| 摘要 |
PURPOSE:To prepare yellow pigment of iron oxide like grains of rice, having improved color tone, dispersibility, and heat resistance, by adding an aqueous solution of a ferric salt to an alkali aqueous solution at a specific temperature to give iron hydroxide, aging it, subjecting it to hydrothermal treatment at a specified temperature. CONSTITUTION:An aqueous solution of a ferric salt at <=30 deg.C is added to an alkali aqueous solution at <=30 deg.C to prepare iron hydroxide. Ferric sulfate, etc. is used as the iron salt, its concentration is <=0.5M/l, sodium hydroxide, etc. is used as the alkali, its concentration is <=4M/l, and the reaction is carried out at -5-30 deg.C. The prepared precipitate of iron hydroxide is aged for >=30min, subjected to hydrothermal treatment at 120-250 deg.C for about 1hr, so that iron oxide hydroxide like grains of rice, namely, yellow iron oxide pigment is prepared. The long axis of the yellow iron oxide pigment like grains of rice is in 100-350mm., a ratio of long axis/short axis is 1.5-4.5, and the pigment has improved color tone, dispersibility and stability as pigment. |
