DTY FDY Filament

In the production of pet DTY, there are a lot of stiff yarns sometimes, and it is difficult to take various measures to solve them effectively. This kind of DTY fabric with a lot of stiff silk has obvious color spot, hemp sense and jacquard style after dyeing. It is a good choice to produce this kind of filament with different style by controlling its law artificially. Slub silk is this kind of filament with a lot of stiff silk.

The cause of stiff silk

1. Influence of DTY process parameters

1.1 tensile ratio (DR)

In the process of drawing, due to the orientation and crystallization effect, the internal energy and the elastic recovery force increase. On the other hand, as the ratio of Dr to tension K (T / T) is in direct proportion, and Dr increases, the increase of twisting tension T1 is smaller, the increase of untwisting tension T2 is larger, and the increase of T2 is larger than the increase of elastic recovery force. Therefore, with the increase of DR, the number of rigid wires decreases. On the contrary, the reduction of untwisting tension is also greater than that of elastic recovery force, resulting in the untwisting tension is not enough to overcome the elastic recovery force, and then the rigid wires appear.

1.2 speed ratio (D / y)

After the machine speed, Dr and the number of friction discs are basically determined, the tension ratio (k) is controlled by adjusting D / y to make it close to 1.0. At this time, the stability of deformation processing is the best, and the rigidity is the least, as shown in Figure L.

When k is less than 1.0, D / y decreases, twisting tension T1 increases less, while untwisting tension T2 increases more, which is easy to cause obvious tension fluctuation, resulting in poor false twisting effect and stiff silk. When k is greater than 1.0, increasing D / y ratio, T2 decreases more, while T1 slightly increases, unable to fully decompose the twists, resulting in overlapping twists.

1.3 deformation temperature

When the deformation temperature is set too high, the protection of the oil agent to the wire strip is damaged. At the same time, the friction between the tow and the friction cross examination makes the accumulated heat in the part hard to be emitted, and the local temperature can reach the melting point, forming the melting tight point. If the deformation temperature is too high, the viscosity of the oil agent will also be reduced, the wire strip is easy to slide, unable to fully untwist, resulting in tight point. However, if the temperature is too low, the heat required for drawing is insufficient, and the tow can not be deformed in the hot box. Generally, the deformation temperature for producing long section of rigid wire shall be controlled at 180-200 ℃, and the maximum temperature shall not exceed 210 ℃. See Table 1 for the number of spindles for producing rigid wire on single-sided machine (108 spindles) under different deformation temperatures.

1.4 impact of other parameters

Generally, the processing speed depends on the variety and quality of the raw silk. When processing coarse denier, the speed can be higher, while when processing fine denier, the speed will be lower; when the speed increases, the breaking ends will increase, and the tightening points will also increase; in addition, the combination of friction discs also has an impact on the false twist effect of the tow. When the number of friction discs increases, the twisting effect will increase, and the false twist effect will be significant. If there are too many friction discs, the thread is easy to slip and produce tight points. When using the all ceramic disc, the combination of 1-9-1 can be used for processing 165dtexdty, 1-7-1 for processing 110dtexdty, and 1-6-1 for processing 83dtexdty.

2. POY quality impact

2.1 unevenness of strip

If the unevenness of POY is too high, the tension of the system is unstable during post-processing, and the system is bouncing back and forth within a certain range, at this time, DTY may appear stiff and hairy at the same time, generally U% value is required to be below 1.2, or CV value is below 1.5.

2.2 type of oil agent and oil application

The heat resistance, lubricity, wear resistance and interface characteristics of the oil agent have a direct impact on the post-processing of POY. If the heat resistance of the oil agent is poor, volatile and easy to decompose at high temperature, the post-processing of the wire rod is not only easy to produce filaments and broken ends, but also cause friction fluctuations, resulting in false twist tension fluctuations, resulting in long stiff filaments. If the interface characteristics of the oil agent are not good, it will cause fibers The oil on the surface is uneven, and it is easy to appear point like stiff wire during post processing. The oil content of POY is required to be moderate. The oil content of POY is generally controlled between 0.25 and 0.4 when the friction plate is used for post processing. If the oil loading rate is too low, the cohesion of the tow is poor, and it is easy to produce filaments and stiff wire. If the oiling rate is too high, the white powder will increase during the post-processing, which will easily lead to the sliding of the wire and the fluctuation of false twist tension, resulting in the stiff wire; moreover, because the oil film is too thick, the heat is not easy to be emitted, which will easily lead to the tight twist of the wire; at the same time, the hot coking oil drop will increase, which will seriously affect the quality of DTY.

2.3 influence of floating wire

When POY has a floating yarn, it usually breaks twice when processing a full roll of POY, and it is easy to have a long section of stacked twisted yarn, which is caused by the yarn cluster at the floating yarn, which causes the instantaneous tension fluctuation, and the twist exceeds the normal twist range due to the thinning of the size. When POY has two or three floating wires at the same time, the dead wires and broken ends are more serious in post-processing.

3. Impact of equipment status

The intact rate of the equipment and the sanitary condition of the equipment have a direct impact on the quality of DTY. The use of the machine must run under the technological requirements and ensure the smoothness of the silk track to reduce the wear of the silk bar. At the same time, it is necessary to strengthen the inspection of the equipment and the management of the spindle position. If the strangler is damaged, it can make the silk bar deviate from the normal silk track and transfer the twist to the free zone, resulting in tension fluctuation and wear of the silk bar, and at the same time, there are stiff silk and wool Silk; if the false twister, the first roller and the second roller are worn seriously for too long, or if they are not installed properly, they will lead to slippage, tension fluctuation, and stiff silk; if the hot box is too dirty and coking seriously, it will not only damage the silk, but also cause uneven heating of the silk, at this time, there are many filaments and stiff silk; if the friction disk is too dirty and too much white powder, the silk is easy to slip at the false twister, It causes tension fluctuation and stiff wire.