Composite, vacuum indicating closure

Abstract

A vacuum indicating closure for a container for the packaging of a vacuum-packed product, the closure being of two-piece construction and having a metal lid portion which is retained in sealing engagement with the rim of a container by a plastic ring portion. The metal lid portion has a vacuum indicating button centered therein, which vacuum indicating button can flex downwardly from its normal position into the headspace of a container under the influence a sub-atmospheric or negative pressure in the headspace. The ring portion of the closure has a radially inwardly projecting annular flange at the top thereof to urge a peripheral portion of the lid portion of the closure against the rim of the container, the ring portion of the container further having a radially inwardly projecting annular bead to lock the lid portion of the closure against the underside of the annular flange of the ring portion so that the lid portion and the ring portion can be conveniently handled in unison. The ring of the closure further has an annular skirt with radially inwardly projecting ribs thereon, whereby the closure can be mechanically attached to a helical threaded container finish by a push-on action, the ribs being deformable under compressive loadings by the helical thread on the container finish to deform and thereby ensure that the closure under normal circumstances can be removed from the container by an unscrewing motion.