Additive for oil-based ink for a ball point pen and oil based ink for a ball point pen containing the same

摘要

A additive for an oil based ink for a ball point pen containing at least one or plural kinds of organic solvents, a resin and an inorganic fine particle thickener, wherein the additive has a viscosity of 1000 mPa·s or more at a shear rate of 5/s and at 0° C. and a viscosity of 50000 mPa·s or less at a shear rate of 5/s and at 50° C., and has an absorbance of from 0.01 to 5 at a wavelength of 900 nm when a cell is 1 cm long. This additive is added to an oil based ink for a ball point pen such that an amount of the additive becomes 0.1 to 30% by weight based on the total ink.