Patent ID: 8623261

Claim:
A method for preparing a thermoformed article comprising: (a) providing an isotactic propylene polymer produced by the polymerization of propylene in the presence of an isospecific metallocene catalyst, said polymer having a melt flow rate (MI 2 ) within the range of 1-5 grams/10 minutes and a melting temperature of no more than 160° C.; (b) extruding said polypropylene to provide a sheet which is oriented in at least one direction and has a thickness within the range of 10-100 mils after orientation; (c) heating said sheet at a temperature within the range of 135-160° C. and thermoforming said sheet over a template having a desired configuration to produce said thermoformed article, wherein said sheet is subjected to a pre-stretching extension prior to production of said thermoformed article; (d) cooling said thermoformed article and retrieving said thermoformed article from said template; and wherein said thermoformed article has a uniform shrinkage of at least 85% as determined by a differential in transverse and longitudinal shrinkages 48 hours after said thermoformed article has been cooled and retrieved; wherein the thermoformed article comprises a single polymer comprising the isotactic propylene polymer.