With the development of society, people have higher and higher requirements for the various properties of clothing fabrics. In addition to stiffness, drape, and softness, they also require fabrics to be multi-color, warm, and elastic. Ordinary polyester Filament yarn can no longer meet the above requirements, requiring manufacturers to continuously develop differentiated products. At the same time, with the rapid development of the polyester industry and the increasing updating of production technology, conventional products produced by old equipment are at a disadvantage in terms of quality and cost and cannot compete with new equipment. Therefore, for old equipment, Transforming and producing differentiated varieties is the only way out. Our company introduced French FTF-8E3 equipment in the early 1990s and has been using it for 20 years. In recent years, through gradual transformation of equipment, it has produced polyester composite (POY + DTY) yarn. The fabric has obvious two-color and concave-convex effects, and has a – Fixed elasticity, widely used in men’s T-shirts in summer and thermal underwear in winter. It is very popular among users and achieves ideal economic benefits. Different specifications of POY and DTY composites can produce different colors and feels. This article takes the market mainstream product 170 dtex/120 f composite yarn as an example to discuss its production process.
Experiment
Raw materials
The POY produced by our company has specifications of 135 dtex/72 f and 88 dtex/48 f. The physical properties are shown in Table 1.
Winding oil produced by Guangdong Xinhui Changhe Chemical Industry Group Co., Ltd., model DA-1.
Equipment and instruments
Equipment: FTF-8E3 texturing machine produced by French ICBT company, After modification, a zero roller was added in front of the first roller; the fixed wire rack was changed to a rotating wire rack, and a wire path was added; a row of wire detectors was added; a network device was added; and a wire doubling device was added.
Instrument: Tensile tester produced by Changzhou Second Textile Machinery Factory, model YG-023A.
Process flow and process conditions
Process flow
Results and Discussion
Processing speed
The processing speed of normal DTY is mainly affected by the spinnability of POY and the maximum process speed of the texturing machine. Since the composite yarn is composed of a DTY and a POY, the 135dtex/72f POY is processed into 83dtex/72f DTY according to the normal production route, while the 88dtex/48f POY is not drawn and twisted. The second roller is combined with the 83 dtex/72 f DTY network to form a composite yarn. The tension between the two is very different. If the normal processing speed is used, the network stability is difficult to control, and instantaneous network unevenness will occur during the processing. Since it occurs intermittently, it is difficult to detect it with conventional sock dyeing, which is woven on the cloth surface. Irregular short white stripes will appear, affecting the quality. After repeated experiments and long-term tracking feedback from customers, the composite wire processing speed was selected to be lower than the normal 83 dtex/72 f DTY processing speed. At 550~600m/min, the network degree was stable.
D/Y ratio
D/Y ratio refers to friction The ratio of the surface speed of the disk to the speed of the filament leaving the false twister. As the D/Y ratio increases, the DTY untwisting tension T2 decreases significantly. Since the composite yarn is made of DTY and POY, reducing the tension difference between the two is conducive to stable cohesion. Therefore, the D/Y ratio when producing composite yarn is a little larger than the normal production of 83 dtex/72 f DTY. However, it is too large. The D/Y ratio can easily cause DTY to produce point-like stiff threads, and intermittent dark spots will appear on the cloth surface. Through experiments, the D/Y ratio is selected in the range of 1. 68 to 1.70, and the quality of the composite yarn is good.
Stretching ratio
Within a certain range, with the stretching The stretch ratio decreases and the untwisting tension T2 decreases. When producing composite yarn, low DTY tension is beneficial to the network with POY, but too low a draw ratio will cause tension fluctuations and incomplete twist elimination, causing fiber bonding to produce point-like or linear stiffness. In severe cases, the cloth Long dark thin stripes appear on the surface. Through experiments, when the stretching ratio is 1.68~1.72, a composite yarn with a uniform network can be obtained while avoiding the formation of stiff yarns.
Zero roller underfeed coefficient
When choosing the transformation process route, some manufacturers did not add zero rollers, thinking that they had little effect and were dispensable. Practice has proved that since the POY tension is very small, if there is no underfeeding and it is directly connected to the DTY network, the network uniformity will be poor. Moreover, for the same POY and DTY, by adjusting the underfeed coefficient of the zero roller (zero roller underfeed coefficient = zero roller speed/second roller speed), the composite yarn presents different styles, which can meet different customer requirements. The underfeeding coefficient is large, and the two-color difference is more obvious; the underfeeding coefficient is small, and the two-color difference is mild. By controlling the underfeed coefficient of the zero roller between 0.95 and 1.00, products with better two-color effect and better hand feel can be produced.
Hot box temperature
The first hot box temperature is the deformation temperature , when the deformation temperature increases, the plasticity of the filament increases, the false twist resistance becomes smaller, the false twist tension also decreases, and the fiber is fully deformed; but when the temperature is too high, the fiber is fragile and prone to fuzz and bonding into stiff filaments. The second hot box temperature is the setting temperature. In the second hot box, the fiber is supplemented with heat setting treatment to eliminate the internal stress of the fiber and promote the deorientation of some high-energy chain segments. It is generally 30°C lower than the first hot box.�right. Since there is a POY in the composite yarn, the thermal shrinkage rate is large, so when processing the composite yarn, the temperature of the second hot box should be reduced accordingly. However, composite yarn uses the difference in heat shrinkage properties of POY and DTY to coat the yarn well and produce a plump and uniform two-color effect. Therefore, the temperature of the second heat box cannot be too low. After debugging, the temperature of the first hot box is controlled within the range of 180~190℃, and the temperature of the second hot box is controlled within the range of 120~140℃. The product quality is good, the hand feels fluffy, and the two-color effect is obvious.
Network nozzle and network pressure
Since the composite yarn is made of a network of DTY and POY – a fiber with core-covering effect, the network is uniform and stable, and good cohesion is an important quality indicator. Network nozzles have an important impact on network fastness, network degree and network uniformity. Our company began to use domestic nozzles. The network fastness of the product was poor, the network was unstable, and the degradation rate was more than 15%. Repeated adjustments to the process parameters and cleaning of the nozzles did not improve the situation. Later, we switched to imported nozzles, and the degradation rate dropped to 3%. about. Usually the network pressure is high and the network uniformity will be improved, but the compressed air consumption will be large and the cost will rise accordingly. It must be of good quality and cost-effective. After many tests, the network pressure has reached above 0.23MPa, which can obtain a uniform network degree and good yarn cohesion.
Product quality indicators
I The quality indicators of the 170dtex/120f composite yarn produced by the factory are shown in Table 3.
Conclusion
(1) In the production of composite yarn, choosing a processing speed of 550~600m/min, a D/Y ratio of 1.68~1.70, a draw ratio of 1.68~1.72, and adding zero rollers can better control the POY and DTY network merging. The tension is conducive to network stability.
(2) Choose the temperature of the first hot box within the range of 180~190℃ and the temperature of the second hot box within the range of 120~140℃ to ensure good product quality.
(3) Select the appropriate network nozzle, the network pressure reaches above 0.23MPa, and the product can obtain uniform network degree.
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