Pentel Kabushiki Kaisha

Natsumi Koide

Yuichi Kobayashi

Yoshitaka Morimoto

Aya Otsubo

An oil-based ink composition for a ballpoint pen has an ink viscosity at 25&#xb0; C. is 200,000 mPa&#xb7;s or more at a shear rate of 0.019 sand 5,000 mPa&#xb7;s or less at a shear rate of 10,000 sand a storage modulus at an angular frequency of 0.019 rad/sec is 10 Pa or more. The ink composition ensures a thin-width writing line, without bleeding or feathering, and prevents ink-depleted regions at the central part of the writing line so that the writing line is uniform and clear.

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Tokyo, Japan

Natsumi Koide