Patents by Inventor Keiichiro Ishikawa

Keiichiro Ishikawa 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).

  • Curing agents for epoxy resins
    Patent number: 6433042
    Abstract: A curing agent for epoxy resin which comprises at least one selected from the compound of the formula (1) and its salt, as an effective component wherein X is —(CH2)n- or —(CH2)1-Y—(CH2)m- , Y is —N(R1)—, —O— or —S—, R1 is alkyl having 1 to 8 carbon atoms or amino. n is a number of 2, 3, 5 to 11, 1 and m are each a number of 1 to 8.
    Type: Grant
    Filed: February 5, 2001
    Date of Patent: August 13, 2002
    Assignee: Otsuka Kagaku Kabushiki Kaisha
    Inventors: Yoshihisa Tomotaki, Takashi Kitajima, Keiichiro Ishikawa, Akihiro Nabeshima, Tomohiro Furuichi
  • Aqueous solution of water-soluble epoxy resin, solid obtained therefrom, and processes for producing these
    Patent number: 6372825
    Abstract: The present invention provides an aqueous solution of an epoxy resin and a solid thereof, which is obtained by the following manner that an epoxy compound or a solution of the epoxy compound in organic solvent, and an amine compound of the formula (1), an aqueous solution thereof, a solution of the amine compound in organic solvent, or a solution thereof in a mixture of water and organic solvent, are mixed together so that the epoxy compound and the amine compound are reacted or polymerized to obtain a solution of an epoxy resin, to which water is added and heated to remove the organic solvent and unreacted amine compound, and a process for preparing the same NH2N(R1)(R2)  (1) wherein R1 and R2 are the same or different and each is alkyl having 1 to 6 carbon atoms, alkylene having 2 to 11 carbon atoms or a group represented by —R3—N(R4)—R5— which are formed when both are bonded, R3 and R5 are the same or different and each is alkylene having 1 to 6 carbon atoms, and R4 is a
    Type: Grant
    Filed: May 9, 2000
    Date of Patent: April 16, 2002
    Assignee: Otsuka Kagaku Kabushiki Kaisha
    Inventors: Yoshihisa Tomotaki, Takashi Kitajima, Keiichiro Ishikawa, Akihiro Nabeshima, Tomohiro Furuichi
  • 1-Aminopyrrolidine or its salt as epoxy resin hardener
    Patent number: 6359036
    Abstract: A curing agent for epoxy resin which comprises at least one selected from 1-aminopyrrolidine and its salt.
    Type: Grant
    Filed: December 1, 1999
    Date of Patent: March 19, 2002
    Assignee: Otsuka Kagaku Kabushiki Kaisha
    Inventors: Yoshihisa Tomotaki, Takashi Kitajima, Keiichiro Ishikawa, Akihiro Nabeshima, Tomohiro Furuichi
  • Process for producing 1-aminopyrrolidine, and 1-aminopyrrolidine according to the process
    Patent number: 5981764
    Abstract: 1-Aminopyrrolidine which is obtained by reacting hydrazine hydrate with a compound represented by the following formula (I):X.sup.1 --C.sub.4 H.sub.8 --X.sup.2 (I)wherein X.sup.1 and X.sup.2 are the same or different, and each represents a leaving group, in methanol; and a process for producing 1-aminopyrrolidine, comprising the step of reacting hydrazine hydrate with the above compound represented by formula (I) in methanol.
    Type: Grant
    Filed: July 24, 1998
    Date of Patent: November 9, 1999
    Assignee: Otsuka Chemical Co., Ltd.
    Inventors: Tsukasa Maekawa, Yoshihisa Tomotaki, Keiichiro Ishikawa, Akihiro Nabeshima, Tomohiro Furuichi
  • Method for producing electrolytic manganese dioxide
    Patent number: 4405419
    Abstract: A method for producing electrolytic manganese dioxide is disclosed, comprising the electrolysis of a slurry of particles of manganese oxides in an aqueous solution of manganese sulfate. The concentration of the particles of manganese oxides is 0.01 to 0.4 grams per liter of the solution.
    Type: Grant
    Filed: July 12, 1980
    Date of Patent: September 20, 1983
    Assignee: Japan Metal and Chemical Co., Ltd.
    Inventors: Masatoshi Misawa, Kusuhiko Takahashi, Kinnosuke Okuda, Kiyoshi Matsuura, Hisao Takehara, Keiichiro Ishikawa