Patent GB-565489-A (GB)
Title: Improvements in the production of artificial filaments, films, foils and like materials
IPC: D01D1/04
Filed: 1943-01-04
Abstract: <PICT:0565489/IV/1> A fusible organic filament-forming composition is fed, to a point from which it is to be extruded, through a body of inert heating liquid maintained at a temperature sufficiently high to melt the composition in its passage through the liquid, and the molten composition is then extruded to form filaments, films, foils or other articles.  The heating liquid is preferably of lower density than the composition so that the molten composition collects below the heating liquid and can readily be drawn off and extruded. Extrusion of the molten composition can be initiated by allowing the heating liquid to be extruded in the first instance, and then changing over to the extrusion of the filament-forming composition. As heating liquid there may be used stearyl alcohol or an aliphatic hydrocarbon having 30-40 carbon atoms, e.g. paraffin wax.  The filament-forming composition may consist of or have a basis of a cellulose ester or ether, a polyvinyl compound, or a synthetic linear polyamide.  As shown, the extrusion apparatus comprises a melt chamber 1, pump chamber 2, and jet and filter assembly 3.  Passing through cover 5 is a valve rod 9.  The lower end 12 may be raised from or engaged with the apex of the conical part of chamber 1, by operating the wheel 11.  Valve rod 9 has an axial bore in which fits another valve rod 17 which may be raised or lowered by hand wheel 20. The lower end 21 of rod 17 fits on a seating 22 above which are openings 23 giving access between the bore of rod 9 and the melt chamber.  A sieve or grid 24 extends across chamber 1 and supports pieces of solid composition 37 until they are melted.  Solid composition is admitted to chamber 1 through a lock 38 comprising two plug valves 39, 40 with notched discs which interlock so that neither valve can be opened unless the other is completely closed. Electrical connection between wires 32, 33 is made through a movable rod 29 attached to a float 27, and a fixed rod 30.  The opening of electrical connection between wires 32, 33 gives an indication that fresh composition is required.  Heating elements 47 maintain the liquid 36 at such a temperature as to melt the solid composition 37 at the required rate.  The molten composition collects to form a pool 35.  When the operation is started the valve 17 may be opened so that liquid 36 passes through apertures 23 to the pump 16, filter 50 and jet 51.  When a sufficient pool of molten composition has collected, valve 17 is closed and valve 9 is opened so that molten composition may pass to the pump 16 and spinning jet 51.  The action of pump 16 is assisted by introducing nitrogen into chamber 1 above the liquid 36.  If desired, the pump 16 may be omitted, extrusion being effected solely by the pressure of the nitrogen.  The apparatus is insulated against loss of heat. The space around the pump 16 is filled with metal turnings 54 which augment the heat capacity of that part of the apparatus and help to maintain a uniform temperature.  Separate heating means and separate control may be provided for different parts of the apparatus.  If desired, the device for indicating the level of the liquid in the melt chamber may control means for operating the pressure lock and for automatically feeding solid composition through it to the chamber.