Closure having improved resistance to unseating

Claim 2

In a closure for a container having a bead retention groove disposed in the wall thereof, said closure comprising a diaphragm, a side wall extending generally upwardly from the periphery of said diaphragm and a rim extending generally outwardly from the upper extent of said side wall, said side wall having forward therein an outwardly directed, inwardly opening retention bead structure adapted to snap into the bead retention groove of the container to releasably secure the closure to the container by the engagement of the upper portion of said retention bead structure against the upper portion of the bead retention groove of the container, the improvement comprising at least a portion of the outer surface of the upper portion of the retention bead structure which contacts the upper portion of the bead retention groove of the container being textured to increase the coefficient of friction thereof, the coefficient of friction of the textured portion of the retention bead structure being significantly higher than the coefficient of friction of the surface of the lower portion of the retention bead structure.

Claim 3

A closure in accordance with claim 1 the closure having been fabricated by thermoforming a sheet of synthetic organic thermoplastic material in a polished female mold, the portion of the mold which forms the upper portion of the retention bead structure having been sandblasted to provide a rougher surface texture for said upper portion of the retention bead structure than for the remainder of the closure.

Claim 4

A closure in accordance with claim 1 wherein said upper portion of the retention bead structure has a grainy texture, and the lower portion of the retention bead structure has a glossy smooth surface to minimize frictional resistance to the insertion of the closure into the container.

Claim 5

A package comprising a closure in accordance with claim 1 and further comprising a container having a bottom wall, an upstanding side wall extending generally upwardly and outwardly from the periphery of said bottom wall, a rim forming the mouth of the container, and a ring section extending generally upwardly from the upper extent of said upstanding side wall to said rim and having a circumferentially continuous outwardly directed, inwardly opening retention groove formed therein, said ring section also having an upwardly and outwardly extending camming wall section between said bead retention groove and said rim adapted to serve as a centering guide for said closure upon the contact of the lower portion of retention bead structure of the closure therewith, the outer diamter of the outermost portion of said retention bead structure being greater than the inner diameter of the lower end of said camming wall section and the innermost diameter of the upper portion of said bead retention groove and less than the inner diameter of the upper end of said camming wall section and the inner diameter of the laterally adjacent portion of said bead retention groove.

Claim 6

A package in accordance with claim 4 wherein said container and said closure have substantially circular horizontal cross-sections, and wherein the textured portion of said retention bead structure is at least substantially circumferentially continuous.