Hybrid marking instrument and writing ink composition

摘要

A writing ink composition having a pseudoplasticity index value between about 0.02 and 0.18, a low-shear viscosity between about 25,000 and 120,000 cP, and a high-shear viscosity between about 6 and 26 cP can be used in a hybrid, ball-point marking instrument which combines advantageous features of both paste-ink and liquid-ink ballpens. The writing ink can be prepared using a colloid milling procedure.