Method for producing biaxially oriented polystyrene heavy gauge sheet

Abstract

Abstract Biaxially oriented heavy gauge polystyrene sheet is produced by initially extruding a tube of thermoplastic material readily workable over a forming and cooling mandrel, preferably a foamed polystyrene tube from an annular extrusion orifice of an extruder containing polystyrene admixed with a nucleating agent and a foaming agent, passing the tube (or other workable thermoplastic) over a forming and cooling mandrel having a diameter larger than the orifice, slitting the tube and taking up sheets on takeup rolls, wherein the tube between the orifice and the mandrel is supported by injecting a gaseous medium (e.g., air) insided the tube. Thereafter, in the case of polystyrene foam initiation, the addition of nucleating agent and foaming agent is discontinued, extrusion temperature is adjusted, and the rate of injection of gas inside the tube is adjusted to an amount that a gas cushion forms between the polystyrene tube and the mandrel, and the operation is continued to produce clear oriented polystyrene sheet.

Inventors

• 👤 Frank A Carlson Jr

Bibliographic Details