METHOD FOR PRODUCING AQUEOUS PIGMENT DISPERSION

• US 20190309180A1
• Filed: 12/16/2016
• Published: 10/10/2019
• Est. Priority Date: 12/18/2015
• Status: Active Grant

• Current Assignee: KAO Corporation
• Original Assignee: KAO Corporation
• Inventors: TANAKA, Satoshi, ASHIZAWA, Takeshi, FUKUDA, Teruyuki
• Granted Patent: US 10,800,937 B2
• Time in Patent Office: Days
• CPC Class Codes: B41M 5/00 Duplicating or marking methods; Sheet materials for use therein by using light-sensitive materials G03; electrography, magnetography G03G ; repeatedly usable boards or tablets for writing or drawing B43L1/00
• CPC Class Codes: B41M 5/0023 Digital printing methods characterised by the inks used inks per se C09D11/00
• CPC Class Codes: C09D 11/033 characterised by the solvent
• CPC Class Codes: C09D 11/037 characterised by the pigment
• CPC Class Codes: C09D 11/10 based on artificial resins
• CPC Class Codes: C09D 11/106 containing macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
• CPC Class Codes: C09D 11/107 from unsaturated acids or derivatives thereof
• CPC Class Codes: C09D 11/322 Pigment inks
• CPC Class Codes: C09D 11/324 containing carbon black
• CPC Class Codes: C09D 11/326 characterised by the pigment dispersant
• CPC Class Codes: C09D 17/00 Pigment pastes, e.g. for mixing in paints artists' paints C09D5/06
• CPC Class Codes: C09D 17/001 in aqueous medium C09D17/003, C09D17/004 take precedence
• CPC Class Codes: C09D 17/005 Carbon black

Abstract

The present invention relates to [1] a process for producing a pigment water dispersion, including step 1 of mixing a water dispersion (A) formed by dispersing a pigment (I) with a water-dispersible polymer and a water dispersion (B) of a self-dispersible pigment (II) to obtain a water dispersion (C); and step 2 of subjecting the water dispersion (C) obtained in the step 1 to heat treatment at a temperature of not lower than 40° C. to obtain the pigment water dispersion, and [2] a pigment water dispersion containing a pigment (I) dispersed with a water-dispersible polymer and a self-dispersible pigment (II), in which the water-dispersible polymer is adsorbed onto the pigment (I) and the self-dispersible pigment (II).

Claims

1. A process for producing a pigment water dispersion, comprising the following steps 1 and 2:

Step 1;

mixing a water dispersion (A) formed by dispersing a pigment (I) with a water-dispersible polymer and a water dispersion (B) of a self-dispersible pigment (II) to obtain a water dispersion (C); and

Step 2;

subjecting the water dispersion (C) obtained in the step 1 to heat treatment at a temperature of not lower than 40°

C. to obtain the pigment water dispersion.

2. The process for producing a pigment water dispersion according to claim 1, wherein a time of the heat treatment in the step 2 is not less than 0.5 hour.

3. The process for producing a pigment water dispersion according to claim 1, wherein a temperature used upon the heat treatment in the step 2 is not higher than 100°

C.

4. The process for producing a pigment water dispersion according to claim 1, wherein the water dispersion (A) is a water dispersion formed by dispersing the pigment (I) with a crosslinked water-dispersible polymer.

5. The process for producing a pigment water dispersion according to claim 1, wherein a mass ratio of the pigment (I) to the self-dispersible pigment (II) [(I)/(II)] in the step 1 is from 90/10 to 25/75.

6. The process for producing a pigment water dispersion according to claim 1, further comprising the following step 1-1 prior to the step 1:

Step 1-1;

subjecting a pigment mixture comprising the water-dispersible polymer, an organic solvent, the pigment (I) and water to dispersion treatment and then removing the organic solvent from the resulting dispersion to obtain the water dispersion (A) formed by dispersing the pigment (I) with the water-dispersible polymer.

7. The process for producing a pigment water dispersion according to claim 1, wherein the pigment (I) is a carbon black having a DBP oil absorption of not more than 140 mL/100 g.

8. The process for producing a pigment water dispersion according to claim 1, wherein a total content of the pigment (I) and the self-dispersible pigment (II) in the pigment water dispersion is not less than 10% by mass and not more than 20% by mass.

9. The process for producing a pigment water dispersion according to claim 1, wherein a content of the water-dispersible polymer in the pigment water dispersion is not less than 3.0% by mass and not more than 10% by mass.

10. The process for producing a pigment water dispersion according to claim 1, wherein a content of a water-soluble organic solvent in the pigment water dispersion is not less than 0% by mass and not more than 5% by mass.

16. The process for producing a pigment water dispersion according to claim 1, wherein the water-dispersible polymer is a vinyl-based polymer that comprises a constitutional unit derived from (a) a hydrophobic monomer and a constitutional unit derived from (b) an ionic monomer.

17. The process for producing a pigment water dispersion according to claim 16, wherein the vinyl-based polymer further comprises a constitutional unit derived from (c) a nonionic monomer.

18. The process for producing a pigment water dispersion according to claim 1, wherein the hues of the pigments (I) and (II) are identical to each other.

19. The process for producing a pigment water dispersion according to claim 1, wherein the water dispersion (A) is a water dispersion prepared by dispersing the pigment (I) with a crosslinked water-dispersible polymer.

20. The process for producing a pigment water dispersion according to claim 6, wherein, in the step 1-1, after removing the organic solvent, a crosslinking agent is further added to the resulting water dispersion to subject the water-dispersible polymer in the water dispersion to crosslinking reaction with the crosslinking agent.

21. The process for producing a pigment water dispersion according to claim 20, wherein the crosslinking agent is an epoxy group-containing compound.

22. The process for producing a pigment water dispersion according to claim 21, wherein the water-dispersible polymer comprises a reactive group capable of reacting with the crosslinking agent, and the reactive group is a carboxy group.

11. (canceled)

12. A pigment water dispersion comprising a pigment (I) dispersed with a water-dispersible polymer and a self-dispersible pigment (II), in which the water-dispersible polymer is adsorbed onto the pigment (I) and the self-dispersible pigment (II).

13. A water-based ink for ink-jet printing comprising the pigment water dispersion according to claim 12, an organic solvent (D) and water.

14. An ink-jet printing method comprising the step of ejecting the water-based ink according to claim 13 onto a printing medium by a thermal method to print characters or images on the printing medium.

15. (canceled)