Patent ID: 8088493

Claim:
An aqueous composition comprising a polyurethane vinyl hybrid dispersion and ≦0.5 wt % of 1-methyl-2-pyrrolidinone by weight of the composition, wherein the polyurethane has an acid value in the range of from to 24 to 65 mgKOH/g and is the reaction product of: A) an isocyanate-terminated prepolymer formed from components comprising: (i) 36 to 60 wt % of at least one aromatic polyisocyanate; (ii) 0 to 30 wt % of at least one aliphatic polyisocyanate; (iii) 0 to 15 wt % of at least one isocyanate-reactive polyol bearing ionic and/or potentially ionic water-dispersing groups with a weight average molecular weight ≦500 g/mol; (iv) 0 to 10 wt % of at least one isocyanate-reactive polyol bearing non-ionic water-dispersing groups; (v) 0 to 15 wt % of at least one isocyanate-reactive polyol with a weight average molecular weight ≦500 g/mol not comprised by (iii) or (iv); (vi) 20 to 58 wt % of at least one isocyanate-reactive polyol not comprised by (iii), (iv) or (v); where (i)+(ii)+(iii)+(iv)+(v)+(vi) add up to 100 wt %; and where the NCO/OH ratio is from 1.2 to 2.5; and B) at least one active-hydrogen chain extending compound; in the presence of (a) ≦5 wt % of 1-methyl-2-pyrrolidinone by weight of polyurethane, (b) 5 to 100 wt % of 1-ethyl-2-pyrrolidinone by weight of polyurethane and (c) water.