Polymeric dispersant and production method therefor, aqueous pigment dispersion, and water-based ink-jet ink

Patent metadata

Field	Value
Publication number	US-12559639-B2
Application number	US-202118546549-A
Country	US
Kind code	B2
Filing date	Nov 26, 2021
Priority date	Feb 17, 2021
Publication date	Feb 24, 2026
Grant date	Feb 24, 2026

Abstract

The present invention provides a polymeric dispersant that is to be blended in an aqueous pigment dispersion in which a pigment is finely dispersed in a stable manner and at a high level, the aqueous pigment dispersion enabling preparation of an aqueous inkjet ink capable of recording an image excellent in adhesiveness and durability on plastic media and textiles. The polymeric dispersant is a polymer that includes a constituent unit (i) derived from styrene, a constituent unit (ii) derived from methyl methacrylate and/or the like, a constituent unit (iii) derived from 2-ethylhexyl methacrylate and/or the like, a constituent unit (iv) derived from 2-hydroxyethyl methacrylate and/or the like, and a constituent unit (v) derived from methacrylic acid, and at least part of carboxy groups is neutralized with an alkali.

First claim

The invention claimed is:

1 . A polymeric dispersant for dispersing a pigment and is configured to be blended in an aqueous pigment dispersion for an aqueous inkjet ink and to be printed on a plastic media or a textile, the polymeric dispersant comprising a polymer, wherein
(1) the polymer comprises:
(i) a styrene-based constituent unit formed from a styrene monomer in an amount from 10 to 30% by mass,
(ii) a first methacrylate-based constituent unit in an amount from 10 to 30% by mass, wherein a first methacrylate monomer forming the first methacrylate-based constituent unit is at least one material selected from the group consisting of methyl methacrylate and ethyl methacrylate,
(iii) a second methacrylate-based constituent unit in an amount from 10 to 30% by mass, wherein a second methacrylate monomer forming the second methacrylate-based constituent unit is at least one material selected from the group consisting of 2-ethylhexyl methacrylate and dodecyl methacrylate,
(iv) a third methacrylate-based constituent unit in an amount from 10 to 20% by mass, wherein a third methacrylate monomer forming the third methacrylate-based constituent unit is at least one material selected from the group consisting of 2-hydroxyethyl methacrylate and 2-hydroxypropyl methacrylate, and
(v) a methacrylic acid-based constituent unit formed from a methacrylic acid monomer in an amount of 10 to 20% by mass, wherein the methacrylic acid-based constituent unit has a carboxylic acid group of the methacrylic acid monomer therein, and at least part of the carboxylic acid group is neutralized with at least one alkali selected from the group consisting of ammonia and dimethylaminoethanol,
a total content of the constituent units (i) to (v) is 90% by mass or more, and
the polymer comprises the constituent units (i) to (v) formed from 6 or more different monomers, and
(2) the polymer has:
a number average molecular weight in a range from 15,000 to 25,000,
a peak top molecular weight in a range from 25,000 to 50,000,
a polydispersity index, which is a ratio of weight average molecular weight/number average molecular weight, being in a range from 1.7 to 2.4, and
an area ratio (H/T) is in a range from 15 to 30%, where an area H is a peak of a molecular weight of 50,000 or higher, and an area T is a total area of a molecular weight peak, in a gel permeation chromatograph.

2 . The polymeric dispersant according to claim 1 , wherein the second methacrylate-based constituent unit (iii) is a constituent unit formed from dodecyl methacrylate as a monomer, or a constituent unit formed from 2-ethylhexyl methacrylate and dodecyl methacrylate as monomers.

3 . A method for producing a polymeric dispersant according to claim 1 , the method comprising:
subjecting monomers to solution polymerization in a polymerization solvent comprising diethylene glycol monobutyl ether, and then adding an alkali to make a polymerization solution into an aqueous solution.

4 . The method for producing a polymeric dispersant according to claim 3 , wherein the solution polymerization is performed in the polymerization solvent comprising 70% by mass or more of diethylene glycol monobutyl ether based on an amount of the polymeric dispersant that is the polymer to be produced.

5 . An aqueous pigment dispersion for an aqueous inkjet ink configured to be printed on plastic media or textile, comprising:
a pigment; water; a water-soluble organic solvent; and a polymeric dispersant according to claim 1 that disperses the pigment.

6 . The aqueous pigment dispersion according to claim 5 , wherein the water-soluble organic solvent is diethylene glycol monobutyl ether.

7 . The aqueous pigment dispersion according to claim 5 ,
wherein in the dispersion, a content of the pigment is in a range from 5 to 60% by mass, a content of the water is in a range from 20 to 80% by mass, a content of the water-soluble organic solvent is 30% by mass or less, and a content of the polymeric dispersant is in a range from 0.5 to 20% by mass.

8 . An aqueous inkjet ink for plastic media printing and textile printing, comprising the aqueous pigment dispersion according to claim 5 .

Assignees

• Dainichiseika Color Chem

Inventors

• Shimanaka Hiroyuki
• Kano Katsuhiko
• Kume Kosuke
• Miyazaki Chikako
• Murakami Yoshikazu
• Yoshikawa Sachio

Classifications

• B41J2/2107

  characterised by the ink properties (supplying ink in a solid state B41J2/17593) · CPC title

• B41J2/01

  Ink jet · CPC title

• C09D11/32 Primary

  characterised by colouring agents · CPC title

• C09D11/322 Primary

  Pigment inks · CPC title

• C09D11/107

  from unsaturated acids or derivatives thereof · CPC title