Study On High-Speed Spinning Techniques Of Polyethylene Terephthalate Filaments With Different Cross-section Shapes

With China's living standard improvement and life style manifold, people gradually give much more attention to the texture and comfort and style of clothing. Fibers, the elementary materials for garments, are naturally forced to improve their quality and multiply fiber and yarn products, such as PET filaments with different cross-section shapes. These products can be one kind of fibers to meet such ever-growing diversified demands. Under these circumstances, although the high-speed spinning techniques have to be updated, they will still be effective and feasible way to obtain the mentioned fibers.The thesis work is the study and development of the techniques - the high-speed spinning of the center-emptied POY, and of the U-shaped POY and DTY and of the POY with the different shape holes in a spinneret, especially focused on the operational factors affecting the degree of emptiness in the center-emptied POY and the properties of U-shaped POY and DTY and of the POY with multi-shaped hole spinneret. Our results show that the design of spinneret assembly, the distribution of multi-shaped holes, and the spinning and cooling conditions are technological importance for the fiber products to satisfy customer's demands for the feel, lightness, fluffy, gloss and moisture adsorption and perspiration conduct of both knitted and woven fabrics.The main findings are as follows:1. PET POY with the degree of emptiness 15-25% were obtained via the specially designed spinnerets and the high-speed spinning with spinning rate 3200m/min, tank temperature 300℃ and lateral wind rate 0.45m/s.2. The fibers with multi-different cross section were successfully made by the optimization of the capillary size of spinneret, spinning temperature and lateral wind.3. The properties of U-shaped POY made by assembling the five circularholes are superior to those of C-shaped.4. The spinnabilities of U-shaped POY were maximized when the denier per filament was 5-10dtex and the spinning rate was 3000-3400 m/min.5. The properties of U-shaped DTY are strongly affected by the content of oiling agent and the spinning rate of POY, tensile, the temperature of the first heat box. The alkaline weight reduction of U-shaped DTY was much faster than and the moisture uptake was better than that of the circular ones, the moisture uptake was 4.68% when the alkaline weight reduction of U-shaped POY was 9.30%.6. The hand feel, lightness, fluffy, moisture uptake and perspiration conduction of both knitted and woven fabrics made from center-emptied POY, ATY and U-shaped DTY were much better than those of ordinary PET fibers. These yarns can be mingled with other filaments, such as DY and FDY, to produce the fabrics styled with multi-different characteristic, and are important substitutes for jute and wool. U-shape not only improved the hand feel and gloss, but also formed the tiny gaps among fibers, and thus endowed the fabrics with water adsorption and breathing properties. POY made by the spinneret with multi-shaped holes could replace the conjugated filaments, and thus reduced the production cost and strengthened product competition.The novelties in the thesis mainly include the high-speed spinning techniques of the center-emptied POY and of the POY with multi-shaped holes in a spinneret, and the spinneret assembly of the U-shaped POY and DTY.