Oriented polyethylene films and a method for making the same

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 I2 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 I2 greater than or equal to 2 g/10 min; wherein the first polyethylene composition has an 12 from 0.5 to 10 g/10 min and a density from 0.910 to 0.940 g/cc is provided.

We claim: 
     
         1 . An oriented film comprising a polyethylene composition which comprises:
 from 50 to 80 wt % of a linear low density polyethylene polymer having a density greater than 0.925 g/cc and an I 2  less than 2 g/10 min; and   from 50 to 20 wt % of an additional linear low density polyethylene polymer having a density lower than 0.920 g/cc and an I 2  greater than 2 g/10 min;   wherein the 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   wherein the oriented film is produced by a tenter frame process.   
     
     
         2 . The oriented film according to  claim 1 , wherein the linear low density polyethylene polymer is produced using a Ziegler-Natta catalyst. 
     
     
         3 . The oriented film according to  claim 1 , wherein the additional linear low density polyethylene polymer is produced using a molecular catalyst. 
     
     
         4 . The oriented film according to  claim 1 , wherein the linear low density polyethylene polymer has a density greater than 0.930 g/cc and an I 2  lower than 1 g/10 min. 
     
     
         5 . The oriented film according to  claim 1 , wherein the additional linear low density polyethylene polymer has a density less than 0.915 g/cc an I 2  greater than 4 g/10 min. 
     
     
         6 . The oriented film according to  claim 1 , wherein the polyethylene composition has an MW HDF>95  greater than 135 kg/mol and I HDF>95  greater than 42 kg/mol. 
     
     
         7 . The oriented film according to  claim 1 , wherein the oriented film is oriented below the melting point of the polyethylene composition. 
     
     
         8 . The oriented film according to  claim 1 , wherein the oriented film is a biaxially oriented film. 
     
     
         9 . The biaxially oriented film according to  claim 8  which has been oriented via a sequential orientation process with an MD draw ratio greater than 3 and a TD draw ratio greater than 5. 
     
     
         10 . The biaxially oriented film according to  claim 8  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. 
     
     
         11 . A co-extruded film comprising at least one film layer comprising the oriented film according to  claim 1 . 
     
     
         12 . A laminated film comprising at least one film layer comprising the oriented film according to  claim 1 . 
     
     
         13 . The biaxial oriented film according to  claim 8  wherein the biaxial 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.