| 摘要 |
<p>A bag, made of a gastight foil, esp. plastic for packaging of food, is equipped with a vent valve. This consists pref. of two strips with their outsides coated by a hot seal layer which is bonded to the foil by the application of pressure and temp. This allows CO2 or other gases, which may affect the durability of the food, to escape but prevents the ingress of air.</p> |
