Characterization of Softwood Lignin Derivatives in the Alkaline PEG Treated Dried Black Liquor Powder of Soda-AQ Cooking

摘要

Softwood soda lignin does not have thermal melting property. To change the thermal property of softwood soda lignin, we have invented a new method of lignin modification using dried black liquor powder and polyethylene glycol (PEG). In the process, the black liquor powder of the soda cooking of softwood was directly cooked with PEG in alkaline condition to produce PEG modified lignin derivatives (alkaline PEG treatment). The dried black liquor powder which was prepared by a spry dryer was dissolved into PEG with heating at 120°C or 160°C under atmospheric pressure. The modified lignin derivatives (alkaline PEG treated lignin) were precipitated and filtrated out. The collected alkaline PEG treated lignin showed thermal melting property. The chemical analysis data suggested that the number of possible reaction site on lignin with PEG was limited at the treatment of 120°C. On the other hand, the higher introduction of PEG at the 160°C of the reaction suggested that the number of the reaction siteon the lignin was newly produced by the reaction at 160°C.