Patent ID: 8669318

Claim:
An oil-based ink composition for ink jet printing comprising a colorant, an organic solvent and a polymeric compound, wherein the colorant comprises at least one pigment selected from the group consisting of azo pigments, azomethine pigments, polyazo pigments, phthalocyanine pigments, quinacridone pigments, anthraquinone pigments, indigo pigments, thioindigo pigments, quinophthalone pigments, benzimidazolone pigments, isoindoline pigments, isoindolinone pigments, carbon black and titanium oxide, the organic solvent comprises at least one (poly)alkylene glycol derivative selected from the group consisting of monoalkylether monoalkylesters, dialkylethers and dialkylesters of (poly)alkylene glycol, the amount of the organic solvent is from 30 to 99% by weight based on based on the total weight of the ink composition, the polymeric compound is at least one polymeric compound selected from the group consisting of polyester resins, polyurethane resins and vinyl chloride resins, the amount of the polymeric compound is from 5 to 200% by weight based on the weight of the pigment, and pH of an aqueous phase is from 5.5 to 8.0, when ions in the ink composition are transferred to water, which pH is obtained by adding 15 parts by weight of the oil-based ink composition to 85 parts by weight of ultrapure water, stirring the mixture, filtrating the mixture to obtain a filtrate, and measuring pH of the filtrate.