WERKWIJZE EN INRICHTING VOOR HET VERVAARDIGEN VAN BIAXIAAL GEORIENTEERDE BANDEN, FOLIES EN MASSIEVE PROFIELEN UIT THERMOPLASTISCHE KUNST- STOF.

摘要

A method is disclosed for biaxially stretching a band of thermoplastic resin which comprises attenuating a band of unstretched resin, in a forming zone while the resin is in the thermoelastic condition, by passing the band between two surfaces spaced at a distance less than the thickness of said band of unstretched resin while permitting said band to expand in width, and then cooling said band to a temperature below the softening point of the resin while maintaining the dimensions of the attenuated and expanded band; apparatus for performing such a method is also disclosed.