| 摘要 |
Compounds of the formula ? <IMG> (?) in which R1 is, for example, C1-C20alkyl or phenyl-C1-C6alkyl which radicals are unsubstituted or substituted; R2, R3 and R4 independently of one another are phenyl or bipheny l, which radicals are unsubstituted or substituted; wherein the sum of the Hammett .sigma . constants (.SIGMA..sigma.) of the substituents on the aromatic radicals R2, R3 and R4 is between +0.36 and +2.58; R8, R9, R14, R15 and R16 are, for example, C1-C12alkyl, phenyl-C1-C6alkyl or phenyl, and G is a radical which is able to form positive ions are suitable as photoinitiators for photopolymerizable compositions which contai n acid groups, in the presence of a coinitiator if desired.
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