Flat-bottomed multi-layer sack - has inner layer sealed at ends by welding intermediate layer

摘要

The flat-bottomed sack has multi-layer walls of foldable material, the base and top each being closed by end envelopes enclosing both walls and glued to one of them. The sack layers enclosing the inner layer are offset from each other, the outermost layer protruding in relation to the inner layer and one or more intermediate layers. The outer layer glued to the envelope is set back from the inner and intermediate layers and the inner layer is sealed by welds at the ends inside the envelopes. The inner layer(1) is of a material whose electrical surface resistance on the inside is 108 Ohms maximum, and at both ends the intermediate layer(4) extends past it.