Patent ID: 7754809

Claim:
An aqueous polyurethane dispersion containing polyurethane solids and a non-aqueous, organic solvent content of less than 5 weight percent wherein the polyurethane solids are obtained from a polyurethane prepolymer prepared by reacting (a) a polyol or polyol blend having a mean average equivalent weight of 240 to 480, and (b) at least one polyisocyanate (c) optionally additional stabilizers; and (d) optionally chain extenders wherein the prepolymer has an isocyanate (NCO) content of from 8 to 13 weight percent and the polyisocyanate to polyol molar ratio is from 2.0:1 to 3.0:1; with the proviso when the equivalent weight of the polyol or polyol blend is less than 260, a chain extender is present.