Analysis of the influence of melt spinning process parameters on the quality of finished products

1、 Melt temperature control

1. ‌☉The relationship between temperature range and fiber properties‌

2. ·The melt temperature should be strictly controlled between the melting point and decomposition temperature of the polymer (such as 285-290 ℃ for polyester fibers). If the temperature is too high, it can lead to melt degradation, nozzle defects, increased elongation and decreased strength of the finished yarn; If the temperature is too low, it can cause problems such as stretching of fibers and breakage.

3. ·Spinning temperature fluctuations exceeding ± 1 ℃ can lead to poor fiber dyeing uniformity. High viscosity slices require higher temperatures (290-294 ℃) to maintain melt flowability, while low linear density fiber spinning requires appropriate temperature reduction.

2、 Optimization of cooling conditions

1. ‌☉Wind speed and temperature gradient regulation‌

2. ·The cooling airflow speed (usually 0.3-0.6m/s) needs to be matched with the fiber line density: high line density fibers require higher airflow speed, but exceeding 0.6m/s will increase the spinning tension and disrupt the steady-state spinning conditions.

3. ·Improper temperature gradient control in the cooling zone can lead to deformation of the fiber cross-section or internal defects, and premature solidification of the outer layer can hinder heat transfer. Therefore, a multi-stage temperature control system (such as side blowing temperature of 25 ℃± 1 ℃) is needed to optimize heat transfer efficiency.

3、 Winding and stretching parameters

1. ☉‌Speed and tension synergy‌

2. ·The winding speed (conventional 1500-6000m/min) directly affects the uniformity of fiber fineness, and high-speed winding (>4000m/min) requires precise matching of stretching ratios (such as POY spinning speed 2900m/min corresponding to elongation of 125-135%).

3. ·During the stretching process, it is necessary to balance the rheological resistance and tension. Insufficient stretching ratio can lead to low orientation, while excessive stretching can cause wire breakage; Crystallization uniformity can be improved by temperature grading of the hot roller (such as preheating the first hot roller at 125 ℃ and stretching the second hot roller at 160 ℃).

4、 Auxiliary process parameters

1. ‌☉Metering pump and oil treatment‌

2. ·Insufficient pressure of the metering pump (≥ 3MPa) can cause fluctuations in the melt flow rate, affecting the stability of the linear density; High precision gear pump (flow rate 0.1-150cc/rev) can adapt to multi head spinning requirements and reduce fiber size deviation.

3. ·The concentration of oil agent and the position of oil application (600-900mm) affect the fiber bundling. Reasonable oil application can reduce static electricity, improve subsequent processing lubricity, and reduce the fuzz rate.

5、 Example of comprehensive impact

Process parameters directly affect the mechanical properties (strength, elongation), dyeing uniformity, and processability of finished products by regulating molecular orientation, crystallinity, and fiber morphology. Multi parameter collaborative optimization is needed to achieve quality stability.