Patent ID: 8058343

Claim:
An aqueous polyurethane dispersion, comprising: a prepolymer, which comprises: a) at least one polyether or polyester polyol, wherein said polyether or polyester polyol has a number average molecular weight of about 600 to about 3,500; b) a mixture of 4,4â€²- and 2,4â€²-methylene bis(phenyl isocyanate) (MDI) isomers, wherein the ratio of 4,4â€²-MDI to 2,4â€²-MDI isomers ranges from about 65:35 to about 35:65; and c) at least one diol compound comprising: (i) hydroxy groups capable of reacting with the mixture of MDI isomers of component b) and (ii) at least one carboxylic acid group capable of forming a salt upon neutralization, wherein said at least one carboxylic acid group is incapable of reacting with the mixture of MDI isomers of component b); wherein the aqueous polyurethane dispersion is a substantially solvent-free system that further comprises: d) at least one neutralizing agent to form an ionic salt with the at least one diol compound; and e) at least one monofunctional dialkyl amine compound as a blocking agent for isocyanate groups; and further comprising at least one surface active agent; at least one antifoam agent at least one rheological modifier; at least one diamine chain extension component, and at least one polymeric component selected from the group consisting of polyethylenimine dendrimers, poly(vinylamine) dendrimers, poly(allylamine) dendrimers, and poly(amidoamine) dendrimers, with at least three or more primary and/or secondary amino groups per mole of the polymer.