α-alkylaminoacetophenones (α-AK) have higher absorption coefficients in the near UV region than the usual benzoin ether and acetophenone type photoinitiators. Their initiating ability can be further improved by the addition of other initiators with longer wavelength absorption than the α-AK. The experimental results show that the reactivity enhancement depends on the combination components. An important increase can be obtained by coupling a-AK with CTX

DETX or ITX

whereas the addition of MK is less effective than TX

and BP has not significant synergetic effects on the photocuring. It should be noted that these combination systems are more suitable for the curing of pigmented formulations than clear coatings compared with other usually used commercial photoinitiators.