Process for producing polyolefin

In a process for producing a polyolefin film comprising:

• providing a primary polymer component comprising a high crystallinity isotactic propylene homopolymer having a xylene solubles content of no more than 1 wt. %, produced by the polymerization of propylene in the presence of a Ziegler-Natta catalyst;
• providing a secondary polymer component comprising a Ziegler-Natta polymerized ethylene-propylene random copolymer containing no more than 0.5 wt. % ethylene and having a xylene solubles content of at least twice the xylene solubles content of said primary polymer;
• mixing said primary and secondary polymer components together to provide a mixture of said primary and secondary polymer components in which the secondary polymer component is present in an amount within the range of 10–15 wt % of said polymer mixture;
• and
• forming a biaxially oriented film layer of said polymer mixture by stretching said polymer mixture in longitudinal and transverse directions.

In a process for producing a polyolefin film comprising:

• providing a primary polymer component comprising a high crystallinity isotactic propylene homopolymer having a xylene solubles content of no more than 1 wt. %, produced by the polymerization of propylene in the presence of a Ziegler-Natta catalyst;
• providing a secondary polymer component comprising a metallocene-polymerized ethylene-propylene random copolymer produced by the copolymerization of propylene and ethylene in the presence of a metallocene polymerization catalyst;
• mixing said primary and secondary polymer components together to provide a mixture of said primary and secondary polymer components in which the secondary polymer component is present in an amount of less than 5 wt. %;
• and
• forming a biaxially oriented film layer of said polymer mixture by stretching said polymer mixture in longitudinal and transverse directions.

In a process for producing a polyolefin film comprising:

• providing a primary polymer component comprising a high crystallinity isotactic propylene homopolymer having a xylene solubles content of no more than 1 wt. %, produced by the polymerization of propylene in the presence of a Ziegler-Natta catalyst;
• providing a secondary polymer component comprising a metallocene-polymerized ethylene-propylene random copolymer having a melting temperature of no more than 110° C., produced by the copolymerization of propylene and ethylene in the presence of a metallocene polymerization catalyst;
• mixing said primary and secondary polymer components together to provide a mixture of said primary and secondary polymer components in which the secondary polymer component is present in an amount of 1–10 wt. %;
• and
• forming a biaxially oriented film layer of said polymer mixture by stretching said polymer mixture in longitudinal and transverse directions.