| 摘要 |
1,163,638. Producing embossed film of organic thermoplastic material. UNION CARBIDE CORP. 8 Nov., 1967 [27 Feb., 1967], No. 50696/67. Heading B5B. As shown in the drawing, an apparatus for producing by a continuous process an embossed film of organic thermoplastic polymeric material comprises an extruder 10 having a slot die 11, an endless belt conveyer 14 consisting of a wire screen trained about a freely rotatable roll 16 and a positively driven roll 18, a vacuum box 20 connected by a conduit 22 to a source of vacuum, an optionally provided device 24 for directing cooling air on to the film 12a supported by the upper run of the belt conveyer 14, idler rolls 26 and wind-up roll 28. The conveyer belt 14 functions also as an embossing member and may be a wire screen of mesh size between 4 and 100, e.g. 30 (U.S. Standard Sieve size). The wire screen belt conveyer 14 is preferably coated with a heat-resistant substance to which the hot film will not adhere, such as polytetrafluoroethylene. The web of molten film 12 extruded through the die 11 on to the wire screen conveyer 14 is conveyed by the conveyer 14 over the vacuum box 20 where it is drawn down into embossing engagement with the member 14 and thereby embossed. The embossed film 12a is then conveyed past the cooling device 24 and when it has solidified is stripped from the conveyer 14, passed over the guide rolls 26 and collected on the wind-up roll 28. Polymers which may be used to form the films may be polyethylene, polypropylene, ethylene-vinyl acetate copolymers or ethylene-ethyl acrylate copolymers. The ratio of the thickness of the embossed film to the thickness which the film would have had had it not been embossed may be from 4À0:1À0 to 20À0:1À0. |
