PROCESS FOR PRODUCING A BIAXIALLY ORIENTED POLYPROPYLENE FOIL

摘要

A process for producing a biaxially oriented polypropylene foil in which, in the prior art manner, a polypropylene raw material is prepared, it is melted and a primary foil is produced from the melt by extrusion and cooling the extrudate, the primary foil is taken to the stretch temperature by reheating, it is stretched biaxially in the machine direction (MDO) and transversely (TDO) either sequentially or simultaneously and the stretched, biaxially oriented polypropylene foil is rolled up after cooling, where, according to the invention, a polypropylene wax with a median mean molecular weight Mw of over 8,000 g/mol is added to the raw polypropylene material to improve the stretch behaviour of the foil and permit higher machine speeds during the production of the foil.