| 摘要 |
PURPOSE: To ensure that a predetermined opening part is torn apart even when the diameter of the opening part is large by a method wherein a thin wall part is provided at each diametrical end of the predetermined opening part and the one thin wall part is projected to a tab means and the other thin wall part near the tab means is projected outwardly. CONSTITUTION: A tab means 4 with a ring is integrally formed on the upper surface of a predetermined opening part 3 and a thin wall part 20 near the tab means 4 is convexly curved outwardly along the outer peripheral contour of a base part 41 of the tab means 4, whereby, when the tab means 4 is pulled up, the tensile strength is concentrated at the thin wall part. A vertex is formed between the lines inwardly extending from the circular line to the tab means 4 in a thin wall part 21 at the opposite end of the diameter (b) of the predetermined opening part 3 from the thin wall part 20. By pulling up the tab means 4, therefore, the tearing starts at the thin wall part 20 and is progressed easily even within the thin wall part 21. |
