Patent ID: 7276111

Claim:
An ink composition, wherein at least water, a phthalocyanine group cyan dye indicated by the general formula (I) below, and an aromatic compound having a sulfone group and/or the salt thereof represented by the general formulae (a) and/or (b) below are contained: wherein, X 1 , X 2 , X 3 and X 4 each independently represents either —SO-Z or —SO 2 -Z; wherein Z each independently represents a substituted or unsubstituted alkyl group, substituted or unsubstituted cycloalkyl group, substituted or unsubstituted alkenyl group, substituted or unsubstituted aralkyl group, substituted or unsubstituted aryl group, or substituted or unsubstituted heterocyclic group; Y 1 , Y 2 , Y 3 and Y 4 each independently represents a hydrogen atom, halogen atom, alkyl group, cycloalkyl group, alkenyl group, aralkyl group, aryl group, heterocyclic group, cyano group, hydroxy group, nitro group, amino group, alkylamino group, alkoxy group, aryloxy group, amide group, arylamino group, ureide group, sulfamoylamino group, alkylthio group, arylthio group, alkoxycarbonylamino group, sulfonamide group, carbamoyl group, alkoxycarbonyl group, heterocyclic oxy group, azo group, acyloxy group, carbamoyloxy group, silyloxy group, aryloxycarbonyl group, aryloxycarbonylamino group, imide group, heterocyclic thio group, phosphoryl group, acyl group or ionic hydrophilic group; and these various groups may have substituents; a 1 to a 4 and b 1 to b 4 represent the number of substituents of X 1 to X 4 and Y 1 to Y 4 respectively; and a 1 to a 4 each independently is an integer of 0 to 4, but not all may be 0 at the same time; b 1 to b 4 each independently is an integer of 0 to 4; M represents a hydrogen atom, metal element or oxide thereof, hydroxide, or halogenated compound; with the proviso that, at least one of X 1 , X 2 , X 3 , X 4 , Y 1 , Y 2 , Y 3 , and Y 4 is an ionic hydrophilic group or a group having an ionic hydrophilic group as a substituent; wherein, M 1 indicates a counter-ion comprising a salt; X indicates an integer of 1 to 3; R 1 and R 2 indicate respectively a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms; and R 1 and R 2 may be the same or different; wherein M 2 indicates a counter-ion comprising a salt; Y indicates an integer of 1 to 4; R 3 and R 4 indicate respectively a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an alkoxy group having 1 to 6 carbon atoms; and R 3 and R 4 may be the same or different.