Aqueous emulsion of thermally reactive polyurethane composition

In an aqueous emulsion of a thermally reactive polyurethane-forming composition, comprising (a) a uniformly dispersed hydrophobic, blocked polyisocyanate having a plurality of masked isocyanate groups, said groups being only non-electrolytic masked isocyanate groups capable of regenerating free isocyanate groups at an elevated temperature, and (b) a dispersing effective amount of a surfactant, the improvement wherein said surfactant is a thermally reactive anionic surfactant of the formula [R--X--CH.sub.2 CH.sub.2 O).sub.l CONH].sub.m A--NHCOSO.sub.3 Na).sub.n wherein R is a C.sub.7-26 alkyl, alkaryl or alkenyl group;

• X is --O--, --COO--, --S-- or --NR'-- wherein R' is a polyoxyethylene group or a C.sub.1-22 alkyl group;
• l is 0 or an integer from 1 to 200;
• m and n are each an integer from 1 to 4, the sum of m+n being not greater than 5;
• and A is an organic bridging group.