Luo Liyang Shih Fibration Specialized Fiber Bar Co., Ltd. co-organized 55dtex/48f polyester fine denier FDY production process Feng Naida (Luoyang Petrochemical General Factory, Luoyang 4710212, Henan Province) selection of spinning plate, spinning temperature, spinning speed , Cooling conditions, stretching conditions, setting of the cooler, and oiling conditions affect the production of fine denier FDY. By properly adjusting the process conditions, fine quality FDY can be obtained: melt spinning; FDY process; fine denier; polyethylene terephthalate with the continuous development of the chemical fiber industry, common conventional varieties After being unable to meet the needs of the market, it is becoming more and more urgent to develop high value-added products. Polyester fine denier yarn is a high value-added textile raw material due to its small single filament fineness, and its fabric has excellent hand feeling, good drape and gorgeous appearance. This article describes the technology of melt spinning in our factory to produce 55dtex/48f polyester denier FDY for the peers.
1 Process Technology 1.1 Equipment and Instruments The melt delivery and distribution system is designed by DuPont, USA. The pressure pump is designed and manufactured by MAAG, Switzerland; the spinning equipment is designed by Toray Engineering Co., Ltd. and manufactured by Beijing Zhongli Chemical Fiber Machinery Manufacturing Co., Ltd.
The main test instruments are the USTER*3 extensometer and the USTER*4C stripper produced by the Swiss company USTER.
1.2 Raw materials and products The melt produced by the polyester plant of Luoyang Petrochemical Plant has an intrinsic viscosity of 0.645, a carboxyl group <32 melting point> 256*C, and a diethylene glycol (DEG) content of 1.2%. FDY produced by German S+S company Oil agent. 1.3 Process Pre-filters-> Booster Pumps-> Metering Pumps> Spinning Modules> Side Blow> Oiling Rollers> First Hot Roller> Second Hot Roller> Network Machines> Winder> 1.4 Main Process Conditions Spinning The main processing parameters of wire and winding: spinning temperature, 290~292*C; slow cooler temperature, 290~ 2 Analysis of influencing factors 2.1 Melt conveying system To reduce the degradation of the melt in the conveying process to control the conveying temperature and stay Time is very important. Due to the lower titer of the produced product, the residence time of the melt on the conveying pipe is longer, resulting in a greater viscosity drop during the conveying process. In order to reduce the drop of the melt viscosity during the conveying process, the melt conveying temperature must be reduced. However, if the melt delivery temperature is too low, the viscosity of the melt flow will be large, resulting in uneven melt distribution and unfavorable for spinning. Therefore, we control the melt transfer temperature at 285 G to control the melt to the spinning box. The viscosity drop of the 286 ~ 288G melt in the conveying process is less than 0.025, basically meeting the spinning requirements.
2.2 Pre-filter accuracy The accuracy of the melt filter is generally selected from 15 to 2 (Fm, the filter's accuracy is too high, resulting in a large pressure difference between the filter before and after, will shorten the filter's life cycle, resulting in frequent filter cleaning, Increase the consumption of glycol cleaning fluid and the workload of cleaning personnel; in addition, frequent switching of the filter is also unfavorable for spinning, so considering comprehensively, our factory sets a filtration accuracy after the final polymerization reactor of the polyester device. The 20m melt filter basically meets the requirements for producing fine denier yarns.
2.3 The selection of spinneret and the control of the pressure of the component The choice of the hole diameter of the spinneret and the design of the spinneret is one of the keys to the spinning of the fine denier. The choice of the pore size is mainly based on the conformity of the melt in the pores. The rate of shear, but also to make the spinneret draw ratio in the appropriate range. For fine denier FDY, the shear rate is generally controlled within 0.7X104 104s-1, and the aspect ratio of the capillary holes of the spinneret can not be less than 2.5. For spinnerets of 55dtex/48fFDY with a single filament fineness of 1dpf, we choose the spinneret. Due to the finer single-filament fineness of the produced variety, the higher pressure of the assembly will result in a more uniform melt. However, if the pressure of the module is too high, the service life of the module will be shortened. Considering these two factors, the author believes that the initial pressure of the module is best at 12-15 MPa.
2.4 Selection of hot roller speeds The delivery process and the residence time in the spinning box require an increase in the spinning speed; however, excessively high spinning speeds inevitably increase the spinning tension, resulting in yam and yarn breakage; The selected spinning dosing pump is 1.6 cc/rev. In order to make the spinning dosing pump operate at the optimum rotation speed, the spinning speed must be controlled within a suitable range. Considering synthetically, we choose the spinning speed at 4800 m/. Min. 2.5 draw ratio and heat roll temperature Because the degree of orientation of the primary fibers of the fine denier filaments is relatively high, the draw ratio between the first thermo roll and the second heat roll must be reduced compared to the conventional variety. FDY with a certain strength and elongation is obtained, and the smaller the single filament denier, the lower the stretching magnification.
Since the degree of orientation of the primary fibers of fine denier filaments is large, the tensile stress is high and the boiling water shrinkage is also high; therefore, when producing fine denier filaments, the temperature of the first heat roll should be slightly higher than that of the conventional ones in order to reduce Tensile stress reduces hairline and breakage. The setting temperature of the second hot roll should also be higher than that of the conventional ones in order to obtain a suitable boiling water shrinkage.
2.6 Spinning temperature higher spinning temperature can reduce the viscosity of the melt, improve the rheological properties of the melt through the spinneret hole, and can delay the cooling time of the melt stream, so that the board surface to maintain a higher temperature, Therefore, in the production of fine denier yarn, the spinning temperature is usually 2~4*C higher than that of the conventional ones. However, when the spinning temperature is increased, the viscosity of the oil-free filaments should preferably be kept within 0.025, not more than 0.03. It shows that the molecular weight distribution of the melt is too wide, which is not favorable for spinning.
2.7 Oiling and cooling conditions Due to the lower fineness of the fine denier filaments, the spinning tension is large.
The two factors of large surface area of ​​the tow and high spinning tension make the friction between the tow and the yarn guide drastic, easily producing filaments and broken ends; at the same time, the spinning tension is too large, so that the degree of orientation and crystallinity of the fibers are large. In order to eliminate this unfavorable factor, it is necessary to shorten the bundle length, increase the height of the oil nozzle, and lower the spinning tension. In addition, the choice of the height of the nozzle must also take into account the irregularity of the fibers. If the height of the nozzle is too large or too small, the unevenness of the strip will increase. After several tests, the unevenness of the stem was minimal when the nozzle height was positioned at 1,300.
Because the specific surface area of ​​the fine denier filaments is large, the contact area between the tow bundles and the yarn guides is relatively large and the friction force is large, so the oiling rate of the fibers must be increased to reduce the frictional force. Generally, the OPU of the fine denier FDY is controlled at 1.0%. Right and left are better. The type of oil used in production is D61 produced by S+S, Germany. The concentration of oil is 13%. In order to further reduce the degree of orientation and crystallinity, the cooling conditions need to be moderated. The side blowing speed is too large or too small. This causes a rise in the unevenness of the strip and affects the tensile properties and the dyeing properties. After several tests, when the wind speed was chosen to be 0.4m/s, the side blow air temperature was 20 ~ 22*Q rheumatism 70%~90%, and the unevenness of the stem was minimal.
2.8 Retarder setup Since the melt stream just extruded from the spinneret is very fragile and cannot withstand any impact from airflow, it is necessary to install a slow-cooler below the spinneret to block the exchange with the outside air flow. In addition, a certain temperature of the cooler can also heat the plate surface of the spinneret so that the plate surface temperature of the spinneret is even, eliminating the spinning temperature difference between the inner and outer monofilaments; at the same time, setting a certain temperature of the cooler It can avoid that the melt stream that has just been extruded from the spinneret encounters the quenching of the side blow and generates more fine crystal nuclei inside the fiber, and also reduces the residence time of the fiber near 190 *C, thus avoiding The crystallinity of the primary fiber is too large; in addition, a certain level of the cooler is set to reduce the quenching area of ​​the melt stream, and to avoid quenching in the melt thin stream rapid refinement area, which aligns and pulls the orientation of the thread. The increase in orientation when stretched has great benefits.
The denier of fine denier monofilament is relatively low, and it is easy to process on the network. Under a relatively low pressure, a satisfactory degree of network can be obtained. The network device we use is a network device manufactured by HERBERLEIN. The network pressure is controlled at 0.3~0.4MPa and the network degree is 20~30 pcs/m. 2.10 Winding conditions The winding conditions of fine denier yarns are different from those of conventional products. Large, we set the winding angle of 5.5 * ~ 6.5 * winding tension is generally controlled at 0.15 3 product quality 2.68%; elongation at break, 33.09%; elongation at break CV, 7.17%; uneven dry rate CV , 1.40%; Boiling Water Shrinkage, 6.6%; Dyeing,> Grade 4; Grade A
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