Process for coating a substrate and an improved coating therefore

Claim 1

A composition comprising (1) 100 parts by weight of a diorganopolysiloxane-based formulation which is heat curable to an elastomer by the addition of methylhydrogenpolysiloxanes to silicon-bonded alkenyl groups, (2) from 0.5 to 90 parts by weight of a toluene soluble copolymer of (a) R 3 SiO 1/2 units, (b) (CH 2 ═CH)R 2 SiO 1/2 units and (c) SiO 4/2 units, the ratio of said (a) and (b) units to (c) units being from 0.6:1 to 1.1:1 and the silicon bonded hydroxy content of (2) being no more than 0.7 weight percent based on the weight of (2), where R is a monovalent hydrocarbon radical of no more than 2 carbon atoms, and (3) a catalyst comprising complexes of rhodium selected from the group consisting of (i) RhX 3 (SR' -2 ) 3 and (ii) Rh 2 (CO) 4 X 2 , wherein each X represents a halogen atom and each R' represents an alkyl, aryl, aralkyl or alkaryl radical having from 1 to 8 inclusive carbon atoms or the R" -3 SiQ- group in which Q represents a divalent aliphatic hydrocarbon radical having from 1 to 6 inclusive carbon atoms and R" - represents an alkyl, aryl, aralkyl or alkaryl radical having from 1 to 8 inclusive carbon atoms or a (CH 3 ) 3 Si- group, not more than one R" - per molecule being (CH 3 ) 3 Si-, the entire composition being essentially free of solvents.