
Beechwood and birchwood as hardwoods were subjected to solvolysis pulping using cresols and water (CW) (7 : 3 or 1 : 1 by volume) including small amounts of acetic acid (A). When beechwood chips were cooked with CW (7 : 3) including 10% of A (based on chips) for 3 hr at 170°C, the chips produced pulps with the highest selectivity of delignification and with the satisfactroy strength properties. If they were cooked with CW (1 : 1) systems, the selectivity of delignification was decreased. Birchwood was delignified more readily than beechwood. Under almost the same cooking conditions as those for beechwood (using 2 hr of the cooking time instead of 3 hr), birchwood chips produced pulps with the good strength properties. Therefore, a much improved delignification of hardwoods was found to be achieved with CW (7 : 3) including 10% of A for 2-3 hr at 170°C.Polysaccharidic products (CWPS) and solvolysis lignin (CWL) were obtained by fractional precipitation from the spent liqour. The results obtained from the analysis of sugar composition for CWPS showed that CWPS consisted of 10% of xylose and 90% of xyloligomers for the xylose residue. CWL was separated into a high molecular weight fraction (CWL-1) and a low molecular weight fraction (CWL-2). CWL-1 and CWL-2 were characterized with respect to elemental composition, contents of functional groups and oxidation products. The results indicated that CWL-1 contained most of the original lignin structure intact, but it contained 9-13% of condensed cresols. CWL-2 was found to have 20-30% of condensed cresols and to be modified stringly. CWL may be utilized more effectively as constituents for phenolic resins, because it has the higher content of phenolic hydroxyl groups than that for commercial lignins.
Solvolysis pulping, Hardwoods, Resorcinol, Delignification, Lignin-based resin adhesives, Wood refinery, Organosolv pulping
Solvolysis pulping, Hardwoods, Resorcinol, Delignification, Lignin-based resin adhesives, Wood refinery, Organosolv pulping
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