Methods and devices for processing polymer films

Abstract

Stretched polymeric films can be used in a variety of applications, including optical applications. The stretching conditions and shape of the stretching tracks in a stretching apparatus can determine or influence film properties. Take-away systems can be used to receive the film after stretching. The configuration of the take-away system can, in at least some instances, influence final film properties.

1 . An apparatus for processing a film, the apparatus comprising: 
 a conveyor configured and arranged to convey the film along a machine direction within the apparatus, the conveyor comprising gripping members that are configured and arranged to hold opposing edge portions of the film, and a portion of the conveyor is configured and arranged to provide diverging paths along which the gripping members move to stretch the film; and    an isolated take-away system that receives the film from the conveyor after stretching the film, the take-away system comprising opposing tracks and gripping members configured and arranged to grasp opposing take-away regions of the film after a desired amount of stretching and convey the opposing take-away regions of the film along the opposing tracks, wherein the opposing tracks define a region in which at least a portion of at least one of the opposing tracks is angled with respect to the machine direction.    
   
   
       2 . The apparatus of  claim 1 , wherein the opposing tracks are angled with respect to each other.  
   
   
       3 . The apparatus of  claim 2 , wherein the opposing tracks are angled toward each other.  
   
   
       4 . The apparatus of  claim 2 , wherein the opposing tracks are angled away from each other.  
   
   
       5 . The apparatus of  claim 2 , wherein the opposing tracks are angled with respect to each other along an entire length of the opposing tracks.  
   
   
       6 . The apparatus of  claim 2 , wherein the take-away system is disposed at an angle relative to the machine direction.  
   
   
       7 . The apparatus of  claim 1 , wherein the opposing tracks are disposed at an angle of at least 10 with respect to the machine direction.  
   
   
       8 . The apparatus of  claim 7 , wherein the opposing tracks are disposed at different angles with respect to the machine direction.  
   
   
       9 . The apparatus of  claim 7 , wherein the opposing tracks of the take-away system are configured and arranged to grasp the opposing take-away regions of the film at a position in which the opposing take-away regions of the film have a same transverse directional draw ratio.  
   
   
       10 . The apparatus of  claim 7 , wherein the opposing tracks of the take-away system are configured and arranged to grasp the opposing take-away regions of the film at a position in which the opposing take-away regions of the film have different transverse directional draw ratios.  
   
   
       11 . The apparatus of  claim 7 , wherein the diverging paths of the conveyor are configured and arranged to stretch the film so that a centerline of the film is angled with respect to a machine direction of the conveyor prior to stretching the film.  
   
   
       12 . An apparatus for processing a film, the apparatus comprising: 
 a conveyor comprising gripping members that hold opposing edge portions of the film and convey, under influence of a drive member, the film along a machine direction within the apparatus, wherein a portion of the conveyor is configured and arranged to provide diverging paths along which the gripping members move to stretch the film; and    an isolated take-away system that receives the film from the conveyor after stretching the film, the take-away system comprising opposing tracks and a plurality of gripping members configured and arranged to grasp opposing take-away regions of the film after a desired amount of stretching and convey the opposing take-away regions of the film along the opposing tracks, wherein the apparatus is configured and arranged to allow selection of a final transverse direction draw ratio of the film by changing a position of the isolated take-away system with respect to a position of the conveyor.    
   
   
       13 . An apparatus for processing a film, the apparatus comprising: 
 a conveyor configured and arranged to convey the film along a machine direction, the conveyor comprising gripping members that are configured and arranged to hold opposing edge portions of the film;    a stretching region in which the gripping members are configured and arranged to travel along diverging paths to stretch the film; and    a post-conditioning region disposed after the stretching region and comprising at least one zone in which the gripping members are configured and arranged to travel along converging paths.