Patent ID: 7271213

Claim:
Water-based pigment dispersion which comprises a pigment dispersing resin (I), pigment, aqueous medium, other pigment dispersing resin (II) and, optionally, dispersing agent, said pigment dispersing resin (I) being a copolymer of: (A) polymerizable unsaturated monomer containing at least one kind of ionic functional group selected from the group consisting of tertiary amino group, quaternary ammonium salt and sulfonic acid group; (B) nonionic polymerizable unsaturated monomer having polyoxyethylene chain; (C) ultraviolet-absorbing polymerizable unsaturated monomer and/or ultraviolet-stabilizing polymerizable unsaturated monomer; and (D) other ethylenically unsaturated monomer, said copolymer being a copolymerization product of 0.5 to 30% by weight of ionic function group-contaning polymerizable unsaturated monomer (A), 5 to 40% by weight of nonionic polymerizable unsaturated monomer (B), 0.1 to 5% by weight of ultraviolet-stabilizing polymerizable unsaturated monomer (C) and 25 to 94.4% by weight of other ethylenically unsaturated monomer (D) on the basis of the total weight of monomers (A), (B), (C) and (D), said other pigment dispersing resin (II) being selected from the group consisting of acrylic resin having a weight average molecular weight within a range of 2,000 to 150,000, an acid value in a range of 5 to 150 and a hydroxyl value in a range of 10 to 160, and polyester resin having a weight average molecular weight within a range of 1,000 to 100,000, an acid value in a range of 5 to 150, and a hydroxyl value in a range of 10 to 160.