Bag or bag-forming material of a synthetic material for vacuum preservation of articles, particularly of foodstuffs

Abstract

The bag consists of two walls made from sheets of a multi-layer, synthetic material, welded together along part of the perimeter. One of the walls has two or three rectilinear, longitudinal rough stripes on its inner surface, obtained by hot-printing and extending substantially along the full length of the bag. The stripes are obtained by pressing a welding bar, coated with a rough, non-adhesive material, such as teflon cloth, against the multi-layer sheet forming the wall of the bag.

What is claimed is:  
     
         1 . A bag of a synthetic material for vacuum preservation of foodstuffs, comprising two walls joined along a peripheral welding line, wherein at least one of said walls has, on its inner surface, at least one rough stripe extending longitudinally and obtained by hot-printing.  
     
     
         2 . The bag of  claim 1 , wherein said at least one rough stripe extends substantially along the full length of the bag.  
     
     
         3 . The bag of  claim 1 , wherein said at least one rough stripe is substantially rectilinear.  
     
     
         4 . The bag of  claim 1 , wherein said at least one wall is provided with three of said rough stripes.  
     
     
         5 . The bag of  claim 1 , wherein said at least one rough stripe is obtained by pressing a welding bar having a welding surface coated with a rough, non-adhesive material, against the inner surface of said at least one wall.  
     
     
         6 . The bag of  claim 5 , wherein said rough, non-adhesive material is a teflon cloth.  
     
     
         7 . The bag of  claim 6 , wherein said teflon cloth has preferably 5 to 20 meshes/cm.  
     
     
         8 . The bag of  claim 6 , wherein said teflon cloth has 12 meshes/cm.  
     
     
         9 . The bag of  claim 1 , wherein the wall provided with rough stripes consists of a multi-layer sheet in which at least the most internal layer is compatible with foodstuffs.  
     
     
         10 . The bag of  claim 9 , wherein said most internal layer is made of polyethylene.  
     
     
         11 . The bag of  claim 1 , wherein the wall provided with rough stripes comprises an outer, multi-layer sheet and an inner, single-layer sheet made of a food-compatible material.  
     
     
         12 . The bag of  claim 11 , wherein said inner, single-layer sheet is polyethylene.  
     
     
         13 . The bag of  claim 11 , wherein said single-layer sheet is welded to the multi-layer sheet along the rough stripes.  
     
     
         14 . A tube of a synthetic material for vacuum preservation of articles, comprising two walls joined along opposite lateral welding lines, wherein at least one of said walls has, on its inner surface, at least one rough stripe extending longitudinally and obtained by hot-printing.