GB741342A - Improvements in or relating to the spinning of synthetic linear polymers - Google Patents

Abstract

<PICT:0741342/IV(a)/1> <PICT:0741342/IV(a)/2> <PICT:0741342/IV(a)/3> A molten synthetic linear polymer is extruded from a spinneret to form one or more filaments which are passed, before being wound into a thread package, through an elongated space at the boundary of which there is caused to flow a stream of liquid, this liquid being exposed to any gases or vapours given off by the extruded filaments. The stream of liquid absorbs volatile monomer fractions which are evolved from the filaments. Preferably the liquid flows within a space bounded externally by a sheath and in this case the liquid prevents the air enclosed by the sheath from becoming overheated, A screen may be positioned between the filaments and the liquid, the openings in the screen having a sufficient overall area not to obstruct the passage of gases or vapours to any significant extent. The liquid may be in part re-cycled so as to obtain a more concentrated solution of monomer fractions and thus to facilitate recovery of the monomers. The polymer may be a polyamide obtained from caprolactam or amino-caproic acid and the liquid used for absorbing the vapours of monomers during the production of the filaments may be water. As shown in Fig. 1, filaments 11 are extruded from spinneret 10 and pass downwardly through a tubular sheath 12 to rollers 14 and bobbin 13. A metal net 16 is located within the sheath and a film of water 17 is kept constantly flowing between the sheath and the net. The water, which has absorbed monomer fractions, collects in a basin 21 from which it is discharged through pipe 22. A portion of the liquid is recycled by means of the pump 20 and pipe 19, and the rest is continuously drawn off through pipe 24 and conveyed to a recovery apparatus. As shown in Fig. 2, Raschig rings or like elements 30 are disposed between sheath 12 and net 16 to permit the formation of a water film of large surface area. A pipe 31 is located internally of the net 16 and has holes of considerable overall area to permit easy passage of vapours therethrough. As shown in Fig. 3, several spinning nozzles are located near to one another and several bundles of filaments 11 are formed. A perforated pipe 31 is placed in correspondence to each filament bundle. A single sheath or casing 40 for all the filament bundles is employed and the Raschig rings 41 are positioned within the casing and held in place by longitudinal nets 42. Perforated tubes parallel to the nets, acting as shower nozzles (not shown), are located at the top of the casing 40, and the water collects in the basins 43.