THIOXANTHONE DERIVATIVES, AND THEIR USE AS CATIONIC PHOTOINITIATORS

摘要

Photoinitiator compounds of formula (I): F {where: A represents a direct bond or a group of formula ___[O(CHR7CHR6)a]y___, ___[O(CH2)bCO]yç, or - [O(CH2)bCO)(y-1)-[O(CHR7CHR6)a]-, where one of R6 and R7 is hydrogen and the other is hydrogen or methyl; a is a number from 1 to 2; b is a number from 4 to 5; Q is a residue of a polyhydroxy compound having 2 to 6 hydroxy groups; x is a number greater than 1 but no greater than the number of available hydroxyl groups in Q; y is a number from 1 to 10; R1, R2, R3 and R4 are individually the same or different and each is hydrogen, hydroxy, or alkyl; or R1 and R3 are joined to form a fused ring system with the benzene rings to which they are attached; and R5 represents a direct bond, an oxygen atom or a methylene group } are useful as cationic photoinitiators, especially for use in surface coating applications, such as printing inks and varnishes, and which are intended to be cured by polymerisation initiated by radiation.