| 摘要 |
A plastic film sack having gussetted side walls, and in the bottom of said sack, a heat-seal stripe welding together the four film layers in the gusseted regions of the sack and a heat seal stripe welding together the two film layers between said gusseted regions; and between the heat-seal stripes of the four film layers and the heat-seal stripe of the two film layers are unsealed, arcuate stress-relief regions and the method of forming the same.
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