Patent ID: 7611571

Claim:
An ink comprising at least two coloring materials of a first coloring material and a second coloring material, wherein the first coloring material is a compound represented by the following general formula (I): wherein A, B, C, and D each independently represent a six-membered ring having aromaticity and at least one of A, B, C, and D in the general formula (I) is a pyridine ring or a pyrazine ring, M's each independently represent a hydrogen atom, alkali metal, ammonium, or organic ammonium, E's each independently represent an alkylene group, X's each independently represent a sulfo-substituted anilino group, a carboxyl-substituted anilino group, or a phosphono-substituted anilino group, and the substituted anilino groups may have 1 to 4 of at least one substituent selected from the group consisting of a sulfonic acid group, a carboxyl group, a phosphono group, a sulfamoyl group, a carbamoyl group, a hydroxyl group, an alkoxy group, an amino group, an alkylamino group, a dialkylamino group, an arylamino group, a diarylamino group, an acetylamino group, an ureido group, an alkyl group, a nitro group, a cyano group, halogen, an alkylsulfonyl group, and an alkylthio group, Y's each independently represent a hydroxyl group or an amino group, and 1, m and n satisfy 0≦1≦2, 0≦m≦3 and 0.1≦n≦3, and 1+m+n=1 to 4, and wherein the second coloring material is a compound represented by the general formula (II): wherein X 1 , X 2 , X 3 and X 4 each independently represent —SO-Z, —SO 2 -Z, —SO 2 NR 1 R 2 , a sulfonic acid group, —CONR 1 R 2 , or CO 2 R 1 , wherein Z's each independently represent a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted aralkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heterocyclic group, R 1 and R 2 each independently represent a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted aralkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heterocyclic group, Y 1 , Y 2 , Y 3 , Y 4 , Y 5 , Y 6 , Y 7 and Y 8 each independently represent a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a cyano group, a substituted or unsubstituted alkoxy group, an amide group, an ureido group, a sulfonamide group, a substituted or unsubstituted carbamoyl group, a substituted or unsubstituted sulfamoyl group, a substituted or unsubstituted alkoxycarbonyl group, a carboxyl group or a sulfonic acid group, and a 1 , a 2 , a 3 and a 4 represent the numbers of substituents of X 1 , X 2 , X 3 and X 4 , respectively, and each independently represent an integer of 1 or 2.