Process for manufacturing a food container by extrusion and vacuum forming

Claim 1

A process for making a container especially adapted for use in storing and heating comestibles intended for final preparation in microwave ovens, consisting of essentially the steps of: (a) providing a tray constructed of a molded paper pulp member having a continuous inside surface defined by an upstanding sidewall tapered inwardly from an open top to a smoothly rounded corner which joins with a bottom wall, said molded pulp member comprising pulp fiber material defining a multiplicity of interstices in said member to provide said member with sufficient porosity to allow passage of gas therethrough; (b) placing the outer surface of the tray in contact with a support having means associated therewith for drawing a vacuum through said support; (c) preparing a film of heated plastic material by forcing a melt through a film-forming die, and maintaining said film in a molten condition until contact with said paper pulp member; (d) placing said film of heated and molten plastic material into contact with at least the periphery of the upstanding wall at the top of the tray; and (e) drawing a vacuum through said support means and tray to pull the molten film into uniform adherent contact with the entire continuous inside surface of the tray.