Twist-wrap film and use thereof as packaging film

Abstract

The invention relates to a twist-wrap film ( 1, 2, 3 ) which is produced by coextrusion of a plurality of plastic layers. The inventive film is characterized in that at least a) one or more plastic layer(s) ( 4, 4 ′) consist of one or more semicrystalline polyolefin(s) having a uniform structure and b) at least one additional layer from an amorphous cycloolefin copolymer ( 5 ) having a uniform structure, the layers a) and b) being in direct contact. The selection of an amorphous cycloolefin copolymer having a uniform structure in at least one layer of the inventive twist-wrap film combined with a semicrystalline polyolefin having a uniform structure allows to provide a twist-wrap film that can be easily produced and that has the rigidity required for twist-wrap packagings and a satisfactory deadfold behavior, i.e., recovery behavior.

1 . Twist-wrap film ( 1 ,  2 ,  3 ), which can be produced by co-extrusion of several plastic layers, characterized in that at least a) one or more plastic layer(s) ( 4 ,  4 ′) of partially crystalline polyolefin(s) that is (are) uniform in its (their) structure, and b) at least one additional plastic layer, uniform in its structure, consists of amorphous cycloolefin copolymer ( 5 ), whereby the plastic layers a) and b) are in direct contact with one another. 
   
   
       2 . Twist-wrap film according to  claim 1 , wherein the inner layer ( 4 ) consists of polyolefin that is uniform in its structure, which has two outer layers ( 5 ), in each case directly adjacent on two sides, of cycloolefin copolymer that is uniform in its structure. 
   
   
       3 . Twist-wrap film according to  claim 2 , wherein at least one additional layer ( 6 ) of partially crystalline polyolefin, uniform in its structure, in each case directly adjoins the outer layers ( 5 ). 
   
   
       4 . Twist-wrap film according to  claim 1 , wherein an inner layer ( 8 ) of partially crystalline polyolefin, bilaterally uniform in its structure in each case, shows another layer ( 7 ), directly adjoining, of a polyolefin that is different in its structure, whereby directly adjoining layers ( 5 ) of amorphous cycloolefin copolymer that is bilaterally uniform in its structure in each case adjoin this three-layer structure ( 4 ′). 
   
   
       5 . Twist-wrap film according to  claim 1 , wherein the layers ( 4 ,  4 ′) consist of polyolefin or polyethylene, preferably in the form of homo-PP, random-PP or LLDPE. 
   
   
       6 . Twist-wrap film according to  claim 1 , wherein the latter in addition has a cover layer, preferably in the form of an imprint and/or a metal coating, on at least one of the outside layers. 
   
   
       7 . Method of packaging a material which comprises: providing a multilayer plastic film, produced by co-extrusion, which consists of a) one or more plastic layer(s) ( 4 ,  4 ′) of partially crystalline polyolefin(s), uniform in its (their) structure), and b) at least one plastic layer ( 5 ), uniform in its structure, of amorphous cycloolefin copolymer, whereby the plastic layers a) and b) are in direct contact with one another, as packaging film for twist-wrap packagings; and wrapping the multilayer plastic film around the material. 
   
   
       8 . Method according to  claim 7 , provided that the plastic film consists of an inner layer ( 4 ) of polyolefin that is bilaterally uniform in its structure in each case, which has two outer layers ( 5 )—directly adjoining on both sides in each case—of cycloolefin copolymer that is uniform in its structure. 
   
   
       9 . Method according to  claim 8 , provided that at least one additional layer ( 6 ) of a partially crystalline polyolefin that is uniform in its structure in each case directly adjoins the outer layers ( 5 ). 
   
   
       10 . Method according to  claim 7 , provided that the plastic film has an inner layer ( 8 ) of partially crystalline polyolefin that is uniform in its structure, which, bilaterally adjoining in its structure, has different polyolefin layers ( 7 ) in this respect and provided that amorphous cycloolefin copolymer layers ( 5 ), which are bilaterally uniform in their structure in each case, directly adjoin this three-layer structure ( 4 ′). 
   
   
       11 . Method according to  claim 7 , provided that as polyolefins, polypropylene, or polyethylene are used, preferably in the form of homo-PP, random-PP or LLDPE. 
   
   
       12 . Method according to  claim 7 , provided that the plastic film in addition has at least one cover layer, preferably in the form of an imprint and/or a metal coating.