Aqueous ink composition for ballpoint pen

Abstract

To provide an aqueous ink composition for ballpoint pen having excellent ink discharge properties at the initial writing (initial touch) even after exposure of the pen tip for a long period of time. The aqueous ink composition for ballpoint pen contains at least 0.1 to 5% by mass of a graft compound of an allyl alcohol-maleic anhydride-styrene copolymer composed of: (a) a polyoxyalkylene alkyl ether unit represented by Formula (I), (b) a maleic anhydride unit, and (c) a styrene unit, the allyl alcohol-maleic anhydride-styrene copolymer having the composition ratio (a):(b):(c) of 25 to 75:25 to 75:0 to 50% by mol and having a mass average molecular weight from 1000 to 50000, and polyoxyalkylene monoalkyl alcohol; 5 to 40% by mass of resin particles; and water; wherein in Formula (I), R represents an alkyl group having 1 to 5 carbons, and m is a positive number of 5 to 50.

Dependencies are inferred from the claim text.