Patent ID: 7977402

Claim:
A radiation curable ink composition for impulse printheads, comprising: a) a photoinitiator system which comprises both a photocation polymerization initiator and a free-radical photoinitiator, each in the amount of about 1 to about 12 wt. %; b) from about 0.5 to about 30 wt. % of an acrylate ester of a carboxylic acid ester represented by the formula: having a carboxylate ester moiety containing groups R 1 , R 2 and R 3 , which are each independently alkyl, aryl, alkylaryl, alkoxyaryl or cycloaliphatic groups, where the total number of carbon atoms included in groups R 1 , R 2 and R 3 range from 1 to 10, and wherein R 4 is a group selected from hydrogen, methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, phenyl and alkoxy phenyl; and c) from about 3 to about 60 wt. % of at least one radiation curable material containing a radiation curable functional group; wherein the ink composition has a viscosity of less than about 70 cPs at 25° C.