Patents by Inventor Taro Amamoto

Taro Amamoto has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 4560544
    Abstract: A process for preparing acicular .alpha.-FeOOH by partially neutralizing and then oxidizing a ferrous salt solution in the presence of phosphoric acid or a salt thereof to form seed crystals of .alpha.-FeOOH and optionally further oxidizing said solution while neutralizing said solution with an alkali to grow said seed crystals, wherein pyrophosphoric acid or a salt thereof is used as said phosphoric acid and the seed crystals of .alpha.-FeOOH are formed at a temperature of 50.degree. to 100.degree. C. The .alpha.-FeOOH obtained according to the process of this invention is composed of fine particles and appreciably improved in acicularity and particle size distribution. Also, a magnetic recording medium made from the magnetic iron oxides derived therefrom in a usual way have a low noise characteristic and, are excellent in coercivity and other magnetic properties.
    Type: Grant
    Filed: December 10, 1984
    Date of Patent: December 24, 1985
    Assignee: Ishihara Sangyo Kaisha, Ltd.
    Inventors: Kazuo Nakata, Tsuneo Ishikawa, Taro Amamoto, Toshihiko Kawamura