Patent ID: 8048939
Filing Date: 2011-11-01
Classification: C09D

Abstract:
1. A process for producing a water-based ink for ink-jet printing comprising: (1): wet-pulverizing a mixture containing a water-insoluble polymer, an organic solvent, a pigment and water in a dispersing apparatus using a dispersing media, (2) dispersing the wet-pulverized mixture using a high-pressure homogenizer to obtain a dispersion; and (3): removing the organic solvent from the dispersion obtained in the step (2); wherein the water-based ink that is produced comprises: (A) water-insoluble polymer particles containing a pigment, wherein the pigment-containing water-insoluble polymer particles have an average particle size of from 0.03 to 0.25 μm, and the number of the pigment-containing water-insoluble polymer particles having a particle size of 0.57 μm or more among the pigment-containing water-insoluble polymer particles contained in the ink is 1.2×10 (B) water-insoluble polymer particles containing a pigment, wherein a weight ratio of the pigment to the water-insoluble polymer (pigment/water-insoluble polymer) in the pigment-containing water-insoluble polymer particles is from 75/25 to 10/90, the pigment-containing water-insoluble polymer particles have an average particle size of from 0.03 to 0.25 μm, and the number of the pigment-containing water-insoluble polymer particles having a particle size of 0.57 μm or more among the pigment-containing water-insoluble polymer particles contained in the ink is 10×10 (C) water-insoluble polymer particles containing a yellow pigment, wherein the ink contains the yellow pigment in an amount of 4.5% by weight or more, and the number of the pigment-containing water-insoluble polymer particles having a particle size of 0.57 μm or more in the ink is 1.2×10 (D) water-insoluble polymer particles containing a magenta pigment or a cyan pigment, wherein the ink contains the magenta pigment or the cyan pigment in an amount of 3.0% by weight or more, and the number of the pigment-containing water-insoluble polymer particles having a particle size of 0.57 μm or more in the ink is 1.2×10