| abstract |
A water base ink for use in inkjet printer printing, writing material, etc., which is low in sedimentation rate so as to exhibit low clogging tendency, being free from viscosity increase or increase of carbon black particle size and which can be stably stored for a prolonged period of time, realizing printing with velvety black at high printing density; and a modified carbon black dispersion liquid for use in the preparation thereof. In particular, a liquid having, dispersed therein, modified carbon black obtained by oxidizing raw carbon black powder, which modified carbon black at its surface comprises carboxyl groups and lactone groups, the lactone groups amounting to 0.8 to 1.1 times, in molar ratio, that of carboxyl groups and amounting to 500μmol/g or more in terms of molarity per weight of modified carbon black. |