Packaging laminate for a retortable packaging container

Abstract

A packaging laminate for a retortable packaging container can include a core layer; outer, liquid-tight coatings; and an aluminium foil serving as gas barrier between the core layer and one of the two outer liquid-tight coatings. The packaging laminate can include at least one additional layer serving as gas barrier between the core layer and the aluminium foil. The additional gas barrier layer can be bonded to the core layer by an interjacent lamination or adhesive layer.

1 . A method of producing a packaging laminate for a retortable packaging container, comprising: 
 forming at least one gas barrier layer over a first side of a core layer;    forming at least one adhesive layer of polypropylene between the first side of the core layer and the at least one gas barrier layer so as to bond the core layer to the at least one gas barrier layer; and    forming a first outer liquid-tight coating over the at least one gas barrier layer.    
   
   
       2 . The method of  claim 1 , wherein the core layer is formed of paper or paperboard.  
   
   
       3 . The method of  claim 1 , wherein the at least one gas barrier layer is formed of ethylene vinyl alcohol copolymers (EVOH).  
   
   
       4 . The method of  claim 1 , wherein the at least one gas barrier layer is formed of a material selected from the group consisting of polyethylene terephthalate (PET), amorphous polyethylene terephthalate (APET), cyclic olefin copolymers (COC), polyamide (PA), amorphous polyamide (APA), liquid crystalline polymers (LCP), and polyvinyl alcohol (PVOH).  
   
   
       5 . The method of  claim 1 , wherein the quantity or thickness of the at least gas barrier layer is 10-30 g/m 2 .  
   
   
       6 . The method of  claim 1 , wherein the quantity or thickness of the at least one gas barrier layer is 5-20 g/m 2 .  
   
   
       7 . The method of  claim 1 , further comprising: 
 forming an aluminum foil between the at least one gas barrier layer and the first outer liquid-tight coating; and    forming a second outer liquid-tight coating over a second side of the core layer.    
   
   
       8 . The method of  claim 1 , wherein the first outer liquid-tight coating is formed of a mixture of polypropylene and polyethylene.  
   
   
       9 . The method of  claim 1 , which comprises forming more than one adhesive layer of polypropylene between the first side of the core layer and the at least one gas barrier layer.  
   
   
       10 . The method of  claim 1 , further comprising fold forming and sealing the packaging laminate to produce a packaging container, the first outer liquid-tight coating forming an inner surface of the packaging container.  
   
   
       11 . The method of  claim 10 , further comprising: 
 filling the packaging container; and    heat treating the filled packaging container in a retort to extend the shelf life of the contents of the packaging container.    
   
   
       12 . A method of producing a packaging laminate for a retortable packaging container, comprising: 
 forming at least one gas barrier layer of ethylene vinyl alcohol copolymers (EVOH) over a first side of a core layer;    forming at least one adhesive layer of polypropylene between the first side of the core layer and the at least one gas barrier layer so as to bond the at least one gas barrier layer to the core layer;    forming an aluminum foil over the at least one gas barrier layer;    forming a first outer liquid-tight coating over the aluminum foil layer; and    forming a second liquid-tight coating over a second side of the core layer.    
   
   
       13 . The method of  claim 12 , wherein the core layer is formed of paper or paperboard.  
   
   
       14 . The method of  claim 12 , wherein the quantity or thickness of the at least gas barrier layer is 10-30 g/m 2 .  
   
   
       15 . The method of  claim 12 , wherein the quantity or thickness of the at least one gas barrier layer is 5-20 g/m 2 .  
   
   
       16 . The method of  claim 12 , which comprises forming more than one adhesive layer of polypropylene between the first side of the core layer and the at least one gas barrier layer.  
   
   
       17 . The method of  claim 12 , wherein the first outer liquid-tight coating is formed of a mixture of polypropylene and polyethylene.  
   
   
       18 . The method of  claim 12 , further comprising fold forming and sealing the packaging laminate to produce a packaging container, the first outer liquid-tight coating forming an inner surface of the packaging container.  
   
   
       19 . The method of  claim 18 , further comprising: 
 filling the packaging container; and    heat treating the filled packaging container in a retort to extend the shelf life of the contents of the packaging container.