Aqueous pigment dispersion

Patent metadata

Field	Value
Publication number	US-11072719-B2
Application number	US-201716324026-A
Country	US
Kind code	B2
Filing date	Aug 9, 2017
Priority date	Aug 12, 2016
Publication date	Jul 27, 2021
Grant date	Jul 27, 2021

Abstract

The present invention relates to a pigment water dispersion containing pigment-containing water-insoluble crosslinked polymer A particles, a water-soluble basic compound and water, in which a water-insoluble crosslinked polymer A constituting the particles has a carboxy group and a crosslinked structure containing an ester group derived from a water-insoluble crosslinking agent, a saponification value of the water-insoluble crosslinked polymer A is from 170 to 300 mgKOH/g, and the water-soluble basic compound contains a water-soluble amine compound; a process for producing the pigment water dispersion; a water-based ink for ink-jet printing which contains the pigment water dispersion; and an ink-jet printing method using the water-based ink.

First claim

The invention claimed is:

1. A pigment water dispersion comprising pigment-containing water-insoluble crosslinked polymer A particles, a water-soluble basic compound and water,
in which a water-insoluble crosslinked polymer A constituting the particles comprises a carboxy group and a crosslinked structure comprising an ester group derived from a water-insoluble polyfunctional epoxy crosslinking agent comprising not less than 2 and not more than 3 glycidyl ether groups derived from a polyhydric alcohol comprising a hydrocarbon group having not less than 3 and not more than 6 carbon atoms, wherein the water-insoluble crosslinked polymer A is a polymer obtained by subjecting a carboxy group-containing water-insoluble polymer A′ to crosslinking treatment;
a saponification value of the water-insoluble crosslinked polymer A is not less than 170 mgKOH/g and not more than 300 mgKOH/g; and
the water-soluble basic compound comprises a water-soluble amine compound.

2. The pigment water dispersion according to claim 1 , wherein a content of the water-soluble amine compound in the water-soluble basic compound is not less than 50 mol %.

3. The pigment water dispersion according to claim 1 , wherein a boiling point of the water-soluble amine compound is not lower than 85° C. and not higher than 350° C.

4. The pigment water dispersion according to claim 1 , wherein the water-soluble amine compound is an alkanolamine having not less than 2 and not more than 8 carbon atoms.

5. The pigment water dispersion according to claim 1 , wherein a water solubility rate of the water-insoluble crosslinking agent is not more than 50% by mass.

6. The pigment water dispersion according to claim 1 , wherein a mass ratio of the pigment to the water-insoluble crosslinked polymer A [pigment/water-insoluble crosslinked polymer A] is not less than 30/70 and not more than 90/10.

7. A process for producing a pigment water dispersion comprising pigment-containing water-insoluble crosslinked polymer A particles, a water-soluble basic compound and water, said process comprising:
Step I: subjecting a mixture comprising a carboxy group-containing water-insoluble polymer A′, a water-soluble basic compound and water to dispersion treatment to obtain a polymer dispersion;
Step II: adding a pigment to the polymer dispersion obtained in the step I and then subjecting the resulting mixture to dispersion treatment to obtain an aqueous pigment dispersion solution; and
Step III: adding a water-insoluble polyfunctional epoxy crosslinking agent comprising not less than 2 and not more than 3 glycidyl ether groups derived from a polyhydric alcohol comprising a hydrocarbon group having not less than 3 and not more than 6 carbon atoms to the aqueous pigment dispersion solution obtained in the step II to subject the polymer to crosslinking treatment, thereby obtaining the pigment water dispersion,
in which a saponification value of a water-insoluble crosslinked polymer A constituting the particles is not less than 170 mgKOH/g and not more than 300 mgKOH/g; and
the water-soluble basic compound in the pigment water dispersion comprises a water-soluble amine compound.

8. The process for producing a pigment water dispersion according to claim 7 , wherein a neutralization degree of the carboxy groups in the water-insoluble polymer A′ in the step I is not less than 10 mol % and not more than 80 mol %.

9. The process for producing a pigment water dispersion according to claim 7 , wherein the water-insoluble polymer A′ comprises a constitutional unit derived from (a-1) a carboxy group-containing monomer and a constitutional unit derived from (a-2) a hydrophobic monomer.

10. A water-based ink for ink-jet printing comprising the pigment water dispersion according to claim 1 , and a water-soluble organic solvent,
in which the water-soluble organic solvent comprises one or more organic solvents each having a boiling point of not lower than 90° C., and a boiling point of the water-soluble organic solvent as a weighted mean value of boiling points of the one or more organic solvents which are weighted by contents (% by mass) of the respective organic solvents is not higher than 250° C.

11. An ink-jet printing method comprising the steps of:
ejecting the water-based ink for ink-jet printing according to claim 10 by an ink-jet ejecting method to allow the water-based ink to adhere onto a printing medium; and
then drying the printing medium onto which the water-based ink is adhered, at a temperature of not lower than 40° C.

12. The ink-jet printing method according to claim 11 , wherein the printing medium is a fiber.

13. The pigment water dispersion according to claim 1 , wherein the water-insoluble polymer A′ comprises a constitutional unit derived from (a-1) a carboxy group-containing monomer and a constitutional unit derived from (a-2) a hydrophobic monomer.

14. The pigment water dispersion according to claim 13 , wherein a mass ratio of the component (a-1) to the component (a-2) [component (a-1)/component (a-2)] is not less than 0.05 and not more than 1.2.

15. The pigment water dispersion according to claim 1 , wherein the water-soluble amine compound is at least one compound selected from the group consisting of N-methyl diethanolamine, N,N-dimethyl ethanolamine, diethanolamine and triethanolamine.

16. The pigment water dispersion according to claim 1 , wherein the content of the pigment in the pigment water dispersion is not less than 3.0% by mass and not more than 20% by mass.

17. The water-based ink according to claim 10 , further comprises pigment-free water-insoluble polymer B particles.

18. The pigment water dispersion according to claim 1 , wherein a content of the water-soluble amine compound in the water-soluble basic compound is not less than 70 mol %.

19. The pigment water dispersion according to claim 1 , wherein a boiling point of the water-soluble amine compound is not lower than from 100° C. and not higher than to 350° C.

20. The pigment water dispersion according to claim 1 , wherein the water-soluble amine compound is a tertiary ethanolamine.

Assignees

• Kao Corp

Inventors

• Eguchi Tetsuya
• Hyakuda Hirokazu

Classifications

• D06P1/5228

  Polyalkenyl alcohols, e.g. PVA · CPC title

• D06P1/5221

  Polymers of unsaturated hydrocarbons, e.g. polystyrene polyalkylene · CPC title

• C08L33/02

  Homopolymers or copolymers of acids; Metal or ammonium salts thereof · CPC title

• C08F220/06

  Acrylic acid; Methacrylic acid; Metal salts or ammonium salts thereof · CPC title

• C08F212/08

  Styrene · CPC title