Patent ID: 6913725

Claim:
A method of making a plastic closure that comprises the steps of: (a) providing a closure shell having a base wall, a peripheral skirt, means on said skirt for securing the closure to a container, and an annular lip extending from said skirt adjacent to said base wall and defining an inside lip surface at an acute angle to said base wall, and (b) compression molding a liner in situ onto said base wall and peripherally within said lip such that said liner has a liner base portion extending along said base wall and a peripheral portion extending along said lip surface, said step (b) being such that said liner as molded has an interior surface that has a first flat axially facing surface portion on said base portion adjacent to said peripheral portion, an inwardly concave surface portion where said base portion blends into said peripheral portion, a second flat axially facing surface portion at an axial edge of said concave surface portion, and a conical surface portion that extends from a radially outer edge of said second flat surface portion to said inside surface of said lip.