Patents by Inventor Marshall D. Ledbetter

Marshall D. Ledbetter 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 highly birefringent film
    Patent number: 5474730
    Abstract: A thin, biaxially oriented polyester film which is asymetrically oriented by stretching 1-2 times in the machine direction and about 3-5 times in the transverse direction in the plane of the film is disclosed. The film has a birefringence of at least 0.085, an optical retardation of at least 9000 nanometers and a shrinkage of less than 2% in any direction at 150.degree. C. The film produced is substantially free of color fringes when viewed in partially polarized light. There are also disclosed two processes for the production of said film.
    Type: Grant
    Filed: June 9, 1993
    Date of Patent: December 12, 1995
    Assignee: Hoechst Celanese Corporation
    Inventors: Stephen J. Gust, Gregory W. Farell, Marshall D. Ledbetter