Container and closure

Claim 1

A package for pressure fluid containment comprising a container having a neck defining annular wall about the center axis of the container with external threads formed along said wall thereon, an external, frustoconical sealing surface (22) formed above said threads and sloped upwardly and radially inwardly toward said center axis and a flat annular top surface (23) defining the mouth opening of the container, a plastic closure comprising a top panel section, and an integral depending annular skirt section defining internal threads to cooperate with the complementary threads on the neck of the container, an annular side sealing rib forming a series connected part of said skirt section extending radially inwardly from the inside surface of said skirt above said threads and having an internal surface dimensioned to form an interference fit only with said external frustoconical sealing surface of the container such that when the closure is threaded on the container, the rib is compressed into sealing relation with the external frustoconical sealing wall, means on said panel section comprising a downwardly extending annular portion (24) for engaging the annular top surface of said container finish to form a top seal with the flat top surface of the container neck, and an axially extending flexible annular wall section integrally connecting the periphery of said top panel section and said side sealing rib, said flexible annular wall section extending upwardly and inwardly from said rib to said panel section, and said wall section being of less thickness than said panel and said annular side sealing rib, whereby increasing internal container pressure on said top panel section increases the radial compressing force on said side sealing rib.