| 摘要 |
The present invention relates to a photopolymerization process comprising irradiating a photopolymerizable material with U.V. light of wave length 250 to 400 nm in the presence of a photosensitizing amount of a photoinitiator of formula I, <IMAGE> I in which R is hydrogen or halogen R1 is alkyl, cycloalkyl, benzyl, optionally substituted phenyl or (a) <IMAGE> (a) either R2 is optionally substituted alkyl, benzyl, C6H5-CH=CH-, 2-thienyl, 2-furyl, 2-(3-chloro)benzothienyl or optionally substituted phenyl, and R3 is hydrogen or R2 and R3 form a radical of formula (b) <IMAGE> (b) in which X is a direct bond, -O-, -S-, -CH2-, <IMAGE> and R4 and R' have one of the significances of R2 and R, respectively, with the proviso that when R1 is (a) R3 is hydrogen and R2 and R4 are free from halogen atoms.
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