Patents by Inventor Pia Hellstrom

Pia Hellstrom 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).

  • Method of bleaching
    Patent number: 5188814
    Abstract: The invention concerns a method of bleaching particles containing calcium carbonate by keeping them in contact with an aqueous solution containing hydrogen peroxide and having a pH-value below 8.
    Type: Grant
    Filed: October 28, 1991
    Date of Patent: February 23, 1993
    Assignees: Eka Nobel AB, Faxe Kalk
    Inventors: Pia Hellstrom, Ivan Dalin, Steen Linderstrom-Lang