a six - sided sealed carton which is formed by folding a generally rigid , unitary , die - cut blank of a composite polymeric material , in which one of the ends is provided with a reclosable pour - out spout that includes an integral part of the blank , at least some of the corners of such carton being self - sealed by webbed areas or gussets which are integral portions of such blank but which are of reduced thickness relative to the major portions of the remainder thereof , such carton being adapted to contain a particulate material which is in direct contact with the inner surfaces thereof . in a preferred embodiment the carton is formed from a die - cut sheet of a composite polymeric material , a major portion of the thickness of which is an expanded polymeric material .