Patents by Inventor David L. K. Wang

David L. K. Wang 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).

  • Sequential bleaching of de-inked paper pulp with sodium bisulfite, dithionite and borohydride
    Patent number: 5562803
    Abstract: Paper pulp, especially recycled paper pulp which has been deinked, is bleached in a synergistic two-stage process first with sodium bisulfite and then with sodium borohydride. The borohydride is preferably added in an aqueous mixture with sodium hydroxide. A weak acid such as acetic acid may be added to the pulp to advance further the brightness gain.
    Type: Grant
    Filed: November 18, 1994
    Date of Patent: October 8, 1996
    Assignee: Morton International, Inc.
    Inventors: David L. K. Wang, Patrick Meyers