Ink composition for ballpoint pen based on water; refill for a ballpoint pen; ballpoint pen and ballpoint pen, disposable

摘要

A water-based ink composition for ballpoint pens which ensures smooth writing at the early stage and after time passage, shows no faint part in handwriting and can sustain a stable writing performance to thereby give favorable handwriting continuously. Namely, a water-based ink composition for ballpoint pens wherein a coloring agent is dissolved or dispersed in an aqueous vehicle. The aqueous vehicle substantially consists of water and is free from water-soluble organic solvents. It contains a shear-thinning tackifier together with a thickening-controlling agent. This thickening-controlling agent is one or more members selected from the group consisting of a polyalkylene glycol, a polypropylene glycol derivative, polyvinyl alcohol, polyvinylpyrrolidone, a cellulose-derived high molecule compound, a high molecule compound having a polyalkylene oxide group and/or a surfactant having a polyoxyethylene group.