Hinged semi-rigid container having wall stiffening means

Claim 1

In a semi-rigid thermoplastic container including base and lid members having uniformly thick, vertically fluted walls and a single uniformly thick living hinge joining the base and lid members along a straight edge thereof and having open container cavities facing upward when in an open condition, the improvement which comprises: a horizontal first flange portion formed along a top edge and extending around the periphery of the base member; a mating second flange portion formed along an opposing edge of the lid member, adapted for engagement with the first flange portion and thereby forming a seal upon closure of the container, said hinge joining the base and lid members along the flange portions thereof in said open container condition; said base member having a top shoulder, said top shoulder comprising an upwardly extending wall portion, a transversely extending wall portion and a downwardly extending wall portion terminating in a lower edge, said first flange portion extending transversely from said lower edge toward said hinge along said straight edge; said horizontal first flange being in one plane about the periphery of said base member; a spaced series of channels along the top shoulder adjacent to the hinge, each of said channels extending from the shoulder top to the flange portion, thereby stiffening the base wall in the vicinity of the hinge; and a mating series of protruding lugs formed in the lid member opposite the channels and adapted for closing into the channels, thereby stiffening the lid wall in the vicinity of the hinge.