| 摘要 |
The present invention provides a hematite particle powder that exhibits a bright red color suitable for coloring paint, printing ink, plastic, film, pottery, cosmetics, and the like without using iron salts such as nitrates and the like which have a significant environmental impact and also has excellent dispersibility. The present invention is a method for producing hematite particle powder consisting of a first-stage reaction for adding an organic acid having a carboxylic acid group and a hydroxyl group such as tartaric acid or the like to a ferrous salt reaction solution containing a ferrous hydroxide colloid or iron-containing precipitate colloid obtained by reacting a ferrous salt aqueous solution and an alkali aqueous solution and producing magnetite particles by conducting an oxidation reaction in a temperature range of 30-50°C; and a second-stage reaction for introducing a ferrous salt aqueous solution after bringing the reaction solution to a temperature range of from 90°C to the boiling point after completion of the first-stage reaction, adding an alkali aqueous solution so as to maintain a pH in the 3.5-5.0 range, conducting an oxidation reaction by passage of oxygen-containing gas, and producing hematite particles. |
