| 摘要 |
PURPOSE:To obtain the titled compound used as starting material for magnetic powder for a magnetic recording medium by adding alpha-iron oxyhydroxide formed at a low temp. when oxygen gas is blown and reacted with ferrous hydroxide or the like at a specified temp. in the alkali region. CONSTITUTION:An aqueous soln. of 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 insoluble ferrous salt, and an oxygen-contg. gas is blown at 40-60 deg.C in the alkali region to form alpha-iron oxyhydroxide. At this time, alpha-iron oxyhydroxide of fine uniform particles obtd. by separately carrying out the above-mentioned alpha-iron oxyhydroxide forming reaction at <40 deg.C low temp. is added to the above-mentioned reaction system. 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. |
