Storage stable polyorganosiloxane compositions

Claim 1

A polyorganosiloxane composition consisting essentially of (a) a polyorganosiloxane comprising organosiloxane units (1) of the formula R 1 a R 2 b SiO (4-a-b)/2 , wherein R 1 represents an alkenyl radical containing from 2 to 4 carbon atoms or a methacrylyl radical, R 2 represents a monovalent hydrocarbon radical which is substantially free of ethylenic unsaturation and contains from 1 to 20 carbon atoms, a is an integer from 1 to 3, inclusive, b is an integer from 0 to 2, inclusive, and the sum of a and b is 3 or less, with the proviso that said polyorganosiloxane does not contain any halogenated hydrocarbon radicals; (b) a polyorganohydrogensiloxane comprising organosiloxane units (2) of the formula H c R d SiO 4-c-d/2 , where R 3 represents a hydrocarbon radical selected from the same group as R 2 , c is an integer from 1 to 3, inclusive, d represents an integer of from 0 to 2, inclusive, and the sum of c and d is 3 or less, with the proviso that said polyorganohydrogensiloxane does not contain any halogenated hydrocarbon radicals, and the amount of said polyorganohydrogensiloxane is sufficient to provide at least 0.2 equivalent of silicon-bonded hydrogen atoms per equivalent of alkenyl radicals present in said polyorganosiloxane; (c) an amount of a platinum, palladium, or rhodium catalyst sufficient to provide from 0.1 to 1000 ppm of metal, based on the combined weight of components (a) and (b); and characterized by (d) a silane of the general formula where R 4 , R 5 and R 6 are identical or different monovalent hydrocarbon radicals containing from 1 to 10 carbon atoms, or R 5 and R 6 jointly form a divalent hydrocarbon radical, the amount of said silane being sufficient to retard curing of said curable polyorganosiloxane composition at room temperature.