Title: Apparatus for forming multiaxially oriented containers

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Abstract: Multiaxially oriented containers are formed from an extruded, molecularly orientable thermoplastic parison having a programmed wall thickness. The parison while at extrusion temperature is sealed at one end and expanded incrementally in a conditioning mold into the shape of a preform which is allowed to set therein for a brief time period in order to develop an outer skin at reduced temperature. The full wall of the variable thickness preform is then reduced in temperature to within the orientation temperature range and the preform then stretched longitudinally and expanded radially in a finishing mold to develop axial and radial orientation while forming the container. Since the thicker portion(s) of the programmed parison do not cool as much in the conditioning mold as do the thinner portion(s) they consequently subsequently stretch to a greater extent, and this phenomenom must be compensated for in the initial programming step. The container finish is preferably formed in the conditioning mold while the thermoplastic is at elevated temperature. The molecularly orientable thermoplastic may be a high nitrile-group-containing polymer having excellent barrier properties of the type covered by the trademark LOPAC.


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