| abstract |
An oil-based ink composition for a ballpoint pen has an ink viscosity at 25° C. is 200,000 mPa·s or more at a shear rate of 0.019 s −1 and 5,000 mPa·s or less at a shear rate of 10,000 s −1 and 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. |