Patent ID: 8389622

Claim:
A non-aqueous pigment ink comprising a pigment, a pigment dispersant and a non-aqueous solvent, wherein the pigment dispersant is an acrylic polymer comprising, as constituent monomers: (M1) an alkyl (meth)acrylate having an alkyl group of 12 or more carbon atoms, (M2) a (meth)acrylic acid derivative having an amino group, and (M3) (meth)acrylic acid and/or a (meth)acrylic acid derivative having a carboxyl group, wherein the monomer (M2) is in an amount of from 8 to 15 mol % and the monomer (M3) is in an amount of from 0.6 to 8 mol %, based on the total weight of the constituent monomers; and the molar ratio of (M2)/(M3) is maintained between 1.3/1 and 15/1.