Process for preparation of amphoteric resinous aqueous emulsions

Claim 1

A process for preparing an amphoteric polyurethane aqueous emulsion, which comprises: 1. reacting, in the liquid phase and in a ketone solvent, at a temperature of from -20° to +70° C, (A) isocyanate-terminated urethane prepolymer prepared by reacting organic polyol having a molecular weight in the range of from 200 to 10,000 with an excess of organic polyisocyanate, with (B) an excess of polyalkylene polyamine having at least two primary or secondary amino groups, the total mole number of primary and secondary amino groups in the polyalkylene polyamine being greater than the total mole number of isocyanate groups in the isocyanate-terminated urethane prepolymer, the reaction being carried out until the presence of --NCO groups cannot be detected, whereby to form polyurethane-urea-polyamine, 2. reacting with the polyurethane-urea-polyamine of step 1, a substance selected from the group consisting of alkyl isocyanates having an alkyl group containing 12 to 22 carbon atoms and α-olefin epoxides having from 12 to 22 carbon atoms, to form an alkyl-substituted polyurethane-urea-polyamine, the amount of said substance being from 10 to 80 mole %, based on the number of moles of amino groups in the molecule of said polyurethane-urea-polyamine, 3. reacting the reaction product of step 2 with a material selected from the group consisting of β-propiolactone, δ-valerolactone, ε-caprolactone, 1,3-propane sultone and 1,4-butane sultone to render amphoteric the alkyl-substituted polyurethane-urea-polyamine, the amount of said material being from 0.5 to 2.0 moles per mole of amino groups in said alkyl-substituted polyurethane-urea-polyamine, 4. treating the reaction product of step 3 to remove the solvent therefrom and adding water thereto to form an aqueous amphoteric polyurethane emulsion.