Propylene polymers for films

A process for preparing a crystalline polypropylene composition comprising the steps of:

• (a) polymerizing propylene in one stage;
• (b) copolymerizing propylene and a comonomer in a separate stage;
• and
• (c) recovering crystalline propylene polymer comprising from 0.5 to 8 wt % comonomer units based on the total weight of the polymer, wherein the polymerization steps (a) and (b) are conducted in the presence of a metallocene catalyst system comprising two different metallocene catalyst components, and wherein the molecular weight distribution of the polymer is characterized as being bimodal, the polymer having a Mz value of from 500,000 to 1,500,000 molecular weight units.

A process for preparing a crystalline polypropylene comprising the steps of:

• (a) polymerizing propylene in a first stage;
• then
• (b) copolymerizing propylene and a comonomer in a second stage in the presence of the product of the first stage;
• and
• (c) recovering crystalline propylene polymer comprising from 0.05 to 15 wt % comonomer units based on the total weight of the polymer and wherein the hexane extractables is less than 3 wt % as measured by 21 CFR 177.1520(d)(3)(ii), and wherein the polymerization steps (a) and (b) are conducted in the presence of a metallocene catalyst system comprising two different metallocene catalyst components.

A process for preparing a crystalline polypropylene comprising the steps of:

• (a) polymerizing propylene in a first stage;
• then
• (b) copolymerizing propylene and a comonomer in a second stage in the presence of the product of the first stage;
• and
• (c) recovering crystalline propylene polymer comprising from 0.05 to 15 wt % comonomer units based on the total weight of the polymer, wherein the hexane extractables is less than 3 wt % as measured by 21 CFR 177.1520(d)(3)(ii), and wherein the polymerization steps (a) and (b) are conducted in the presence of a metallocene catalyst system comprising two different metallocene catalyst components, and wherein the molecular weight distribution of the polymer is characterized as being bimodal, having a Mz value of from 500,000 to 1,500,000 molecular weight units.

A process for preparing crystalline isotactic propylene polymer comprising the steps of:

• (a) copolymerizing propylene and a comonomer in one stage;
• and
• (b) recovering crystalline propylene polymer comprising from 0.5 to 8 wt % comonomer units based on the total weight of the polymer;
• wherein the polymerization steps (a) and (b) are conducted in the presence of a metallocene catalyst system comprising two different metallocene catalyst components, and wherein the molecular weight distribution of the polymer is characterized as being bimodal, the polymer having a Mz value of from 400,000 to 2,000,000 molecular weight units.

A process for preparing crystalline isotactic propylene polymer comprising the steps of:

• (a) polymerizing propylene and a comonomer in one stage;
• (b) copolymerizing propylene and a comonomer in a separate stage;
• and
• (c) recovering crystalline propylene polymer comprising from 0.5 to 8 wt % comonomer units based on the total weight of the polymer;
• wherein the polymerization steps (a) and (b) are conducted in the presence of a metallocene catalyst system comprising two different metallocene catalyst components, and wherein the molecular weight distribution of the polymer is characterized as being bimodal, the polymer having a Mz value of from 400,000 to 2,000,000 molecular weight units.