Carton with sift-proof end closure

Claim 1

An end closure for a paperboard carton having four enclosing body walls, a pair of inner closure flaps hingedly connected to the end edges of an opposing pair of said body walls, an intermediate closure flap hingedly connected to the end edge of a third of said body walls, and an outer closure flap hingedly connected to the end edge of the fourth body wall, at least one score line formed in each of said inner closure flaps extending in parallel spaced relation to the end edges of the body walls to which said inner closure flaps are hingedly connected, said score lines defining grooves in the outer surfaces of said flaps and corresponding ridges on the inner surfaces of said flaps, debossed areas extending from the outer ends of said score lines to the inner corner edges of said inner closure flaps, said debossed areas defining troughs in the outer surfaces of said inner closure flaps in communication with the grooves defined by said score lines having edges coinciding with the end edges of said inner closure flaps, mating score lines in said intermediate flap positioned to mate with the score lines in said inner closure flaps when the carton is closed, whereby when the flaps are infolded with a thin layer of adhesive interposed between said intermediate closure flap and said inner closure flaps and sealing pressure applied to the flaps, increments of the adhesive will be forced into the troughs to form plugs of adhesive which close and seal the corner edges of the end closure.