| 摘要 |
A bag of the type having a side and a closed end which adjoin at corner portions which are turned inwardly to form a valve opening. The bag is made of a thermoplastic material, and a flap of thermoplastic material is secured around the interior of the valve opening by heat sealing. The heat sealed regions are arranged to form, in addition to the valve opening, a vent passageway system for quickly venting air from the bag during and immediately subsequent to filling. The flap is relatively flexible and projects into the bag beyond the valve opening to effectively close the valve opening and prevent loss of contents after the bag has been filled. In one form, the flap is formed with a cuff which projects exteriorly of the valve opening and has interior surfaces heat sealable to provide a moistureproof closure for the opening.
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