| 摘要 |
PROBLEM TO BE SOLVED: To obtain an oil-base ink that can prevent a ball-point pen from having ink leakage from the penpoint and penpoint plugging without spoiling smooth feeling in writing, by adding microparticulate silica having a specified particle diameter and a specified specific surface area to the oil-base ink comprising at least one organic solvent, a colorant and a resin. SOLUTION: This ink desirably has a viscosity of 1,000-5,000mPa.s at 25 deg.C and is prepared by adding 0.01-2.5wt.%, based on the total ink weight, microparticulate silica having a mean primary particle diameter of 7-40nm and a specific surface area (BET method) of 50-380cm<2> /g, 0.01-10.0wt.%, based on the total ink weight, polyvinylpyrrolidone being a dispersant for the microparticulate silica and optionally common additives such as a surfactant, an antibacterial and a lubricant to an oil-base ink containing at least one organic solvent and a resin for controlling the viscosity of the ink. |
