Patents by Inventor Yosiro Okuda

Yosiro Okuda 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).

  • Spindle-like magnetic iron oxide particles and process for producing the same
    Patent number: 4873010
    Abstract: Disclosed herein are magnetic iron oxide particles comprising spindle-like magnetite or maghemite particles having an aspect ratio(major:minor) of less than 4:1 and containing 0.1 to 20 atomic % of Si to Fe, and a process for producing the same.
    Type: Grant
    Filed: April 15, 1987
    Date of Patent: October 10, 1989
    Assignee: Toda Kogyo Corp.
    Inventors: Atsushi Takedoi, Hiroyuki Kondo, Masaru Isoai, Yoshitaka Yoshinaga, Tosiharu Harada, Yosiro Okuda, Hiroshi Sumita, Hirofumi Kawasaki, Kohji Mori
  • Spindle ferromagnetic alloy particles
    Patent number: 4773931
    Abstract: Disclosed herein is spindle ferromagnetic alloy particles having the aspect ratio (major:minor) of less than 3:1 and the coercive force of 500 to 100 Oe, and containing 0.1 to 13 atomic % of Si to Fe, and a process for producing the same.
    Type: Grant
    Filed: January 23, 1987
    Date of Patent: September 27, 1988
    Assignee: Toda Kogyo Corp.
    Inventors: Akio Mishima, Yosiro Okuda, Hiroshi Sumita, Yoshitaka Yoshinaga, Akira Mukaizaka, Tokihiro Kurata
  • Process for producing acicular magnetite or acicular maghemite
    Patent number: 4495164
    Abstract: A process for producing acicular magnetite or maghemite of high axial ratio, which comprisespreparing an iron (II) hydroxide suspension at a pH of at least 11 with a magnesium sulfate or magnesium chloride in an amount of 0.5 to 7.0 atomic % based on the amount of the iron (II) hydroxide in the suspension and calculated as the ratio of Mg to Fe (II),oxidizing the resultant suspension with the oxygen-containing gas to form an acicular iron (III) oxide hydroxide in the form of particles having a long axis length of 0.3 to 2.0 .mu.m and an axial ratio of more than 20:1,reducing said acicular iron (III) oxide hydroxide into the acicular magnetite, and oxidizing the resultant acicular magnetite to form the acicular maghemite, if necessary.
    Type: Grant
    Filed: July 11, 1983
    Date of Patent: January 22, 1985
    Assignee: Toda Kogyo Corp.
    Inventors: Yosiro Okuda, Tosiharu Harada
  • Process for producing acicular ferromagnetic alloy particles and acicular ferromagnetic alloy particles obtained by the said process
    Patent number: 4406694
    Abstract: A process for producing an acicular ferromagnetic alloy particles mainly containing iron and magnesium, which comprises preparing a suspension of iron(II) hydroxide and water-soluble magnesium salt, the suspension having a pH value of at least 11 and containing the magnesium salt in an amount of 0.5 to 20.0 atomic % based on the amount of the iron(II) hydroxide in the suspension and calculated as the ratio of Mg to Fe(II), oxidizing the suspension with an oxygen-containing gas to form an acicular particles of iron(III) oxide hydroxide substituted with magnesium, forming coats of phosphorus compound and subsequent silicon compound on the acicular particles, heating the resultant particle at 500.degree. to 900.degree. C. under a non-reducing atmosphere and then reheating the particle thus treated at 350.degree. to 600.degree. C. under reducing atmosphere.
    Type: Grant
    Filed: July 23, 1981
    Date of Patent: September 27, 1983
    Assignee: Toda Kogyo Corp.
    Inventors: Akio Mishima, Yosiro Okuda, Tosiharu Harada, Akira Mukaizaka
  • Production of acicular magnetic iron oxides
    Patent number: 4136158
    Abstract: In the production of acicular ferromagnetic iron oxide of highly uniform particle size by oxidizing an iron (II) hydroxide suspension at a pH of at least 11 with an oxygen-containing gas to form acicular iron (III) oxide hydroxide, reducing and optionally further reoxidizing this into ferromagnetic iron oxide, the improvement which comprises providing the iron (II) hydroxide suspension with a water-soluble silicate in an amount of less than 1.7% by atom based on the amount of the iron (II) hydroxide in the suspension and calculated as the ratio of Si to Fe (II) while prior to the oxidation of the suspension with the oxygen-containing gas.
    Type: Grant
    Filed: November 1, 1977
    Date of Patent: January 23, 1979
    Assignee: Toda Kogyo Corp.
    Inventors: Yosiro Okuda, Nanao Horiishi, Hiroshi Sumita, Tosiharu Harada