AQUEOUS PIGMENT DISPERSION AND INKJET RECORDING INK

PROBLEM TO BE SOLVED: To provide a method for producing an aqueous pigment dispersion having a violet color, excellent in water resistance, light resistance and color development and simultaneously expressing high luster and preservation stability for a long period of time at high temperature. SOLUTION: The method comprises a mixing and kneading process for producing a colored, mixed and kneaded product by mixing and kneading a mixture comprising (a) C. I. pigment violet 23, (b) a styrene-acrylic acid-based copolymer having 50-300 mgKOH/g acid value, (c) an alkali metal hydroxide, (d) water and (e) a humectant and a dispersing process for dispersing the colored, mixed and kneaded product in an aqueous medium by dispersing device using media. In the mixing and kneading process, the mass ratio of (b)/(a) is in the range of 0.15-0.45 and the mass ratio of (d)/(a) in the front half of the mixing and kneading process is in the range of 0.04-0.42. In the dispersion process, viscosity change of the dispersant is ≤10%. COPYRIGHT: (C)2007,JPO&INPIT