METHOD OF MANUFACTURING NEEDLE-LIKE ALPHA-FEOOH FOR MAGNETIC RECODING MATERIAL,申请号JP19810159066-传众专利搜索

METHOD OF MANUFACTURING NEEDLE-LIKE ALPHA-FEOOH FOR MAGNETIC RECODING MATERIAL

申请公布号：JPS5860505(A)

申请号：JP19810159066

申请日期：1981.10.06

申请公布日期：1983.04.11

申请人：

ISHIHARA SANGYO KK

发明人：NAKADA KAZUO;ISHIKAWA TSUNEO;OGASAWARA MAKOTO;AMAMOTO TAROU;KAWAMURA TOSHIHIKO

分类号：C01G49/02;C09D5/23;C09D7/12;G11B5/706;H01F1/11

主分类号：C01G49/02

摘要：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.