Patent ID: 6852817

Claim:
A pigment dispersing resin which is a copolymer of (A) sulfonic group-containing polymerizable unsaturated monomer; (B) polyoxyalkylene chain-containing nonionic polymerizable unsaturated monomer; (C) (C-1) (meth)acrylic acid ester type polymerizable monomer having two tertiary alkyl groups per molecule and/or (C-2) (meth)acrylic acid ester type polymerizable monomer having one tertiary alkyl group and one secondary hydroxyl group per molecule; and (D) other ethylenically unsaturated monomer and where the copolymer is obtained by the copolymerization of monomers (A), (B), (C) and (D) at the following proportion on the basis of the total weight of monomers (A), (B), (C) and (D): Monomer (A): 0.1 to 10% by weight; Monomer (B): 5 to 50% by weight; Monomer (C): 1 to 30% by weight; and Monomer (D): 10 to 93.9% by weight.