JPS6332243B

PURPOSE:To improve grain size distribution and grain shapliness by a method wherein the pH value is held at a specified level during a period from before the completion of generation reaction of an alpha-FeOOH core crystal to the completion of growth reaction thereof. CONSTITUTION:A ferrous salt sol...

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Bibliographic Details
Main Authors AMAMOTO TARO, ISHIKAWA TSUNEO, OGASAWARA MAKOTO, NAKADA KAZUO, KAWAMURA TOSHIHIKO
Format Patent
LanguageEnglish
Published 29.06.1988
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
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Summary:PURPOSE:To improve grain size distribution and grain shapliness by a method wherein the pH value is held at a specified level during a period from before the completion of generation reaction of an alpha-FeOOH core crystal to the completion of growth reaction thereof. CONSTITUTION:A ferrous salt solution is partially neutralized with alkali to allow a part of the Fe content to be formed into a core crystal of alpha-FeOOH. The pH value at the beginning of this core crystal generation reaction is ca. 3. An addition amount of alkali is selected at a level necessary to precipitate Fe ions of 5-25g/l, and the resultant pH value is raised up to ca. 8. Then, an oxidizer is introduced to translate the precipitate of hydrooxide into a core crystal of alpha-FeOOH. During this period the pH value is lowered gradually, but it is adjusted to locate within a range of 4.5-5.5. The reaction temperature and reaction time are normally adjusted to be in a range of 35-85 deg.C and 10-100min, respectively. Next, afterthe core crystal generation reaction the solution of pH 4.5-5.5 is oxidized while beind added with alkali so as to grow the core crystal. From the beginning to the completion this growth reaction is performed under adjustment of both neutralization and oxidizing speed, so that the pH value is held in a range of 4.5-5.5.
Bibliography:Application Number: JP19810159066