Sensitizers for photopolymerization

DETAILED DESCRIPTION What is claimed is: 1.
In a method for the photopolymerisation of unsaturated compounds or for the photochemical crosslinking of polyolefins employing a sensitizer, the improvement according to which the sensitizer is a compound of the formula ##STR58## wherein Ar is a tetrahydronaphthyl or indanyl radical, X represents one of the groups --NR.
sup.
4 R.
sup.
5, --OR.
sup.
6, O--Si(R.
sup.
7)(R.
sup.
8).
sub.
2, hydroxymethoxy, (C.
sub.
1 -C.
sub.
4 alkoxy)methoxy, (C.
sub.
2 -C.
sub.
8 acyloxy)methoxy or together with R.
sup.
1 represents --OCH(C.
sub.
1 -C.
sub.
8 alkyl)--O(CH.
sub.
2).
sub.
1-2 --, --OCH(C.
sub.
6 -C.
sub.
14 aryl)--O--, --OCH(C.
sub.
1 -C.
sub.
8 alkyl)-- or --OCH(C.
sub.
6 -C.
sub.
14 aryl)--, R.
sup.
1, if X is --OR.
sup.
6, represents (a) C.
sub.
1 -C.
sub.
8 alkyl, (b) C.
sub.
1 -C.
sub.
8 alkyl substituted by C.
sub.
2 -C.
sub.
8 acyloxy, --COO--(C.
sub.
1 -C.
sub.
4)alkyl or --CN, (c) C.
sub.
5 -C.
sub.
6 cycloalkyl or (d) C.
sub.
7 -C.
sub.
9 phenylalkyl, and, in all other cases, represents (a) alkyl of 1 to 8 carbon atoms, (b) alkyl of 1 to 8 carbon atoms substituted by OH, C.
sub.
1 -C.
sub.
4 alkoxy, C.
sub.
2 -C.
sub.
8 acyloxy, --COO--(C.
sub.
1 -C.
sub.
4)alkyl or --CN, (c) cycloalkyl of 5 to 6 carbon atoms or (d) phenylalkyl of 7 to 9 carbon atoms, R.
sup.
2 has one of the meanings assigned to R.
sup.
1 or represents allyl, methallyl, 2-carbamoylethyl, 2-(N-C.
sub.
1 -C.
sub.
4 alkylcarbamoyl)ethyl, 2-(N,N-di-C.
sub.
1 -C.
sub.
4 alkylcarbamoyl)ethyl, 2-(2-pyridyl)ethyl, 2-(2-oxo-1-pyrrolidinyl)ethyl or 2-(di-O-C.
sub.
1 -C.
sub.
4 alkylphosphono)ethyl, or R.
sup.
1 and R.
sup.
2 together represent alkylene of 4 to 6 carbon atoms, oxaalkylene of 3 to 4 carbons or azaalkylene of 3 to 4 carbon atoms, or R.
sup.
1 and R.
sup.
2 are both hydroxymethyl, R.
sup.
4 represents (a) alkyl of 1 to 12 carbon atoms, (b) alkyl of 2 to 4 carbon atoms which is substituted by --OH or --Oalk, (c) allyl, (d) cyclohexyl, (e) phenylalkyl of 7 to 9 carbon atoms, (f) phenyl or (g) phenyl which is substituted by Cl, alk, OH, --Oalk or --COOalk, R.
sup.
5 represents (a) alkyl of 1 to 12 carbon atoms, (b) alkyl of 2 to 4 carbon atoms which is substituted by --OH or --Oalk, (c) allyl, (d) cyclohexyl or (e) phenylalkyl of 7 to 9 carbon atoms, or R