Heat sealable food packaging films, methods for the production thereof, and food packages comprising heat sealable food packaging films

Abstract

Heat sealable food packaging films, methods for the production thereof, and food packages comprising heat sealable food packaging films are provided. The heat sealable food packaging film includes a humidity-dependent permeable film having a moisture vapor transmission rate that increases with an increase in relative humidity (RH). An outer coating comprises a coating material on at least one surface of the humidity-dependent permeable film. The coating material is selected from a nanoclay dispersed in a poly-vinylidene chloride (PVdC) polymer or a stretchable urethane polymer, a stretchable acrylic polymer, or a combination of stretchable urethane polymer and stretchable acrylic polymer. The coating material may further comprise an anti-blocking agent. The heat sealable food packaging film is biaxially oriented.

1 . A heat sealable food packaging film comprising:
 a humidity-dependent permeable film; and   an outer coating comprising a coating material on at least one surface of the humidity-dependent permeable film, the coating material selected from a nanoclay dispersed in a poly-vinylidene chloride (PVdC) polymer, a stretchable urethane polymer, a stretchable acrylic polymer, or a combination of stretchable urethane polymer and stretchable acrylic polymer.   
     
     
         2 . The heat sealable food packaging film of  claim 1 , wherein the humidity-dependent permeable film comprises a nylon film, a polylactic acid film, or a reconstituted cellulose film. 
     
     
         3 . The heat sealable food packaging film of  claim 1 , wherein the nanoclay content of the coating material is in an amount of from about 0.2 wt % to about 5 wt % of the PVdC polymer. 
     
     
         4 . The heat sealable food packaging film of  claim 1 , wherein the coating material is applied to the humidity-dependent permeable film using an emulsion, the emulsion having about 15 wt % to about 50 wt % solids content. 
     
     
         5 . The heat sealable food packaging film of  claim 4 , wherein the coating material further comprises an anti-blocking agent in an amount of about 0.25 wt % to about 5.0 wt % of the solids content of the emulsion. 
     
     
         6 . The heat sealable food packaging film of  claim 5 , wherein the coating material further comprises an anti-fog composition in an amount of from about 0.5 wt % to about 2.0 wt % of the solids content of the emulsion. 
     
     
         7 . A method for producing a heat sealable food packaging film comprising:
 providing a humidity-dependent permeable film;   coating at least one surface of the humidity-dependent permeable film with a coating material to provide a coated film, the coating material selected from a nanoclay dispersed in a poly-vinylidene chloride (PVdC) polymer, a stretchable urethane polymer, a stretchable acrylic polymer, or a combination of stretchable urethane polymer and stretchable acrylic polymer; and   biaxially orienting the coated film; and   
       wherein the coating material is adapted to form an outer coating. 
     
     
         8 . The method of  claim 7 , wherein the step of providing a humidity-dependent permeable film comprises providing a nylon film, a polylactic acid film, or a reconstituted cellulose film. 
     
     
         9 . The method of  claim 7 , wherein the step of coating at least one surface of the humidity-dependent permeable film with a coating material comprising a nanoclay dispersed in a PVdC polymer wherein the nanoclay is dispersed in an amount of from about 0.2 wt % to about 5 wt % of the PVdC polymer. 
     
     
         10 . The method of  claim 7 , wherein the step of coating comprises coating the at least one surface of the humidity-dependent permeable film using an emulsion, the emulsion having about 15 wt % to about 50 wt % solids content. 
     
     
         11 . The method of  claim 10 , wherein the step of coating comprises coating the at least one surface of the humidity-dependent permeable film with the coating material further comprising an anti-blocking agent in an amount of about 0.25 wt % to about 5.0 wt % of the solids content of the emulsion. 
     
     
         12 . The method of  claim 11 , wherein the step of coating comprises coating the humidity-dependent permeable film with a coating material further comprising an anti-fog composition in an amount of from about 0.5 wt % to about 2.0 wt % of the solids content of the emulsion. 
     
     
         13 . The method of  claim 7 , wherein the step of biaxially orienting the coated film comprises biaxially orienting to a draw ratio of from about 2.6 to about 3 in each of its machine (longitudinal) direction and transverse direction. 
     
     
         14 . The method of  claim 7 , wherein the step of biaxially orienting the coated film comprises biaxially orienting at an elevated temperature of about 190° C. to about 220° C. 
     
     
         15 . The method of  claim 7 , wherein the step of biaxially orienting the coated film comprises reducing the final coat weight by a stretch factor from about 7.5 to about 10. 
     
     
         16 . The method of  claim 7 , further comprising the step of heat setting the coated film prior to biaxially orienting the coated film. 
     
     
         17 . The method of  claim 16 , wherein the step of heat setting the coated film comprises heating the coated film to temperatures between about 65° C. to about 120° C. for about 2 seconds to about 30 seconds. 
     
     
         18 . A food package comprising:
 a heat sealable food packaging film comprising:
 a humidity-dependent permeable film; and 
 an outer coating comprising a coating material on at least one surface of the humidity-dependent permeable film, the coating material selected from a nanoclay dispersed in a poly-vinylidene chloride (PVdC) polymer, a stretchable urethane polymer, a stretchable acrylic polymer, or a combination of stretchable urethane polymer and stretchable acrylic polymer; and 
   wherein the heat sealable food packaging film is heat sealed to form the food package.   
     
     
         19 . The food package of  claim 18 , wherein the coating material further comprises an anti-blocking agent. 
     
     
         20 . The food package of  claim 18 , further comprising a container having an open portion and the heat sealable food packaging film sealing the open portion.