| 摘要 |
1,066,493. Making flat films by melt extrusion. KALLE A.G. Aug. 4, 1964 [Aug. 6, 1963], No. 31611/64. Heading B5B. Films in sheet form are made by downwardly melt-extruding a normally solid thermoplastic organic polymer through the slot-shaped extrusion orifice of a die E (Fig. 1, not shown) on to a rotating roller F immediately below and parallel to the die orifice to form a quenched film H. A suction box A is bounded on one side by the die E and on another is sealed by the peripheral surface of the roller and the interposed resilient arcuate seals G. Suction is applied to the box A through a pipe J, thereby reducing the air pressure in space D. The extruded melt H is thereby drawn vertically downwards into intimate contact with the roller F instead of following an inclined free path to the right. The peripheral surface of the roller is maintained at a quenching temperature below that at which the film would adhere to the surface if no vacuum were applied. The roller F is rotated in the direction shown by the arrow. Instead of applying suction to the box A through the pipe J (which communicates with a source of reduced pressure), the reduced pressure in the box Amay be maintained by means of an air injector nozzle the outlet of which is positioned in an aperture of the box near the peripheral surface of the roller F where it first approaches the box. The process increases the degree to which the molten film can be quenched and enables fibres of a more amorphous nature to be obtained. |
