| 摘要 |
PROBLEM TO BE SOLVED: To make opening of an inner stopper with a holding member easy by a method wherein an arc-shaped holding member is provided integrally at a side wall part with a pair of separated connecting parts that are smooth at their inside, and the holding member is provided in extension at the side of a circumference that is longer than the other out of the circumferences between the connecting parts. SOLUTION: For an inner stopper, an arc-shaped holding member 4 is provided integrally at a side wall part 2 with a pair of separated connecting parts 5 that are smooth at their inside, and the holding member 4 is made to extend to the side of a circumference a that is longer than the other out of the circumferences a and b between the the connecting parts 5. The connecting structure for the holding member 4 and the connecting parts 5 is such that each of the connecting parts 5 is made thicker in thickness as compared with the side wall part 2 and the holding member 4 and made hardly expandable when the holding member 4 is pulled, and thereby a tensile force is easily transmitted to the side wall part 2. Thereby, opening of the inner stopper by the holding member 4 becomes easy and progressive smoothly, and seal break can be made, preceding opening of the stopper. |
