Derivatives of aryl ketones based on 9,10-dihydro-9,10-ethanoanthracene and p-dialkyl-aminoaryl aldehydes as visible sensitizers for photopolymerizable compositions

A composition having the formula ##STR13## wherein:

• ##STR14## R.sup.1 and R.sup.2 are each H, or, R.sup.1 +R.sup.2 is --CH.sub.2 --;
• R.sup.3 is H, or R.sup.3 +R.sup.5 is selected from --CH.sub.2 CH.sub.2 --and --CH.sub.2 CH.sub.2 CH.sub.2 --;
• R.sup.4 is H, or, R.sup.4 +R.sup.6 is selected from --CH.sub.2 CH.sub.2 -- and --CH.sub.2 CH.sub.2 CH.sub.2 --;
• R.sup.5 and R.sup.6 are alkyl groups of 1 to 5 carbon atoms, or together are selected from --Ch.sub.2 ) .sub.4 and --CH.sub.2 CH.sub.2 OCH.sub.2 CH.sub.2 --;
• R.sup.7 is H or CH.sub.3 ;
• and
• n is 0 or 1, with the proviso that when n is 1, R.sup.1 and R.sup.2 are H.