| 摘要 |
PROBLEM TO BE SOLVED: To provide a bag with a zipper in which the engagement strength is rather increased when the internal pressure is applied to the bag. SOLUTION: In a zipper 2 in a bag body 1, a make zipper tape 3 achieves the heat seal 5 along its upper part and keeps a lower part in a free 3a condition. When the internal pressure is applied in this condition, the internal pressure is applied to a back side of the male zipper tape 3, and the free side 3a is inverted to the reverse side in a turned up manner, and a male part 4 is firmly pressed against a female part 7 to firmly engage the make part 4 with the female part 7.
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