Two-layer system

Claim 1

In a radiation-curable two-layer system comprising a layer containing polymerization photoinitiator and applied to a substrate, and a second layer containing photopolymerizable compounds superposed on said first layer, the improvement wherein said photoinitiator is immobilized on a macrostructure and attached to a polymer matrix by a covalent bond and wherein said photoinitiator is of the formula Ar--CO--R wherein Ar is ##STR3## R is Ar or CR 2 R 3 R 4 , R 1 is H, halogen, C 1 -C 12 -alkyl, C 1 -C 12 -alkoxy, C 1 -C 12 -alkylthio or A, R 2 and R 3 independently of one another are each H, C 1 -C 6 -alkyl or phenyl, or one of R 2 and R 3 is C 1 -C 6 -alkylene-O-A, or R 2 and R 3 together are C 2 -C 6 -alkylene or C 1 -C 6 -oxaalkylene, R 4 is OR 5 , N(R 5 ) 2 , SR 5 , or A, R 5 is H, C 1 -C 6 -alkyl or C 1 -C 6 -alkanoyl, A is ##STR4## X is O, NH OR (C 1 -C 6 -alkyl)--N, Y is O, N or S, Z is in each case independently of one another H or CH 3 , m is 0 to 4 and n is 2 to 10 6 , subject to the proviso that said initiator contains at least one radical of the formula A.