups, (D) an organic polymer having at least one alkenyl group in a molecule, selected from the group consisting of a polyether polymer, a polyester polymer, a hydrocarbon polymer, an acrylate ester polymer and a polycarbonate polymer, and (E) a hydrosilylation catalyst.