Patent GB-828986-A (GB)
Title: Improvements in the manufacture of oriented melt-spun artificial fibres
IPC: D02J1/22
Filed: 1958-01-15
Abstract: In producing oriented artificial filamentary materials by a melt-spinning method in which the filaments formed are stretched to orient them continuously with their formation, the freshly formed filaments are passed directly through a bath of liquid and drawn from the bath under tension, the viscosity of the liquid, the length of the path of travel of the filaments through the bath and their rate of travel through the bath being such that the drag of the bath on the filaments provides at least the <PICT:0828986/IV (a)/1> <PICT:0828986/IV (a)/2> greater part of the tension employed to stretch the filaments. The filaments are preferably quenched, e.g. in air, until they are solidified prior to entering the bath. Alternatively, particularly at lower spinning speeds, the filaments may be quenched, at least to some extent, in the bath.  In the high-speed air quenching process, the filaments are usually cooled from the asspun temperature to at least 50 DEG  C., and preferably 100 DEG  C. or more, below the melting-point of the filaments, before contacting them with the bath.  The filaments may be of linear polyamides, e.g. polyhexamethylene adipamide, or polyesters such as polyethylene terephthalate.  Other suitable materials are also specified.  The preferred liquid for the bath is water, which may contain a textile finishing agent.  The bath liquid may also be trichlorotrifluoroethane or a mixture, in parts by weight, of 5 parts of sorbitan monolaurate, 10 parts of silicone oil and 85 parts of refined kerosine.  As shown in Fig. 1, the melt is extruded from spinneret 1 to form a number of fine streams 2 which are quenched by exposure to a current of air 5 before entering the bath 3 contained in a vessel 4, which the filaments leave as a yarn 7 via an orifice 6.  The yarn 7 is deflected through an angle (a) by passage over a deflecting pin 8, so that entrained liquid 9 is separated and falls into receiver 10, whence it is returned to the bath 3 via conduit by means of a pump 12.  The yarn is pulled through the bath 3 by means of a pair of slightly axially-skewed driven draw-rolls 13, about which it passes in multiple wraps, and is delivered to a wind-up package 14, which is surface-driven by contact with a drive roll 15 and is traversed by a reciprocating guide 16.  The roll 15 is preferably driven at a lower peripheral speed than the rolls 13, to permit a controlled relaxation of the yarn and packaging at low tensions.  The rolls 13 may be dispensed with.  Fig. 2 shows a preferred bath design, especially suitable for polyamide yarns, in which the container 41 contains a cylindrical wire screen 16 surrounding the path of travel of the yarn and resting on the inverted conical base 17 of the container, to minimize turbulence of the bath liquid.  The yarn leaves the container 41 via an orifice 6, as in Fig. 1.  Multiple pins may be used instead of the single pin 8 and the angle (a) may be increased to 90 degrees.  Alternatively the pin or pins may be dispensed with and the yarn deflected at the bath orifice.  The container 4 may be in the form of a long tube having a side inlet near the bottom through which liquid may be supplied by a pump so that it passes up the tube, countercurrent to the yarn, and overflows at the top of the tube into a catch basin, from which it returns to the pump.  The bath may be cooled or heated, e.g. by steam coils inserted in the receiver 10 (Fig. 1).  In an example, polyethylene terephthalate is melt spun at about 290 DEG  C. and the bundle of filaments thus formed is drawn downwards and quenched through 2 feet of quiescent air, and then drawn through a liquid bath maintained at 80 DEG  C. or 93 DEG  C.  The yarn, after leaving the bath, is deflected through an angle of 90 degrees by passage over six pins.  Specifications 461,236, 533,304, 543,466 and 578,079 are referred to.