Retortable container

A retortable container of at least two co-formed laminas, comprising:

• a wall having a first load-carrying lamina of a first plastic material formed after an initial melt phase without mechanical hysteresis in a second melt phase by a thermal pressure forming apparatus to cause strengthening by recooling with random orientation of the first plastic material therein without memory of a shape of an intermediate plastic blank;
• a rim having the first load-carrying lamina of the first plastic material formed int he solid phase by the thermal pressure forming apparatus to cause strengthening;
• said wall and said rim both having a second sealing lamina of a second plastic material being coextensive with the first load-carrying lamina;
• said first load-carrying lamina and said second sealing lamina being co-formed laminas highly impermeable to fluids selected from the group consisting of oxygen and aromatic vapors;
• whereby said container can withstand temperatures and pressures of a retort chamber without undergoing significant and permanent distortion;
• wherein said container is made by a method of thermal pressure forming of the intermediate plastic blank cut from an initial plastic sheet, said method comprising the steps of:
• a. bringing the plastic blank from a solid phase to the second melt phase by heating said plastic blank to a melting temperature sufficient to relieve internal stresses in said plastic blank while conveying the plastic blank on a conveying means through the heating means;
• said conveying means including at least a plurality of trays, each having a plurality of holes therethrough in which preventing means are placed;
• b. preventing the plastic blank in the solid phase from going into the second melt phase while in the heating means only along outer peripheral edges thereof so that the plastic blank maintains its hoop strength and peripheral dimensions;
• said preventing step including the substep of suspending the plastic blank across said preventing means;
• and
• c. forming the plastic blank into said container.