| 摘要 |
<p>A packing container e.g. for sterile milk is manufactured from laminated material which is folded and sealed to the desired container shape. In the seal, cut surfaces facing towards the inside will occur which have to be sealed so as to prevent the central paper layer of the material from absorbing some of the contents. Usually this is done by means of a strip of a plastic material which is impermeable to liquid. When the packing material is sterilized and exposed to high temperatures these strips are often damaged, because the moisture present in the paper layer of the laminate is converted into vapor and penetrates the strip softened by the heat. In accordance with the invention the seal is now ventilated with the help of ducts extending through the seal in such a manner that the vapor can escape to the surrounding air without affecting the sealing strip which thus remains intact and can fulfil its intended sealing function.</p> |
