Net replacement film

Abstract

The present invention relates to a prestretched polyethylene film having a longitudinal stretch ratio of from about 1:2 to about 1:4 and having a longitudinal elongation capability of at least 170%, said elongation capability comprising an elastic component. The invention also relates to a method for producing said film and to a method of wrapping compressed bulk material such as a round bale using said film, the method comprising further stretching the prestretched film and applying the film around the compressed bulk material in direct contact therewith. The film according to the invention may be used as a net replacement film and allows increasing the efficiency and the economics in the baling process by allowing faster baling, use of a lesser amount of wrapping film and/or improved protection of the product.

1 . A prestretched polyethylene film having a longitudinal stretch ratio of from about 1:2 to about 1:4 and having a longitudinal elongation capability of at least 170%, said elongation capability comprising an elastic component. 
     
     
         2 . A prestretched film according to  claim 1 , having a stretch ratio of about 1:2.5. 
     
     
         3 . A prestretched film according to  claim 1 , wherein the film comprises linear low density polyethylene (LLDPE). 
     
     
         4 . A prestretched film according to  claim 3 , wherein the film further comprises low density polyethylene (LDPE). 
     
     
         5 . A prestretched film according to  claim 4 , having a content of LLDPE in the range of 60-99.9% by weight and a content of LDPE in the range of 0.1-20% by weight. 
     
     
         6 . A prestretched film according to  claim 1 , further comprising a tackifying agent. 
     
     
         7 . A prestretched film according to  claim 1 , having a thickness in the range of 5 to 40 micrometers. 
     
     
         8 . A method for producing a prestretched polyethylene film according to  claim 1 , comprising: producing a precursor polyethylene film;
 stretching said precursor film to a stretch ratio of from about 1:2 to about 1:4 to form a prestretched film; and collecting said prestretched film.   
     
     
         9 . A method according to  claim 8 , comprising stretching said film to a stretch ratio of about 1:2.5. 
     
     
         10 . Use of a prestretched polyethylene film as defined in  claim 1 , for wrapping a bale of compressed bulk material, wherein the film is applied in direct contact with the compressed bulk material. 
     
     
         11 . A method for wrapping compressed bulk material, comprising the steps of
 (a) compressing bulk material in a chamber to form a bale of compressed bulk material;   (b) further stretching a prestretched polyethylene film as defined in  claim 1 , to a stretch ratio of from 1:1.02 to 1:2.5 relative to the length of the prestretched film;   (c) applying said film under tension around said bale, in direct contact with the compressed bulk material; and   (d) wrapping said film under tension at least 1.5 turns around said bale,   wherein substantially no expansion of the bale of compressed bulk material occurs when the bale is removed from the chamber.   
     
     
         12 . A method according to  claim 11 , wherein a further compression of the compressed bulk material is achieved by said film. 
     
     
         13 . A method according to  claim 11 , wherein said compressed bulk material is a round bale ( 200 ,  300 ) having an envelope surface ( 201 ,  301 ) and two side surfaces ( 202 ,  202 ′,  302 ,  302 ′), and the film in step (b) is applied on the envelope surface along its circumference, and such that the film extends over an edge of said envelope surface to cover part of at least one of said side surfaces. 
     
     
         14 . A method according to  claim 13 , wherein a single layer of the film covers the entire width of the envelope surface. 
     
     
         15 . A method according to  claim 11 , wherein 2-10 layers of said prestretched film are applied around the bale of compressed bulk material, as measured centrally on an envelope surface of the bale of compressed bulk material.