| 摘要 |
PURPOSE:To provide high coercive force, favorable saturation magnetizability and square ratio to needlelike alpha-FeOOH obtd. by a reaction in an acidic range by separating the alpha-FeOOH by filtration, washing it in water, and coating the surface with a phosphoric acid compound in the presence of an org. carboxylic acid compound. CONSTITUTION:Needlelike alpha-FeOOH is formed by a reaction in an acidic aqueous soln., separated by filtration, and washed in water. The washed alpha-FeOOH is dispersed in water at about 10-250g/l concn. in the presence of an org. carboxylic acid compound to prepare a slurry of 1-6pH. Citric acid, tartaric acid, maleic acid or the like is used as the org. carboxylic acid compound, and the amount of the compound is about 0.1-4wt% basing on the amount of the alpha- FeOOH. By adding a phosphoric acid compound such as o-phosphoric acid to the slurry by about 0.05-0.8wt% basing on the amount of the alpha-FeOOH, the surface of the alpha-FeOOH is coated with the phosphorus component. |
