Patent ID: 7427641

Claim:
An ink composition comprising an admixture of: an alkali-soluble copolymer; water; a colorant; and at least one member selected from the group consisting of wax, a viscosity modifier, and a wetting agent, said alkali-soluble copolymer being a copolymer, with an acid value of not more than 40, which is produced, prior to its admixture with the colorant and the at least one member, by polymerizing an ethylenically unsaturated carboxylic acid monomer and other monomer copolymerizable with the ethylenically unsaturated carboxylic acid monomer in the presence of an alcoholic hydroxyl-containing water-soluble polymer compound or a copolymerizable surfactant and has been adjusted to a pH value, at which the copolymer is soluble in water, by the addition of an inorganic base.