Patents by Inventor Walter Francis Johnston

Walter Francis Johnston 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).

  • Compositions of polycondensed branched polyester polymers and aromatic polycarbonates, and the closed cell polymer foams made therefrom
    Patent number: 6214897
    Abstract: A foamable polyester composition comprising a combination of blowing agent and mixed polymer composition comprising: a) a semi-crystalline polyester composition comprising a polycondensed branched polyester polymer, and b) an aromatic polycarbonate polymer. The foamable composition has a high extrusion melt strength, and can pulled across a die without ripping, to form a continuous thermoformable closed cell polyester sheet. The foamed sheets have a uniform, fine, and closed cell morphology; and simultaneously are less dense but have a higher impact strength than comparable closed cell polymers made in only with linear polyesters as the polyester component or without the aromatic polycarbonate.
    Type: Grant
    Filed: November 22, 1999
    Date of Patent: April 10, 2001
    Assignee: Shell Oil Company
    Inventors: Deborah Ann Snell Tung, Kevin Rollick, John Michael Scoarste, Walter Francis Johnston
  • Compositions of polycondensed branched polyester polymers and aromatic polycarbonates, and the closed cell polymer foams made therefrom
    Patent number: 6100307
    Abstract: A foamable polyester composition comprising a combination of blowing agent and mixed polymer composition comprising:a) a semi-crystalline polyester composition comprising a polycondensed branched polyester polymer, andb) an aromatic polycarbonate polymer.The foamable composition has a high extrusion melt strength, and can pulled across a die without ripping, to form a continuous thermoformable closed cell polyester sheet. The foamed sheets have a uniform, fine, and closed cell morphology; and simultaneously are less dense but have a higher impact strength than comparable closed cell polymers made in only with linear polyesters as the polyester component or without the aromatic polycarbonate.
    Type: Grant
    Filed: March 17, 1998
    Date of Patent: August 8, 2000
    Assignee: Shell Oil Company
    Inventors: Deborah Ann Snell Tung, Kevin Rollick, John Michael Scoarste, Walter Francis Johnston
  • Compositions of polycondensed branched polyester polymers and aromatic polycarbonates, and the closed cell polymer foams made therefrom
    Patent number: 6080824
    Abstract: A foamable polyester composition comprising a combination of blowing agent and mixed polymer composition comprising:a) a semi-crystalline polyester composition comprising a polycondensed branched polyester polymer, andb) an aromatic polycarbonate polymer.The foamable composition has a high extrusion melt strength, and can pulled across a die without ripping, to form a continuous thermoformable closed cell polyester sheet. The foamed sheets have a uniform, fine, and closed cell morphology; and simultaneously are less dense but have a higher impact strength than comparable closed cell polymers made in only with linear polyesters as the polyester component or without the aromatic polycarbonate.
    Type: Grant
    Filed: July 26, 1999
    Date of Patent: June 27, 2000
    Assignee: Shell Oil Company
    Inventors: Deborah Ann Snell Tung, Kevin Rollick, John Michael Scoarste, Walter Francis Johnston
  • Compositions of polycondensed branched polyester polymers and aromatic polycarbonates, and the closed cell polymer foams made therefrom
    Patent number: 6025405
    Abstract: A foamable polyester composition comprising a combination of blowing agent and mixed polymer composition comprising:a) a semi-crystalline polyester composition comprising a polycondensed branched polyester polymer, andb) an aromatic polycarbonate polymer.The foamable composition has a high extrusion melt strength, and can pulled across a die without ripping, to form a continuous thermoformable closed cell polyester sheet. The foamed sheets have a uniform, fine, and closed cell morphology; and simultaneously are less dense but have a higher impact strength than comparable closed cell polymers made in only with linear polyesters as the polyester component or without the aromatic polycarbonate.
    Type: Grant
    Filed: July 26, 1999
    Date of Patent: February 15, 2000
    Assignee: Shell Oil Company
    Inventors: Deborah Ann Snell Tung, Kevin Rollick, John Michael Scoarste, Walter Francis Johnston
  • Cellularized polyesters
    Patent number: 5641549
    Abstract: This invention is a composition, a kit to prepare the composition, cellular sheet made from the composition and thermoformed articles made from the sheet, in which the composition comprises polyethylene terephthalate, sufficient inert gas to give a sheet density of 0.4 to 1.25 gm/cc, a polytetrafluoroethylene nucleating agent and optionally a polyolefin additive and a heat stabilizer.
    Type: Grant
    Filed: December 14, 1995
    Date of Patent: June 24, 1997
    Assignee: Shell Oil Company
    Inventors: Walter Francis Johnston, Donald Edward Richeson, William George Perkins