Patent ID: 7901867

Claim:
A compound of the formula I, II, III or IV wherein R is hydrogen, C 1 -C 20 alkyl; C 2 -C 20 alkyl interrupted by one or more O; -L-X-R 2 or -L-R 2 ; R 1 has one of the meanings as given for R or is R 2 is a monovalent sensitizer or photoinitiator moiety; Ar 1 and Ar 2 independently of one another are phenyl substituted by one or more C 1 -C 20 alkyl, halogen, OR 3 or COOR 1 ; or are unsubstituted naphthyl, anthryl, phenanthryl or biphenylyl; or are naphthyl, anthryl, phenanthryl or biphenylyl substituted by one or more C 1 -C 20 alkyl or OR 3 ; or are -Ar 4 -A-Ar 3 or Ar 3 is unsubstituted phenyl, naphthyl, anthryl, phenanthryl or biphenylyl; or is phenyl, naphthyl, anthryl, phenanthryl or biphenylyl substituted by one or more C 1 -C 20 alkyl, OR 3 , C 2 -C 12 alkanoyl or benzoyl; Ar 4 is phenylene, naphthylene, anthrylene or phenanthrylene; A is a direct bond, S, O or C 1 -C 20 alkylene; X is CO, C(O)O, OC(O), O, S or NR 3 ; L is C 1 -C 20 alkylene or C 2 -C 20 alkylene interrupted by one or more O; R 3 is C 1 -C 20 alkyl or C 1 -C 20 hydroxyalkyl; or is C 1 -C 20 alkyl substituted by O(CO)R 13 ; Z is S, CO or NR 3 ; Z 1 is a direct bond, CH 2 , O or S; R 4 and R 11 independently of one another are hydrogen, halogen, C 1 -C 8 alkyl, C 1 -C 8 alkoxy or phenyl; R 13 is C 1 -C 20 alkyl; and Y is an anion.