The solvent used for dry gel spinning is generally decalin with low boiling point, high volatility and good solubility for UHMWPE. UHMWPE and decalin are mixed into a solution with a concentration of no more than 10% in a twin-screw extruder, and then extruded through a spinneret to enter a heated nitrogen passage to remove solvents. After cooling, dry gel filaments are formed, and then UHMWPE fibers are made by multi-stage high power hot stretching. The dry gel spinning process is technically difficult and requires high sealing of the recovery system, but its advantages mainly lie in:
1. Shorter process, higher productivity and lower cost.
2. The solvent can be directly recycled, which is more conducive to environmental protection.
3. Under the same other conditions, the fibers prepared by dry method have higher crystallinity, mechanical properties, higher fiber density and better thermal stability.
4. It has good luster, soft feel and low solvent residue, and is suitable for medical and home textile fields. At present, the main manufacturers are DSM Company of the Netherlands, TOYOBO Company of Japan, and Yizheng Chemical Fiber Company of Sinopec.
In the wet spinning production process, white oil with high boiling point and low volatility is used as the solvent. Ultrahigh powder is dissolved in white oil to make spinning stock solution. Then, it is extruded into a liquid filament by spinning components. Then, it is cooled in a water bath to form a gel filament. The gel filament is extracted, dried and desolvated to form an unstretched precursor, and then it is hot stretched for several times to make a finished fiber. The wet process technology is less difficult and requires less equipment. At present, most domestic enterprises adopt the wet spinning process, which can produce military and civilian fiber products with different denier numbers and strengths. However, the focus of the current wet process route research is to optimize the existing process route, further improve the mechanical properties, stability and functionality of the fiber, focusing on the middle and low-end products. At present, the main manufacturers are Honeywell Company in the United States, Beijing Tongyizhong Company in China, and Nantong Jiujiujiu Company.
Post time: Oct-28-2022
