| 摘要 |
PROBLEM TO BE SOLVED: To provide a pigment ink for ball-point that has excellent long-term stability, causes no ink leakage from the ball point, even when it is allowed to stand for many hours, as the pen point is kept downward. SOLUTION: In a water-base pigment ink composition for ball point pen that mainly comprises a pigment, a pigment dispersant, water, a water-soluble solvent, and a water-soluble polymer resin as essential components, microfine, porous or nonporous and hydrophilic particles of anhydrous silica with a specific surface area of >=250 m2/g according to the BET method are used in an amount of 0.03-0.3 wt.%. In a preferred embodiment, both of a straight-chain polymer having the filament-drawing properties and of a crosslinkable and three- dimensional structure-forming polymer can be used as the water-soluble polymer resin. In addition, the amount of the straight chain polymer that can form filaments is preferably made more than that of the hydrophilic, porous or nonporous, microfine, anhydrous silica. |
