Stable aqueous polyurethane dispersions

A method for the preparation of a stable aqueous polyurethane dispersion comprising the steps of:

• 1) providing at least one water-dispersible isocyanate-terminated polyurethane prepolymer (A) comprising the reaction product of:
• i) at least one polyisocyanate;
• ii) at least one hydroxy carboxylic acid;
• and
• iii) at least one polymeric polyol, and
• iv) optionally at least one sulfonated polyol;
• 2) providing at least one water-based polyurethane dispersion (B) comprising the reaction product of:
• i) at least one isocyanate terminated polyurethane prepolymer (B);
• ii) at least one amine chain extender;
• iii) at least one alcoholamine chain terminator;
• and
• iv) optionally, water;
• 3) dispersing 1) in 2) and water under vigorous agitation to form a dispersion mixture;
• 4) heating said dispersion mixture to a temperature of about 35 to about 95.degree. C. to form a stable aqueous polyurethane dispersion substantially free of isocyanate.