Plastic end closure for hermetically sealed container

In a reclosable end cap closure container having a cylindrical end or neck, said closure including a plastic cap proper having a rim portion for sealing engagement with the end or neck of the container and an end wall portion generally depressed below the rim portion, said end wall portion of said cap proper including a center region and a radially intermediate region between said center region and said rim, said radially intermediate region of said end wall portion containing, within itself and to the exclusion of said center region, a tab, said tab being readily breakable by manual force exerted on the tab, in a direction toward the interior of a container on which the cap is placed, to open said tab and form a window, a rotatable disc with openings therein alignable with said tab or window, said disc being rotatably attached to the cap proper at said center region thereof with the bottom surface of said disc in sliding face-to-face contact with the top surface of the cap proper to close said window, after it is formed by opening of said tab, when said openings in said disc are turned out of alignment with said window, the improvement which comprises the cap proper constituting a hermetically sealed closure member prior to opening of said tab, an integral central upstanding boss formed on and permanently integrally associated with said end wall portion of said cap proper at said center region thereof, said disc being received on said upstanding boss and being permanently rotatively associated with said end wall portion, retainer means at the free end of the boss and slidably engaging the top side of the disc to thereby clamp the bottom surface of the boss-mounted disc in said sliding face-to-face contact with the top surface of said end wall portion, the height of the boss and retainer means being limited to avoid projection thereof above the plane of the upper extent of the rim portion, the disc being free of contact with structure radially outward of said end wall portion of the cap proper whereby the disc is retained on a hermetically sealed end closure prior to opening of the tab and remains rotatably associated with the end closure after opening of the tab to provide reclosability without gapping between said disc and said end wall portion and without springing of the disc from the end wall portion.