| 摘要 |
The method involves making a sleeve for each document from one layer (1) of a plastics or cellulose material, and a second layer (3) of a different plastics material. These are joined by a connecting strip (4,4') using ultrasound, high-frequency or another welding procedure. The first layer is made from a material selected from the group comprising cardboard, paper, wood, woven or non-woven textile materials, polyesters, polypropylene, polyethylene, PVC and similar products. The second layer is of polypropylene, PVC or similar, and the connecting strip is of the same material. The first layer may be made with perforations to allow the softened material of the connecting strip to pass through. |
