Research On The Key Technology Of Flexible Melt Spinning

According to statistics,the total production of global chemical fiber in 2017 reached 66.94 million tons,and the production of chemical fiber in China was 47.14 million tons,an increase of 5%,accounting for 71% of the global fiber production,ranking first in the world for many years.While the production of chemical fiber is increasing,the development of chemical fiber products is more rapid,the variety of products is more abundant,and the added value of the products is further improved.Flexible melt spinning refers to the technology of producing various kinds of fibers by using or replacing different functional modules or devices on the same spinning equipment.It includes the flexibility of equipment,process and products.The spinning process is the main factor that restricts the production of flexible spinning.When the spinning equipment expands the production range of the product specifications,it is necessary to consider the matching problem between the variety and the production process of the existing equipment,and to ensure the stability of the newly developed fiber varieties.Starting from the optimization design of spinning components and the analysis of fiber properties,combined with the production process of fibers,and based on the multi-component flexible composite spinning test platform,profiled fiber of the same spinneret profiled fiber and the dope dyeing polychromatic filament bundle were developed,which further enriched the varieties of the test platform and provided some reference for the industrial production of flexible spinning.In the production of the profiled fiber of the same-spinneret,the extrusion of the fiber is more complicated.This paper starts with the theoretical study of polymer rheology and draws the basic equation of spinning melt extrusion.Based on the conventional design method of the profiled spinneret,a circular-trilobal samespinneret profiled spinneret is designed.POLYFLOW software was used to simulate the spinning melt of the same spinneret profiled fibers,and the differences of shear rate,pressure and speed of the melt in different porous micropore were analyzed.By observing the cross-section of the same spinneret profiled fibers prepared in the laboratory,it can be concluded that the uniformity of circular fibers increases with the increase of spinning flow,but the profiled degree of trilobed fibers decreases obviously.The profiled degree of trilobate fiber can be improved obviously by increasing spinning speed.In this paper,the mechanical properties of the same spinneret profiled fibers were studied from the aspects of monofilament titer and crystallinity of fibers.Firstly,the theoretical model of fiber drawing was studied,and the constitutive relation of the fiber drawing was obtained.Then,the temperature and crystallinity of the same spinneret profiled fibers are numerically simulated by using POLYFLOW software,and the variation rule of the temperature of the filament along the spinning line is obtained.The cold-drawn test of the same spinneret profiled fibers shows that the yield point of the fibers increases with the increase of fiber size,and the corresponding yield strength and breaking strength also increase.The crystallinity test of the same spinneret profiled fibers samples showed that the monofilament titer of the fiber had little effect on the crystallinity when the spinning flow-rate was the same;the cross-sectional shape of the fiber had little effect on the crystallinity,which was consistent with the results of numerical simulation of crystallinity.For fibers of the same cross-section,with the decrease of crystallinity,the yield point of the fibers moves down,and the yield strength and breaking strength of the fibers also decrease.Based on the color matching principle of the polychromatic filament bundle,considering the position distribution of different color monofilaments in the tow,several different runner forms were designed,and concentric circle distribution was selected.Through numerical simulation and optimization of POLYFLOW software,the spinning components of polychrome filament bundle were designed and processed.Based on the multi-component flexible composite spinning test platform,the polychrome filament bundle with dope dyeing was prepared,which proved the feasibility of the production process of polychrome filament bundle.Polychrome filament bundle of the dope dyeing without dyeing and finishing process can greatly reduce production costs,environmental pollution and damage,which has great economic value and environmental protection value.POY filament bundle can be formed by spinning polychrome filament bundle dyed in raw liquor at a drawing speed of 3000 m/min.Its total color difference can meet the requirements of industrial production,which has guiding significance for industrial production of polychrome filament bundle dyed in raw liquor.