Discussion on the production process of 55dtex/48f polyester fine denier FDY in Luoyangyang fibrillation special fiber column factory Feng Naida (Luoyang Petrochemical Complex, Luoyang, Henan 471012), selection of spinning plate, spinning temperature, spinning speed The effects of cooling conditions, stretching conditions, setting of the retarder, oiling conditions, etc. on the production of fine denier FDY. By properly adjusting the process conditions, fine denier FDY with good quality can be obtained: melt direct spinning; FDY process; fine denier; polyethylene terephthalate. With the continuous development of chemical fiber industry, common conventional varieties have been It is increasingly urgent to develop high value-added products without being able to adapt to the needs of the market. Polyester fine denier yarn is a high value-added textile material because of its small fineness and excellent fabric feel, good drape and gorgeous appearance. This paper introduces the process technology of 55dtex/48f polyester fine denier FDY produced by our factory. 1 Process Technology 1.1 Equipment and Instrument The melt conveying and distribution system is designed by DuPont of the United States. The pressure pump is designed and manufactured by MAAG, Switzerland. The spinning equipment is designed by Japan Toray Engineering Co., Ltd. and manufactured by Beijing Zhongli Chemical Fiber Machinery Manufacturing Co., Ltd. The main test equipment is the USTER*3 type extensometer and USTER*4C type dry meter produced by Swiss company USTER. 1.2 Raw materials and products The melt produced by the polyester plant of Luoyang Petrochemical Complex has an intrinsic viscosity of 0.645, a terminal 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 Flow Pre-Filter 1> Booster Pump 1> Metering Pump> Spinning Assembly> Side Blowing> Oiling Roller> First Hot Roller> Second Hot Roller> Networker*> Winding Head> 1.4 Main Process Conditions Spinning Main process parameters of wire and winding: spinning temperature, 290~292*C; retarder temperature, 290~ 2 Influencing factors analysis 2.1 Melt conveying system In order to reduce the degradation of the melt during transportation, control the conveying temperature and stay Time is very important. Due to the low fineness of the produced varieties, the residence time of the melt on the conveying pipe is longer, resulting in a larger viscosity drop during the conveying process. In order to reduce the decrease of the melt viscosity during the conveying process, the melt conveying temperature must be lowered. However, if the melt delivery temperature is too low, the melt flow viscosity will be large, resulting in uneven melt transport, which is unfavorable for spinning. Therefore, we control the melt delivery temperature to 285G to control the melt to the spinning box. The viscosity drop of the melt in the 286 ~ 288G process is less than 0.025, which basically meets the requirements of spinning. 2.2 Pre-filter accuracy The accuracy of the melt filter is generally 15 ~ 2 (Fm, the accuracy of the filter is too high, resulting in too much pressure difference before and after the filter, will shorten the filter life cycle, resulting in frequent filter cleaning, Increase the consumption of glycol cleaning solution and the workload of cleaning personnel; in addition, the frequent switching of the filter is also unfavorable for spinning. Therefore, considering the comprehensive consideration, our factory sets a filtration precision after the final polymerization kettle of the polyester device. The 20m melt filter basically meets the requirements for producing fine denier. 2.3 Selection of spinneret and control of component pressure Choosing the aperture of the spinneret and designing the spinneret is one of the keys to spinning fine denier. The choice of pore size is mainly in accordance with the melt in the capillary. The rate of shear rate is such that the draw ratio of the spinneret is within a suitable range. For fine denier FDY, the shear rate is generally controlled within 0.7X104 104s-1, while the capillary diameter of the spinneret is not less than 2.5. For the 55dtex/48fFDY with a single filament fineness of 1dpf, we choose the spinneret. Due to the fineness of the capillary of the produced variety, the selection of a higher component pressure results in a more uniform melt. However, if the component pressure is too high, the service life of the component will be shortened. Combining the two factors, the author thinks that the initial pressure of the component is optimal at 12~15MPa. 2.4 Selection of hot roll speed The conveying process and the residence time in the spinning box need to increase the spinning speed; however, the excessively high spinning speed will inevitably make the spinning tension larger, resulting in filaments and broken ends; The spinning metering pump selected is 1.6cc/rev. In order to operate the spinning metering pump at the optimum speed, the spinning speed must be controlled within a suitable range. Considering the combination, we have chosen the spinning speed at 4800m/ Min. 2.5 draw ratio and hot roll temperature Since the orientation of the fine fibers of the fine fibers is originally higher, the draw ratio between the first heat roll and the second heat roll must be lower than that of the conventional one. FDY with a certain strength and elongation is obtained, and the smaller the monofilament fineness, the lower the stretching ratio. Due to the large degree of orientation of the fine fibers of the fine denier, the tensile stress is higher and the boiling water shrinkage is higher; therefore, when the fine denier is produced, the temperature of the first hot roll should be slightly higher than that of the conventional one to reduce Tensile stress reduces the generation of wool and broken ends. The setting temperature of the second heat roller should also be higher than that of the conventional product to obtain a suitable boiling water shrinkage. 2.6 The spinning temperature with higher spinning temperature can reduce the viscosity of the melt, improve the rheological properties of the melt through the orifice of the spinneret, and delay the cooling time of the melt flow to maintain the plate surface at a higher temperature. Therefore, when producing fine denier, the spinning temperature is usually 2~4*C higher than the conventional one. However, when the spinning temperature is increased, the oil-free viscosity drop is preferably kept within 0.025, not more than 0.03. The viscosity drop is too large. It indicates that the molecular weight distribution of the melt is too wide and is unfavorable for spinning. 2.7 Oiling and Cooling Conditions Due to the low fineness of the fine filaments, the spinning tension is large. The double factor of the large surface area of ​​the tow and the large spinning tension makes the friction of the tow contact with the yarn guide easy, and the filament is easily broken. At the same time, the spinning tension is too large, so that the degree of orientation and crystallinity of the fiber are large. In order to eliminate this unfavorable factor, it is necessary to shorten the bundle length, increase the height of the grease nipple, and lower the spinning tension. In addition, the choice of the height of the nozzle should also consider the unevenness of the strip of the fiber. If the height of the nozzle is too large or too small, the unevenness of the strip will increase. After many tests, when the nozzle height is positioned at 1300, the unevenness of the strip is the smallest. Since the specific surface area of ​​the fine denier is large, the contact area between the tow and the yarn guide is large, and the friction is large, so the oiling rate of the fiber must be increased to reduce the friction. Generally, the OPU of the fine denier FDY is controlled at 1.0%. Good left and right. The oil type used in the production is D61 produced by S+S Company of Germany. The concentration of the oil agent is 13%~ In order to further reduce the degree of orientation and crystallinity, the cooling conditions need to be moderated, and the side blowing wind speed is too large or too small. This causes an increase in the unevenness of the strip and affects the tensile properties and dyeing properties. After several tests, when the wind speed is selected at 0.4m/s, the side air blowing temperature is 20 ~ 22 * ​​Q rheumatism 70% ~ 90%, and the unevenness of the strip is the smallest. 2.8 The setting of the retarder Since the melt flow just extruded from the spinneret is very fragile and cannot withstand the impact of any airflow, it is necessary to provide a slow cooler under the spinneret to isolate the exchange with the external airflow. In addition, the retarder of a certain temperature can also heat the surface of the spinneret to make the temperature of the surface of the spinneret uniform, eliminating the difference in spinning temperature of the inner and outer monofilaments; at the same time, setting a certain temperature of the slow cooler It can avoid the rapid cooling of the melt stream extruded from the spinneret and the generation of more fine crystal nucleus inside the fiber, and reduce the residence time of the fiber near 190 * C, thus avoiding the The crystallinity of the nascent fiber is too large; in addition, a certain height of the slow cooler is set to lower the quenching area of ​​the melt stream to avoid quenching in the rapid refinement zone of the melt stream, which is uniformity and pull of the yarn. The improvement in the degree of orientation during stretching has great advantages. The fine denier single filament has a low fineness and is easy to be processed by the network, and a relatively satisfactory network degree can be obtained at a lower pressure. The network device we selected is the network device produced by HERBERLEIN. The network pressure is controlled at 0.3~0.4MPa and the network degree is 20~30/m. 2.10 Winding condition The winding condition of fine denier is different from the control characteristics of conventional varieties. Large, we set the winding angle to 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%; strip unevenness CV , 1.40%; boiling water shrinkage, 6.6%; dyeing, > grade 4; grade A Emf Bed Canopy,Square Type Canopy,Emf Shielding Canopy,Emf Shield Canopy Shandong EMF New Material Technology Co., Ltd , https://www.earthingsilver.com