Mitsubishi Pencil Company, Limited

Kosuke Ogura

A composite colored particle may include a resin particle carrying a positive electric charge on a particle surface, a colored particle carrying a negative electric charge on a particle surface, and a low-density particle, the colored particle and the low-density particle forming a composite with the resin particle through Coulomb force. A water-based ink composition may contain such composite colored particles dispersed in a water-based medium. A writing instrument may be loaded with such a water-based ink composition.

Composite colored particle

An aqueous ink composition suitable for ballpoint pens may achieve excellent smooth writing without causing deterioration of the smooth writing and wear of a tip socket while colored resin particles encapsulating a pigment are used. An embodiment of such ink compositions is an aqueous ink composition suitable for ballpoint pens containing at least colored resin particles (A) encapsulating a pigment (a) and non-colored resin particles (B) containing no pigment.

Ink composition for aqueous ballpoint pens

An aqueous ink composition suitable for writing instruments may achieve excellent color development and excellent darkness of a drawn line, while colored resin particles encapsulating a pigment are used. An embodiment of the aqueous ink composition for writing instruments includes an aqueous ink composition for writing instruments containing at least colored resin particles (A) having a pigment (p) encapsulated in, and colored resin particles (B) having a pigment (p) exposed on a surface.

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Shinagawa-ku, Japan

Kosuke Ogura