SYNTHETIC RESIN CAP FOR CARBONATED BEVERAGE-FILLED CONTAINER, CLOSURE DEVICE, AND BEVERAGE-CONTAINING CLOSURE DEVICE

摘要

A synthetic resin cap fitted on the mouth section of a container filled with a carbonated beverage. The cap is provided with a top plate and a cylindrical section extending down from the rim thereof. On the inner surface of the top plate, a ring-shaped inner seal projection that is fitted inside the mouth section and an outer seal projection that abuts the outer surface of the mouth section are formed. On the outer surface of the inner seal projection, a ring-shaped contacting protrusion that contacts the inner surface of the mouth section is formed. The outer seal projection has an inner surface, the internal diameter of which decreases towards the leading edge, and the smallest internal diameter section, which is the lower end of the inner surface, contacts the outer surface of the mouth section at a position that is towards the container body side and is at a distance from the open end.