| 摘要 |
PURPOSE:To obtain the titled compound suitable for use as starting material for magnetic powder for a magnetic recording medium by carring out reaction at a low temp. and growing crystals by heating when oxygen gas is blown in the alkali region and reacted with ferrous hydroxide or the like. CONSTITUTION:An aqueous soln. on a ferrous salt such as ferrous sulfate or ferrous chloride is reacted with a basic reagent such as caustic soda or sodium carbonate to precipitate ferrous hydroxide or slightly soluble ferrous salt, and an oxyge-contg. gas is blown in the alkali region to form alpha-iron oxyhydroxide. At this time, crystal nuclei of alpha-iron oxyhdroxide having unifrom grain size are formed at <40 deg.C low temp. as the 1st stage, and the liq. temp. is raised to 40-60 deg.C as the 2nd stage to grow alpha-iron oxyhydroxide crystals. Thus, alpha-iron oxyhydroxide of uniform grain size is obtd. It is suitable for use as starting material for iron oxide magnetic powder or metallic iron magnetic powder for a magnetic recording medium. |
