Pattern Laminated Double Wall Hot Formable Plastic Web With Enhanced Puncture Resistance

Abstract

The present disclosure is concerned with thermoformable webs with improved puncture resistance suitable for use in semi-automatic horizontal form fill and seal (HFFS) packaging machines and a process for packaging hard food items with sharp angular surfaces using such webs in such machines. The webs have a double wall partially laminated structure. The structure is conveniently formed by adhesively laminating two component films in a face to face configuration using a pattern of adhesive which leaves a substantial portion of the two facing surfaces unlaminated. The lamination just needs to be sufficient that the two component films will hot form together when they are vacuum drawn into a die to form a cavity for packaging the food items. The lamination pattern can vary from just edge strips to the edge strips and a honey comb pattern or a pattern of dots over the facing surfaces between the edge strips.

What is claimed is: 
     
         1 . A double wall partially laminated hot formable web with enhanced puncture resistance comprising two independently manufactured thermoplastic films, each capable of forming a product containing cavity upon being heated and drawn into a mold, said films being partially laminated to each other such that
 a. a substantial portion of the surfaces of the two films facing each other are unlaminated;   b. the laminate is capable of forming a product containing cavity upon being heated and drawn into a mold; and   c. the unlaminated surface of one of said films is heat sealable.   
     
     
         2 . The web of  claim 1  wherein the web can be deep drawn. 
     
     
         3 . The web of  claim 1  wherein the two films are adhesively laminated. 
     
     
         4 . The web of  claim 1  wherein less than 50% of said surfaces are laminated to each other. 
     
     
         5 . The web of  claim 3  wherein the adhesive is present in a repeating pattern. 
     
     
         6 . The web of  claim 5  wherein said pattern is a honeycomb or spaced apart circles. 
     
     
         7 . The web of  claim 1  wherein at least one of said films includes an oxygen barrier. 
     
     
         8 . The web of  claim 1  wherein the structures of the two films are identical. 
     
     
         9 . The web of  claim 7  wherein both of said films includes an oxygen barrier. 
     
     
         10 . The web of  claim 1  wherein the surfaces of said films which face each other are heat sealable. 
     
     
         11 . The web of  claim 1  wherein each of said independently formed films is between about 2 and 24 mil thick. 
     
     
         12 . The web of  claim 10  wherein each of said independently formed films is between about 4 and 20 mil thick. 
     
     
         13 . The web of  claim 1  wherein the adhesive joining said independently formed films is between about 2 and 5 microns thick. 
     
     
         14 . A process for packaging hard food items with sharp angular surfaces in hot drawn pouches comprising:
 a. Providing a double wall partially laminated hot formable web with enhanced puncture resistance comprising two independently manufactured thermoplastic films, each capable of forming a product containing cavity upon being heated and drawn into a mold, said films being partially laminated to each other such that
 i. a substantial portion of the surfaces of the two films facing each other are unlaminated; 
 ii. the laminate is capable of forming a product containing cavity upon being heated and drawn into a mold; and 
 iii. the unlaminated surface of one of said films is heat sealable; 
   b. heating a portion of said double wall web to a forming temperature;   c. forming said portion of said double wall web into an open mouth cavity to accommodate the hard food items to be packaged;   d. placing said hard food items into said cavity;   e. covering the mouth of said cavity with a web of thermoplastic film;   f. evacuating the interior of said cavity;   g. heat sealing a portion of said covering web of thermoplastic film to said portion of said double wall web which forms said cavity to seal said open mouth; and   h. isolating said sealed package from the remainder of said double wall web and from the remainder of said covering web of thermoplastic film.   
     
     
         15 . The process of  claim 14  wherein the cavity forming step is a deep drawing step. 
     
     
         16 . The process of  claim 14  wherein said films are adhesively laminated to each other. 
     
     
         17 . The process of  claim 14  wherein said hard food items are bones or meat products containing exposed bone. 
     
     
         18 . The process of  claim 14  wherein the packaged food items also contain liquid. 
     
     
         19 . The process of  claim 14  wherein one of the films forming said double wall web includes an oxygen barrier. 
     
     
         20 . The process of  claim 19  wherein both of the films forming said double wall web includes an oxygen barrier. 
     
     
         21 . The process of  claim 14  wherein the surfaces of the films forming said double wall web which face each other are heat sealable. 
     
     
         22 . The process of  claim 14  wherein said covering web of thermoplastic film is also a partially laminated double wall web.