SYNTHETIC RESIN CAP, SYNTHETIC RESIN CAP LINER, CLOSURE DEVICE AND BEVERAGE-CONTAINING CLOSURE DEVICE

摘要

A synthetic resin cap is provided with: a cap body having a top plate and a cylinder that is vertically lowered from the peripheral edge thereof; and a liner provided on a lower surface of a top plate. The liner has: a flat plate; an inter-seal projection that contacts an inner-edge side of an opening end; an outer-seal projection that contacts an outer-edge side of the opening end. An outer edge of the liner is spaced apart from the cylinder in an internal side and is formed to ensure a space between the outer edge and the cylinder. The outer diameter of the outer-seal projection is smaller than an outer diameter of the opening end.