Patent ID: 7094279

Claim:
A black water-based ink composition, containing: at least one type of black dye selected from the group consisting of compounds expressed by the following formula (1) and salts thereof: wherein, in (the formula (1), R 1 is a phenyl group having a substituent or a naphthyl group having a substituent, R 2 is a phenylene group having a substituent or a naphthylene group having a substituent, R 3 is a 5- to 7-member heterocyclic group having a substituent and at least one double bond, and the substituents in R 1 to R 3 are independently selected from the group consisting of OH, SO 3 H, PO 3 H 2 , CO 2 H, NO 2 , C 1 to C 4 alkyl groups, alkyl groups having a substituent, C 1 to C 4 alkoxy groups, alkoxy groups having a substituent, amino groups having a substituent, and phenyl groups having a substituent), and at least one yellow dye and one magenta dye, wherein each of the yellow dye and magenta dye is a compound that has at least one type of group selected from the group consisting of an —SO 3 H group, —COOH group, —SO 3 M group, and —COOM group, where M in these groups is an alkali metal atom, has no primary amino group, and is not an ammonium salt or a salt with an organic cation, wherein the yellow dye and magenta dye provide the ink composition with a hue that is different than a hue of the black dye.