Ketone sensitisers - for hexarylbiimidazole/leuco dye/photopolymerisa cpd system (300-600 mu)

摘要

Sensitisers (300-600 m mu) of formula (1) for compsn. contg. a hexaarylbi-imidazole (255-275 m mu) which dissociates into triarylimidazolyl radicals with UV light. (where Q is NRR2; R1 and R2 are H or 1-4C alkyl, R3 is Cl, methoxy or as R1, R4 and r5 are as R1 or phenyl or form 5-7C ring and n is 0 or 1. The compsn. also contains a leuco dye oxidisable by the triarylimidazolyl gps. also a photopolymerisable substance pref. pentaerythritol triacrylate. Improved efficiency particularly over 366-430 m mu. Without the sensitiser the system is prone to variations in absorption also in light source.