Patents by Inventor Hidemi Takemoto

Hidemi Takemoto 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).

  • Method for producing an aromatic polycarbonate and method of keeping raw materials thereof
    Patent number: 6605686
    Abstract: An aromatic polycarbonate having excellent color is obtained by keeping an aromatic dihydroxy compound and a carbonic acid diester which are raw materials for the production of an aromatic polycarbonate in consideration of the influences of storage atmosphere, temperature, temperature difference from a storage tank and residence time.
    Type: Grant
    Filed: March 15, 2002
    Date of Patent: August 12, 2003
    Assignee: Teijin Limited
    Inventors: Hidemi Takemoto, Toru Sawaki, Keiichi Kaneko, Katsushi Sasaki
  • Process for producing a polycarbonate and method of cleaning a production unit
    Patent number: 6525171
    Abstract: A method of cleaning the aromatic polycarbonate production unit with a carbonic acid diaryl ester at a temperature of 200 to 350° C. in an inert gas atmosphere.
    Type: Grant
    Filed: October 4, 2001
    Date of Patent: February 25, 2003
    Assignee: Teijin Limited
    Inventors: Hidemi Takemoto, Toru Sawaki, Katsushi Sasaki, Keiichi Kaneko
  • Process for producing aromati polycarbonate and method of storing raw materials therefor
    Publication number: 20020183477
    Abstract: An aromatic polycarbonate having excellent color is obtained by keeping an aromatic dihydroxy compound and a carbonic acid diester which are raw materials for the production of an aromatic polycarbonate in consideration of the influences of storage atmosphere, temperature, temperature difference from a storage tank and residence time.
    Type: Application
    Filed: March 15, 2002
    Publication date: December 5, 2002
    Inventors: Hidemi Takemoto, Toru Sawaki, Keiichi Kaneko, Katsushi Sasaki
  • Process for producing a polycarbonate and method of cleaning a production unit
    Publication number: 20020052467
    Abstract: A method of cleaning the aromatic polycarbonate production unit with a carbonic acid diaryl ester at a temperature of 200 to 350° C. in an inert gas atmosphere.
    Type: Application
    Filed: October 4, 2001
    Publication date: May 2, 2002
    Applicant: TEIJIN LIMITED
    Inventors: Hidemi Takemoto, Toru Sawaki, Katsushi Sasaki, Keiichi Kaneko
  • Carbonic acid diester, aromatic polycarbonate and facilities, and preparation thereof
    Patent number: 6323302
    Abstract: Aromatic polycarbonate having a reduced discoloration and improved heat stability, hue, etc. is provided by keeping a pressure in a raw material melting vessel and the linear velocity of a gas in a transporting piping in a specific range, keeping the concentration of a nitrogen-containing basic compound in a specific range, recycling a byproduct containing specific amounts of impurities, suppressing the amounts of a nitrogen-containing basic compound, metallic elements and a silicic acid derivative in the carbonic acid diester at specific values or less, prescribing the material quality of the reaction facilities, and/or forming an oxide layer at the inner wall surfaces of the reaction facilities.
    Type: Grant
    Filed: December 14, 1999
    Date of Patent: November 27, 2001
    Assignee: Teijin Limited
    Inventors: Katsushi Sasaki, Wataru Funakoshi, Toru Sawaki, Masumi Hirata, Hiroaki Kaneko, Masanori Abe, Masasi Simonaru, Hidemi Takemoto, Jyuhou Matsuo, Yoshiki Matsuoka
  • Process for the preparation of aromatic polycarbonate
    Patent number: 6265524
    Abstract: A process for producing an aromatic polycarbonate through an ester interchange reaction between an aromatic carbonic acid diester and an aromatic dihydroxy compound, wherein the aromatic carbonic acid diester is obtained through the decarbonylation reaction of an aromatic oxalic acid diester represented by the following general formula (1): wherein two Ar's are the same or different aromatic hydrocarbon groups having 6 to 14 carbon atoms, and has a hydrolyzable halogen content of 5 ppm or less. According to the present invention, an aromatic polycarbonate having a high molecular weight and excellent color can be easily produced without impairing ester interchange reactivity for the production of the aromatic polycarbonate by using an aromatic carbonic acid diester obtained through the decarbonylation of an aromatic oxalic acid diester and controlling the amount of hydrolyzable halogen contained in the aromatic carbonic acid diester to a value smaller than a predetermined value.
    Type: Grant
    Filed: November 22, 1999
    Date of Patent: July 24, 2001
    Assignees: Teijin Limited, UBE Industries, Ltd.
    Inventors: Hidemi Takemoto, Toru Sawaki, Katsushi Sasaki