摘要 |
<p>The invention relates to a close sack with a tubular mantle with an air-permeable inner layer (1) of paper, outside of which a separate air-impermeable barrier layer (2) and outside of that an outer layer (3) of paper. Both ends of the mantle have a plane bottom, one of which has a filling valve (12) on its end. During the filling of the sack, air flows from the sack to the area between the inner layer (1) and the barrier layer (2) and is allowed to escape from between the layers in the bottom to the area between the side flaps (5.1, 5.2) and out from there through the ends of the bottom. The sack can have a completely intact barrier film yet air exhaustion is efficient. The bottom glueing is nevertheless as tight as possible.</p> |