| 摘要 |
1284321 Cooling tubular film; extruded film IMPERIAL CHEMICAL INDUSTRIES Ltd 19 April 1971 [3 March 1970] 10139/70 Heading B5A and B5B In the extrusion of a tubular thermoplastic film which, after initial cooling, may be reheated and subjected to longitudinal and/or inflation orientation, initial cooling is effected by passing the tube over a cooled mandrel, there being maintained between the tube and mandrel a film of liquid, the pressure of which is kept above the external pressure on the tube by means of a liquid head maintained in the tube at the downstream end of the mandrel. As shown, the tube 1 passes over a slightly tapering mandrel 4, and is kept spaced therefrom by water supplied from space 5 through line 21. The liquid head is located in space 6 between the mandrel and a rubber disc seal 7, and excess liquid leaves via pipe 22. Vacuum is applied to line 23 to remove this liquid, the position of the end of line 23 being adjustable, fluid pressure may also be applied to the liquid head. To assist in proper feed of the film to the mandrel a line 27 may supply excess or reduced pressure air. The mandrel is cooled internally by circulating water. A second rubber disc seal 8 may be present, the space between the seals being pressurized. A sponge 11 connected to a vacuum source may remove any liquid passing the seals. Line 20 supplies inflating air. The film may be cooled externally by a surrounding water bath 13. Films of polypropylene or other specified polyolefines and polyesters may be cooled. |
