| 摘要 |
The valve bag has a corner closing flap which is folded inwards, and over which are folded side flaps at its filler aperture in one end. First and second valve sheets are connected to the flaps to form a tube in the filler aperture. - The first valve sheet of relatively thin, slightly stiff paper, whilst the other sheet is of soft, pliant plastics. In the position where the side flaps are not folded over, both valve sheets cover the inner end parts of the flaps. |
