Film suitable for food packaging

Abstract

Controlled permeability films are described that comprise at least on film-forming polymer and an inert, nonporous filler material having an average particle size such that the ratio of the average particle size of the filler to the film thickness is 0.67 to 0.99. Packages comprising such a controlled permeability film, and methods for making the film and using it to improve the storage life of a perishable article are also described.

1 . A controlled permeability film comprising: 
 A. A polymeric film (i) made from a film-forming polymer, and (ii) having an intrinsic thickness, and    B. A nonporous, inert, particulate filler (ii) incorporated into the film at a weight percent, based on the combined weight of the filler and the film-forming polymer, between about 0.01 and about 8, and (ii) having an average particle size such that the ratio of the average particle size of the filler to the film thickness is 0.67 to 0.99, the film having been subjected to a compressive force sufficient to crush at least a portion of the particulate filler.    
   
   
       2 . (canceled)  
   
   
       3 . (canceled)  
   
   
       4 . (canceled)  
   
   
       5 . (canceled)  
   
   
       6 . (canceled)  
   
   
       7 . (canceled)  
   
   
       8 . The film of  claim 1  having a beta ratio of 0.5 to 2.5.  
   
   
       9 . (canceled)  
   
   
       10 . The film of  claim 1  having an intrinsic film thickness of 10 to 125 microns.  
   
   
       11 . The film of  claim 1  having a monolayer construction.  
   
   
       12 . The film of  claim 1  having a multilayer construction in which filler is incorporated into a single layer.  
   
   
       13 . The film of  claim 1  having a multilayer construction in which the filler is incorporated into at least two layers.  
   
   
       14 . (canceled)  
   
   
       15 . The film of  claim 1  in which the filler is a spherulitic mineral.  
   
   
       16 . The film of  claim 1  in which the filler is a silicaeous material.  
   
   
       17 . The film of  claim 1  in the form of a bag or a pouch.  
   
   
       18 . A package comprising the controlled permeability film of  claim 1 .  
   
   
       19 . A method of improving the storage life of a perishable article comprising packaging the article with a controlled permeability film of  claim 1 .  
   
   
       20 . (canceled)  
   
   
       21 . (canceled)  
   
   
       22 . The film of  claim 1  in which the filler comprises from about 0.05 to about 6 weight percent of the film.  
   
   
       23 . The film of  claim 1  having a beta ratio of 1.5 to 3.5.  
   
   
       24 . A method of making a controlled permeability film, the method comprising: 
 A. Blending at least one film-forming polymer with about 0.01 to about 8 weight percent of an inert, nonporous particulate filler having an average particle size, the weight of the filler based on the combined weight of the film-forming polymer and filler;    B. Forming a film from the blend of (A) with an intrinsic thickness such that the ratio of the average particle size of the filler to the film thickness is 0.67 to 0.99, and    C. Subjecting the film of (B) to a compressive force sufficient to crush at least a portion of the particulate filler.    
   
   
       25 . The method of  claim 24  in which the particulate filler is crushed at an elevated temperature.  
   
   
       26 . The method of  claim 24  in which the particulate filler is crushed at a temperature between about 10 and about 15 degrees C. below the melting point of the highest melting point polymer from which the film is made.