Patent DE-19920177-A1 (DE)
Title: Melt spinning of continuous polymer filaments
Inventor: KOSLOWSKI GERHARD
IPC: D02G1/08
Filed: 1999-05-03
Abstract: Melt spinning continuous polymer filaments, includes false twisting them within a false twisting zone, where they are heated at a temperature above the glass transition temperature of the polymer and then immediately cooled to a lower temperature. An Independent claim is included for a filament melt spinning assembly with a heater (14) at the false twisting zone (2) between the spinneret (1) and the false twister (16), followed by a cooling unit (15) for the thermal treatment applied to the filaments (17).  Preferred Features: The heating temperature of the filaments = 150-250 deg C and their cooling temperature = 50-120 deg C. Within the false twisting zone, the filaments are subjected to draw tension forces equal to or greater than the draw force required to give them a plastic distortion. The draw forces are applied by a take off godet in front of the false twisting zone, in the direction of filament travel, and a drawing godet after the false twisting zone. The false twisting zone has a lateral air stream directed at the filaments. The air stream is at a cooling temperature, to reduce the filament temperature level. At least one friction surface of a false twister is in contact with the filaments, to give a false twist. The filaments are drawn partially between the spinneret and the false twisting zone, using a heated longitudinal guide tube or narrow heated groove, where the filaments are heated and drawn without contact with a heated surface. The filaments are given a heat treatment, to prevent shrinkage, between the false twisting zone and the bobbin winder.  The heater (14) has a longitudinal heating surface, with a gap between it and the moving filaments (17) and without contact between them. The false twisting zone (2) is after a take off godet (13), which takes the filaments (17) from the spinneret (1). A drawing godet (18) is after the false twister (16), working with the take off godet (13) to apply a draw tension to the filaments (17). A pneumatic twisting jet, at the false twisting zone (2), has a jet channel opening at a tangent into the filament channel and connected to a compressed air supply. The cooling unit has a cooling tube, where the filaments pass through generally without contact. The twisting jet is at the outlet from the cooling tube to deliver an air stream into the filament channel against the direction of filament travel along the cooling tube, to reduce the filament temperature. The twisting jet with the cooling tube are in a cooling circuit, together with the compressed air supply and a heat exchanger, to give a cooing air stream from the jet. The false twister (16) has a rotating friction disk and at least one belt drive. The friction disk lies on a plane at right angles to the filament path, so that the filaments (17) are in contact with the disk circumference at a friction point. The belts of the belt drives press the filaments (17) against the friction points at the disk with the belts aligned at an angle to the disk plane. The friction disk has a number of friction points round its circumference, each with a belt drive to press the filaments against its friction circumference surface, to give a simultaneous false twisting action to a number of filaments. A drawing unit partially draws the filaments (17) before they enter the false twisting stage (2), using a heated tube round the filament path where the filaments (17) pass through it without contact to be drawn. An air stream flows through the heated tube, against the direction of filament movement. A relaxation stage, for filament shrinkage treatment, is between the false twister (16) and the bobbin winder (3).