| 摘要 |
<p>PURPOSE:To realize the simplification of packaging process and the reduction of the costs of the packaging material, by forming a small hole in a top film and sealing the top and bottom films together around said hole in a means for automatically forming the hole in the package during heating by an electronic oven. CONSTITUTION:In a deep drawn vacuum packaging operation, a top film with a small hole 1 formed at the central portion thereof is heat sealed to a bottom film around the hole to form a vapor escaping opening seal 2 and, when the package thus formed is heated by a microwave oven, the vapor releasing opening seal 2 at the central portion thereof becomes swollen into a doughnut form and the top and bottom films are thereafter partially separated in the aforesaid opening seal area, thereby expelling the vapor from the interior of the package to the outside through the small hole 1. Further heating leads to a complete separation of the top and bottom films at the vapor releasing opening seal 2 and the shaped of the package becomes pillow-like but the vapor will not release from an outer edge seal 3, thereby obtaining an inexpensive packaged article from which the contents such as juice will not leak out.</p> |
