Patent ID: 7396400
Filing Date: 2008-07-08
Classification: C09D

Abstract:
1. A water base erasable ink composition for use in marking pens which comprises 0.05-20% by weight of a colorant, and 1-20% by weight of an oily material which is nonvolatile at normal temperatures (25° C.); a) wherein the colorant is dispersed in the water with the aid of a polyvinyl alcohol resin as a dispersing agent which has a saponification degree of 70-85 mol % and of which an aqueous solution of 4% concentration has a viscosity of 2-30 mPa·s at 20° C.; and an aliphatic lower alcohol of number of carbon atoms of 2 to 4 as a wetting agent for the colorant in an amount of 0.1-2 parts by weight in relation to one part by weight of the colorant, in a weight ratio of the resin to the colorant of 0.5 to 5 and in an amount of 1 to 10% by weight based on the ink composition to form a dispersion of colorant; and then b) an O/W emulsion of oily material prepared with the aid of a non-ionic surfactant as an emulsifier in an amount of 1-20% by weight based on the emulsion and having a viscosity of 5-40 mPa·s at 20° C. is added to the dispersion of colorant.