AQUEOUS INK

• US 20200131389A1
• Filed: 06/29/2018
• Published: 04/30/2020
• Est. Priority Date: 07/03/2017
• Status: Active Grant

• Current Assignee: KAO Corporation
• Original Assignee: KAO Corporation
• Inventors: INOUE, Masashi, KAWATA, Daiki
• Granted Patent: US 11,180,671 B2
• Time in Patent Office: Days
• CPC Class Codes: B41J 2/01 Ink jet
• CPC Class Codes: B41J 2/2107 characterised by the ink properties supplying ink in a solid state B41J2/17593
• CPC Class Codes: B41M 5/0023 Digital printing methods characterised by the inks used inks per se C09D11/00
• CPC Class Codes: B41M 5/5254 characterised by the use of polymers obtained by reactions only involving carbon-to-carbon unsaturated bonds, e.g. vinyl polymers
• CPC Class Codes: C09D 11/023 Emulsion inks
• CPC Class Codes: C09D 11/033 characterised by the solvent
• CPC Class Codes: C09D 11/037 characterised by the pigment
• CPC Class Codes: C09D 11/106 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 11/326 characterised by the pigment dispersant

Abstract

The present invention relates to a water-based ink containing at least pigment-containing water-insoluble crosslinked polymer particles (A), a polymer emulsion (B) and water, in which a water-insoluble crosslinked polymer constituting the crosslinked polymer particles (A) is obtained by subjecting a polymer that contains a constitutional unit derived from a carboxylic acid monomer having an acid value of not less than 200 mgKOH/g and a constitutional unit derived from a hydrophobic monomer, to crosslinking reaction with an epoxy compound, and a polymer constituting the polymer emulsion (B) contains a constitutional unit derived from a carboxylic acid monomer and a constitutional unit derived from a hydrophobic monomer. The water-based ink of the present invention is excellent in ejection stability and fastness of the printed characters or images while maintaining good optical density.

Claims

1. A water-based ink comprising at least pigment-containing water-insoluble crosslinked polymer particles (A), a polymer emulsion (B) and water, in which a water-insoluble crosslinked polymer constituting the crosslinked polymer particles (A) is obtained by subjecting a polymer that comprises a constitutional unit derived from a carboxylic acid monomer having an acid value of not less than 200 mgKOH/g and a constitutional unit derived from a hydrophobic monomer, to crosslinking reaction with an epoxy compound, a polymer constituting the polymer emulsion (B) comprises a constitutional unit derived from a carboxylic acid monomer and a constitutional unit derived from a hydrophobic monomer, the polymer constituting the polymer emulsion (B) is in the form of a crosslinked polymer, and an acid value of the crosslinked polymer constituting the polymer emulsion (B) is not less than 50 mgKOH/g.

2. The water-based ink according to claim 1, wherein a crosslinking degree of the water-insoluble crosslinked polymer is not less than 20 mol % and not more than 80 mol %.

3. The water-based ink according to claim 1, wherein an acid value of the water-insoluble crosslinked polymer is not less than 80 mgKOH/g and not more than 180 mgKOH/g.

4. The water-based ink according to claim 1, wherein the epoxy compound is a glycidyl ether compound of a polyhydric alcohol comprising a hydrocarbon group having not less than 3 and not more than 8 carbon atoms.

5. The water-based ink according to claim 1, wherein an acid value of a crosslinking polymer constituting the polymer emulsion (B) is not less than 50 mgKOH/g and not more than 300 mgKOH/g.

7. The water-based ink according to claim 1, wherein the crosslinked polymer constituting the polymer emulsion (B) is obtained by crosslinking reaction with a glycidyl ether compound of a polyhydric alcohol comprising a hydrocarbon group having not less than 3 and not more than 8 carbon atoms.

8. The water-based ink according to claim 1, wherein a crosslinking degree of the polymer constituting the polymer emulsion (B) is not less than 5 mol % and not more than 80 mol %.

9. The water-based ink according to claim 1, wherein a content of the pigment-containing water-insoluble crosslinked polymer particles (A) in the water-based ink is not less than 2% by mass and not more than 17% by mass.

10. The water-based ink according to claim 1, wherein a content of the polymer emulsion (B) in the water-based ink is not less than 1% by mass and not more than 10% by mass.

11. The water-based ink according to claim 1, wherein a mass ratio of the pigment-containing water-insoluble crosslinked polymer particles (A) to polymer particles in the polymer emulsion (B) [pigment-containing water-insoluble crosslinked polymer particles (A)/polymer particles)] in the water-based ink is from 10/1 to 0.3/1.

13. The water-based ink according to claim 1, for ink-jet printing.

15. An ink-jet printing method, comprising the steps of loading the water-based ink according to claim 1 to an ink-jet printing apparatus and ejecting the water-based ink in the form of droplets of the ink from the ink-jet printing apparatus onto a printing medium to print characters or images on the printing medium.

16. An ink-jet printing method according to claim 15, wherein the printing medium is at least one film selected from the group consisting of a polyester film, a polyvinyl chloride film, a polypropylene film and a polyethylene film.

6. (canceled)

12. (canceled)

14. (canceled)