Patents Assigned to Nippon Bengara Kogyo Co., Ltd.
  • Patent number: 7390424
    Abstract: A ferrite magnetic powder for bonded magnets bonded using a rubber-base resin as binder, which powder is a ferrite magnetic powder containing an alkaline earth metal and having a chlorine content of 0.05 wt % or less and a powder pH of less than 6. The magnetic powder is produced by pulverizing a calcinated product of ferrite composition containing an alkali earth metal, annealing the pulverized ferrite composition to relieve crystal strain, dispersing the annealed powder in water and adding to it a mineral acid, adding a dispersant thereto, and subjecting the dispersion to solid-liquid separation followed by vacuum drying to obtain a ferrite magnetic powder having a chlorine content of 0.05 wt % or less and a powder pH of less than 6.
    Type: Grant
    Filed: February 13, 2004
    Date of Patent: June 24, 2008
    Assignees: Dowa Electronics Materials Co., Ltd., Nippon Bengara Kogyo Co., Ltd.
    Inventors: Masayasu Senda, Shinichi Suenaga, Hideki Katayama
  • Patent number: 7384571
    Abstract: A ferrite magnetic powder for bond magnet that experiences only small decrease in coercivity when molded into a bond magnet is provided, which is a ferrite magnetic powder that includes an alkaline-earth metal constituent and exhibits a decrease in coercivity of not greater than 600 Oe when subjected to a prescribed molding test. The magnetic powder can be obtained by mixing a fine ferrite powder of an average particle diameter of greater than 0.50 to 1.0 ?m and a coarse ferrite powder of an average particle diameter of greater than 2.50 to 5.0 ?m at ratio to incorporate the fine powder at a content ratio of 15-40 wt %.
    Type: Grant
    Filed: February 6, 2007
    Date of Patent: June 10, 2008
    Assignees: Dowa Electronics Materials Co., Ltd., Nippon Bengara Kogyo Co., Ltd.
    Inventors: Masayasu Senda, Shinichi Suenaga, Keisuke Ayabe, Toshiyuki Sakai