Patent ID: 6943230

Claim:
A method for increasing viscosity of an aqueous system which comprises: admixing with the aqueous system a nonionic, water soluble, polyurethane having a weight average molecular weight of from 10.000 to 200,000 and consisting essentially of the groups; (a) —O—(CH 2 —CH 2 O—) n , wherein n is a number of 8-300; (b) —CO—NH—X—NH—CO— wherein X is an aliphatic, aromatic or cycloaliphatic group; and (c) —O—Y—O—, wherein Y comprises a hydrophobic moiety selected from the group consisting of (—CH 2 —CH(CH 3 )—O) m —CH 2 —CH(CH 3 )—, (CH 2 —CH(C 2 H 5 )—O) m —CH 2 —CH(C 2 H 5 )—, (CH 2 —CH 2 —CH 2 —CH 2 O) m —CH 2 —CH 2 —CH 2 —CH 2 —, alkylene groups having from 6 to 44 carbon atoms, cycloalkylene groups having from 6 to 44 carbon atoms and mixtures thereof wherein m is a number of 8 to 500, the nonionic polyurethane forms a homogenous mixture with water; the mixture having a specific viscosity of at least 0.4 at a 1% by weight solution in water at 20° C. wherein (c) comprises from 5% to 40% by weight, based on (a)+(c) of the polyurethane.