Kabushiki Kaisha Pilot Corporation

The Pilot Ink Co., Ltd.

Masayuki Mita

Yoshiaki Ono

Katsuyuki Fujita

Yasuaki Kambe

Tomoyuki Yamamura

The present invention provides a thermochromic color-memory composition including (a) an electron-donating color-developing organic compound, (b) an electron-accepting compound, and (c) an ester compound represented by the following formula (1) or (2), as a reaction medium which controls color reaction of the component (a) and the component (b); and a thermochromic color-memory microcapsule pigment encapsulating the thermochromic color-memory composition. 

Thermochromic color-memory composition and thermochromic color-memory microcapsule pigment encapsulating the same

To provide a reversibly thermochromic aqueous ink composition excellent in dispersion stability of a reversibly thermochromic microcapsule pigment and a writing instrument using the same. Disclosed is a reversibly thermochromic aqueous ink composition comprising a reversibly thermochromic microcapsule pigment encapsulating a reversibly thermochromic composition comprising (a) an electron-donating color-developing organic compound, (b) an electron-accepting compound, and (c) a reaction medium to determine an occurrence temperature of a coloring reaction of the component (a) and the component (b), and a vehicle comprising water and a specific gravity adjuster selected from the group consisting of an oxyacid belonging to Group 6 having an atomic weight of 90 to 185 or salt thereof.

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Aichi-ken, Japan

Masayuki Mita