Patent ID: 9725612
Date: 2017-08-08
CPC Classifications: B41J,C09D

Claim:
1. A process for producing a water-based ink for ink-jet printing, comprising the step of dispersing a pigment in a polymer by means of a disperser using dispersing media particles comprising a zirconium compound to introduce a solid zirconium compound into the water-based ink, the water-based ink comprising the pigment-containing polymer particles and the solid zirconium compound, and having a zirconium compound content of not less than 2 ppm and not more than 200 ppm in terms of a concentration of zirconium in the water-based ink, wherein the process comprises the following steps (I) to (V) in which the step of introducing the solid zirconium compound into the water-based ink is conducted in the step (II): step (I): preparing a mixture comprising the polymer, an organic solvent, the pigment and water; step (II): subjecting the mixture obtained in the step (I) to dispersing treatment using the dispersing media particles comprising the zirconium compound to obtain a dispersion of the pigment-containing polymer particles; step (III): removing the organic solvent from the dispersion of the pigment-containing polymer particles obtained in the step (II) to obtain a water dispersion of the pigment-containing polymer particles; step (IV): removing coarse particles from the water dispersion obtained in the step (III) to obtain a water dispersion for ink-jet printing; and step (V): preparing the water-based ink for ink-jet printing using the water dispersion obtained in the step (IV), wherein a use history of the dispersing media particles is controlled such that a cumulative net power as measured by operating the disperser packed with the dispersing media particles is not less than 1500 kwh/kg and wherein a packing rate of the dispersing media particles in the disperser in the step (II) is not less than 50% and not more than 95%.