Patent ID: 7176249

Claim:
An aqueous ink composition, which comprises at least: 1) an alkali neutralized product of a copolymer containing constituent units of: (i) at least one monomer selected from the group consisting of alkene, styrene, styrene derivatives, vinyl naphthalene, and vinyl naphthalene derivatives; (ii) at least one monomer selected from the group consisting of monomers containing an acidic group that ion dissociate; and (iii) at least one α,β-ethylenic unsaturated carboxylic acid alkyl ester; 2) a pigment; and 3) an aqueous medium, wherein the alkali neutralized product of the copolymer in the aqueous ink composition forms micelle aggregations with an average diameter being set in the range of 10 nm to 300 nm; and wherein an acid value of the copolymer is in the range of 60 to 160.