Heat resistant foam-in-bag packaging

Abstract

The invention is a thermoplastic film having a heat resistant coating. The film is particularly useful in the preparation of bags and associated packaging systems that are used for protecting and packaging articles. Typically, the heat resistant coating has a melting range that is greater than the melting temperature of the thermoplastic film and exceeds the temperature of the heat generated during foam formation. As such, packaging films and bags that are prepared in accordance with the invention help prevent foam-in-bag cushions from fusing together. Particularly useful heat resistant coatings include ink varnishes and resins that are solvent-based, water-based, or energy cured.

1 . A sheet of thermoplastic film adapted for use in foam-in-place packaging, the film having a heat resistant coating having a self-adhesion temperature in the range from about 250° F. to 450° F. and wherein the coating substantially covers a surface of the film sufficient to reduce self-adhesion of the film at temperatures below the self-adhesion temperature of the coating so that the foam-in-placed packages formed therefrom are easily separated after the foam is formed.  
   
   
       2 . The film sheet according to  claim 1 , wherein the coating has a self-adhesion temperature in excess of about 275° F.  
   
   
       3 . The film sheet according to  claim 1 , wherein the coating comprises ink resin; ink varnish; a silicone release coating; polyvinyl alcohol; cellulose acetate butyrate; cellulose acetate propionate; or a crosslinked varnish.  
   
   
       4 . The film sheet according to  claim 1 , wherein the coating comprises a flexographic or gravure ink.  
   
   
       5 . The film sheet according to  claim 4 , wherein the ink coating is solvent-based, water-based, or energy cured.  
   
   
       6 . The film sheet according to  claim 5 , wherein the ink coating comprises a resin, varnish, or combination thereof that is comprised of urethanes, acrylics, carboxylated acrylics, nitrocellulose, ethyl cellulose, polyvinyl butryl, polyamides, polyimides, polyketones, or cellulose esters, or combinations thereof, acrylics, acrylates, urethane acrylics, acrylated or methacrylated prepolymers, acrylated oils, acrylated silicone oils, acrylated amines, soy protein, or combinations thereof.  
   
   
       7 . The film sheet according to  claim 1 , wherein the heat resistant coating contains silicone.  
   
   
       8 . The film sheet according to  claim 7 , wherein the silicone is present in an amount that is from 0.1 to 10% by weight relative to the total weight of the coating.  
   
   
       9 . The film sheet according to  claim 1 , wherein the thermoplastic material is polypropylene, high density polyethylene, low density polyethylene, linear low density polyethylene, ethylene vinyl acetate, ethylene methyl acrylate, ethylene ethyl acrylate, very low density polyethylene, ultra low density polyethylene, ionomers, polyurethane, polyvinyl chloride, or polybutylene, or copolymers or blends thereof.  
   
   
       10 . The film sheet according to  claim 1 , wherein the film is a continuous roll of heat resistant film.  
   
   
       11 . The film sheet according to  claim 1 , wherein the heat resistant coating has a coat weight from about 0.05 to 1 lb/ream.  
   
   
       12 . A sheet of thermoplastic film having a heat resistant coating substantially covering at least one surface of the film, the coating comprising a varnish, resin, or combination thereof having a self-adhesion temperature that is greater than the self-adhesion temperature of the film.  
   
   
       13 . A sheet of thermoplastic film according to  claim 12 , wherein the coating comprises a flexographic ink, gravure ink, or combination thereof.  
   
   
       14 . A sheet of thermoplastic film according to  claim 13 , wherein the coating comprises a solvent-based ink, water-based ink, energy cured ink, or a combination thereof.  
   
   
       15 . A sheet of thermoplastic film according to  claim 12 , wherein the coating has a self-adhesion temperature from about 250° F. to 450° F.  
   
   
       16 . A method of producing a heat resistant film comprising: 
 providing a sheet of thermoplastic film; and    applying a heat resistant coating to a surface of the film that substantially covers the surface, the heat resistant coating comprising an ink resin, ink varnish, or combination thereof, and wherein the film has a self-adhesion temperature of about 275° F. or less and the heat resistant coating has a self-adhesion temperature that is greater than the self-adhesion temperature of the film.    
   
   
       17 . The method according to  claim 16 , further comprising the step of printing the heat resistant coating onto a surface of the film.  
   
   
       18 . The method according to  claim 16 , further comprising one or more of the following steps: 
 curing the heat resistant coating after it has been applied to a surface of the film; or    evaporating a solvent component of the heat resistant coating.    
   
   
       19 . The method according to  claim 16 , wherein the heat resistant coating has a self-adhesion temperature that is from about 250° F. to 450° F.  
   
   
       20 . The method according to  claim 16 , wherein the heat resistant coating is capable of being crosslinked or thermoset to form a coating that is adhered to a surface of the film.