| 摘要 |
PROBLEM TO BE SOLVED: To reduce force required for cutting a coupling of an outer cylinder and starting tear of a cut groove by inclining a cut of the outer cylinder, by forming a tab into a trapezoid having a gradient side corresponding to the inclined cut and an upper end of the outer cylinder as a longer side, and by providing a finger hook at an intersection of the gradient side and the longer side. SOLUTION: A notch 13 is provided at a predetermined position of an outer cylinder 6, and an upper part of a coupling 12 is made into a gradient cut 14 extending slantly. A form of a tab 16 is formed to be a trapezoid having an upper end rim of the outer cylinder 6 as a longer side and the gradient cut 14 side as a gradient side, while an intersection of the gradient side and the longer side is an arcuate finger hook 17. Since the tab 16 is formed in a trapezoidal form having the gradient cut 14 side as a gradient side and the upper end rim of the outer cylinder 6 as a longer side in this constitution, a distance from the finger hook 17 to the coupling 12 is longer than the case where a cut is provided longitudinally on the outer cylinder 6. Therefore, even if force for pulling out the finger hook 17 is equal, larger tearing force may function to the coupling 12.
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