Process for preparing an ink jet ink

Abstract

A process for making an ink jet ink comprising: a) providing an organic pigment dispersion containing a pigment and a carrier; b) mixing the pigment dispersion with rigid milling media having an average size less than about 100 μm; c) introducing the mixture from step b) into a high speed mill; d) milling the mixture from step c) until a pigment particle size distribution is obtained wherein about 50% by weight of the pigment particles have a particle size less than about 100 nanometers; e) separating the milling media from the mixture milled in step d); and f) diluting the mixture from step d) to obtain the ink jet ink; wherein the milling media comprises negatively-charged polymeric beads which are crosslinked sufficiently to prevent swelling of the polymeric beads to levels greater than or equal to about 50 volume % within 4 hours at 25° C. in the carrier.

Dependencies are inferred from the claim text.