Abstract: A retortable container has a wall of at least two co-formed laminas. This wall is highly impermeable to fluids selected from the group consisting of oxygen and aromatic vapors. The wall includes a first load-carrying lamina of a first plastic material. This load-carrying lamina has been formed without mechanical hysteresis in the melt phase by a thermal pressure forming apparatus to cause strengthening with orientation of the load-carrying lamina in at least one axis but without memory of its pre-melt phase shape. The wall also includes a second sealing lamina of a second plastic material. This second sealing lamina is coextensive with the first load-carrying lamina. Consequently, the container formed by the apparatus is retortable, i.e. it can withstand temperatures and pressures of a retort chamber without undergoing significant and permanent distortion.

Abstract: A retortable container has a wall of at least two co-formed laminas. This wall is highly impermeable to fluids selected from the group consisting of oxygen and aromatic vapors. The wall includes a first load-carrying lamina of a first plastic material. This load-carrying lamina has been formed without mechanical hysteresis in the melt phase by a thermal pressure forming apparatus to cause strengthening with orientation of the load-carrying lamina in at least one axis but without memory of its pre-melt phase shape. The wall also includes a second sealing lamina of a second plastic material. This second sealing lamina is coextensive with the first load-carrying lamina. Consequently, the container formed by the apparatus is retortable, i.e. it can withstand temperatures and pressures of a retort chamber without undergoing significant and permanent distortion.

Abstract: An apparatus for the thermal pressure forming of plastic blanks into containers includes several elements. A heater brings the plastic blanks to a melt phase by heating them to a melting temperature sufficient to relieve internal stresses therein. A conveying arrangement takes the plastic blanks through the heater. This conveying arrangement includes a device for preventing the plastic blanks from reaching the melting point only along their outer peripheral edges so that the plastic blanks maintain dimensional stability. Thereafter, a press forms the plastic blanks into retortable containers.