Patent ID: 7135505

Claim:
A radiation curable coating composition comprising the reaction product of i) one or more polyisocyanates, wherein at least 10 equivalent percent of the isocyanate groups are in the form of uretdione groups, and ii-a) one or more hydroxy functional lactone ester (meth)acrylates having a number average molecular weight of from about 200 to about 2000 and having the formula: CH 2 =C(R 1 )—C(O)—O—R 2 —[O—C(O)—R 3 —] n —OH wherein n is an integer of from 1 to 5, R 1 is hydrogen or methyl, R 2 represents an alkylene group or substituted alkylene group having from 2 to 10 carbon atoms and which may be substituted with one or more alkyl groups having from 1 to 12 carbon atoms, and R 3 represents a straight or branched chain alkylene group of from 3 to 8 carbon atoms, and which may be substituted with one or more alkyl groups having from 1 to 12 carbon atoms, and ii-b) one or more hydroxy functional (meth)acrylate esters according to the formula: CH 2 =C(R 1 )—C(O)—O—R 2 —OH wherein R 1 and R 2 are as defined above, and wherein the amount of component i), on an isocyanate equivalent basis, is essentially equal to the amount of hydroxy equivalents of hydroxy containing materials in the composition.