Patents by Inventor Kiyoaki Tokunaga

Kiyoaki Tokunaga 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: 4332930
    Abstract: Undesirable deposition of polyoxymethylene onto the inner wall of a polymerization vessel and onto a stirrer, which deposition is observed in the slurry polymerization of formaldehyde carried out in an inert organic liquid medium in the presence of a polymerization catalyst, can be minimized by carrying out the slurry polymerization in the presence of at least one polyvalent metal salt selected from polyvalent metal salts of alkylsalicylic acids and polyvalent metal salts of dialkyl esters of sulfosuccinic acid. Optionally, a polyethylene glycol monoether may be used in addition to the polyvalent metal salt.
    Type: Grant
    Filed: August 22, 1980
    Date of Patent: June 1, 1982
    Assignee: UBE Industries, Ltd.
    Inventors: Takami Ishii, Naohisa Takikawa, Kiyoaki Tokunaga, Nobuhiro Ogawa
  • Patent number: 4035338
    Abstract: A method of stabilizing oxymethylene copolymers which comprises heating an oxymethylene copolymer in a hydrocarbonaceous mixed medium consisting of about 50 - 92% by weight of a hydrocarbon having 5 - 7 carbon atoms, about 6 - 48% by weight of an alcohol and about 2 - 20% by weight of water based on the total amount of the medium, at a temperature of from about 100.degree. to about 170.degree. C. in the presence of a salt selected from the group consisting of the sodium and potassium salts of ethylenediaminetetraacetic acid under the conditions of a pH value of from about 4 to about 7.
    Type: Grant
    Filed: June 17, 1975
    Date of Patent: July 12, 1977
    Assignee: UBE Industries, Ltd.
    Inventors: Takami Ishii, Taro Suzuki, Naohisa Takikawa, Kiyoaki Tokunaga, Choji Arima, Hiroshi Kojima