| 摘要 |
1464135 Extruding multi-layer films J KUBAT and K S BERGGREN 12 March 1974 [16 March 1973] 11009/74 Headings B5A and B5B In a process for producing a multi-layer film by extrusion, the outermost layer is stretched longitudinally, the inner layer(s) is stretched transversely and the layers are united together before the layers have lost their viscous flowability. The inner layer(s) may also be stretched longitudinally. Longitudinal stretching may be achieved by drawing and transverse stretching by blowing with pressurized air, N 2 or Ar. The layers may be of the same or of different material e.g. polythene, polypropylene, polyamides, and ethylene-E.V.A. copolymers. Fillers such as wood flour, chalk, carbon black or magnetic particles which can be orientated by magnetic fields may be injected between the layers to become homogeneously distributed therethroughout. A die which may be used in the process is shown in Fig. 2 and comprises a central conical part 1, 2, an outer ring 4 and an intermediate part 3. Fluid material is fed from an extruder via a feed passage 7 to a chamber 8 where part of the material is fed to an inner concentric layerforming slot 5 and part of the material is fed via passageways 9, 9a to the outer layer-forming concentric slot 6. Blowing gas is fed through a passage 14 and may be fed through a passage 15 to control the pressure between the layers. The widths of slots 5, 6 may be adjusted by providing detachable or conical slot-defining parts.
|
