Patent ID: 7919146
Filing Date: 2011-04-05
Classification: C08F,C08G,C09D

Abstract:
1. An aqueous polyurethane composition comprising a polyurethane having an acid value in the range of from 4 to 150 mgKOH/g and which comprises the reaction product of: (A) an isocyanate-terminated prepolymer comprising a terminal isocyanate group, the prepolymer (A) being obtained by the reaction of components comprising: (B) at least one isocyanate reactive active-hydrogen chain-extending compound comprising an isocyanate reactive active-hydrogen group, where the compound (B) comprises at least 0.20 stoichiometric equivalents with respect to the isocyanate content of the isocyanate-terminated prepolymer (A), of an isocyanate reactive active-hydrogen chain-extending compound selected from the group consisting of hydrazine, hydrazine derivatives and mixtures thereof; Wherein the prepolymer (A) and the compound (B) are reacted in a ratio of the isocyanate groups of the prepolymer (A) to the isocyanate reactive active-hydrogen groups of the compound (B) in the range of from 1:0.5 to 1:1; and wherein at least 0.2 stoichiometric equivalents of the anionic or potentially anionic water-dispersing groups are neutralised with ammonia.