Cartons having molded pulp end walls

Claim 1

A LIGHTWEIGHT CONTAINER COMPRISING A PLURAL GENERALLY RECTANGULAR SIDE WALLS FLEXIBLY JOINED AT THEIR EDGES TO FORM A TUBULAR STRUCTURE COLLAPSIBLE TO ASSUME A GENERALLY FLAT CONFIGURATION FOR STORAGE PURPOSES OR EXPANSIBLE TO ASSUME AN OPEN CONFIGURATION OF POLYGONAL CROSS-SECTION FOR CONTAINER PURPOSES, A PAIR OF SIMILAR END WALL MEMBERS OF HEAVY DUTY MOLDED PULP MATERIAL, THE END WALL MEMBERS BEING DETACHABLE FROM THE SIDE WALLS SO THAT THEY MAY BE MADE OF A MATERIAL DIFFERENT FROM THE SIDE WALLS, EACH BEING SHAPED TO FIT TELESCOPICALLY WITHIN THE OPEN TUBULAR STRUCTURE FOR CLOSING THE ENDS THEREOF, ONE EDGE OF EACH END WALL MEMBER BEING FLEXIBLY ATTACHED TO A FLAP ON AN END OF ONE OF THE RECTANGULAR SIDE WALLS TO SWING INTO THE SAME GENERAL PLANE AS THE COLLAPSED SIDE WALLS FOR STORAGE PURPOSES OR INTO A PLANE GENERALLY NORMAL TO THE EXPANDED SIDE WALLS FOR END CLOSING PURPOSES, EACH END WALL MEMBER HAVING FLANGE MEANS AT ITS PERIPHERY TO AFFORD ADEQUATE MOLDED PULP MATERIAL FOR FASTENING WITH THE ENDS OF THE REMAINING RECTANGULAR SIDE WALLS, SAID FLANGE MEANS FLARING OUTWARDLY, AND INTERMITTENT PERFORATIONS BEING ON AT LEAST ONE OF THE RECTANGULAR SIDE WALLS FOR PROVIDING SIDE ACCESS TO THE CONTAINER FOR EMPTYING THE CONTENTS THEREOF.