| 摘要 |
1,018,515. Seaming non-metallic sheet material; laminates. O.-B. RASMUSSEN. July 20, 1964 [May 22, 1963], No. 20338/63. Headings B5K and B5N. A laminate of films of cross-laminated thermoplastic material is seamed by placing the films 5, 6 on top of one another, punching a series of holes 7 through the layers along the desired seam, applying on each side of the laminate thermoplastic material over the holes 7, and causing this thermoplastic material from each side to unite within the holes 7 while embracing each side of the laminate without bonding to the sides of the laminate. Each of the films 5, 6 comprises two plies of high density polyethylene oriented by stretching and which is laminated so that the directions of orientation of the two plies form an angle with one another. The holes 7 may be punched in a curved or straight line and are preferably circular. Molten thermoplastic material, preferably polyvinyl chloride, may be extruded upon or rolled on to each side of the films 5, 6 and solidifies to form knobs or caps 8, 9 connected at 10 through the holes 7. In an alternative embodiment, Fig. 2 (not shown), continuous strips 11, 12 are placed on each side of the films 5, 6 and are united by highfrequency or ultrasonic welding located at the holes 7. In a third embodiment, Fig. 3 (not shown), a single strip 13 is folded around the edges of the two films to be united and welding performed through the holes 7. The invention is applicable to forming a bottom seam on flattened tubular bags. |
