| 摘要 |
1,083,842. Films. T. J. SMITH & NEPHEW Ltd. May 27, 1964 [March 28, 1963], No. 12400/63. Heading B5B. A molten organic thermoplastic film is cooled by passing it, immediately it is formed by extrusion, into contact with a liquid metal or metal alloy maintained at a temperature at least 10‹ C. below the softening point of the film. The film may be immersed in the liquid metal or contacted therewith on one surface only for a period sufficient to bring the film to the " frozen " condition. The metal, e.g. Wood's metal, mercury or mercury alloys may be maintained at a desired temperature by surrounding it with a coil containing water. In one embodiment (Fig. 1) (not shown) a film (6) extruded from (5) is passed by driven rollers (7, 8) and guides (12, 13, 16) along the surface of a bath of liquid metal (11) maintained at the desired temperature by means of heated water circulating in jacket (9). The " frozen " film is withdrawn at (14). Alternatively, the extruded film is immersed in the liquid metal. The driven rollers or guides may be formed from or coated with polytetrafluorethylene. In a further embodiment (Fig. 3) (not shown) a tubular film extruded from die (20) is contacted on its inner surface by a sleeve of polytetrafluorethylene (25) and on its outer surface by a surrounding bath of liquid metal (22) contained by sleeve (21). Water-carrying coil (23) maintains the metal at the desired temperature. Alternatively, the tubular film is contacted on both inner and outer surfaces by the liquid metal bath (Fig. 4) (not shown) which is circulated by a system containing a pump (33) and a heater (34). The invention enables cooling of an extruded and blown tubular film to be commenced immediately the molten material leaves the die. |
