| 摘要 |
PURPOSE:To obtain the titled pigment having excellent stability, appearance and touch, by dispersing titanium dioxide-coated mica in water, adjusting its pH and adding an aq. soln. contg. an oxidizing agent and a ferrous salt to precipitate tri-iron tetroxide on the surfaces of mica particles. CONSTITUTION:Titanium dioxide-coated mica is dispersed in water and the pH of the dispersion is adjusted to 7-12 by adding a base (e.g. ammonium hydroxide or potassium hydroxide). At the same time, an aq. soln. contg. an oxidizing agent (e.g. sodium nitrate or potassium chlorate) and a ferrous salt (e.g. ferrous sulfate or ferrous chloride) is slowly added thereto to precipitate tri-iron tetroxide on the surfaces of the titanium dioxide-coated mica particles, thus obtaining a black pearlescent pigment and an iron oxide-coated surface. When the pigment is heat-treated at 500-1,000 deg.C in the air, a red pearlescent pigment can be obtd. |
