Biodegradable bags for packing foods available in high speed production

Abstract

It is an object of the present invention to provide a biodegradable bag for packing a food capable of storing a food such as a snack food which is required to have an oxygen barrier property and a water vapor barrier property, which can be produced at a high speed by a bag making and packaging machine, which can be degraded by naturally occurring microorganisms in soil or water finally to a non-hazardous degradation product, which can be biorecycled, and which is not accumulated in nature. The present invention is directed to a biodegradable bag for packing a food, which comprises a laminated film obtainable by laminating in the following order; a sealant layer comprising a biodegradable polymer; a barrier layer having an oxygen barrier property and a water vapor barrier property; and a barrier layer-supporting substrate layer comprising a biodegradable polymer, said laminated film being heat-sealed in order for the sealant layer to be inside.

1 . A biodegradable bag for packing a food, 
 which comprises a laminated film obtainable by laminating in the following order;    a sealant layer comprising a biodegradable polymer;    a barrier layer having an oxygen barrier property and a water vapor barrier property; and    a barrier layer-supporting substrate layer comprising a biodegradable polymer,    said laminated films being heat-sealed in order for the sealant layer to be inside.    
     
     
         2 . The biodegradable bag for packing a food according to  claim 1 , 
 wherein the sealant layer is a non-oriented film layer comprising a biodegradable polymer with the melting point of 120° C. or below.    
     
     
         3 . The biodegradable bag for packing a food according to  claim 1  or  2 , 
 wherein the sealant layer is formed by laminating a biodegradable polymer via an extrusion molding onto a barrier layer supported by a barrier layer-supporting substrate layer.  
 
     
     
         4 . The biodegradable bag for packing a food according to any of  claims 1  to  3 , 
 wherein the barrier layer is formed by means of a vapor deposition of a ceramic and/or a metal.  
 
     
     
         5 . The biodegradable bag for packing a food according to  claim 4 , 
 wherein the barrier layer is a single component vapor deposition layer comprising at least one selected from the group consisting of SiO x , Al 2 O 3  and Al, or a dual component vapor deposition layer comprising at least one combination of two components selected from the group consisting of SiO x /Al 2 O 3 , SiO x /ZnO, SiO x /CaO, SiO x /B 2 O 3  and CaO/Ca(OH) 2  and has a thickness of 1500 angstrom or less.    
     
     
         6 . The biodegradable bag for packing a food according to any of  claims 1  to  5 , 
 wherein the barrier layer-supporting substrate layer comprises a biaxial oriented film of a biodegradable polymer.  
 
     
     
         7 . The biodegradable bag for packing a food according to  claim 6 , 
 wherein the barrier layer-supporting substrate layer comprises a biaxial oriented film of a biodegradable polymer with the melting point of 150° C. or higher.    
     
     
         8 . The biodegradable bag for packing a food according to any of  claims 1  to  8 , 
 wherein the laminated film further comprises a paper substrate layer made of a paper outside the barrier layer-supporting substrate layer.  
 
     
     
         9 . The biodegradable bag for packing a food according to  claim 8 , 
 wherein the barrier layer-supporting substrate layer is formed by laminating a biodegradable polymer via an extrusion molding onto a paper substrate layer.    
     
     
         10 . The biodegradable bag for packing a food according to  claim 8 , 
 which is obtainable by extruding a biodegradable polymer onto the paper substrate layer to effect a lamination whereby forming the barrier layer-supporting substrate layer, followed by effecting a vapor deposition of a ceramic and/or a metal onto the barrier layer-supporting substrate layer to form the barrier layer, followed by laminating the sealant layer via a biodegradable adhesive onto the barrier layer.    
     
     
         11 . The biodegradable bag for packing a food according to  claim 8 , 
 which is obtainable by laminating a biaxial oriented film of a biodegradable polymer via a biodegradable adhesive onto the paper substrate layer whereby forming the barrier layer-supporting substrate layer, followed by effecting a vapor deposition of a ceramic and/or a metal onto the barrier layer-supporting substrate layer to form the barrier layer, followed by laminating the sealant layer via a biodegradable adhesive onto the barrier layer.    
     
     
         12 . The biodegradable bag for packing a food according to any of  claims 8  to  11 , 
 wherein the thickness of the sealant layer is 5 to 50 mm, the thickness of the barrier layer is 300 to 1500 angstrom, the thickness of the barrier layer-supporting substrate layer is 5 to 20 mm and the thickness of the paper substrate layer converted into a basis weight is 15 to 100 g/m 2 .  
 
     
     
         13 . The biodegradable bag for packing a food according to any of  claims 8  to  12 , 
 which further comprises a printed layer comprising a biodegradable ink outside the paper substrate layer.  
 
     
     
         14 . The biodegradable bag for packing a food according to any of claims  1  to 13, 
 wherein the laminated film further comprises a print-protecting layer comprising a biodegradable polymer between the sealant layer and the barrier layer.  
 
     
     
         15 . The biodegradable bag for packing a food according to  claim 14 , 
 which is obtainable by effecting a vapor deposition of a ceramic onto the barrier layer-supporting substrate layer comprising a biaxial oriented film of a biodegradable polymer to form the barrier layer, followed by molding the print-protecting layer onto the barrier layer, followed by forming a printed layer onto the print-protecting layer, followed by laminating the sealant layer via a biodegradable adhesive onto the printed layer.    
     
     
         16 . The biodegradable bag for packing a food according to  claim 14  or  15 , 
 wherein the thickness of the sealant layer is 5 to 50 mm, the thickness of the print-protecting layer is 0.02 to 0.2 mm, the thickness of the barrier layer is 300 to 1500 angstrom, and the thickness of the barrier layer-supporting substrate layer is 5 to 20 mm.  
 
     
     
         17 . The biodegradable bag for packing a food according to any of  claims 1  to  16 , 
 which further comprises an adhesive layer comprising a biodegradable adhesive between respective layers.  
 
     
     
         18 . The biodegradable bag for packing a food according to any of  claims 1  to  17 , 
 which is used for packaging a snack food.  
 
     
     
         19 . A method for packing a food, 
 which comprises a back seal step. in which a laminated film obtainable by laminating in the following order;    a sealant layer comprising a biodegradable polymer;    a barrier layer having an oxygen barrier property and a water vapor barrier property; and    a barrier layer-supporting substrate layer comprising a biodegradable polymer is made tubular with the sealant layer being inside to bring the both back sides into contact and heat-sealed with each other,    a food introducing step in which a food is introduced to the inside of the tube of the laminated film, and    an end seal step in which the both ends of the tube of the laminated film containing the food are heat-sealed.