• Journal of the Korean Wood Science and Technology
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• v.16 no.3
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• pp.5-16
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• 1988

This experiment was executed to investigate the effect of activation of veneer surface by oxidizing agents, hydrogen peroxide and nitric acid, on bonding characteristics of Malas(Homalium foetidum Benth) plywood, in which the effects of these oxidizing agents amount, pretreatment time, and pressing time and temperatue on shear strength of the plywood were examined and discussed. In this research the activation of veneer surface by oxidants was effective in raising shear strength but the difference in shear strength was not observed between hydrogen peroxide and nitric acid treatment. Hydrogen peroxide treatment, however, seemed to be more profitable to industrial application because of its lower concentration and easier handling than nitric acid. The bonding method by lignin-phenol adhesive through surface activation revealed inferior shear strength to phenol- and urea-formaldehyde adhesive but superior water resistance to urea-formaldehyde adhesive and this bonding method, in addition, have the advantage of lower cost compared with phenol-formaldehyde adhesive, Therefore, this bonding method by lignin-phenol adhesive through surface activation seemed to economical in manufacturing of water-resistant wood panel materials in future.

• Journal of the Korean Wood Science and Technology
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• v.24 no.3
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• pp.45-50
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• 1996

Wood chips of oak(Quercus mongolica) and larch(Larix leptolepis) were treated with low pressure steaming explosion. Main components of exploded wood were separated with hot water and methanol extraction. Crude lignin separated from those extractives were purified and those chemical characteristics were investigated. And also, lignin adhesive was prepared from crude lignin and studied those chemical characteristics. The results can be summarized as follows ; 1. The purified lignin by Bj$\ddot{o}$kman's method from crude lignin is about 30% in exploded oak wood and is about 11% in exploded larch wood as a low amount. 2. The phenolic hydroxyl groups in the purified lignins are little higher than those of MWL and molecular weight distributions of the purified lignins are some lower than that of MWL. 3. Alkaline nitrobenzene oxidation products are very low in the clude lignin but those are increased in the purified lignin 4. The gravity of lignin resins(1.15 and 1.13) are a little lower than that of phenol resin(1.16) and the compressive shearing strength of lignin resins are higher than those of phenol resin.

• Journal of the Korean Chemical Society
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• v.20 no.3
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• pp.240-243
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• 1976

A lignin resin, synthesized from the reaction of lignin, phenol and formaldehyde using NaOH as catalyst, showed a strong adhesive property. From a series adhesive strength test it has been shown that the synthetic resin can be used as a good adhesive material for wood.

• Journal of the Korean Wood Science and Technology
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• v.15 no.1
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• pp.1-11
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• 1987

A kraft black liquor obtained from pulping of pine (Pinus densiflora Sieb et Zucc) was used for producing three kinds of adhesive such as black liquor-phenol formaldehyde resin, methyloeated kraft lignin-phenol formaldehyde resin, and lignin cake-phenol resin. In case of producing black liquor-phenol formaldehyde resin, about 60 percent of the phenolic resin could be replaced by black liquor. Also the optimal press condition appeared to be $160^{\circ}C$ for 7 min. (l5.77Kg/$cm^2$ in dry test, 8.54Kg/$cm^2$ in 4 hr. boil test). Phenol could be substituted up to 80-90 percent by methylolated kraft lignin. The suitable conditions of factors affecting bond quality were pH to 2.6, methanol as solvent and 0.2ml formaldehyde per 1g of the adhesives, respectively. The optimal press condition was $150^{\circ}C$ for 4 min. (188.54Kg/$cm^2$ in dry test, 10.08Kg/$cm^2$ in 4 hr. boil test). In preparing lignin cake-phenol resin, a suitable mixing ratio of phenol to powered kraft lignin was one to one by weight. The optimal press condition was $150^{\circ}C$ for 4 min.(18.46Kg/$cm^2$ in dry test, 12.31Kg/$cm^2$ in 4 hr. hoil test).