Reinforced automatic bottom closure

Claim 1

In a heavy-duty, collapsible carrying carton adapted to be brought from a collapsed condition to an erected condition by the application of pressure against two diagonally opposed corners thereof and being formed from a unitary blank of foldable paperboard, the combination of: a. opposed pairs of major and minor side walls hingedly interconnected to form a tubular structure open at the top and bottom; b. at least one of said major side walls including handle means for grasping and carrying the carton; c. top and bottom closure means for closing the top and bottom of the carton; d. said bottom closure means including opposed first and second pairs of closure flaps associated with said pairs of major and minor side walls, respectively; e. said closure flaps of said first pair each including: i. a flat, unscored, bottom panel hingedly attached at one edge to a lower edge of a related major side wall and presenting in a medial area thereof a recess adapted to interlock with a corresponding recess in the bottom panel of the other closure flap of said first pair when the carton is in erected condition; ii. a reinforcing side panel hingedly attached to said bottom panel, at an edge parallel to and opposite from the edge of the bottom panel which is hinged to a major side wall, and disposed to lie against the inner surface of the opposed major side wall when the carton is in an erected condition; f. said closure flaps of said second pair each including: i. a first panel section hingedly attached at one edge to a lower edge of a related minor side wall; ii. a second panel section hingedly attached to said first panel section and in fold-back relation therewith, when said carton is in a collapsed condition; iii. said second panel section being secured to an adjacent bottom panel and interposed between said first panel section and said bottom panel when the carton is in a collapsed condition.