2004 年 53 巻 4Appendix 号 p. 84-89
Through the phase-separation system composed of phenol derivatives and concentrated acid, lignocellulosics were separated to highly hydrolyzed carbohydrates and lignin-based material (lignophenols) quantitatively. Lignophenols mainly composed of 1, 1-bis(aryl) propane type units had unique properties such as high phenolic property, obvious phase transition point and switching function (nucleophilic attack of Cα-phenoxide to adjacent Cβ followed by the cleavage of aryl ether linkages). Controlling the hydrolysis of carbohydrates in the system, lignophenol-carbohydrate (LC) composites containing lignophenols and carbohydrates which left no fibrous structures were prepared in the yield of 80-90% from the wood meals. LC composites had significant thermal plasticity at around 170°C. The softening point of the acetylated LC composites was much lower than that of the original ones due to blocked hydrogen bonds of lignophenol and carbohydrates. On the other hand, the hydroxymethylated LC composites (grafted phenol derivative in lignophenol; p-cresol) had no softening point because of linked structures formed in lignophenol. The hydroxymethylated LC composites (phenol derivative: 2, 4-dimethylphenol), however, softened at 170°C because lignophenols in the composites were hydroxymethylated at terminal phenolic nuclei to give linear type polymer. The molds from the acetylated LC composites had the highest density and excellent water resistance. The hydroxymethylated LC molds with p-cresol type lignophenol showed high dimensional stability having slight water absorption and volumetric swelling, because of porous structures and the network of lignophenol. LC composites and molds could be separated into lignophenol and carbohydrate moieties efficiently by simple solvent extraction or using switching function of lignophenol.
