Biaxially oriented MDPE film
AssigneeNOVA Chemicals (International) S.A.
InventorsNorman Aubee, Owen Lightbody, Maryam Fereydoon, Bronwyn Gillon, Patrick Lam, Shivendra Goyal
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Abstract
A Biaxially Oriented Polyethylene (BOPE) process uses a selected polyethylene having a medium density and a very broad molecular weight distribution. The use of this selected polyethylene facilitates stretching in the BOPE process in comparison to previously used polyethylene resins having a higher density and/or a narrower molecular weight distribution.
Claims10
A biaxially oriented polyethylene film comprising at least 60 weight percent of a medium density polyethylene having:
- 1) A density of 0.94 to 0.95 grams per cubic centimeter;
- 2) a melt index, I2, as measured by ASTM D1238 at 190° C. using a 2.16 kg load of 0.2 to 5 grams/10 minutes;
- and
- 3) a molecular weight distribution, Mw/Mn, of 10 to 50;
- wherein said biaxially oriented polyethylene film has at least three layers, and wherein at least one core layer of said biaxially oriented polyethylene film comprises said medium density polyethylene;
- wherein said medium density polyethylene has an Mz of 550,000 to 1,500,000;
- and
- wherein said medium density polyethylene is made by the copolymerization of ethylene with butene in a solution polymerization process using a Zeigler Natta catalyst or is made by the copolymerization of ethylene with hexene in a gas phase process using a chromium catalyst.
A process to prepare a biaxially oriented polyethylene film, the process comprising:
- A) providing a base structure comprising at least 60 weight % of a medium density polyethylene having:
- 1) a density of 0.94 to 0.95 grams per cubic centimeter;
- 2) a melt index, I2, as measured by ASTM D1238 at 190° C. using a 2.16 kg load of 0.2 to 5 grams/10 minutes;
- and
- 3) a molecular weight distribution, Mw/Mn, of 10 to 50;
- B) stretching said base structure to a degree of about 3:1 to about 10:1 in the machine direction;
- and
- C stretching said base structure to a degree of about 3:1 to about 10:1 in the transverse direction,
- wherein said base structure comprises at least three layers, and wherein at least one core layer of said base structure comprises said medium density polyethylene;
- wherein said medium density polyethylene has an Mz of 550,000 to 1,500,000;
- and
- wherein said medium density polyethylene is made by the copolymerization of ethylene with butene in a solution polymerization process using a Zeigler Natta catalyst or is made by the copolymerization of ethylene with hexene in a gas phase process using a chromium catalyst.
Dependencies are inferred from the claim text.