Patents by Inventor Takayoshi Kuwajima

Takayoshi Kuwajima 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).

  • Publication number: 20040005479
    Abstract: The present invention provides a high recording density magnetic recording medium with excellent surface smoothness, as well as excellent electromagnetic conversion characteristics and durability. A magnetic recording medium comprising a lower non-magnetic layer containing at least a non-magnetic powder and a binder resin on a non-magnetic support, and an upper magnetic layer with a thickness of 0.2 &mgr;m or less on said lower non-magnetic layer, wherein said lower non-magnetic layer contains an acicular powder of hydrated iron oxide as the non-magnetic powder, and said lower non-magnetic layer contains a fatty acid and a fatty acid amide. Preferably the acicular powder of hydrated iron oxide is goethite with an average long axial length of 0.15 &mgr;m or less.
    Type: Application
    Filed: March 27, 2003
    Publication date: January 8, 2004
    Inventors: Kenichi Kitamura, Takayoshi Kuwajima, Sadafumi Iijima
  • Patent number: 6127039
    Abstract: A magnetic recording medium comprising a non-magnetic base having on at least one side a non-magnetic layer (undercoat) containing electron beam-curable resins which in turn is over-laid with a magnetic layer (topcoat) containing an iron (Fe) based magnetic powder, said magnetic layer having a glass transition temperature (Tg) of at least 65.degree. C. and said non-magnetic layer being an electron beam cured coating that is formed by coating the non-magnetic base with a non-magnetic coating mix containing electron beam curable resins, the yet to be cured coating having a glass transition temperature (Tg) of 30-53.degree. C. and said electron beam curable resins comprising an electron beam curable vinyl chloride based resin having a sulfur-containing polar group and an electron beam curable urethane resin having a phosphorus-containing polar group.
    Type: Grant
    Filed: January 22, 1999
    Date of Patent: October 3, 2000
    Assignee: TDK Corporation
    Inventors: Akira Saitoh, Akihiko Seki, Takayoshi Kuwajima, Satoru Tsuchida
  • Patent number: 5792548
    Abstract: A magnetic recording medium having an intermediate layer excellent in conductivity, surface properties and strength, and excellent in electromagnetic characteristics, physical properties, etc., which comprises a non-magnetic intermediate layer having a thickness of 0.5 .mu.m to 3.0 .mu.m formed on at least one surface of a non-magnetic support, and a magnetic layer formed on the intermediate layer, the magnetic layer being mainly composed of a ferromagnetic powder and a binder and having a thickness of 0.1 .mu.m to 0.5 .mu.m, in which said magnetic layer is formed on the intermediate layer at least in a dry state, and the intermediate layer comprises(A) an inorganic material having an average particle size of 10 nm to 50 nm and a Mohs' hardness of 7 or less,(B) an inorganic material having an average particle size of 100 nm to 500 nm and a Mohs' hardness of 9 or more,(C) carbon black,a lubricant and a binder.
    Type: Grant
    Filed: February 29, 1996
    Date of Patent: August 11, 1998
    Assignee: TDK Corporation
    Inventors: Takayoshi Kuwajima, Tsunehiko Ikarashi, Yuko Motegi
  • Patent number: 5698286
    Abstract: A magnetic layer is provided on a nonmagnetic base with a non-ferromagnetic layer interposed between them. Non-ferromagnetic particulate iron oxide is incorporated in the non-ferromagnetic layer. In addition to, or in place of, this iron oxide, non-structural carbon having a mean particle diameter of 10 to 60 nm, a specific surface area of 150 m2/g as measured by the BET method and a DBP oil absorption of 100 ml/100 g or less may be used. This makes it possible to achieve a magnetic recording medium having excellent surface properties and good-enough electromagnetic transducing characteristics.
    Type: Grant
    Filed: September 25, 1996
    Date of Patent: December 16, 1997
    Assignee: TDK Corporation
    Inventors: Tsunehiko Ikarashi, Yasufumi Takasugi, Tsutomu Aoyama, Akira Saitoh, Yuko Motegi, Takayoshi Kuwajima
  • Patent number: 5688591
    Abstract: A magnetic recording medium has a magnetic layer on a non-magnetic substrate. The magnetic layer contains ferromagnetic powder dispersed in a binder and a lubricant which is an unsaturated fatty acid diester of a dihydric alcohol and an unsaturated fatty acid, preferably a C.sub.2-6 dihydric alcohol and a C.sub.14-24 unsaturated fatty acid, typically neopentyl glycol dioleate. The lubricant remains effective in low-temperature, high-temperature, and thermal cycling environments without bleed-out. The medium is low in rotational torque, abrasion resistant and durable.
    Type: Grant
    Filed: December 19, 1994
    Date of Patent: November 18, 1997
    Assignee: TDK Corporation
    Inventors: Takayoshi Kuwajima, Hideki Sasaki