Patents by Inventor Takehisa Ohkawa

Takehisa Ohkawa 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: 4579780
    Abstract: A magnetic recording medium is provided which is assured of smoothly and stably running properties and is free of the so-called "squeal" phenomenon, especially in an environment of high temperature and high humidity. A highly viscous silicone oil having a viscosity of 100,000 or more is incorporated as a lubricating agent in the magnetic coating of the magnetic recording medium in an amount of 0.5 to 2% by weight based on binder. Such silicone oil is a dimethyl silicone oil having the following rational formula: ##STR1## where n is a number which determines a viscosity thereof.
    Type: Grant
    Filed: August 10, 1982
    Date of Patent: April 1, 1986
    Assignee: TDK Electronics Co., Ltd.
    Inventors: Kuniichi Shinomiya, Masahiro Takizawa, Takehisa Ohkawa
  • Patent number: 4436786
    Abstract: A magnetic recording medium is provided which has smooth and stable running performances and is free of "squeal" phenomenon, especially in an environment of high temperature and high humidity. A highly viscous silicone oil having a viscosity of 100,000 centistokes or more is incorporated in combination with a higher fatty having a melting point of 44.degree. C. or more into a magnetic coating layer of the magnetic recording medium. Such silicone oil is represented by the general formula: ##STR1## wherein R is CH.sub.3, R' is CH.sub.3, C.sub.6 H.sub.5 or F and n is a number which determines a viscosity thereof. Such higher fatty acid is selected from lauric acid, myristic acid, palmitic acid, stearic acid, arachic acid, behenic acid and the like.
    Type: Grant
    Filed: March 31, 1982
    Date of Patent: March 13, 1984
    Assignee: TDK Electronics Co., Ltd.
    Inventors: Takehisa Ohkawa, Kuniichi Yoda
  • Patent number: 4416948
    Abstract: A magnetic recording medium is provided which has smooth and stable running performances and is free of "squeal" phenomenon, especially in an environment of high temperature and high humidity. A highly viscous silicone oil having a viscosity of 100,000 centistokes or more is incorporated in combination with a higher fatty acid glycerine ester composed of a higher fatty acid having a melting point of 44.degree. C. or more and glycerine into a magnetic coating layer of the magnetic recording medium. Such silicone oil is represented by the general formula: ##STR1## wherein R is CH.sub.3, R' is CH.sub.3, C.sub.6 H.sub.5 or F and n is a number which determines a viscosity thereof. Such higher fatty glycerine ester is selected from monoglyceride of myristic acid, monoglyceride of palmitic acid, monoglyceride of stearic acid, monoglyceride of oleic acid and the like.
    Type: Grant
    Filed: March 31, 1982
    Date of Patent: November 22, 1983
    Assignee: TDK Electronics Co., Ltd.
    Inventors: Takehisa Ohkawa, Kuniichi Yoda
  • Patent number: 4416947
    Abstract: A magnetic recording medium is provided which has smooth and stable running performances and is free of "squeal" phenomenon, especially in an environment of high temperature and high humidity. A highly viscous silicone oil having a viscosity of 100,000 centistokes or more is incorporated in combination with a higher fatty acid ester composed of a higher fatty having a melting point of 44.degree. C. or more and a monohydric alcohol containing 3 to 8 carbon atoms into a magnetic coating layer of the magnetic recording medium. Such silicone oil is represented by the general formula: ##STR1## wherein R is CH.sub.3, R' is CH.sub.3, C.sub.6 H.sub.5 or F and n is a number which determines a viscosity thereof. Such higher fatty acid ester is selected from butyl myristate, butyl palmitate, propyl stearate, butyl stearate and the like.
    Type: Grant
    Filed: March 31, 1982
    Date of Patent: November 22, 1983
    Assignee: TDK Electronics Co. Ltd.
    Inventors: Kuniichi Yoda, Takehisa Ohkawa
  • Patent number: 4409300
    Abstract: A magnetic recording medium is provided which has smooth and stable running performances and is free of "squeal" phenomenon, especially in an environment of high temperature and high humidity. A highly viscous silicone oil having a viscosity of 100,000 centistokes or more is incorporated in combination with a sorbitan fatty acid ester into a magnetic coating layer of the magnetic recording medium. Such silicone oil is represented by the general formula: ##STR1## wherein R is CH.sub.3, R' is CH.sub.3, C.sub.6 H.sub.5 or F and n is a number which determines a viscosity thereof. Such sorbitan fatty acid ester is selected from sorbitan monopalmitate, sorbitan monostearate, sorbitan distearate, sorbitan tristearate, sorbitan monooleate and the like.
    Type: Grant
    Filed: March 31, 1982
    Date of Patent: October 11, 1983
    Assignee: TDK Electronics Co., Ltd.
    Inventors: Takehisa Ohkawa, Kuniichi Yoda
  • Patent number: 4400435
    Abstract: A magnetic recording medium comprises a substrate coated with a magnetic layer comprising a magnetic powder and a binder comprising an urethane resin and a vinyl chloride-vinyl acetate-maleic acid copolymer having a content of maleic acid component of at least 1.5%.
    Type: Grant
    Filed: July 15, 1981
    Date of Patent: August 23, 1983
    Assignee: TDK Electronics Co., Ltd.
    Inventors: Kuniichi Yoda, Takehisa Ohkawa, Hitoshi Azegami
  • Patent number: 4352859
    Abstract: A magnetic recording medium comprises a substrate coated with a magnetic layer comprising a magnetic powder and a binder comprising an urethane resin or a polyester and a vinyl chloride type copolymer of vinyl chloride-vinyl acetate-vinyl alcohol copolymer, vinyl chloride-vinyl acetate-maleic acid copolymer or vinyl chloride-vinylidene chloride copolymer having a polymerization degree of up to 300.
    Type: Grant
    Filed: July 20, 1981
    Date of Patent: October 5, 1982
    Assignee: TDK Electronics Co., Ltd.
    Inventors: Kuniichi Yoda, Takehisa Ohkawa, Hitoshi Azegami