Modified Lyocell process to improve dissolution of cellulosic pulp and pulp blends in NMMO solvent

Abstract

Utilization of low-cost paper grade pulp is not feasible in Lyocell process due to presence of metallic and hemicellulose impurities that degrade cellulose and N-methyl-morpholine-N-oxide and lower the onset temperature of dope to initiate runway reaction. Conventional Lyocell process is restricted to use good quality dissolving grade pulp for safety reasons. To overcome this limitation, modified Lyocell process is demonstrated by pretreating pulps to remove metallic and hemicellulose impurities. Effectiveness of modified Lyocell process for faster dissolution and impurities removal for pulps/pulp blends is studied. Pretreatment of pulp blends significantly reduce impurities by 14–32% and improve swelling of pulp results in faster dissolution and safer process. Biopolymer prepared from modified process reduces undissolved particles by 50% and impurities by 30% thus improving overall quality and spinnability. This concept provides practical solution for using paper grade/impure pulps and making it more economical, faster dissolution and safe as compared to conventional process.