Container closure with anti-nesting ribs

Claim 1

An injection molded plastic closure for application to a container having a sidewall with a rim at its upper end defining an open mouth, said closure comprising: a top central circular panel for covering an open container; a plug-like portion upwardly extending from the central circuit panel, for insertion into the open mouth of the container for sealing engagement with the container sidewall, said plug-like portion having a generally upright sidewall defining an upwardly-facing cavity bounded at its upper end by an upper portion of said sidewall; an encircling rim on the closure extending radially outwardly from the upright sidewall and having an outer depending skirt; a bead on the skirt for locking engagement with the container rim; and a plurality of spaced-apart rib means inwardly extending from said upright sidewall for contact with another plug-like portion of another closure at a plurality of spaced contact points when the other plug-like portion is inserted within said cavity, so as to prevent a wedged engagement of said other closure with said sidewall, said upright wall having a substantially vertical upper wall portion and a lower wall portion offset radially inwardly from the vertical upper wall portion, a lateral offset portion interconnecting the upper wall portion and the offset lower wall portion, a lower nesting surface on the bottom side of the lateral offset portion, and an upper nesting surface on the top of the vertical upper wall portion, said lower nesting surface engaging the upper nesting surface of another closure stacked therebelow and the upper surface on said closure engaging a lower nesting surface of a closure thereabove to stack the vertical upper wall portions of adjacent stack closures in a vertical column.