Patents by Inventor Hirohiko Nakahara

Hirohiko Nakahara 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: 5905130
    Abstract: Disclosed is a process for the production of a polysilazane containing Si--N linkages in the main chain thereof. According to the present invention, the polysilazane is produced by reacting a polyaminosilane compound with a polyhydrogenated nitrogen-containing compound in the presence of a basic catalyst or by reacting a polyhydrogenated silicon compound with a polyhydrogenated nitrogen-containing compound in the presence of a basic solid oxide catalyst.
    Type: Grant
    Filed: August 25, 1997
    Date of Patent: May 18, 1999
    Assignee: Tonen Corporation
    Inventors: Hirohiko Nakahara, Osamu Funayama, Takeshi Isoda
  • Patent number: 5459114
    Abstract: Repetition of a process of impregnating a metal fiber or ceramic fiber preform or porous ceramic with (3) a mixture of polysilazane-type polymers with a number average molecular weight of 200-3000 and a viscosity adjusted to 100 Pa.s or lower at the impregnation temperature, prepared by mixing (1) one or more types of polysilazane-type polymers with a number average molecular weight of 200-3000 and a viscosity of less than 1 Pa.s at the impregnation temperature with (2) one or more types of polysilazane-type polymers with a number average molecular weight of 200-100,000 and having a viscosity of 1 Pa.s or higher or solid at the impregnation temperature, which are selected from polysilazanes whose main repeating unit is --[(SiH.sub.2).sub.n (NH).sub.r ]-- (where n and r are 1, 2 or 3), and copolymers, modified polymers and crosslinked polymers based thereon, and performing crosslinking curing and then firing, is performed for its conversion into a ceramic.
    Type: Grant
    Filed: July 25, 1994
    Date of Patent: October 17, 1995
    Assignee: Tonen Corporation
    Inventors: Hiroshi Kaya, Kiyoshi Sato, Hiroki Morozumi, Atushi Tezuka, Tomoko Aoki, Hirohiko Nakahara, Tadashi Suzuki, Takeshi Isoda
  • Patent number: 5436398
    Abstract: A preceramic polymetalosilazane substantially free of Si-O groups is produced by reacting a polysilazane with a metal alkoxide in the presence of an alkylsilazane or alkylsilane. The preceramic polymer gives a high strength and heat resistant ceramic body which remains amorphous when calcined at 1,600.degree. C. for 10 hours in the atmosphere of nitrogen.
    Type: Grant
    Filed: April 6, 1994
    Date of Patent: July 25, 1995
    Assignee: Tonen Corporation
    Inventors: Yasuo Shimizu, Hirohiko Nakahara, Tomoko Aoki, Osamu Funayama, Takeshi Isoda