Aqueous pigment dispersion liquid

Patent metadata

Field	Value
Publication number	US-11746247-B2
Application number	US-202017438812-A
Country	US
Kind code	B2
Filing date	Mar 17, 2020
Priority date	Mar 22, 2019
Publication date	Sep 5, 2023
Grant date	Sep 5, 2023

Abstract

The present invention provides an aqueous pigment dispersion liquid being such that a pigment is finely dispersed, and the viscosity, and the particle diameters of the pigment are unlikely to fluctuate, being excellent in storage stability, and enabling preparation of an emulsion-polymerized toner having properly controlled particle diameters while improving the pigment utilization rate. The aqueous pigment dispersion liquid is an aqueous pigment dispersion liquid for an emulsion-polymerized toner containing a pigment, a dispersant, and an aqueous medium. The dispersant is a polymer containing a constitutional unit (A) derived from a monomer (A) such that a group containing a (meth)acryloyloxy group or the like is bonded to one end of a particular polyethylene glycol chain or the like, and a constitutional unit (B) derived from a monomer (B) having a carboxy group or the like, the polymer has a number average molecular weight in terms of polystyrene of 4,000 to 15,000, as measured by gel permeation chromatography, the polymer is contained in a state of being not ionized substantially, and the aqueous pigment dispersion liquid has a pH of 3.0 to 8.4.

First claim

The invention claimed is:

1. An aqueous pigment dispersion liquid comprising:
a pigment;
a dispersant that disperses the pigment; and
an aqueous medium comprising water,
wherein the dispersant is a polymer comprising: a constitutional unit (A) derived from a monomer (A′); and a constitutional unit (B) derived from a monomer (B′) having a carboxy group or an amino group, wherein in the monomer (A′), a group comprising a (meth)acryloyloxy group or a (meth)acryloylamino group is bonded to one end of any one of the following molecular chains of (i) to (iii):
(i) a polyethylene glycol chain having an average number of repeating oxyethylene units n in a range from 4 to 20;
(ii) a polyethylene glycol monoalkyl (C1-18) ether chain having an average number of repeating oxyethylene units n in a range from 4 to 9; and
(iii) a molecular chain represented by the following formula (1), the molecular chain having an average number of repeating oxyethylene oxypropylene units n in a range from 20 to 50 and a content of an oxyethylene unit in a range from 70 to 92% by mass:
R —( OEt ) x -( OPr ) y - A   (1)

wherein R represents a C1-18 alkyl group, A represents OH or NH 2 , Et represents an ethylene group, Pr represents a propylene group, and x+y=n,
a content of the oxyethylene unit derived from the monomer (A′) in the polymer is in a range from 50 to 90% by mass relative to a total mass of the polymer,
the polymer is (a) an A-B block copolymer or (b) an A-B-A block copolymer, having a polymer block A comprising the constitutional unit (A) and a polymer block B comprising the constitutional unit (B),
the polymer has a number average molecular weight in terms of polystyrene in a range from 4,000 to 15,000, as measured by gel permeation chromatography,
the polymer is water-soluble,
the polymer has a clouding point in a range from 50 to 80° C.,
the carboxy group or the amino group present in the monomer (B′) and introduced to the polymer is not neutralized and is not ionized in the polymer,
the aqueous pigment dispersion liquid has a pH in a range from 3.0 to 8.4,
the polymer adsorbs onto a surface of the pigment in the dispersion liquid, and
the aqueous pigment dispersion is configured to provide an emulsion-polymerized toner.

2. The aqueous pigment dispersion liquid according to claim 1 , wherein
the monomer (B′) is (meth)acrylic acid, or at least one monomer selected from the group consisting of vinylpyridine, vinylimidazole, and dimethylaminoethyl (meth)acrylate, and
a content of the constitutional unit (B) in the polymer is in a range from 3 to 15% by mass based on the total mass of the polymer.

3. The aqueous pigment dispersion liquid according to claim 1 , wherein
the pigment is a yellow-based pigment comprising Pigment Yellow 185, and
the monomer (B′) is the monomer having an amino group.

4. The aqueous pigment dispersion liquid according to claim 1 , wherein the pigment has a number average particle diameter in a range from 80 to 300 nm, as measured by a light scattering method.

5. The aqueous pigment dispersion liquid according to claim 1 , wherein
a content of the pigment is in a range from 10 to 40% by mass, and
a content of the dispersant is in a range from 5 to 60% by mass based on the content of the pigment.

6. The aqueous pigment dispersion liquid according to claim 1 , wherein
the pigment is Pigment Yellow 185, and
a content of the pigment is in a range from 20 to 40% by mass.

Assignees

• Dainichiseika Color Chem

Inventors

• Sakai Yosuke
• NARITA Misaki
• Yoshida Yasuhiro
• Aoyagi Shinichiro
• Murakami Yoshikazu
• Shimanaka Hiroyuki

Classifications

• C09D17/001 Primary

  in aqueous medium (C09D17/003, C09D17/004 take precedence) · CPC title

• C08F220/14

  Methyl esters {, e.g. methyl (meth)acrylate} · CPC title

• C08F220/1804

  C4-(meth)acrylate, e.g. butyl (meth)acrylate, isobutyl (meth)acrylate or tert-butyl (meth)acrylate · CPC title

• C08F220/1807

  C7-(meth)acrylate, e.g. heptyl (meth)acrylate or benzyl (meth)acrylate · CPC title

• C08F220/34

  Esters containing nitrogen {, e.g. N,N-dimethylaminoethyl (meth)acrylate} · CPC title