| 摘要 |
A method of preparing a thermoformed article which is relatively isotropic in terms of shrinkage of the final thermoformed article along the sheet extrusion flow path (the longitudinal direction) and the transverse direction. The article is prepared from an isotactic polypropylene produced by the polymerization of propylene with an isospecific metallocene catalyst. The polymer has a melt flow rate within the range of 1-5 grams/10 minutes and a melting temperature of no more than 160° C. The polypropylene is extruded to provide a sheet which is oriented in at least one direction and has a thickness of 10-100 mils. The sheet is heated to a temperature of 135-160° C, and thermoformed in contact with a template having the desired configuration to produce the thermoformed article. The thermoformed article is then cooled and retrieved from the template to arrive at the final product. |
