PLATINUM CATALYST COMPOSITION, ITS PRODUCTION AND CURABLE ORGANOPOLYSILOXANE COMPOSITION

摘要

PROBLEM TO BE SOLVED: To obtain a platinum catalyst compsn. excellent in long-term storage stability by mixing a platinum complex having vinyl group-containing organosiloxane as a ligand and vinyl group-containing organopolysiloxane both of which are respectively represented by specific formulae to subject them to heat treatment. SOLUTION: In an addition reaction catalyst of a compsn. consisting of vinyl group-containing organosiloxane and silicon atom bonded hydrogen atom- containing organohydrogenpolysiloxane, a platinum complex having vinyl group- containing organosiloxane as ligand (A) represented by formula I or II is used. Then, organopolysiloxane containing 10mol% or more of a vinyl group in its side chain (B) represented by formula III is mixed with the platinum complex so that the vinyl group in the component (B) becomes 2mol or more per 1mol of a platinum atom in the component (A) and the resulting mixture is heated. In the formulae, R is a monovalent hydrocarbon group with the number of oxygen atoms of 1-8 and (x) and (y) are 10-50 as the number of silicon atoms in one molecule.