Patent ID: 7160966

Claim:
A polymerizable composition comprising a) at least one ethylenically unsaturated monomer or oligomer, b) a compound of formula IIIa or IVa and c) a source of free radicals capable of initiating polymerization of ethylenically unsaturated monomers, wherein the compounds of formula IIIa and IVa are wherein Y is selected from the group consisting of R 1 is hydrogen, —COOH, —COO(C 1 –C 4 alkyl), —COO-phenyl, —COObenzyl, C 1 –C 8 alkoxy, C 1 –C 18 alkyl, C 2 –C 4 alkenyl, C 1 –C 18 alkyl or C 2 –C 4 alkenyl substituted by OH, —COOH, —COO(C 1 –C 4 )alkyl, C 2 –C 18 alkyl which may be interrupted by one or more oxygen atom, unsubstituted cyclopentyl, cyclohexyl, cyclohexenyl, phenyl or naphthyl; or cyclopentyl, cyclohexyl, cylohexenyl, phenyl or naphthyl which are substituted by C 1 –C 4 alkyl, —COOH or —COO—(C 1 –C 4 alkyl); R 2 is hydrogen, C 1 –C 18 alkyl or R 1 and R 2 together with the nitrogen atom form a 5-membered ring which may have an unsaturated bond or be fused to a benzene ring; and R 3 is hydrogen or C 1 –C 18 alkyl; with the proviso that 2,6-diethyl-2,3,6-trimethyl-4-lauroyloxypiperidine-1-oxyl, 2,6-diethyl-2,3,6-trimethyl-4-stearoyloxypiperidine-1-oxyl, 2,2-dimethyl-6,6-diethyl-4-lauroyloxypiperidine-1-oxyl and 2,2-dimethyl-6,6-diethyl-4-stearoyloxypiperidine-1-oxyl are excluded.