Utilization of Softwood Kraft Lignin as Adhesive for the Manufacture of Reconstituted Wood
Title:
Utilization of Softwood Kraft Lignin as Adhesive for the Manufacture of Reconstituted Wood
Author:
Zhao, Lin-wu Griggs, Bruce F. Chen, Chen-Loung Gratzl, Josef S. Hse, Chung-Yun
Appeared in:
Journal of wood chemistry and technology
Paging:
Volume 14 (1994) nr. 1 pages 127-145
Year:
1994-02-01
Contents:
Reaction conditions for hydroxymethylation of pine kraft lignin (KL) were optimized by kinetic studies of the reaction. Characterization of the resulting hydroxymethylated kraft lignin (HMKL) indicated that about 0.36 mole of the - CH2OH/C9 unit was introduced into the lignin under the optimal reaction conditions, of which about 0.33 mole was introduced into C-5 of guaiacyl moieties via Lederer-Manasse reaction. This result was confirmed by 13C-NMR spectrum of 13C enriched HMKL prepared from KL and 13CH2O (about 7 atomic%) under the same reaction conditions. Lignin-phenolic resins were formulated by blending the HMKL with phenol-formaldehyde (PF). A 50/50 blending of HMKL/PF resulted in a bond strength of about 65 psi in laboratory boards made with sweetgum flakes. In general, bond strength increased with an increase in the PF. Studies on effects of process and wood variables indicate that such resin could yield satisfactory boards made with red oak, black gum, red maple, post oak and sweetgum flakes with: (a) hot press temperature of 410 °F, (b) hot press time of 8 minutes, and (c) minimum resin content of 5%. The present address of Lin-wu Zhao is Research Institute of Utilization and Chemical Processing of Forest Products, Chinese Academy of Forestry, Nanjing, the People's Republic of China. The present address for Bruce F. Griggs is Union Camp Corporation, P. O. Box 3301, Princeton, New Jersey, 08540.