| 摘要 |
A flexible zipper incorporating a layer of gas-impermeable thermoplastic material in one or both flanges. The zipper is installed in the mouth of a reclosable package or bag made of gas-impermeable material shaped to form a receptacle. The gas-impermeable web material of the receptacle and the layer of gas-impermeable material of the zipper form a substantially gastight enclosure for preserving the perishable contents of the package. Flexible zippers having a layer of gas-impermeable thermoplastic material joined to a layer of gas-permeable thermoplastic material are preferably manufactured by a coextrusion process. The resulting gas barrier inside the receptacle has a zone of preferential tearing.
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