Inkjet recording ink set

1. An inkjet recording ink set comprising at least two inks, wherein each of the inks contains at least one dye having an anionic group and at least two heterocyclic groups, and wherein when any two inks in the ink set are mixed, precipitation of the dye does not occur.

2. An inkjet recording ink set comprising at least three inks, wherein each of the inks contains at least one dye having an anionic group and at least two heterocyclic groups, and wherein when any three inks in the ink set are mixed, precipitation of the dye does not occur.

3. The inkjet recording ink set as claimed in claim 1 , wherein the ink set is an ink set containing yellow, magenta, cyan and black ink compositions.

4. The inkjet recording ink set as claimed in claim 1 , wherein a counter cation of the dye having an anionic group is selected from lithium, sodium, potassium and ammonium.

5. The inkjet recording ink set as claimed in claim 1 , wherein a counter cation of the dye having an anionic group is the same in at least two inks.

6. The inkjet recording ink set as claimed in claim 1 , wherein at least one dye of the dyes having an anionic group has an oxidation potential more positive than 1.0 V (vs SCE).

7. The inkjet recording ink set as claimed in claim 1 , wherein at least one dye of the dyes having an anionic group is represented by any one of the following formulae (CI), (MI), (YI) and (BkI):

wherein X 1 , X 2 , X 3 and X 4 each independently represents —SO—Z, —SO 2 —Z, —SO 2 NR 1c R 2c , a sulfo group, —CONR 1c R 2c or —CO 2 R 1c , Z independently represents 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 1c and R 2c each independently represents 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, provided that when a plurality of Zs are present, the Zs may be the same or different, Y 1 , Y 2 , Y 3 and Y 4 each independently represents a monovalent substituent, provided that when a plurality of substituents X 1 , X 2 , X 3 , X 4 , Y 1 , Y 2 , Y 3 or Y 4 are present, the X 1 s, X 2 s, X 3 s, X 4 s, Y 1 s, Y 2 s, Y 3 s or Y 4 s may be the same or different, a 1 to a 4 and b 1 to b 4 represent the numbers of substituents X 1 to X 4 and Y 1 to Y 4 , respectively, a 1 to a 4 each independently represents an integer of 0 to 4 but all are not 0 at the same time, b 1 to b 4 each independently represents an integer of 0 to 4, and M represents a hydrogen atom, a metal element or an oxide, hydroxide or halide thereof;

wherein A 31 represents a 5-membered heterocyclic group; B 31 and B 32 each represents ═CR 1 — or —CR 2 ═, or one of B 31 and B 32 represents a nitrogen atom and the other represents ═CR 1 — or —CR 2 ═, R 5 and R 6 each independently represents a hydrogen atom or a substituent, the substituent is an aliphatic group, an aromatic group, a heterocyclic group, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, a carbamoyl group, an alkylsulfonyl group, an arylsulfonyl group or a sulfamoyl group, the hydrogen atom of each substituent may be substituted, G 31 , R 1 and R 2 each independently represents a hydrogen atom or a substituent, the substituent is a halogen atom, an aliphatic group, an aromatic group, a heterocyclic group, a cyano group, a carboxyl group, a carbamoyl group, an alkoxycarbonyl group, an aryloxy-carbonyl group, a heterocyclic oxycarbonyl group, an acyl group, a hydroxy group, an alkoxy group, an aryloxy group, a heterocyclic oxy group, a silyloxy group, an acyloxy group, a carbamoyloxy group, an alkoxycarbonyloxy group, an aryloxycarbonyloxy group, an amino group, an acylamino group, a ureido group, a sulfamoylamino group, an alkoxycarbonylamino group, an aryloxycarbonylamino group, an alkylsulfonylamino group, an arylsulfonylamino group, a heterocyclic sulfonylamino group, a nitro group, an alkylthio group, an arylthio group, a heterocyclic thio group, an alkylsulfonyl group, an arylsulfonyl group, a heterocyclic sulfonyl group, an alkylsulfinyl group, an arylsulfinyl group, a heterocyclic sulfinyl group, a sulfamoyl group or a sulfo group, the hydrogen atom of each substituent may be substituted, and R 1 and R 5 , or R 5 and R 6 may combine to form a 5- or 6-membered ring;

A 11 —N═N—B 11   Formula (Y1):

wherein A 11 and B 11 each independently represents a heterocyclic group which may be substituted;

A 41 N═N— B 41 m n —N═N—C 41   Formula (BK1):

wherein A 41 , B 41 and C 41 each independently represents an aromatic group which may be substituted or a heterocyclic group which may be substituted (A 41 and C 41 each is a monovalent group and B 41 is a divalent group), m represents 1 or 2, and n represents an integer of 0 or more.

8. The inkjet recording ink set as claimed in claim 1 , wherein at least one of the heterocyclic groups is a 5-membered or 6-membered heterocyclic group containing at least one hetero atom selected from a nitrogen atom, an oxygen atom and a sulfur atom.

9. The inkjet recording ink set as claimed in claim 8 , wherein the heterocyclic group contains at least one heterocyclic ring selected from the group consisting of pyridine, thiophene, thiazole, benzothiazole, benzoxazole and furan.

10. An inkjet recording method comprising jetting an ink of the inkjet recording ink set as claimed in claim 1 .

11. An inkjet recording method comprising ejecting an ink droplet according to a recording signal on an image-receiving material to record an image on the image-receiving material comprising a support having thereon an image-receiving layer containing a white inorganic pigment particle, wherein the ink droplet comprises the ink of the inkjet recording ink set as claimed in claim 1 .