Multifunctional cationic photoinitiators, their preparation and use

Abstract

Compounds of formula (I): [where: Ris a direct bond, oxygen, a group >CH, sulphur, a group >C═O, a group-(CH)— or a group-N—R, where Ris hydrogen or alkyl; R, R, Rand Rare hydrogen or substituentsα; R, R, Rand Rare hydrogen, hydroxy or alkyl; or Rand Rare joined to form a fused ring system with the benzene rings to which they are attached; Ris a direct bond, oxygen or a —CH-group; p is 0 or 1 ; substituentsα are: alkyl, alkoxy, alkenyl, halogen, nitrile, hydroxyl, aryl, aralkyl, aryloxy, aralkyloxy, arylalkenyl, cycloalkyl, carboxy, carboxyalkoxy, alkoxycarbonyl, aryloxycarbonyl, alkylcarbonyloxy, alkanesulphonyl, arenesulphonyl, alkanoyl or arylcarbonyl; n is 1 to 12; Ris hydrogen, methyl or ethyl; A is a group —[O(CHRCHR)]—, —[O(CH)CO]-, or —[O(CH)CO]()-[O(CHRCHR)]—, where: one of Rand Ris hydrogen and the other is hydrogen, methyl or ethyl; a is 1 to 2 ; b is 4 to 5 ; Q is a residue of a polyhydroxy compound having from 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; and Xis 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.