Water-based pigment ink composition for writing utensil

TLDR: In this article, the authors proposed a method to obtain a compsn. which is excellent in dispersion stability an hiding power and does not require operations such as stirring before the use by fixing fine titanium oxide particles on the surfaces of resin particles to form composite particles with specified particle sizes.

Abstract: PURPOSE:To obtain a compsn. which is excellent in dispersion stability an hiding power and does not require operations such as stirring before the use by fixing fine titanium oxide particles on the surfaces of resin particles to form composite particles with specified particle sizes. CONSTITUTION:The compsn. contains, as a coloring matter, composite particle having a mean particle size of 0.2-2mum and obtd. by fixing fine titanium oxide particles having a mean particle size of 0.1mum or lower on the surfaces of resin particles. The resin particle reduces the apparent density of the oxide particles, improving the dispersion stability of the latter particles, and increases the apparent particle size of the latter, improving the whiteness and hiding power of the latter. The composite particles are obtd. by mixing the resin and the oxide particles and fixing the oxide particles on the surfaces of the resin particles by causing the oxide particles to be adsorbed by the surface or to be forced into the resin particles, e.g. by mixing and grinding with an automatic mortar, a jet mill, etc., and/or giving a mechanical impact with a hammer mill, etc.