Photoinitiator mixture comprising at least one alpha-amino ketone compound; and at least one compound of the Formula (I) or (I' ) wherein R1 and R'1 for example are hydrogen, C3-C8cycloalkyl or C1-C12alkyl R2 and R2' for example are hydrogen; unsubstituted C1-C20alkyl or substituted C1-C20alkyI; and R8 and R9 for example are are hydrogen, C1-C12alkyl which optionally is substituted, or phenyl which optionally is substituted; exhibit an unexpectedly good performance in photopolymeri- zation reactions.
