Abstract: Objects are packed in respective receptacles in a unitary body of sheet material having orifices open in a common direction. An annular edge portion of the body envelops the orifices and one or more rib portions of the body separate each orifice from each other orifice. A cover of sheet material is superimposed in a vacuum chamber on the edge portion and the orifices and sealed gastight to the edge portion. When the body with the sealed cover is exposed to atmospheric pressure, the cover is pressed by the air against the rib portions and may be sealed thereto. The sealing die employed in this process need only clamp the edge portion of the sheet material body against a suitable backing die.

Abstract: In the present method a package is produced by forming a pouch in a first foil thereby stretching the material thus creating latent shrinking forces. The package is sealed using a second flat foil or a foil having a pouch extending to the opposite direction as the first pouch. The sealing is done inside an evacuated space and the heating of the first foil in order to shrink the pouch is done prior to or at the same time as the vacuum space is aerated.

Abstract: A tubular, laminar, plastic sheet material having a core layer of oriented plastic and two outer layers of approximately isotropic plastic is prepared in extrusion apparatus whose die block has three channels wider than they are thick, and merging at acute angles to form an extrusion nozzle. The channels are continuously supplied with molten resin compositions webs of which are superimposed on each other in area contact at the junction of the channels. They move as an initially fluid, but coherent, layered structure from the nozzle into an immediately adjacent duct of a cooling head in which the structure is cooled from a first temperature above the melting temperature of the highest-melting resin composition of the central layer to a temperature intermediate that melting temperature and the temperature at which the outer, lower melting layers become solid.