| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for producing granular cobalt oxide black pigment with a small grain size and a sharp grain size distribution combining excellent blackness and high electric resistivity. SOLUTION: Regarding the method for producing granular cobalt oxide black pigment, the neutralization of a cobalt (bivalent) salt aqueous solution and an alkali solution is performed at the pH of 10 to 13, on and after the start of the mixing and neutralization or on and after the completion of the mixing and neutralization, an oxygen-containing gas is continuously bubbled while the temperature of the reaction slurry is held at 10 to 40°C, so as to obtain a cobalt hydroxide precursor, and the cobalt hydroxide precursor is subjected to filtering, washing, drying and cracking, and is thereafter fired at 500 to 850°C for 0.5 to 3 hr in a sealed atmosphere, or is fired at 500 to 850°C in an inert gas-enriched air atmosphere in which the concentration of oxygen is held to 15 to <22 vol.%. COPYRIGHT: (C)2008,JPO&INPIT |
