# US 7,407,537 B2 · Ink set for ink-jet recording, method for producing the same, and the ink-jet printer

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- Number: US 7,407,537 B2
- Document ID: US7407537B2
- Status: Granted
- Kind: B2
- Application number: 11/142,311
- Filed: 2005-06-02
- Published: 2005-12-22
- Granted: 2008-08-05
- Earliest claimed: 2004-06-18
- Assignees: Brother Kogyo Kabushiki Kaisha
- Inventors: Hideo Ohira; Ryuji Kato; Akihiko Taniguchi; Noriatsu Aoi; Masaya Fujioka; Shunichi Higashiyama
- Web page: https://patentgrep.com/patent/US7407537B2

## CPC

- C09D 11/40: Ink-sets specially adapted for multi-colour inkjet printing
- C09D: COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR (cosmetics A61K; processes for applying liquids or other fluent materials to surfaces, in general, B05D; staining wood B27K5/02; glazes or vitreous enamels C03C; natural resins, French polish, drying-oils, driers, turpentine, per se, C09F; polishing compositions other than French polish, ski waxes C09G; adhesives or use of materials as adhesives C09J; materials for sealing or packing joints or covers C09K3/10; materials for stopping leaks C09K3/12; processes for the electrolytic or electrophoretic production of coatings C25D)

## Abstract

An ink set for ink-jet recording includes a pigment-based ink containing a negatively chargeable and self-dispersible pigment as a coloring agent and a dye-based ink containing an anionic dye as a coloring agent, and the ink set satisfies the following expression (1): Dci<1.1×Pci+0.0001 (1) wherein “Dci” represents an amount of counter ion (mol/g) of the anionic dye contained in the dye-based ink, and “Pci” represents an amount of counter ion (mol/g) of the self-dispersible pigment contained in the pigment-based ink. The pigment aggregation can be greatly suppressed, and the high quality printing can be stably performed when the ink set for ink-jet recording composed of the pigment-based ink and the dye-based ink is carried on an ink-jet printer provided with a conventional maintenance system that is simple and at low cost.

## Claims

### Claim 1

An ink set for ink-jet recording comprising:
a pigment ink which contains a negatively chargeable and self-dispersible pigment and;
a dye ink which contains an anionic dye, wherein the following expression (1) is satisfied:
Dci<1.1×Pci+0.0001 (1)
wherein Dci represents an amount of cation (mol/g) in the dye ink, and Pci represents an amount of cation (mol/g) in the pigment ink; and
the amount of cation in the pigment ink being substantially an amount of counter ion of the self-dispersible pigment.

### Claim 2 (depends on 1)

The ink set for ink-jet recording according to claim 1, wherein the amount of cation in the dye ink is substantially an amount of counter ion of the anionic dye.

### Claim 3 (depends on 1)

The ink set for ink-jet recording according to claim 1, wherein Dci (mol/g) satisfies the following expression (2):
0.000074<Dci (2).

### Claim 4 (depends on 1)

The ink set for ink-jet recording according to claim 1, wherein an amount of divalent or polyvalent cation is not more than 10 ppm in each of the pigment ink and the dye ink when the cation includes the divalent or polyvalent cation.

### Claim 5 (depends on 1)

The ink set for ink-jet recording according to claim 1, wherein the dye is a monoazo dye.

### Claim 6 (depends on 1)

The ink set for ink-jet recording according to claim 1, wherein the dye ink is a magenta ink.

### Claim 7 (depends on 1)

The ink set for ink-jet recording according to claim 1, wherein the pigment is carbon black.

### Claim 8 (depends on 1)

The ink set for ink-jet recording according to claim 1, wherein both of the pigment ink and the dye ink contain glycerol.

### Claim 9 (depends on 1)

The ink set for ink-jet recording according to claim 1, wherein both of the pigment ink and the dye ink contain water and a water-soluble organic solvent.

### Claim 10 (depends on 1)

An ink-jet printer comprising the ink set for ink-jet recording as defined in claim 1, a printing head which has a nozzle surface formed with a nozzle which discharges the pigment ink and a nozzle which discharges the dye ink, and a wiper member which wipes the nozzle surface, wherein the pigment ink and the dye ink, which are adhered to the nozzle surface of the printing head, are wiped by the wiper member.

### Claim 11

A method for producing an ink set for ink-jet recording having a pigment ink and a dye ink, the method comprising:
preparing the pigment ink which contains a negatively chargeable and self-dispersible pigment; and
preparing the dye ink which contains an anionic dye, wherein:
an amount of cation in the pigment ink and an amount of cation in the dye ink satisfy the following expression (1):
Dci<1.1×Pci+0.0001 (1)
wherein Dci represents the amount of cation (mol/g) in the dye ink, and Pci represents the amount of cation (mol/g) in the pigment ink; and
the amount of cation in the pigment ink being substantially an amount of counter ion of the self-dispersible pigment.

### Claim 12 (depends on 11)

The method for producing the ink set for ink-jet recording according to claim 11, wherein the amount of cation in the dye ink is substantially an amount of counter ion of the anionic dye.

### Claim 13 (depends on 11)

The method for producing the ink set for ink-jet recording according to claim 11, wherein Dci (mol/g) satisfies the following expression (2):
0.000074<Dci (2).

### Claim 14 (depends on 11)

The method for producing the ink set for ink-jet recording according to claim 11, wherein the pigment ink and the dye ink are prepared respectively so that the amount of divalent or polyvalent cation is not more than 10 ppm.

### Claim 15 (depends on 11)

The method for producing the ink set for ink-jet recording according to claim 11, wherein the dye is a monoazo dye.

### Claim 16 (depends on 11)

The method for producing the ink set for ink-jet recording according to claim 11, wherein the dye ink is a magenta ink.

### Claim 17 (depends on 11)

The method for producing the ink set for ink-jet recording according to claim 11, wherein the pigment is carbon black.