Patent ID: 7629395

Claim:
An inkjet pigment ink comprising: a pigment; a water-soluble solvent; water; and a copolymer, wherein the copolymer is a graft copolymer obtained by copolymerization of: aromatic acrylate (monomer A); (meth)acrylate added with ethylene oxide having a polymerization degree of 5 or more (monomer B); and acrylic acid (monomer C), wherein the graft copolymer has a hydrophilic segment formed by polymerization of a hydrophilic monomer as a side chain unit and a hydrophobic segment formed by polymerization of a hydrophobic monomer as a main chain unit, wherein the monomer used in the formation of the hydrophilic segment comprises the monomer C, wherein the monomer used in the formation of the hydrophobic segment comprises monomer A, monomer B, and monomer C, wherein the mass ratio of monomer A to monomer C (A:C) for the formation of the hydrophobic segment is 6:1 to 16:1, and wherein the mass ratio of monomer A to monomer B (A:B) for the formation of the hydrophobic segment is 4:1 to 10:1.