Ink, printing method, printing device, and printed matter

Patent metadata

Field	Value
Publication number	US-12227660-B2
Application number	US-202117315362-A
Country	US
Kind code	B2
Filing date	May 10, 2021
Priority date	May 25, 2020
Publication date	Feb 18, 2025
Grant date	Feb 18, 2025

Abstract

Provided is an ink including water, an organic solvent, resin particles, and a thickener. The thickener comprises polymer particles having a carboxylic acid structure. A proportion of the thickener in the ink is 0.05% by mass or more. Change in viscosity of the ink between before and after storage of the ink at 70° C. for 1 week is 20% or less. The change in viscosity is expressed by Formula (1): Change in viscosity (%)=[(a−b)/b]×100 . . . Formula (1), where a represents a viscosity (mPa·s) at 25° C. of the ink when the ink is prepared, and b represents a viscosity (mPa·s) at 25° C. of the ink after the ink is stored at 70° C. for 1 week.

First claim

The invention claimed is:

1. An ink comprising:
water;
an organic solvent;
resin particles; and
a thickener, wherein:
the thickener comprises carboxylic acid-based copolymer particles having a carboxylic acid structure;
a proportion of the thickener in the ink is 0.5% by mass or more and 2% by mass or less; and
change in viscosity of the ink between before and after storage of the ink at 70° C. for 1 week is 20% or less, and the change in viscosity is expressed by Formula (1) below:
Change in viscosity (%)=[( a−b )/ b]× 100  Formula (1),

where a represents a viscosity (mPa·s) at 25° C. of the ink when the ink is prepared, and b represents a viscosity (mPa·s) at 25° C. of the ink after the ink is stored at 70° C. for 1 week.

2. The ink according to claim 1 , wherein the change in viscosity expressed by the Formula (1) is 8% or less.

3. The ink according to claim 1 , wherein the proportion of the thickener in the ink is 0.5% by mass or more and 1% by mass or less.

4. The ink according to claim 1 , wherein a ratio (A/B) is 1.50 or less, where A denotes a viscosity of the ink at a shearing rate of 100 (1/s) and B denotes a viscosity of the ink at a shearing rate of 100,000 (1/s).

5. The ink according to claim 1 , wherein the thickener has a thickening rate of 10% or more, and the thickening rate is expressed by Formula (2) below:
Thickening rate (%)=[(α−β)/β]×100  Formula (2),

where α represents a viscosity (mPa·s) at 25° C. of the ink when the thickener in an amount of 0.1% by mass of the ink is added to the ink, and β represents a viscosity (mPa·s) at 25° C. of the ink before the thickener is added to the ink.

6. The ink according to claim 1 , wherein a proportion of the organic solvent in the ink is 5% by mass or more and 30% by mass or less.

7. The ink according to claim 1 , wherein the resin particles comprise at least one selected from the group consisting of acrylic resin particles and polyurethane resin particles.

8. The ink according to claim 1 , wherein the viscosity at 25° C. of the ink is 6 mPa·s or higher and 13 mPa·s or lower.

9. The ink according to claim 1 , wherein the ink is an inkjet ink.

10. A printing method comprising
allowing energy to act on the ink according to claim 1 to discharge the ink, to form an image.

11. The printing method according to claim 10 , further comprising heating the image.

12. A printing device comprising:
an ink container containing the ink according to claim 1 ; and
an ink discharging unit configured to allow energy to act on the ink to discharge the ink, to form an image.

13. A printed matter comprising:
a print medium; and
an ink layer on the print medium, the ink layer containing a solid portion in the ink according to claim 1 .

Assignees

• AKIMA Mio
• Kudo Masaki
• Hirade Tomohiro
• Terai Nozomi
• Ricoh Co Ltd

Inventors

• AKIMA Mio
• Kudo Masaki
• Hirade Tomohiro
• Terai Nozomi

Classifications

• C09D11/107 Primary

  from unsaturated acids or derivatives thereof · CPC title

• C09D11/102

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

• C09D11/38 Primary

  characterised by non-macromolecular additives other than solvents, pigments or dyes · CPC title

• C09D11/322

  Pigment inks · CPC title