| abstract |
Compounds of formula (I): n n n[in which: R 1 represents a direct bond, an oxygen atom, a group >CH 2 , a sulphur atom, a group >C═O, a group —(CH 2 ) 2 — or a group of formula —N—R a , where R a is hydrogen or an alkyl; R 4 , R 5 , R 6 and R 7 are each hydrogen or various groups or atoms; R 8 , R 9 , R 10 and R 11 are each hydrogen, hydroxy, or alkyl; or R 9 and R 11 form a fused ring system with the benzene rings to which they are attached; R 12 is a direct bond, oxygen atom or methylene; and X is an anion; and esters thereof] 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. |