Aqueous pigment dispersion and aqueous ink for inkjet recording use

Patent metadata

Field	Value
Publication number	US-9951236-B2
Application number	US-201415035007-A
Country	US
Kind code	B2
Filing date	Oct 30, 2014
Priority date	Nov 14, 2013
Publication date	Apr 24, 2018
Grant date	Apr 24, 2018

Abstract

Disclosed are an aqueous pigment dispersion and an aqueous ink for inkjet recording each of which includes a polymer (A), a pigment, and water. The polymer (A) has an anionic group, has a solubility in water of 0.1 g/100 mL or less and a number average molecular weight within the range of 1,000 to 6,000, and forms fine particles in water when the degree of neutralization of the anionic groups with the basic compound is 100%. Preferably, the polymer (A) is a polymer represented by general formula (1) (in formula (1), A 1 represents an organic lithium initiator residue, A 2 represents a polymer block of a monomer having an aromatic ring or a heterocycle, A 3 is a polymer block containing an anionic group, n represents an integer of 1 to 5, and B represents an aromatic group or an alkyl group).

First claim

The invention claimed is:

1. An aqueous pigment dispersion comprising a pigment, water, and a polymer (A), wherein the polymer (A) is capable of a solubility in water of 0.1 g/100mL or less when not neutralized, and capable of forming fine particles in water when neutralized to 100%, wherein the polymer (A) has a number average molecular weight within the range of 1,000 to 6,000 and polymer (A) is represented by general formula (1):

wherein, in formula (1), A1 represents an organic lithium initiator residue, A2 represents a polymer block of styrene, A3 represents a polymer block containing an anionic group, n represents an integer of 1 to 5, and B represents an aromatic group or an alkyl group;
wherein the polymer (A) has an acid value within the range of 40 to 190 mg KOH/g, and wherein the degree of neutralization of the anionic group with a basic compound of the polymer (A) is 20% to 200%.

2. The aqueous pigment dispersion according to claim 1 , wherein in the polymer (A) represented by general formula (1):

A 3 is a polymer block including at least one monomer block having an anionic group or composed only of monomer blocks each having an anionic group, the anionic group being a group reconverted from a protecting group in a monomer containing a (meth)acrylate having the protecting group, the protecting group being capable of being reconverted into the anionic group by deprotection .

3. The aqueous pigment dispersion according to claim 1 , wherein the polymer (A) is obtained by living anionic polymerization using a microreactor.

4. An aqueous ink for inkjet recording that contains the aqueous pigment dispersion according to claim 1 .

5. A method of producing an aqueous pigment dispersion, the method comprising the successive steps of: obtaining a dispersion containing a polymer having an anionic group, a basic compound, a water-soluble organic solvent, and a pigment; and mixing water with the dispersion; wherein the polymer having the anionic group is polymer (A) represented by general formula (1):

wherein, in formula (1), A 1 represents an organic lithium initiator residue, A 2 represents a polymer block of a styrene, A 3 represents a polymer block containing the anionic group, n represents an integer of 1 to 5, and B represents an aromatic group or an alkyl group,
wherein the polymer (A) has an acid value within the range of 40 to 190 mg KOH/g,
wherein the polymer (A) is capable of a solubility in water of 0.1 g/100 mL or less when not neutralized, and capable of forming fine particles in water when neutralized to 100%, wherein the polymer (A) has a number average molecular weight within the range of 1,000 to 6,000, and
wherein the polymer (A) forms fine particles in water when the degree of neutralization of the anionic group with a basic compound is 20% to 200%.

6. The aqueous pigment dispersion according to claim 1 , wherein B is selected from the group consisting of diphenylethylene, α-methylstyrene, and p-methyl-α-methyl styrene.

7. The method according to claim 5 , herein B is selected from the group consisting of diphenylethylene, α-methylstyrene, and p-methyl-α-methylstyrene.

Assignees

• Dainippon Ink & Chemicals

Inventors

• Uemura Yukie
• Kimura Toshihisa
• Oji Yasuo
• Tanaka Hisakazu
• Oe Nobuhiro
• Sato Morio
• YOKOYAMA Ryuuji

Classifications

• C08F297/02

  using a catalyst of the anionic type · CPC title

• C09D17/00

  Pigment pastes, e.g. for mixing in paints (artists' paints C09D5/06) · CPC title

• B41J2/165

  Prevention {or detection} of nozzle clogging, e.g. cleaning, capping or moistening for nozzles · CPC title

• C09D11/106

  containing macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds · CPC title

• C08F297/026

  polymerising acrylic acid, methacrylic acid or derivatives thereof · CPC title