| 摘要 |
PROBLEM TO BE SOLVED: To provide a plastic cap which prevents an internal pressure of the cap from increasing so that there is no fear that the cap accidentally removes from a bottle mouth. SOLUTION: The cap for a bottle having a flange 23 on an external surface of the mouth 11 includes a top wall 31 whose periphery is mounted on an upper end surface of the mouth 11 and a peripheral wall 33 hangingly connected with a periphery of the top wall 31 and put over an external surface of the flange 23. An inward annular engaging protrusion 48 to be engaged with the flange 23 from downward is provided at a lower end of an internal surface of the peripheral wall 33. The engaging protrusion 48 extends continuously along the entire periphery 33. The protrusion 48 includes a deaerating groove 49 for preventing an internal pressure of the cap from increasing as the cap is pressed down when the protrusion 48 is to be engaged with the flange 23. |
