Patents by Inventor Stuart Michael Heppell

Stuart Michael Heppell 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).

  • Production of dicarboxylic acids
    Patent number: 5886057
    Abstract: Dicarboxylic acids or esters thereof are recovered from solid phase polyester materials, such as post-consumer products and factory scrap, by subjecting the polyester to at least two hydrolysis stages in at least the first of which the amount of water used is substantially less than needed to effect total conversion of the polyester to the dicarboxylic acid. Also the diol content is controlled in the course of carrying out the hydrolysis. The hydrolysis reactions may be preceded by reaction of the polyester with a diol, the resulting depolymerisation products then being hydrolysed.
    Type: Grant
    Filed: January 4, 1996
    Date of Patent: March 23, 1999
    Assignee: E. I. du Pont de Nemours and Company
    Inventors: James Lumsden Harvie, Stuart Michael Heppell