Patents by Inventor Sadafumi Iijima

Sadafumi Iijima 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: 7601395
    Abstract: A high recording density magnetic recording medium and a manufacturing method therefor are provided. The dilution stability during preparation of magnetic paint is improved and, thereby, even when the magnetic paint concentration is lowered, no problem occurs with the surface roughness and the output of the thin magnetic layer. The magnetic recording medium includes at least a magnetic layer on one surface of a non-magnetic support, wherein the magnetic layer contains a magnetic powder, a vinyl chloride resin having a degree of polymerization of at least 270 and an aliphatic polyester polyurethane resin to serve as binder resins, an aromatic compound having a substituent R (where R is —COOH, —(COOH)2, —OPO(OH)2, —PO(OH)2, or —SO3H), and a phosphoric acid ester. The ratio of binder resins in the magnetic paint is set at 2.0 percent by weight or less relative to a total sum of the binder resins and a solvent.
    Type: Grant
    Filed: January 11, 2005
    Date of Patent: October 13, 2009
    Assignee: TDK Corporation
    Inventors: Takayoshi Kuwajima, Sadafumi Iijima
  • Publication number: 20060210839
    Abstract: A magnetic recording medium which makes it possible to further increase the recording capacity while maintaining a required flexibility thereof. A magnetic tape has a lower non-magnetic layer and a magnetic layer formed on one surface of a base film in the mentioned order. The lower non-magnetic layer is formed of a non-magnetic coating material containing a non-magnetic powder, an electron beam curing binder, a dispersant having an amine group, and a thermosetting agent.
    Type: Application
    Filed: March 14, 2006
    Publication date: September 21, 2006
    Applicant: TDK Corporation
    Inventors: Tsutomu Ide, Katsuhiko Yamazaki, Tomoyuki Kotaki, Sadafumi Iijima
  • Patent number: 7090936
    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 ?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 ?m or less.
    Type: Grant
    Filed: March 27, 2003
    Date of Patent: August 15, 2006
    Assignee: TDK Corporation
    Inventors: Kenichi Kitamura, Takayoshi Kuwajima, Sadafumi Iijima
  • Patent number: 6777061
    Abstract: The present invention provides a high recording density magnetic recording medium with improved dropout and excellent surface smoothness and electromagnetic conversion characteristics, as well as a process for producing such a medium. A magnetic recording medium comprising a lower non-magnetic layer containing at least a non-magnetic powder and a binder resin on one surface of a non-magnetic support, an upper magnetic layer containing at least a ferromagnetic powder and a binder resin on said lower non-magnetic layer, and a back coat layer on an opposite surface of said non-magnetic support, wherein said lower non-magnetic layer contains an acicular powder of hydrated iron oxide as the non-magnetic powder, said ferromagnetic powder has an average long axial length of 0.1 &mgr;m or less, and said upper magnetic layer has a surface roughness (center line average roughness: Ra) of 2.4 nm or less. After curing the lower non-magnetic layer, the magnetic layer is applied and formed.
    Type: Grant
    Filed: March 27, 2003
    Date of Patent: August 17, 2004
    Assignee: TDK Corporation
    Inventors: Kenichi Kitamura, Takayoshi Kuwajima, Sadafumi Iijima
  • Publication number: 20040023067
    Abstract: The present invention provides a high recording density magnetic recording medium with improved dropout and excellent surface smoothness and electromagnetic conversion characteristics, as well as a process for producing such a medium. A magnetic recording medium comprising a lower non-magnetic layer containing at least a non-magnetic powder and a binder resin on one surface of a non-magnetic support, an upper magnetic layer containing at least a ferromagnetic powder and a binder resin on said lower non-magnetic layer, and a back coat layer on an opposite surface of said non-magnetic support, wherein said lower non-magnetic layer contains an acicular powder of hydrated iron oxide as the non-magnetic powder, said ferromagnetic powder has an average long axial length of 0.1 &mgr;m or less, and said upper magnetic layer has a surface roughness (center line average roughness: Ra) of 2.4 nm or less. After curing the lower non-magnetic layer, the magnetic layer is applied and formed.
    Type: Application
    Filed: March 27, 2003
    Publication date: February 5, 2004
    Inventors: Kenichi Kitamura, Takayoshi Kuwajima, Sadafumi Iijima
  • 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: 5510179
    Abstract: A magnetic recording medium has at least two coating layers on a non-magnetic substrate. The uppermost layer of the coating layers is a magnetic layer having a thickness of 0.2-0.5 .mu.m thick and comprising a ferromagnetic powder, inorganic material-containing alumina particles having a mean particle size of 0.1-0.3 .mu.m, and a binder. The medium ensures effective head cleaning and has improved durability and still life.
    Type: Grant
    Filed: December 22, 1994
    Date of Patent: April 23, 1996
    Assignee: TDK Corporation
    Inventors: Kiyoto Fukushima, Sadafumi Iijima, Motoyuki Tsunoda