Patent GB-807804-A (GB)
Title: Production of filaments of synthetic polymers
IPC: D01D10/04
Filed: 1956-05-16
Abstract: <PICT:0807804/IV (a)/1> <PICT:0807804/IV (a)/2> A device for the continuous production of fine diameter elastic filaments of a highly plasticised synthetic polymer comprises means for extruding the polymer as a number of individual closely adjacent filaments, means for contacting the filaments as they advance from the extruding means, means for maintaining the contacting means at a temperature below the tack point of the filaments, means for winding the filaments in substantially parallel relationship upon a spool after contacting the contacting means, and means for preventing contact of the individual filaments with each other during their travel from the extruding means to and beyond the contacting means.  Preferred synthetic polymers are homopolymers of vinyl chloride and copolymers of vinyl chloride with modifying agents such as polyvinyl acetate. The plasticiser may constitute 20-50 per cent by weight of the total composition and may be a phthalate ester such as dioctyl phthalate, a phosphate ester such as tricresyl phosphate, a polyglycol ester such as is prepared by esterifying triethylene glycol with mixed capric and caprylic acids, a sebacic acid ester such as dioctyl sebacate, a nitrile type synthetic rubber or a polymer based on sebacic or adipic acid.  As shown in Fig. 1, the plasticised polymer in comminuted form is fed into the hopper 10 of a conventional extruder having a barrel 12 containing a screw, driven by a motor 11, for extruding the material through a die 13 having a number of closely positioned extrusion orifices in line horizontally across the die, through which the molten material is extruded as continuous fine filaments 24.  The extruder is heated by steam supplied through the connections 14, 15. The parallel extruded filaments 24 disposed in the form of a sheet are immediately passed over the surface of a cooling roller 21, then directed downwards to a second cooling roller 22, around a substantial portion of the circumference of the roller and upwardly to a third cooling roller 23 located above the roller 22.  The filaments are maintained in the form of a travelling sheet or web of closely spaced separate parallel filaments while passing over the rollers 21-23, the axes of the rollers all being parallel to the row of extrusion orifices. After travelling around a substantial portion of the circumference of the cooling roller 23, the filaments are directed downwards to a winding spool 30, upon which the filaments (now cooled below their tack-point) are wound while still in parallel relationship. During their passage from the roller 23 to the spool 30 the filaments pass between a number of rectangular spaced fingers 65 (Fig. 6), secured to and extending upwards from a horizontal shaft 66.  Each individual filament passes between a pair of adjacent fingers 65, which thereby serve as guides for the advancing filaments for parallel winding on the spool 30.  A shaft 68 carrying a freely rotatable roller 681 is pivotally mounted on the upper end of a stout upright 67 secured to one end of the shaft 66.  The shaft and roller assembly 68, 681 may be pivoted upwards to enable the apparatus to be threaded when spinning is begun, and then returned to the horizontal position along the tops of fingers 65 to serve as a keeper.  A similar shaft 69 carrying a roller 691 is pivotally mounted on the lower end of member 67, the filaments passing over the roller 691 en route to the spool 30.  The rollers 21-23 are cooled with water at about 20-28 DEG  C. supplied through pipe 32 and branch pipes 33-35, each communicating with a fixed pipe projecting into the hollow interior of each roller, while water is discharged from the rollers through the pipes 36-38, each communicating with a hollow shaft by means of which each roller is supported in its bearing.  The rollers 21-23 are driven by electric motor 40 through belt 41, variable-speed gear 42, sprocket 43, chain 45, sprocket 46, counter-shaft 44, sprocket 47, chain 50 and sprockets 51-53.  The spool 30 is driven by a constant-torque motor 60 to ensure that the filaments produced are of a constant predetermined size.  In an example, a composition containing 53 per cent of polyvinyl chloride, 43 per cent of dioctyl phthalate, 2 per cent of calcium stearate and 2 per cent of titanium dioxide is extruded as a number of closely-adjacent filaments of about 0.015-0.022 inch diameter at about 280-325 DEG  F.