Fused ring compounds, and their use as cationic photoinitiators

摘要

Compounds of formula (I): [in which: R¹ represents a direct bond, an oxygen atom, a group >CH₂, a sulphur atom, a group >C-O, a group -(CH₂)₂- or a group of formula -N-R^a, where R^a is hydrogen or an alkyl; R⁴, R⁵, R⁶ and R⁷ are each hydrogen or various groups or atoms; R⁸, R⁹, R¹⁰ and R¹¹ are each hydrogen, hydroxy, or alkyl; or R⁹ and R¹¹ form a fused ring system with the benzene rings to which they are attached; R¹² 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.