Polyurethane hydrogels having enhanced wetting rates

Claim 1

A method of improving the wetting rate of a water swellable, lightly crosslinked hydrogel polymer which comprises contacting said polymer with a surface treating composition comprising a mixture of: (A) a surface treating compound selected from the group consisting of: (a) a liquid ketone of the formula RCOR' wherein R is an alkyl group of from 1 to 6 carbon atoms and R' is an alkyl group of 1 to 6 carbon atoms or phenyl, (b) a liquid alkanol having from 1 to 6 carbon atoms, (c) an aliphatic, cycloaliphatic or aromatic amine having up to 12 carbon atoms, (d) an aromatic hydrocarbon having from 6 to 10 carbon atoms, (e) a cyclic oxide having from 2 to 4 ring carbon atoms, (f) an aqueous solution of an alkali metal hydroxide; and (B) from 0 to 5 percent by weight, based on the weight of (A), of a surfactant; wherein said hydrogel polymer is the polymer of the isocyanato terminated prepolymer comprising the reaction product of: (i) a poly (alkyleneoxy) polyol having an average molecular weight up to about 25,000 wherein the alkyleneoxy group contains from 2 to 4 carbon atoms, and (ii) an organic diisocyanate, said prepolymer lightly crosslinked with an equivalent amount of a crosslinking agent of the group: (iii) water or organic polyamine; wherein said poly (alkyleneoxy) polyol is a mixture of a major amount of a poly (ethyleneoxy) diol having a average molecular weight of from about 4,000 to about 25,000, and a monor amount of a higher polyol of the group poly (alkyleneoxy) triol or poly (alkyleneoxy) tetrol or aliphatic polyhydroxy compound of the formula C n H 2n+2-m (OH) m wherein n has a value of 3 to 6 and m has a value of 3 to 4, or mixtures thereof, said triol or tetrol having an average molecular weight of from about 92 to 5,000, wherein the mole ratio of diol to higher polyol in said mixture is from about 6:1 to 40:1; wherein the equivalents ratio of isocyanato groups to hydroxyl groups is from about 1.2:1 to about 1.6:1; wherein the organic polyamine is a primary or secondary diamine or triamine; and wherein the equivalents of reactive crosslinking groups in said crosslinking agent used is equivalent to the number of equivalents of isocyanato groups present in said prepolymer.

Claim 2

A method of improving the wetting rate of a water swellable, lightly crosslinked hydrogel polymer which comprises contacting said polymer with a surface treating composition comprising a mixture of: (A) a surface treating compound selected from the group consisting of: (a) a liquid ketone of the formula RCOR' wherein R is an alkyl group of from 1 to 6 carbon atoms and R' is an alkyl group of 1 to 6 carbon atoms or phenyl, (b) a liquid alkanol having from 1 to 6 carbon atoms, (c) an aliphatic, cycloaliphatic or aromatic amine having up to 12 carbon atoms, (d) an aromatic hydrocarbon having from 6 to 10 carbon atoms, (e) a cyclic oxide having from 2 to 4 ring carbon atoms, (f) an aqueous solution of an alkali metal hydroxide; and (B) from 0 to 5 percent by weight, based on the weight of (A), of a surfactant; wherein said hydrogel polymer is the polymer of the isocyanato terminated prepolymer comprising the reaction product of: (i) a poly (alkyleneoxy) polyol having an average molecular weight up to about 25,000 wherein the alkyleneoxy group contains from 2 to 4 carbon atoms, and (ii) an organic diisocyanate, said prepolymer lightly crosslinked with an equivalent amount of a crosslinking agent of the group: (iii) water or organic polyamine; wherein said poly (alkyleneoxy) polyol is a mixture of a major amount of a poly (ethyleneoxy) diol having a average molecular weight of from about 4,000 to about 25,000, and a monor amount of a higher polyol of the group poly (alkyleneoxy) triol or poly (alkyleneoxy) tetrol or aliphatic polyhydroxy compound of the formula C n H 2n+2-m (OH) m wherein n has a value of 3 to 6 and m has a value of 3 to 4, or mixtures thereof, said triol or tetrol having an average molecular weight of from about 92 to 5,000, wherein the mole ratio of diol to higher polyol in said mixture is from about 6:1 to 40:1; wherein the equivalents ratio of isocyanato groups to hydroxyl groups is from about 1.2:1 to about 1.6:1; wherein the organic polyamine is a primary or secondary diamine or triamine; and wherein the equivalents of reactive crosslinking groups in said crosslinking agent used is equivalent to the number of equivalents of isocyanato groups present in said prepolymer.