Pigmented inks for ink jet printers

Abstract

There is provided an aqueous ink jet ink composition suitable for use in continuous ink jet printers comprising: (a) a surface modified carbon black pigment; (b) at least one organic pigment; and (c) an aqueous carrier medium. The black aqueous pigment ink formulated in accordance with this composition provides a dried ink film whereof the resistivity is increased to a level whereby no printer failure or print defects are caused by electrical shorts when the printer has been out of use for a sufficient time to allow the ink to dry out in parts of the apparatus. The ink may also comprise at least one dispersant for the organic pigment.

Dependencies are inferred from the claim text.