Bag wall, bag tube and bag produced therefrom and method for producing them

Abstract

A bag wall is designed for producing a bag open on a top side by means of at least a connection seam and for closing said bag by means of at least one further connecting seam after being filled with bulk material and is characterized by at least one Kraft paper layer forming a Kraft paper core (1) and essentially determining the load capacity of the bag which core (1) is provided with fine openings (2) in two-dimensional regions covering at least half of the surface of said core (1) and is directly coated on both sides with a plastic layer (3, 4) each wherein both plastic layers consist of plastic material being miscible in liquid states and wherein the plastic layers (3, 4) are connected to each other by material fit through said openings (2) during the coating.

1 . A bag wall designed for producing a bag open on a top side by means of at least a connection seam and for closing said bag by means of at least one further connecting seam after being filled with bulk material, wherein at least one Kraft paper layer forming a Kraft paper core and essentially determining the load capacity of the bag which core is provided with fine openings in two-dimensional regions covering at least half of the surface of said core and is directly coated on both sides with a plastic layer each wherein both plastic layers consist of plastic material being miscible in liquid states and wherein the plastic layers are connected to each other by material fit through said openings during the coating. 
     
     
         2 . The bag wall according to  claim 1 , wherein the openings are distributed over the whole surface of the Kraft paper core. 
     
     
         3 . The bag wall according to  claim 1 , wherein the openings are distributed uniformly over the surface of the Kraft paper core. 
     
     
         4 . The bag wall according to  claim 1 , wherein the openings form a pattern wherein a distance between an opening and an adjacent opening is between 3 and 100 mm, especially between 5 and 50 mm. 
     
     
         5 . The bag wall according to  claim 1 , wherein the openings form a regular pattern which repeats within the two-dimensional region of the surface of the core. 
     
     
         6 . The bag wall according to  claim 1 , wherein the Kraft paper core has a grammage of 70 to 120 g/m 2  and the plastic layers each have a coating weight per unit area of 10 to 30 g/m 2 . 
     
     
         7 . The bag wall according to  claim 1 , wherein the plastic layer designed for the inner side of the bag has a higher coating weight per unit area than the plastic layer designed for the outer side of the bag. 
     
     
         8 . The bag wall according to  claim 1 , wherein at least one plastic layer, preferably both plastic layers, consists of polyethylene. 
     
     
         9 . The bag wall according to  claim 1 , wherein the largest dimension of each opening is between 0.5 and 2 mm. 
     
     
         10 . A method for producing a bag wall wherein a Kraft paper core essentially determining the stability of the bag wall is provided on its whole surface with numerous openings and that the Kraft paper layer is coated on both sides with a plastic layer each in liquid states of the plastics so that the plastic layers are connected with each other through the openings by material fit. 
     
     
         11 . A bag tube formed from a bag wall according to  claim 1  by means of at least one longitudinal seam connecting together longitudinal end portions of the flat bag wall so as to form the tube. 
     
     
         12 . The bag tube according to  claim 11 , wherein the longitudinal seam is a weld seam. 
     
     
         13 . A use of a bag wall according to  claim 1 , wherein a web of the bag wall is formed by means of a longitudinal seam or a folding, a bag open at a top is formed from the web by means of at least one seam and a bag section is separated by a cutting line, the bag open at the top is then filled with bulk material and closed after filling by means of at least one further seam. 
     
     
         14 . The use according to  claim 13 , wherein at least one seam is a weld seam and positioned in a region having openings.