Patent ID: 7431877

Claim:
A method of forming a closure that is mountable to a neck finish of a container, said neck finish comprising an inner surface, an outer surface and a free end extending between said inner surface and said outer surface, the closure comprising a top portion and a skirt portion depending from the top portion, an annular sealing rib projecting downwardly from an underside of the top portion, said rib including a first portion which is contiguous with the top portion and having a substantially cylindrical inner surface, which inner surface lies radially inwardly of the skirt portion, and a second, frusto-conical portion contiguous with an end of the first portion distal to the top portion and extending radially inwardly to terminate in a circular free edge, the first portion having an internal diameter equal to or greater than an external diameter of the outer surface of the neck finish of the container so that during engagement of the closure with the neck finish, the second, frusto-conical portion will be engaged by the free end of the neck finish and folded back against the substantially cylindrical inner surface of the first portion of the rib to form a seal between at least the outer surface of the neck finish of the container and the closure, said method comprising molding a resilient plastics material in a mold which defines the features of the closure and ejecting said closure from the mold.