Elastic composite fiber and fabrication method therefor

A method of producing elastic composite fiber, comprising the following steps:

• step A:
• drying low viscosity PET, high viscosity PET, PTT, and PBT, until water content is less than 15 ppm;
• wherein a viscosity of the low viscosity PET is 0.4-0.7 dL/g, a viscosity of the high viscosity PET is 0.7-0.9 dL/ g, a viscosity of the PTT is 0.7-1.3 dL/g, and a viscosity of the PBT is 0.8-1.2 dL/g;
• step B:
• placing the low viscosity PET, the high viscosity PET, the PTT, and the PBT into a screw extruder to carry out melt extrusion procedure to obtain molten material;
• transferring the molten material into a compound spinning assembly under measurements determined through a metering pump, wherein a weight percentage of the low viscosity PET accounts for 10-90% of total molten material transferred to the compound spinning assembly, a weight percentage of the high viscosity PET accounts for 10-90% of the total molten material transferred to the compound spinning assembly, a weight percentage of the PTT accounts for 10-80% of the total molten material transferred to the compound spinning assembly, and a weight percentage of the PBT accounts for 10-80% of the total molten material transferred to the compound spinning assembly;
• introducing the molten material out from the compound spinning assembly into a spinneret where the molten material is extruded to form parallel vacuum staples which are then subject to spinning, circular cooling, oil application, winding, and arrangement around a bobbin, thereby obtaining a non-crimped top-fiber precursor;
• step C:
• equilibrating the fiber precursor obtained in step B for 20 hours and then performing setting procedure by tension heat setting or relax heat setting;
• wherein said tension heat setting achieves setting through stretching by using a first traction roller, a second traction roller, a third traction roller and a fourth traction roller;
• wherein the first traction roller operates at a speed of 220-280 m/min and a temperature of 150-170° C.;
• the second traction roller operates at a speed of 222-282 m/min and a temperature of 170-180°C;
• the third traction roller operates at a speed of 225-285 m/min and a temperature of 170-180°C;
• and the fourth traction roller operates at a speed of 230-290 m/min and a temperature of 180° C.