| abstract |
Aqueous dispersions of polyurethane polymers in ammonium salt form are prepared by reacting diisocyanates with a polyhydroxy, carboxylic acid to form an isocyanate- terminate prepolymer that is united with an unsaturated fatty acid ester polyol to provide carboxylic-containing, water-dispersible polyurethanes having properties exhibited by organic solvent-based, oil-modified polyurethanes. The aqueous dispersions can be formed by neutralization of "oil-modified," carboxylic group-containing, water-dispersible polyurethanes with ammonium salt-forming materials such as ammonia and amines. The aqueous dispersions are especially desirable coating compositions. An organic phosphite may be incorporated in the compositions to control the development of hardness in films made from the aqueous dispersions and thereby avoid the formation of wrinkles in films that are made from the compositions. |