Recording fluid for ink-jet printing and process for the production thereof

• US 5,716,435 A
• Filed: 09/17/1996
• Issued: 02/10/1998
• Est. Priority Date: 01/27/1995
• Status: Expired due to Fees

• Current Assignee: TOYO Ink Manufacturing Company Limited
• Original Assignee: TOYO Ink Manufacturing Company Limited
• Inventors: Aida, Seiji, Sawada, Seiji, Toyoda, Ichiro, Iida, Yasuharu, Fujigamori, Tsutomu, Uraki, Hisashi, Satake, Sunao
• Primary Examiner(s): KLEMANSKI, HELENE G
• Application Number:
  US08/714,129
• Time in Patent Office: 511 Days
• Field of Search: 106/20 R, 106/20 C, 106/23 D, 106/23 K, 106/412, 106/493, 106/496, 106/497, 106/31.6, 106/31.85, 106/31.73, 106/31.65, 106/31.75
• US Class Current: 106/31.85
• CPC Class Codes: C09D 11/322 Pigment inks

Abstract

A water-dispersed inkjet recording liquid excellent in water resistance and transparency and also excellent in the property of ejection from a nozzle, containing, as a colorant, a water-based dispersion of an organic pigment (A) having an average particle diameter of 10 to 150 nm (measured by laser scattering), the water-based dispersion of the organic pigment (A) being obtained by mechanically kneading a mixture containing at least three components, said components being, the organic pigment (A), a water-soluble inorganic salt (B) in an amount by weight at least three times as large as the amount of the organic pigment (A) and a water-soluble solvent (C) to finely mill the organic pigment (A), and then removing the water-soluble inorganic salt (B) and the water-soluble solvent (C) by washing the kneaded mixture with water, and a process for the production thereof.

Claims

1. A water-dispersed inkjet recording liquid containing, as a colorant, a water-based dispersion of an organic pigment (A) having an average particle diameter of 10 to 150 nm measured by laser scattering, the water-based dispersion of the organic pigment (A) being obtained by mechanically kneading a mixture containing at least the following components, the organic pigment (A), a water-soluble inorganic salt (B) in an amount by weight at least three times as large as the amount of the organic pigment (A), a water-soluble solvent (C) and a resin (E) selected from the group consisting of a rosin, an epoxy resin, a (meth)acrylic resin, a rosin-modified maleic acid resin and a rosin-modified phenolic resin, to finely mill the organic pigment (A), and then removing the water-soluble inorganic salt (B) and the water-soluble solvent (C) by washing the kneaded mixture with water.

2. A water-dispersed inkjet recording liquid according to claim 1, wherein the water-based dispersion of the organic pigment (A) is a product obtained by further adding a pigment derivative of the formula (1),

3. A water-dispersed inkjet recording liquid according to claim 1, wherein the organic pigment (A) is at least one selected from the group consisting of quinacridone organic pigments, phthalocyanine organic pigments, benzimidazolone organic pigments, isoindolinone organic pigments and azo organic pigments.

4. A water-dispersed inkjet recording liquid according to claim 1, wherein the water-dispersed inkjet recording liquid further contains a water-based resin in addition to the colorant.

5. A water-dispersed inkjet recording liquid according to claim 4, wherein the water-dispersed inkjet recording liquid further contains a neutralizing agent.

6. A water-dispersed inkjet recording liquid according to claim 4, wherein the organic pigment (A) is contained in the range of from 0.1 to 10% by weight.

7. A water-dispersed inkjet recording liquid according to claim 4, wherein the water-dispersed inkjet recording liquid has a viscosity in the range of from 0.8 to 15 centipoise (25°

C.).

8. A water-dispersed inkjet recording liquid according to claim 4, wherein the water-based resin is contained in an amount of 0.5 to 10 parts by weight per 100 parts by weight of the recording liquid.

9. A process for the production of a water-dispersed inkjet recording liquid, which comprises the following steps a) - d,

a) mechanically kneading a mixture containing at least the following components, an organic pigment (A), a water-soluble inorganic salt (B) in an amount by weight at least three times as large as the amount of the organic pigment (A), a water-soluble solvent (C) and a resin (E) selected from the group consisting of a rosin, an epoxy resin, a (meth)acrylic resin, a rosin-modified maleic acid resin and a rosin-modified phenolic resin, to finely mill the organic pigment (A),

b) removing the water-soluble inorganic salt (B) and the water-soluble solvent (C) from the mixture of the finely milled organic pigment (A) by washing the mixture with water, to obtain a water-based dispersion of the organic pigment (A) having an average particle diameter of 10 to 150 nm (measured by laser scattering),

c) adding and dispersing a water-based resin to/in the water-based dispersion, and

d) adding water and an additive to the dispersion to dilute the dispersion and filtering the diluted dispersion through a filter having an opening diameter of 3 μ

m or less.

10. A process according to claim 9 wherein the mixture in the step a) further contains a pigment derivative of the formula (1),

11. A process for the production of a water-dispersed inkjet recording liquid according to claim 9, wherein the water-based resin is dispersed in the water-based dispersion in the step c) by kneading the water-based resin and the water-based dispersion.

12. A process for the production of a water-dispersed inkjet recording liquid according to claim 9, wherein in the step c), the organic pigment has a concentration of 10 to 40% by weight and the organic pigment and the water-based resin are dispersed.

13. A process for the production of water-dispersed inkjet recording liquid according to claim 9, wherein the additive in the step d) contains at least one selected from the group consisting of a neutralizing agent for the water-based resin, a dispersing agent, an aqueous solvent for retaining wettability, an antifungal agent, an agent for adjusting penetration, a chelating agent and an antifoaming agent.