Patents by Inventor Fritz Hedborg

Fritz Hedborg 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).

  • Paper production
    Patent number: 4911790
    Abstract: The present invention relates to a process for obtaining retention of the manufacture of paper, whereby one adds a cationic, high polymer polysaccharide at the preparation of a stock of paper pulp; that one adds an anionic aluminium compound, or a combination of an aluminium salt and an alkali or an acid to the formation in situ of such an anionic aluminium compound immediately prior to the head box, whereby pH immediately prior to the head box is kept at pH 7 to 8.
    Type: Grant
    Filed: January 6, 1988
    Date of Patent: March 27, 1990
    Assignee: STFI
    Inventors: Tom Lindstrom, Hans Hallgren, Fritz Hedborg