| 摘要 |
<p>A block form very convenient for stacking is easily taken up by a composite sack with a filling valve on its outside, when it is filled. The sack is formed from a tubular film of e.g. polyethylene enclosed by an outer sack which may be of a woven material such as jute or be of strands of polypropylene welded together. The edges of the two materials where they come into contact are bonded together, and at least the bottom corner of the sack on the opposite side to the filling valve has a triangular section folded over and bonded to the envelope or is folded and turned inside the sack.</p> |
