GB823013A - The production of artificial filamentary materials having irregularly distributed local enlargements in cross-section - Google Patents

Abstract

<PICT:0823013/IV (a)/1> In the manufacture of artificial filaments by melt-spinning, the extruded molten filaments are drawn away from the spinneret through a zone in which they are solidified by cooling and, before the filaments are completely solidified and while they are still spaced apart, a liquid coolant is caused to impinge on the filaments over short lengths thereof so as to cause a sudden local cooling but not a weakening of the filaments at irregular intervals along their length, the liquid coolant being directed in paths which move transversely to and thus intersect the paths of the filaments, whereby local increases in the cross-sectional area of the filaments are produced at irregular intervals along their length. In an example, five separate polyamide filaments 1 are drawn from five extrusion orifices in the spinning nozzle 2 of a melt-spinning apparatus and de-ionized water at room temperature is sprayed out radially through 15 apertures 5 drilled at irregular intervals on a circular line spaced 2.5 cm. from the spinning nozzle on the surface of the cylindrical hollow member 3. The member 3 is rotated at 650 R.P.M. by the motor 9 through pulley 8, a V-belt and the pulley 7 secured on the hollow shaft 4 of the member 3 rotating in the fixed support 6. The cooling water is introduced into the shaft 4 from the supply pipe 10 at a gauge pressure of 0.2 atmospheres. The rotating member 3, instead of being a hollow rotating cylinder coaxial with the group of filaments, may be a rotating hollow circular disc positioned inside the group of filaments and rotatably mounted on a hollow shaft disposed in a plane at right angles to the downward direction of travel of the filaments. Both faces of the disc are provided near their edges with five apertures through which the cooling liquid is sprayed on to the filaments from the hollow interior of the disc. In a third embodiment the hollow spraying member 3 is in the form of a horizontal tube closed at both ends, extending transversely through the group of downward travelling filaments and having fine lateral apertures towards one end. The cooling liquid is supplied to the tube through a flexible pipe connected to the tube which is slidably supported in a guide and reciprocated by means of a crank and connecting rod co-operating with a rotating shaft and flywheel. The reciprocating tube may be reciprocated in a vertical as well as in a horizontal plane. In a further embodiment the cylindrical member 3 is replaced by a toothed disc coaxial with the shaft and secured to it just below the closed upper end of the shaft. Drilled in the hollow shaft immediately above the upper side of the disc are a number of openings through which the cooling liquid is discharged on to the upper side of the disc. Due to the rapid rotation of the disc the liquid flows radially outward over the upper surface of the disc and is flung off in the form of fine droplets from the points of the disc teeth to strike the filaments in a random manner. The liquid coolant may contain dissolved dyestuffs, dispersed pigments, colour intensifying or colour-resisting substances, whereby a colour differing from that of the remainder of the filament may be imparted to the slubs.