Constrained N-alkylamino aryl ketones as sensitizers for photopolymer compositions

Claim 1

A photopolymerizable composition comprising an admixture of (a) at least one nongaseous ethylenically unsaturated compound having at least one terminal ethylenically unsaturated group, a boiling point above 100°C at normal atmospheric pressure and being capable of addition polymerization, (b) at least one organic polymeric binder compound, (c) optionally at least one photoinitiator or photoinitiator system, the improvement wherein the composition contains (d) 0.001 to 15% by weight of the total composition of at least one constrained N-alkylamino aryl ketone of the formula: wherein R 1 and R 5 are H, R 2 is lower alkyl of 1 to 4 carbon atoms, R 3 is lower alkyl of 1 to 4 carbon atoms, R 4 and R 7 are H, R 6 is H, OCH 3 or , R 8 is lower alkyl of 1 to 4 carbon atoms, R 9 is lower alkyl of 1 to 4 carbon atoms, R 1 and R 2 taken together is -CH 2 CH 2 CH 2 -, R 3 and R 4 taken together is -CH 2 CH 2 CH 2 -, R 5 and R 8 taken together is -CH 2 CH 2 CH 2 -, R 7 and R 9 taken together is -CH 2 CH 2 CH 2 - and Z is H-, H- or a bridge between the two aromatic rings taken from the group of -GH 2 -, -0-, -S-, with the proviso that when Z is H-, H- at least one of R1 and R2 , R3 and R 4 , R 5 and R 8 and R 7 and R when taken together is -CH 2 CH 2 CH 2 -.