JPS639735B

• Main Authors: AMAMOTO TARO, ISHIKAWA TSUNEO, OGASAWARA MAKOTO, NAKADA KAZUO, KAWAMURA TOSHIHIKO
• Format: Patent
• Language: English
• Published: 01.03.1988
• Subjects: ADHESIVES; BASIC ELECTRIC ELEMENTS; CHEMICAL PAINT OR INK REMOVERS; CHEMISTRY; COATING COMPOSITIONS, e.g. PAINTS, VARNISHES ORLACQUERS; COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSESC01D OR C01F; CORRECTING FLUIDS; DYES; ELECTRICITY; FILLING PASTES; INDUCTANCES; INFORMATION STORAGE; INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORDCARRIER AND TRANSDUCER; INKS; INORGANIC CHEMISTRY; MAGNETS; METALLURGY; MISCELLANEOUS APPLICATIONS OF MATERIALS; MISCELLANEOUS COMPOSITIONS; NATURAL RESINS; PAINTS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; PHYSICS; POLISHES; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES; TRANSFORMERS; USE OF MATERIALS THEREFOR; WOODSTAINS

PURPOSE:To improve acicularity, particle size distribution and so forth, by obtaining acicular alpha-FeOOH in such a manner that an aqueous ferrous salt solution is partially neutralized and oxidized to form alpha-FeOOH core crystals, which are then grown on oxidation. CONSTITUTION:First, an aqueous ferrous salt solution is partially neutralized with an alkali and oxidized to form a part of the Fe content in the solution into alpha-FeOOH core crystals. The solution having completed the core crystal forming reaction is an aqueous ferrous salt solution having the alpha-FeOOH core crystals suspending therein. The core crystals are grown on oxidation by adding an alkali in the presence of phosphorus acid or phosphite to obtain a desired alpha- FeOOH. Thus, the obtained alpha-FeOOH is corpuscular and therefore has a sharp particle size distribution, with less branching, and has an axial ratio of 10- 18. Accordingly, it is made possible to improve acicularity, particle size distribution and so forth.