Cruciform bottom valved sack - has internal valve of heavy paper and thin sheet glued together along strips

摘要

The valved sack with cruciform bottom is of one or more layers of paper or other suitable material. An internal valve of flexible material is glued between the corner fold and the two bottom flaps placed one above the other at the centre. The valve is assembled from heavy paper sheet (10,11) twice the width of the sack bottom and a thin sheet of paper or plastic (12) sufficiently wide than the bottom to allow its attachment to the paper sheet by two strips of glue (13), the distance between which is equal to the bottom width.