Polyester fiber spinning is a complicated physical change process. In this process, with the transfer of heat and force, polymer undergoes solid (chip)-liquid (melt)-solid (fiber) changes. These changes have an important influence on fiber properties.
1.Melt polymer preparation
When using a screw extruder, the chips gradually heat up and partially melt in the input section. After reaching the compression stage, due to the thread groove changes from deep to shallow, the material is compressed and completely melted. Subsequently, it is measured and homogenized in the measurement section. Finally, impurities in the melt are filtered through Metal Powder, Leaf Disc Filter, Candle Filter, Spin Pack Filter, and other filtering products.
2.Melt polymer fluid and solidification formation
Melt polymer fluid becomes thinner and longer under the comprehensive action of winding force and cooling air flow, and solidifies into nascent fiber. During the forming process of melt polymer trickle, there are gradient distribution fields of viscosity, velocity, stress and temperature, which are called viscosity field, velocity field, stress field and temperature field. The properties of cured fibers are closely related to the role of these fields.
a. Inlet area: refers to the bell mouth part of each spinneret hole through which the melt polymer passes.
b. Hole flow area: refers to the area where the melt flows in the capillary hole of the spinneret.
c. Puffing area: refers to the area after the melt trickle leaves the spinneret hole.
d. Deformation zone: The deformation zone is also called condensation zone, which is the most important zone in the spinning process.
e. Stablization zone: after the melt trickle is solidified into fiber, the diameter is stable and the speed is no longer changed.
3.Oiling, wetting and winding formation
As spinning fiber is relatively dry, which is easy to generate static electricity. In addition, the cohesion between monofilaments is poor, the filaments are loose, and the friction coefficient is high, so it is impossible to carry out post-processing. By oiling and wetting, the filaments contain certain oil and moisture, which can eliminate static electricity and lubricate, which is beneficial to bundling, stretching and false twisting. The winding is completed by the cooperation of upper and lower godets, transverse godets and friction rollers. The function of the upper and lower godets is to change the thread direction and adjust the winding tension.
4. Structure of winding filament
The process in which the melt polymer stream is elongated and solidified, that is, the formation and development of the winding filament structure. It is the result of the interaction among rheological factors, heat transfer in spinning process and crystallization kinetics of polymers. Orientation and crystallization are the main structural factors of fiber, which have an important influence on post-processing and product quality. Macromolecule orientation is the phenomenon that macromolecules or segments in polymers are arranged along the direction of force under the action of external force. Orientation is the preferred arrangement of structural units along the direction of external force in the stress field of macromolecules. This arrangement is the response of macromolecular structural units to external forces. Because there is another orientation in the subsequent drawing process, the orientation in the spinning process is called pre-orientation. There are two orientations in the spinning process. One is the flow orientation in the melt state, and the other is the deformation orientation of the fiber after curing, the former is the main one. The tensile flow orientation of melt is mainly controlled by axial velocity gradient. Under the condition of conventional spinning, the winding wire basically does not produce crystallization. Low orientation and non-crystallization are the structural characteristics of wound wire.
Futai can provide all kinds of filtration products used in the synthetic fiber spinning process, such as Candle Filter, Spin Pack Filter, Leaf Disc Filter, Metal Sand,Filter Screen,Filtration System and Cleaning Equipments.etc.
Post time: Jan-13-2025