Oriented polyethylene films and a method for making the same

Patent metadata

Field	Value
Publication number	US-10457787-B2
Application number	US-201415302967-A
Country	US
Kind code	B2
Filing date	Apr 9, 2014
Priority date	Apr 9, 2014
Publication date	Oct 29, 2019
Grant date	Oct 29, 2019

Abstract

A first oriented film comprising a first polyethylene composition which comprises: from 20 to 50 wt % of a first linear low density polyethylene polymer having a density greater than 0.925 g/cc and an I 2 lower than 2 g/10 min; and from 80 to 50 wt % of a second linear low density polyethylene polymer having a density lower than or equal to 0.925 g/cc and an I 2 greater than or equal to 2 g/10 min; wherein the first polyethylene composition has an I 2 from 0.5 to 10 g/10 min and a density from 0.910 to 0.940 g/cc is provided.

First claim

We claim:

1. A oriented film comprising a polyethylene composition which comprises:
from 20 to 50 wt % of a first linear low density polyethylene polymer having a density greater than 0.925 g/cc and melt index (I 2 ) lower than 2 g/10 min, measured according to ASTM D1238, condition 190° C./2.16 kg; and
from 80 to 50 wt % of a second linear low density polyethylene polymer having a density lower than 0.925 g/cc and an I 2 greater than 2 g/10 min, measured according to ASTM D1238, condition 190° C./2.16 kg;
wherein the polyethylene composition has an I 2 from 0.5 to 10 g/10 min, measured according to ASTM D1238, condition 190° C./2.16 kg, and a density from 0.910 to 0.940 g/cc.

2. The oriented film according to claim 1 , wherein the first and/or second linear low density polyethylene polymer is produced using a Ziegler-Natta catalyst.

3. The oriented film according to claim 1 , wherein the first linear low density polyethylene polymer has a density greater than 0.930 g/cc and an I 2 lower than 1 g/10 min, measured according to ASTM D1238, condition 190° C./2.16 kg.

4. The oriented film according to claim 1 , wherein the second linear low density polyethylene polymer has a density lower than 0.920 g/cc and an I 2 greater than 4 g/10 min, measured according to ASTM D1238, condition 190° C./2.16 kg.

5. The oriented film according to claim 1 , wherein the polyethylene composition has a Molecular Weight of High Density Fraction (MW HDF>95 ) greater than 135 kg/mol and a High Density Fraction Index (I HDF>95 ) greater than 42 kg/mol.

6. The oriented film according to claim 1 , wherein the oriented film is oriented below the melting point of the polyethylene composition.

7. The oriented film according to claim 1 , wherein the oriented film is a biaxially oriented film.

8. The oriented film according to claim 1 , wherein the oriented film is a biaxially oriented film which has been oriented via a sequential orientation process with an MID draw ratio greater than 3 and a TD draw ratio greater than 5.

9. The oriented film according to claim 1 , wherein the oriented film is a biaxially oriented film which has been oriented via a simultaneous orientation process with an MD draw ratio greater than 4 and a TD draw ratio greater than 4.

10. A co-extruded film comprising at least one film layer comprising the oriented film according to claim 1 .

11. A laminated film comprising at least one film layer comprising the oriented film according to claim 1 .

12. The oriented film according to claim 1 , wherein the oriented film exhibits one or more of the following properties:
ultimate tensile strength averaged in MD and TD, measured according to ASTM D882, greater than or equal to 40 MPa; and
2% secant modulus averaged in MD and TD, measured according to ASTM D882, greater than or equal to 350 MPa.

13. A biaxially oriented film comprising a polyethylene composition which comprises:
from 20 to 50 wt % of a first linear low density polyethylene polymer having a density greater than 0.925 g/cc and melt index (I 2 ) lower than 2g/10 min, measured according to ASTM D1238, condition 190° C./2.16 kg; and
from 80 to 50 wt % of a second linear low density polyethylene polymer having a density lower than 0.925 g/cc and an I 2 greater than 2 g/10 min, measured according to ASTM D1238, condition 190° C./2.16 kg;
wherein the polyethylene composition has an I 2 from 0.5 to 10 g/10 min, measured according to ASTM D1238, condition 190° C./2.16 kg, and a density from 0.910 to 0.940 g/cc;
wherein the biaxially oriented film has been oriented via a sequential orientation process with an MD draw ratio greater than 3 and a TD draw ratio greater than 5.

14. A biaxially oriented film comprising a polyethylene composition which comprises:
from 20 to 50 wt % of a first linear low density polyethylene polymer having a density greater than 0.925 g/cc and melt index (I 2 ) lower than 2 g/10 min, measured according to ASTM D1238, condition 190° C./2.16 kg; and
from 80 to 50 wt % of a second linear low density polyethylene polymer having a density lower than 0.925 g/cc and an I 2 greater than 2 g/10 min, measured according to ASTM D1238, condition 190° C./2.16 kg;
wherein the polyethylene composition has an I 2 from 0.5 to 10 g/10min, measured according to ASTM D1238, condition 190° C./2.16 kg, and a density from 0.910 to 0.940 g/cc;
wherein the biaxially oriented film has been oriented via a simultaneous orientation process with an MD draw ratio greater than 4and a TD draw ratio greater than 4.

Assignees

• Dow Global Technologies Llc

Inventors

• Lin Yijian
• Demirors Mehmet
• Pan Jianping
• Yun Xiao B

Classifications

• B29C48/0018

  combined with shaping by orienting, stretching or shrinking, e.g. film blowing (B29C48/0017 takes precedence) · CPC title

• B29C48/21

  the layers being joined at their surfaces · CPC title

• B32B2307/518

  bi-axially · CPC title

• B29C48/08

  flexible, e.g. films · CPC title

• B32B27/205

  the fillers creating voids or cavities, e.g. by stretching · CPC title