PROCESS FOR MANUFACTURING INKS AND PIGMENT FORMULATIONS AND INK JET INKS MADE BY THE PROCESS

摘要

A process for manufacturing an ink, or pigment formulation (e.g. a concentrate) for use in inks, comprising filtration of a composition comprising a particulate pigment and a liquid medium through an inorganic filter having pores of a uniform size below 10 microns. The process accurately removes oversized particles that could cause problems in inkjet printers without wasting non-problematic under-sized pigment. High flow rates are achieved even with low trans-filter pressure differences. In one embodiment, high flow rates are maintained by selection of pH and/or ionic strength. The filters are more robust than conventional polymeric filters and withstand cleaning with aggressive cleaning agents.