Ink for ink jet, a method for produing ink for ink jet, ink set for ink jet, and ink jet recording method

1 . An ink for ink jet comprising:

a water-soluble dye having an anionic dissociable group;

at least one of water and a water-soluble organic solvent; and

at least one kind of cationic polymer capable of forming an ion pair with the anionic dissociable group.

2 . An ink for ink jet according to claim 1 , wherein the cationic polymer is a water-soluble polymer.

3 . A method for producing an ink for ink jet, the method comprising:

mixing in advance: a water-soluble dye having an anionic dissociable group; and at least one cationic polymer capable of forming an ion pair with the anionic dissociable group, in water, to form a resulting salt; and

preparing the ink after desalting the resulting salt.

4 . An ink for ink jet according to claim 1 , wherein the ink is provided by:

mixing in advance: said at least one kind of cationic polymer; and the water-soluble dye having the anionic dissociable group, in water, to form a resulting salt; and

preparing the ink after desalting the resulting salt.

5 . An ink for ink jet according to claim 1 ,

wherein said at least one kind of cationic polymer has a cation derived from a nitrogen atom.

6 . An ink for ink jet according to claim 1 , wherein the water-soluble dye comprises at least one of compounds represented by general formulas (1) to (4):

(A 11 -N═N—B 11 ) n -L  general formula (1)

in the general formula (1), A 11 and B 11 each independently represents a heterocyclic group that may be substituted; n represents 1 or 2; L represents a substituent bonded in an arbitrary position with one of A 11 and B 11 , and represents a hydrogen atom in case n=1, a single bond or a divalent connecting group in case n=2;

In the general formula (2), X 21 , X 22 , X 23 and X 24 each independently represents —SO-Z 2 , —SO 2 -Z 2 , —SO 2 NR 21 R 22 , a sulfo group, —CONR 21 R 22 , or —COOR 21 ; Z 2 each independently represents a substituted or non-substituted alkyl group, a substituted or non-substituted cycloalkyl group, a substituted or non-substituted alkenyl group, a substituted or non-substituted aralkyl group, a substituted or non-substituted aryl group or a substituted or non-substituted heterocyclic group; and R 21 and R 22 each independently represents a hydrogen atom, a substituted or non-substituted alkyl group, a substituted or non-substituted cycloalkyl group, a substituted or non-substituted alkenyl group, a substituted or non-substituted aralkyl group, a substituted or non-substituted aryl group or a substituted or non-substituted heterocyclic group;

Y 21 , Y 22 , Y 23 and Y 24 each independently represents a monovalent substituent;

a 21 to a 24 and b 21 to b 24 represent numbers of substituents respectively on X 21 to X 24 and Y 21 to Y 24 ; a 21 to a 24 each independently represents a number of 0 to 4, and at least one of a 21 to a 24 is not zero; b 21 to b 24 each independently represents a number of 0 to 4; and, in case any of a 21 to a 24 and b 21 to b 24 represents a number equal to or larger than 2, plural ones in X 21 to X 24 and Y 21 to Y 24 may be mutually same or different;

M represents a hydrogen atom, a metal atom, an oxide of the metal atom, a hydroxide of the metal atom, or a halide of the metal atom;

in the general formula (3), A 31 , represents a 5-membered heterocyclic ring;

B 31 and B 32 each represents ═CR 31 — or —CR 32 ═, or either one represents a nitrogen atom while the other one represents ═CR 31 — or —CR 32 ═;

R 35 and R 36 each independently represents a hydrogen atom, an aliphatic group, an aromatic group, a heterocyclic group, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, a carbamoyl group, an alkyl- or arylsulfonyl group, or a sulfamoyl group, each of which may further have a substituent;

G 3 , R 31 and R 32 each independently represent a hydrogen atom, 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 aryloxycarbonyl group, a heterocyclic oxycarbonyl group, an acyl group, a hydroxyl 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 (including an arylamino group and a heterocyclic amino group), an acylamino group, an ureido group, a sulfamoylamino group, an alkoxycarbonylamino group, an aryloxycarbonylamino group, an alkyl- or aryl sulfonylamino group, a heterocyclic sulfonylamino group, a nitro group, an alkyl- or arylthio group, an alkyl- or arylsulfonyl group, a heterocyclic sulfonyl group, an alkyl- or arylsulfinyl group, a heterocyclic sulfinyl group, a sulfamoyl group, a sulfo group or a heterocyclic thio group, each of which may be further substituted;

R 31 and R 35 , or R 35 and R 36 may be bonded to form a 5- or 6-membered ring; and

A 41 -N═N—B 41 —N═N—C 41   general formula (4)

in the general formula (4), A 41 , B 41 and C 41 each independently represents an aromatic group or a heterocyclic group, each of which may be further substituted.

7 . An ink for ink jet according to claim 1 , wherein the dye represented by the general formula (2) is a dye represented by general formula (5):

in the general formula (5), X 51 to X 54 , Y 51 to Y 58 and M 1 respectively have same meanings as X 21 to X 24 , Y 21 to Y 24 and M in the general formula (2); and a 41 to a 54 each independently represents an integer 1 or 2.

8 . An ink set for ink jet comprising an ink according to claim 1 .

9 . An ink jet recording method comprising executing an image recording on one of a plain paper and an ink jet exclusive paper with an ink jet printer by using at least one of: an ink according to claim 1; and an ink set for ink jet according to claim 8 .

10 . An ink jet recording method comprising executing an image recording on one of a plain paper and an ink jet exclusive paper with an ink jet printer by using an ink set for ink jet according to claim 8.