US 12,134,281 B2
Writing instrument
Yusuke Nakata, Tokyo (JP); and Hisato Haga, Tokyo (JP)
Assigned to MITSUBISHI PENCIL COMPANY, LIMITED, Tokyo (JP)
Filed by MITSUBISHI PENCIL COMPANY, LIMITED, Tokyo (JP)
Filed on Mar. 1, 2024, as Appl. No. 18/593,289.
Claims priority of application No. 2023-030906 (JP), filed on Mar. 1, 2023.
Prior Publication US 2024/0294029 A1, Sep. 5, 2024
Int. Cl. B43K 8/02 (2006.01); C09D 11/17 (2014.01)
CPC B43K 8/02 (2013.01) [C09D 11/17 (2013.01)] 18 Claims
OG exemplary drawing
 
1. A writing instrument, comprising:
a pen core; and
a water-based ink composition, loaded in the writing instrument,
wherein the water-based ink composition comprises
(i) colored resin particles formed by polymerization of a monomer comprising cyclohexyl (meth)acrylate, the colored resin particles enclosing a basic dye, an oil-soluble dye, or an acid dye, and
(ii) an anionic surfactant.