Patents by Inventor Kojima Yasunobu

Kojima Yasunobu 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).

  • Process for the production of polytetrafluoroethylene porous membranes
    Patent number: 4710331
    Abstract: A process for the production of PTFE porous membranes is provided wherein a PTFE preform is prepared by compression molding a PTFE molding powder of 1-90 .mu.m obtained by suspension polymerization of tetrafluoroethylene, the preform is sintered at a temperature above 327.degree. C., followed by skiving the heated preform into a film form. The thus-obtained film is heat treated at a temperature above 327.degree. C., the heat treated film is slowly cooled at a cooling rate of less than 70.degree. C./hr so as to adjust the crystallinity of PTFE in the sintered film to 60-75% and the film is stretched either uniaxially or biaxially to 1.3 to 6.5 times while heating at a temperature of 100.degree.-320.degree. C.
    Type: Grant
    Filed: May 15, 1986
    Date of Patent: December 1, 1987
    Assignee: Nippon Valqua Kogyo Kabushiki Kaisha
    Inventors: Kawahigashi Nobuo, Hashida Shigesou, Kojima Yasunobu