Patents by Inventor Norman A. Lefevre

Norman A. Lefevre 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).

  • Process for preparing copolymers of alpha-methylstyrene and acrylonitrile
    Patent number: 4972032
    Abstract: Copolymers of .alpha.-methylstyrene and acrylonitrile having improved composition of uniformity are prepared by emulsion polymerizing a first monomer stream having a weight ratio of .alpha.-methylstyrene/acrylonitrile from about 75/25 to about 85/15 and thereafter polymerizing a second monomer feed stream comprising acrylonitrile.
    Type: Grant
    Filed: July 19, 1989
    Date of Patent: November 20, 1990
    Assignee: The Dow Chemical Company
    Inventors: David E. Henton, Robert P. Dion, Norman A. Lefevre
  • Method for shear coagulation of latex resins
    Patent number: 4623678
    Abstract: In accordance with the present invention, solids are recovered from a latex stabilized with a pH sensitive emulsifier by passing carbon dioxide through the latex to lower the pH and thereby destabilize the latex and then subjecting the latex to high shear.
    Type: Grant
    Filed: April 26, 1985
    Date of Patent: November 18, 1986
    Assignee: The Dow Chemical Company
    Inventors: Eugene R. Moore, Norman A. Lefevre