Aqueous pigment dispersion water-base ink composition and recording method using the ink composition

• US 6,488,753 B1
• Filed: 03/09/2000
• Issued: 12/03/2002
• Est. Priority Date: 03/10/1999
• Status: Expired due to Term

• Current Assignee: Orient Chemical Industries Ltd, Seiko Epson Corporation (Seiko Group)
• Original Assignee: Orient Chemical Industries Ltd, Seiko Epson Corporation (Seiko Group)
• Inventors: Hayashi, Hiroko, Ito, Sohko, Ito, Hiroshi, Momose, Masayuki
• Primary Examiner(s): Klemanski, Helene
• Assistant Examiner(s): Faison, Veronica F.
• Application Number:
  US09/521,572
• Time in Patent Office: 999 Days
• Field of Search: 106/31.9, 106/31.86, 106/31.89, 106/472, 106/478
• US Class Current: 106/31.9
• CPC Class Codes: C09D 11/324 containing carbon black
• CPC Class Codes: C09D 17/005 Carbon black

Abstract

Disclosed are an aqueous pigment dispersion and an ink composition which can realize high print density. The aqueous pigment dispersion comprises at least water and a surface-modified carbon black, the surface-modified carbon black being dispersible and/or dissolvable in water without any dispersant and having a hydrophilic functional group content/specific surface area value of 5 to 30 μmol/m².

Claims

1. An aqueous pigment dispersion comprising at least water and a surface-modified carbon black, the surface-modified carbon black being dispersible and/or dissolvable in water without any dispersant and having a hydrophilic functional group content/specific surface area value of 5 to 15 μ

mol/m².

2. The aqueous pigment dispersion according to claim 1, wherein the surface-modified carbon black has been produced by oxidizing an acidic carbon black.

3. The aqueous pigment dispersion according to claim 1, wherein the surface-modified carbon black has been produced by oxidizing a channel carbon black.

4. The aqueous pigment dispersion according to claim 1, wherein the surface-modified carbon black has been produced by oxidizing carbon black with a hypohalogenous acid or its acid.

5. The aqueous pigment dispersion according to claim 1, wherein the content of the hydrophilic functional groups in the surface-modified carbon black is not less than 1.5 mmol/g.

6. A process for producing the aqueous pigment dispersion according to claim 1, comprising the steps of:

grinding carbon black in an aqueous medium having a surface tension of not more than 50 mN/m; and

oxidizing the carbon black in an aqueous medium to introduce hydrophilic functional groups into the carbon black to prepare an aqueous pigment dispersion containing a surface-modified carbon black.

7. The process according to claim 6, wherein the carbon black is oxidized with a hypohalogenous acid and/or its salt.

8. A water-base ink composition comprising at least the aqueous, pigment dispersion according to claim 1.

9. The water-base ink composition according to claim 8, which, when the amount of the ink composition deposited on a recording medium is 1 mg/cm², has a penetrability of less than one sec in terms of the penetration time of the ink composition.

10. The water-base ink composition according to claim 8, which has a surface tension of less than 40 mN/m.

11. The water-base ink composition according to claim 8, which further comprises a glycol butyl ether water-soluble organic solvent.

12. The water-base ink composition according to claim 8, which further comprises a nonionic surfactant.

13. The water-base ink composition according to claim 12, wherein the nonionic surfactant is an acetylene glycol surfactant.

14. The water-base ink composition according to claim 8, wherein the content of the surface-modified carbon black is 1 to 15% by weight based on the total amount of the ink.

15. A recording method comprising the step of depositing an ink composition onto a recording medium to perform printing, wherein the ink composition is the water-base ink composition according to claim 8.

16. An ink jet recording method comprising the steps of:

ejecting droplets of an ink composition; and

depositing the droplets onto a recording medium to perform printing, wherein the ink composition is the water-base ink composition according to claim 8.

18. The aqueous pigment dispersion according to claim 1, wherein the surface-modified carbon black has a hydrophilic functional group content/specific surface area value of 7.5 to 15 μ

mol/m².

17. A process for producing an aqueous pigment dispersion comprising at least water and a surface-modified carbon black, comprising the steps of:

grinding carbon black in an aqueous medium having a surface tension of not more than 50 mN/m; and

oxidizing the carbon black in an aqueous medium to introduce hydrophilic functional groups into the carbon black to prepare an aqueous pigment dispersion containing a surface-modified carbon black.