Valved sack

摘要

A sack is constructed from a thermoplastic film of which the side portions are brought into partial overlapping relationship to define a tube section and top and bottom weld seams are applied transversely. A longitudinal weld seam applied within the confines of the region of overlap terminates at a spacing from the top weld seam to define a filling valve passage. The region of overlap contains a longitudinal inner strip of reduced thickness made in one piece with the walls of the sack.