Pigment dispersing resins

A long chain alkyl-containing pigment dispersing resin having a weight-average molecular weight within a range of 1,000-150,000, which is obtained by copolymerizing a monomeric mixture comprising.

• (c) a long chain alkyl group-containing macromonomer having a resin acid value less than 50 mgKOH/g, which is obtained by either subjecting a carboxyl-containing macromonomer and an epoxy-containing long chain alkyl compound to an esterification reaction, said carboxyl-containing macromonomer being obtained by copolymerizing a monomeric mixture comprising a carboxyl-containing unsaturated monomer and at least one other ethylenically unsaturated monomer in the presence of a metal complex as a catalytic chain transfer agent, or an addition cleavage-type chain transfer agent and if necessary a radical polymerization initiator;
• or by causing an epoxy-containing long chain alkyl compound to be concurrently present in said copolymerization reaction system to effect the copolymerization reaction and the esterification reaction at the same time, and
• (b) at least one copolymerizable unsaturated monomer, wherein at least one monomer among said macromonomer (c) and copolymerizable unsaturated monomer(s) (b) has a functional group selected from substituted or unsubstituted amino group, quaternary ammonium salt group, sulfonic group, phosphoric group and carboxyl group.