US 12,227,660 B2
Ink, printing method, printing device, and printed matter
Mio Akima, Tokyo (JP); Masaki Kudo, Kanagawa (JP); Tomohiro Hirade, Kanagawa (JP); and Nozomi Terai, Tokyo (JP)
Assigned to RICOH COMPANY, LTD., Tokyo (JP)
Filed by Mio Akima, Tokyo (JP); Masaki Kudo, Kanagawa (JP); Tomohiro Hirade, Kanagawa (JP); and Nozomi Terai, Tokyo (JP)
Filed on May 10, 2021, as Appl. No. 17/315,362.
Claims priority of application No. 2020-090360 (JP), filed on May 25, 2020; and application No. 2020-171657 (JP), filed on Oct. 12, 2020.
Prior Publication US 2021/0363369 A1, Nov. 25, 2021
Int. Cl. B32B 3/10 (2006.01); C09D 11/102 (2014.01); C09D 11/107 (2014.01); C09D 11/38 (2014.01)
CPC C09D 11/38 (2013.01) [C09D 11/102 (2013.01); C09D 11/107 (2013.01)] 13 Claims
OG exemplary drawing
 
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.