OILY DISPERSION OF BLACK PIGMENT FOR WRITING IMPLEMENT INK, AND WRITING IMPLEMENTS OILY INK OF BLACK PIGMENT

摘要

PROBLEM TO BE SOLVED: To provide such an oily dispersion of black pigment for writing implements ink as is usable for preparing a writing implements oily ink of black pigment which has a good writing ability with no light handwriting and no patchiness and has an excellent time stability with no viscosity increase of the ink and no aggregation of the pigment. SOLUTION: The oily dispersion of black pigment for writing implements ink contains an alcohol-based, high boiling-point organic solvent showing a boiling point of 150 deg.C or higher under a normal pressure, a pigment dispersing resin dissolved in the above high boiling-point organic solvent, and a carbon black dispersed in the above high boiling-point organic solvent, with a blend ratio (carbon black/resin) of the carbon black to the pigment dispersing resin being in the range of 0.5 to 5, and with the carbon black having an average particle diameter of 130 to 180 nm.