Anionic aqueous polyurethane having blocked NCO groups and process

摘要

An aqueous anionic polyurethane emulsion is prepared by reacting an isocyanate-terminated urethane prepolymer with an excess of a polyalkylene polyamine thereby to form a polyurethane-urea-polyamine, reacting a portion of the free amino groups of said polyurethane-urea-polyamine with a blocked polyisocyanate having a single free isocyanate group, reacting the resulting product with a cyclic dicarboxylic acid anhydride, and mixing the resulting product with an aqueous solution of a basic substance.