Patent ID: 8076445

Claim:
A curable composition curable thermally and by UV radiation comprising a carbodiimide and a film-forming water-dispersible polymer, wherein the carbodiimide comprises a reaction product of a) at least one of an aliphatic C 4 to C 20 polyisocyanate and an araliphatic C 4 to C 20 polyisocyanate, b) at least one of a mono-hydroxyl-functional carboxylic acid and a mono-hydroxyl-functional carboxylic salt, c) optionally, a further compound carrying groups able to react with isocyanate groups in an addition reaction, d) optionally, at least one other isocyanate, and carbodiimide units in the carbodiimide being derived essentially exclusively from the isocyanate groups of component a), wherein the carbodiimide is represented by the structure R 1 —CO—NH—X—N═C═N—X—[—N═C═N—X—] n —NH—CO—R 2 wherein X is at least one of an aliphatic hydrocarbon radical having 4 to 12 carbon atoms, a cycloaliphatic hydrocarbon radical having 6 to 15 carbon atoms, and an araliphatic hydrocarbon radical having 7 to 15 carbon atoms; n is an integer from 0 to 10; and R 1 and R 2 are radicals derived from component b) by abstraction therefrom of a hydrogen atom attached to a hydroxyl group, wherein the carbodiimide is free from units derived from macropolyols having a molecular weight of more than 400, and the water-dispersible film-forming polymer comprises a reaction product of an ethylenically unsaturated carboxylic acid and at least one of a C 1 to C 20 alkyl (meth)acrylate, a vinyl ester of a carboxylic acid containing up to 20 carbon atoms, a vinyl aromatic compound having up to 20 carbon atoms, an ethylenically unsaturated nitrile, a vinyl halide, an aliphatic hydrocarbon having 2 to 8 carbon atoms and 1 or 2 double bonds, and a free-radically polymerizable monomer and the polymer comprises carboxylic acid groups in amounts of from 0.01 to 2 mol/kg and wherein, under cure conditions, the carbodiimide undergoes a crosslinking reaction with the carboxylic acid to form acylurea groups.