| 摘要 |
A plastic zipper including a male hook and a pair of female hooks that are engaged with each other to form a combination thereof. In the plastic zipper, when an opening force is applied to the plastic zipper from an opening side thereof, the pair of female hooks is provided on a flange, a portion of which, being defined by base portions of two female hooks on an opening and content side, becomes flexible. The plastic zipper is favorably used for containers for packaging, since it permits resistance to opening on the opening side to consistently hold a low value of from about 0.9 kg/5 cm to about 1.2 kg/5 cm while permitting resistance to opening on the content side to hold an enough strength of from about 7 kg/5 cm to about 8 kg/5 cm, permits the resistance to opening on both opening and content sides to remain within a specified range of resistance to opening even after opening/closing operations have been executed 100 times or more and, further, avoids a problem of a resin becoming brittle by a low temperature that would cause a problem in the engagement, and avoids an engagement function becoming inoperable after several times of opening/closing operations at an elevated temperature.
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