Patents by Inventor Kin-ichi Shirakawa

Kin-ichi Shirakawa 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).

  • Paperboard impregnated with polyurethane resin
    Patent number: 3953169
    Abstract: A paperboard impregnated with polyurethane resin having specific NCO content and average molecular weight at the rate of 0.05 to 5.0 weight percent relative to the paperboard has excellent mechanical properties such as compressive strength, tensile strength, tearing strength, folding endurance, etc., even in wet state.
    Type: Grant
    Filed: September 5, 1974
    Date of Patent: April 27, 1976
    Assignee: Takeda Chemical Ind., Ltd.
    Inventors: Seiichi Igarashi, Kin-ichi Shirakawa, Kazuo Kimura, Akira Ogino