Photoinitiator combinations comprisingat least one compound of formula (I)R1 is C1-C4alkyl, C1-C4alkoxy or halogen R2 is hydrogen, C1-C4alkyl, C1-C4alkoxy or halogenR3 is, for example, C1-C20alkyl, cyclopentyl, cyclohexyl, phenyl-C1-C4alkyl, naphthyl or biphenylyl or an O-, S- or N-containing 5- or 6-membered heterocyclic ring and at least one compound of formula (II)R1 and R2 are as defined above R9 is, for example, C1-C20alkyl, cyclopentyl, cyclohexyl, phenyl-C1-C4alkyl, naphthyl, biphenylyl or an O-, S- or N-containing 5- or 6-membered heterocyclic ring and R10 is, for example, C1-C20alkyl, C2-C20alkyl interrupted by one or more O atoms, cyclopentyl, cyclohexyl, phenyl-C1-C4alkyl, naphthyl, biphenylyl or an O-, S- or N-containing 5- or 6-membered heterocyclic ring are reactive photo hardeners causing only a low degree of yellowing in the cured substrates.
