| 摘要 |
PROBLEM TO BE SOLVED: To provide a plastic cap wherein tightening torque and opening torque of the cap is relatively small, sealability is good, and functionality and appearance of the cap is not degraded by deformation due to the tightening torque. SOLUTION: The cap comprises a thread part 121 to be screwed with a thread part 211 of a bottle neck 210 on a peripheral wall 120 and a contact ring 130 in close contact with a top surface of the bottle neck hanging from a lower surface of a top plate 110. A cross section of the contact ring in an inverted triangle having a base upward and a vertex downward. In addition, groove rings to be connected with the contact ring are provided outside and inside the top plate of the base of the contact ring, respectively. |
