Patent ID: 6787197
Filing Date: 2004-09-07
Classification: B05D,C09D

Abstract:
A process for producing a scratch-resistant coating, said process comprising:applying at least one UV-curable coating composition comprising a mixture of at least one aliphatic urethane (meth)acrylate prepolymer having at least two double bonds per molecule and having a viscosity in the range from 250 to 11,000 mPa.s, and at least one reactive diluent, to a substrate to form a wet coating and curing said wet coating by exposure to ultraviolet radiation under an inert gas atmosphere, wherein the aliphatic urethane prepolymer is obtained by reacting at least 25% of the isocyanate groups of a compound (A) containing at least two isocyanate groups per molecule with (B) at least one hydroxy alkyl ester of acrylic acid, methacrylic acid or both acrylic acid and methacrylic acid, and subsequently reacting any remaining isocyanate groups of (A) with a chain extender (C) selected from the group consisting of an aliphatic diol having up to 20 carbon atoms, a polyol having up to 20 carbon atoms, a diamine having up to 20 carbon atoms, a polyamine having up to 20 carbon atoms, an alkanolamine having up to 20 carbon atoms, a dimercaptan having up to 20 carbon atoms, a polymercaptan having up to 20 carbon atoms, a hydroxyalkylester of a long-chain dicarboxylic acid, and an alkylamineamide of a long chain dicarboxylic acid, wherein component (A) is obtained by reacting at least one of a low molecular mass aliphatic diisocyanate or polyisocyanate with a compound having at least two isocyanate-reactive functional groups wherein the ratio of the isocyanate groups of component (A) to the functional groups of the compound is in the range of from 3:1 to 1:2.