Lyocell Manufacturing Process and Technology
topic
Lyocell process: (1) cellulose pulp dissolved in 76% NMMO at 95-120°C for 2-4 hours forming 10-15% solution, (2) filtration removing impurities, (3) dry-jet wet spinning through air gap (5-50 mm) into water bath at 10-20°C causing gelation and solvent exchange, (4) washing and solvent recovery via vacuum evaporation (>99.5% recovery), (5) optional fibrillation control treatments, (6) drying and finishing. Spinning speeds reach 100-200 m/min.
Role
The NMMO process eliminates toxic CS₂, achieves near-complete solvent recovery, requires less water (30-40 L/kg vs. 150-200 L for viscose), and produces fibres with higher strength and crystallinity.