アルカリ・メタノール蒸解 ＩＩＩ 蒸解過程におけるリグニンの挙動

Abstract

The behavior of lignin during alkali-methanol cooking has been studied using the lignin model compounds, vanillylalcohol and veratrylalcohol. The amounts of functional groups and molecular weight distributions of isolated alkali-methanol and soda lignins have been measured.Vanillylalcohol was methylated to vanillylmethylether by treating with alkali-methanol, while vanillylalcohol gave the condensation products with soda cooking liquor. These facts indicate that the mehylation of vanillylalcohol prevents the condensation of it. Vaeratrylmethylether was only slightly produced from veratrylalcohol by alkali-methanol treatment.Comparing the functional groups of both isolated lignins, there are higher amounts of methoxyl groups in alkali-methanol lignin and of phenolic hydroxyl groups in soda lignin. Gel filtration curves of both isolated lignins have revealed that there are less high molecular weight fractions in alkali-methanol lignin than in soda lignin under the same cooking conditions.Summarizing the results mentioned above, it can be concluded that the rapid delignification during alkali-methanol cooking is due to the prevention of condensation through the methylation of active benzylalcohol groups in lignin molecule.