Patents by Inventor Frederick D. Stringer

Frederick D. Stringer 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).

  • Heat sealable, multi-ply polypropylene film
    Patent number: 4439478
    Abstract: A heat sealable and shrinkable, coextruded, multi-layer packaging film having a propylene homopolymer base layer and a skin layer of a preferred blend of 60% to 80% propylene-ethylene copolymer with propylene homopolymer provides a sealing temperature range of up to 30.degree. C.
    Type: Grant
    Filed: April 15, 1982
    Date of Patent: March 27, 1984
    Assignee: W. R. Grace & Co., Cryovac Division
    Inventors: Daniel F. Ferguson, Frederick D. Stringer, Michael D. Esakov
  • Heat sealable, multi-ply polypropylene film
    Patent number: 4390385
    Abstract: A heat sealable and shrinkable, coextruded, multi-layer packaging film having a propylene homopolymer base layer and a skin layer of a preferred blend of 60% to 80% propylene-ethylene copolymer with propylene homopolymer provides a sealing temperature range of up to 30.degree. C.
    Type: Grant
    Filed: November 27, 1981
    Date of Patent: June 28, 1983
    Assignee: W. R. Grace & Co., Cryovac Div.
    Inventors: Daniel J. Ferguson, Frederick D. Stringer, Michael D. Esakov
  • Method and apparatus for high speed extrusion of thermoplastic materials
    Patent number: 4287151
    Abstract: In the process of extruding tubular thermoplastic film or tape, the production rate can be improved by using a smooth support plug to stabilize and shape the extrudate after it has been cooled and at least partially solidified. A principal function of the support plug is to assist in supporting the long slender column of partially solidified extrudate which is above the plug. The result is a significant increase in the output of the extrusion process.
    Type: Grant
    Filed: December 13, 1976
    Date of Patent: September 1, 1981
    Assignee: W. R. Grace & Co.
    Inventors: Michael D. Esakov, David C. Hudgens, Jr., Frederick D. Stringer
  • Winding core for heat shrinkable film material
    Patent number: 4242297
    Abstract: A generally cylindrical core for winding a web of sheetlike material has portions with a lesser diameter than other portions such that otherwise baggy areas of the web overlie the lesser diameter area of the core. The core particularly solves the problem of elongated edges on a wound film of heat shrinkable thermoplastic material caused by differential shrinkage about a core.
    Type: Grant
    Filed: December 31, 1979
    Date of Patent: December 30, 1980
    Assignee: W. R. Grace & Co.
    Inventors: Raymond B. Dacey, Frederick D. Stringer