Patent ID: 8771410

Claim:
A ballpoint pen ink containing at least a colorant, a liquid medium in which 50% by weight or more of the liquid medium is an organic solvent, polyoxyethylene castor oil, polyoxyethylene hardened castor oil or a derivative thereof represented by the following formula (I), and one kind of a compound or a mixture of two or more kinds of compounds selected from any of the compounds represented by the following formulae (II), (III) and (IV): (X: an ethylene oxide group, CH 2 CH 2 O, Y: H, CR or COCH 2 CH 2 COOH, R: a fatty acid or hydroxyl group-containing fatty acid having C12 or more, α+β+γ=an integer of 1 or more, δ+ε+ξ=an integer of 1 or more), more, and α+β+γ+δ+ε+ξ<80); (R: an alkyl group or a phenyl group, and α: an integer of 0 or more); (R: an alkyl group or a phenyl group, and α+β=an integer of 0 or more); and (R: an alkyl group or a phenyl group, and α+β+γ=an integer of 0 or more).