GB796376A - Method and apparatus for the melt spinning of threads, films and like products - Google Patents

Abstract

<PICT:0796376/IV (a)/1> <PICT:0796376/IV (a)/2> <PICT:0796376/IV (a)/3> <PICT:0796376/IV (a)/4> In the melt spinning of threads, fibres an like products from polymeric substances, especially polycaprolactams, which contain constituents which are volatile under the spinning conditions but solid at room temperature, by extruding the spinning melt into a zone through which a gaseous cooling medium is passed, the cooling medium in the vicinity of the spinneret is continuously withdrawn and contacted with a solvent for the volatile constituents of the polymer. As shown in Fig. 1, yarn 12 issuing from the spinneret 11 of the spinning head 10 is cooled in a vertically disposed spinning cell 13 which leads to a shaft 14. Cooling air enters the spinning cell at the bottom through the annular space 16, but may alternatively enter the cell through openings (not shown) in its wall, the joint between the cell 13 and shaft 14 in this case being air-tight. The cooling air, together with the volatile constituents given off from the yarn during spinning, is withdrawn from the cell through two inlet ports 19, 20 (Fig. 3) in the inner wall 18 (Figs. 2 and 3) of an annular chamber 15 located between the spinning head 10 (Fig. 1) and the spinning cell 13 coaxially with respect to the axis of the spinneret 11. The annular chamber 15 is provided with a vertical outer wall 17 and a sloping inner wall 18 (Figs. 2 and 3) which define a frustoconical central space through which the freshly extruded yarn 12 passes. The chamber 15 consists of two halves, so as to be easily removable from the spinning head 10, and is provided with ducts 21, 22 leading tangentially away from the chamber and connected to an evacuating pump (not shown), so as to create a negative pressure in the chamber. In each duct there is located a water nozzle 23 having a downstream aperture 24 (Figs. 2 and 4) directed towards the outlet end of the duct 21 or 22. Water is supplied to the nozzles 23 through conduits 25 (Fig. 1); and the ducts 21, 22 are provided with downwardly-sloping outlet ends through which the water sprayed into them drains off. As the cooling air carrying volatile constituents from the yarn passes out of the annular chamber 15 into the ducts 21, 22, it passes through the water sprays from the nozzles 23, which dissolve out soluble volatile constituents which are subsequently recovered, while the air, together with any insoluble innocuous gases, is discharged into the atmosphere. The upper annular wall 27 of the chamber 15 is covered with a layer of heat insulating material 28. In order to promote the volatilization of all monomers from the yarns and to ensure their remaining in the gaseous state until dissolved by the water sprays, the annular chamber 15 is preferably surmounted by an annular electric heater (not shown) which surrounds the space under the spinneret and may be detached as a unitary structure from the chamber 15. The apparatus, particularly when provided with the heating device, prevents the formation of incrustations on and around the spinneret.