Blowing catalyst composition for low density flexible polyurethane foams

Claim 1

A method for preparing low density cellular polyurethanes, said method comprising reacting a polyol having at least two reactive hydrogen atoms, as determined by the Zerewitinoff method, with an organic polyfunctional isocyanate in the presence of (a) from 0.5 to 40%, based on the weight of said polyol, of a blowing agent consisting essentially of water and from 10 to 90%, based on the total weight of said blowing agent, of methylene chloride, (b) a catalytically effective amount of a gel catalyst selected from the group consisting of stannous salts of monocarboxylic acids, wherein the acids contain from 1 to 20 carbon atoms, and organotin compounds of the general formula R a SnX 4-a , wherein R is selected from alkyl and alkenyl radicals, each of which contain from 1 to 18 carbon atoms, cycloalkyl, aryl, alkaryl and aralkyl hydrocarbon radicals, and the foregoing radicals when inertly substituted, and X represents a monovalent radical selected from the group consisting of halogen atoms and radicals of the general formula R'COO--, R'S--, R'O-- and --SR"COOR' wherein R' is in turn selected from the same group as R and R" is an alkylene radical containing from 1 to 8 carbon atoms, and (c) a catalytically effective amount of a blowing catalyst composition consisting essentially of an antimony carboxylate, a potassium carboxylate and a zinc carboxylate, wherein the hydrocarbyl portions of said carboxylates contain from 1 to 20 carbon atoms and wherein each of said antimony and potassium carboxylates constitutes from 10 to 40% by weight of said catalyst composition and the zinc carboxylic constitutes the remaining 20 to 80% by weight.

Claim 2

A method for preparing low density cellular polyurethanes, said method comprising reacting a polyol having at least two reactive hydrogen atoms, as determined by the Zerewitinoff method, with an organic polyfunctional isocyanate in the presence of (a) from 0.5 to 40%, based on the weight of said polyol, of a blowing agent consisting essentially of water and from 10 to 90%, based on the total weight of said blowing agent, of methylene chloride, (b) a catalytically effective amount of a gel catalyst selected from the group consisting of stannous salts of monocarboxylic acids, wherein the acids contain from 1 to 20 carbon atoms, and organotin compounds of the general formula R a SnX 4-a , wherein R is selected from alkyl and alkenyl radicals, each of which contain from 1 to 18 carbon atoms, cycloalkyl, aryl, alkaryl and aralkyl hydrocarbon radicals, and the foregoing radicals when inertly substituted, and X represents a monovalent radical selected from the group consisting of halogen atoms and radicals of the general formula R'COO--, R'S--, R'O-- and --SR"COOR' wherein R' is in turn selected from the same group as R and R" is an alkylene radical containing from 1 to 8 carbon atoms, and (c) a catalytically effective amount of a blowing catalyst composition consisting essentially of an antimony carboxylate, a potassium carboxylate and a zinc carboxylate, wherein the hydrocarbyl portions of said carboxylates contain from 1 to 20 carbon atoms and wherein each of said antimony and potassium carboxylates constitutes from 10 to 40% by weight of said catalyst composition and the zinc carboxylic constitutes the remaining 20 to 80% by weight.