Method of preparing cross-linked polydiorganosiloxane using organic isocyanates and products prepared therefrom

Claim 1

A method of preparing a sponge comprising combining a mercaptofunctional polydiorganosiloxane, an organic diisocyanate, and a catalyst such that a homogeneous mixture is formed, contacting the homogeneous mixture with water in the liquid state promoting foaming and cross-linking, and thereafter recovering a sponge, said mercapto-functional polydiorganosiloxane consisting essentially of a polydiorganosiloxane endblocked with organosiloxy units selected from units represented by unit formulae ##STR9## wherein the polydiorganosiloxane has organic radicals selected from phenyl radicals and alkyl radicals of one to four inclusive carbon atoms, where at least 50 percent of the organic radicals of the polydiorganosiloxane are alkyl radicals, each R is phenyl radical or an alkyl radical of one to four inclusive carbon atoms, each R' is an alkyl radical of one to three inclusive carbon atoms, n is an integer of from 2 to 4 inclusive, there being more than one mole of isocyanate group from the organic diisocyanate for each mole of mercapto group from the mercapto-functional polydiorganosiloxane, and there being at least one mole of water for each mole of isocyanate in excess of one mole of isocyanate group per mole of mercapto group.

Claim 2

A method of preparing a sponge comprising combining a mercaptofunctional polydiorganosiloxane, an organic diisocyanate, and a catalyst such that a homogeneous mixture is formed, contacting the homogeneous mixture with water in the liquid state promoting foaming and cross-linking, and thereafter recovering a sponge, said mercapto-functional polydiorganosiloxane consisting essentially of a polydiorganosiloxane endblocked with organosiloxy units selected from units represented by unit formulae ##STR9## wherein the polydiorganosiloxane has organic radicals selected from phenyl radicals and alkyl radicals of one to four inclusive carbon atoms, where at least 50 percent of the organic radicals of the polydiorganosiloxane are alkyl radicals, each R is phenyl radical or an alkyl radical of one to four inclusive carbon atoms, each R' is an alkyl radical of one to three inclusive carbon atoms, n is an integer of from 2 to 4 inclusive, there being more than one mole of isocyanate group from the organic diisocyanate for each mole of mercapto group from the mercapto-functional polydiorganosiloxane, and there being at least one mole of water for each mole of isocyanate in excess of one mole of isocyanate group per mole of mercapto group.