Aqueous dispersions of blocked polyisocyanates

摘要

The present invention is directed to a process for the preparation of an aqueous dispersion of a blocked polyisocyanate by reacting an aqueously dispersed polyisocyanate having an isocyanate content of at least 12% by weight, based on the weight of the polyisocyanate, with a monofunctional blocking agent which is more reactive with isocyanate groups than water at an equivalent ratio of monofunctional blocking groups to isocyanate groups of 0.5:1 to 2:1. The present invention is also directed to the aqueously dispersed blocked polyisocyanates prepared by this process and to compositions containing these polyisocyanates and an isocyanate-reactive compound.