Heat Shrink Film with Increased Tear Strength

Abstract

This invention provides a process and apparatus for folding the film edges of a heat shrink film to create an overlap whereby the tear strength of openings in a bundle wrapped with heat shrink film.

1 . A process for increasing the tear resistance of a heat shrunk film at the opening at the sides of a film wrapped bundle comprising,
 forming an edge folded heat shrink film while the film is moving by lifting the edges of the film upward to establish a fold point and then folding the lifted edges to overlap the film.   pressing the film to lower the position of the film to establish a desired width of the overlap,   film wrapping the bundle, and   heat shrinking the film wrapping the bundle.   
     
     
         2 . A process according to  claim 1  including electrostatic sealing of the folded edges to maintain the fold in a proper position. 
     
     
         3 . A process according to  claim 1  where the bundle is film wrapped. 
     
     
         4 . A process according to  claim 3  wherein the film wrapped bundle is conveyed to a heat shrink tunnel where the film is heat shrunk. 
     
     
         5 . A process for increasing the tear resistance of a heat shrunk film at the opening located at the sides of a film wrapped article or a bundle of articles comprising,
 forming an edge folded heat shrink film while the film is moving on a twisted plate that lifts the edges of the film upward to establish a fold point and then folds the lifted edges to overlap the film.   film wrapping the bundle. and   heat shrinking the film wrapping the bundle.   
     
     
         6 . A process according to  claim 5  includes pressing the film to lower the position of the film to change the width of the overlap. 
     
     
         7 . An apparatus for increasing the tear resistance of heat shrunk film wrapped around bundle by creating a folded edge comprising,
 means for moving a heat shrink film,   means for lifting the edges of the moving film and folding the edge,   means for establishing the width of the fold by lowering the position of the film while it is being lifted and folded,   means for film wrapping the bundle with the heat shrink film having folded edges, and   means for heat shrinking the film wrapping the bundle.   
     
     
         8 . An apparatus according to  claim 7  having means to maintain the fold in its proper position. 
     
     
         9 . An apparatus according to  claim 8  wherein a static seal is used to maintain the fold in its proper position. 
     
     
         10 . An apparatus according to  claim 7  wherein a twisted plate is used for lifting the edges of the moving film 
     
     
         11 . An apparatus according to  claim 7  wherein a film folding roller establishes the width of the fold by lowering the position of the film while it is being lifted and folded. 
     
     
         12 . An apparatus according to  claim 7  wherein a heat shrink tunnel heat shrinks the film. 
     
     
         13 . An apparatus for increasing the tear resistance of heat shrunk film wrapped around bundle by creating a folded edge comprising,
 means for moving a heat shrink film   means for lifting the edges of the moving film and folding the edges,   means for film wrapping the bundle with the heat shrink film having folded edges, and   means for heat shrinking the film wrapping the bundle.   
     
     
         14 . An apparatus according to  claim 13  wherein the means for lifting the edges of the moving film and folding the edges is a twisted plate.