Chemical Modification of Sugi wood and Broad-leaved tree woods of low quality-Development of materials for exterior use and furniture-

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Impregnation of wood with phenolic resin was investigated with the object of developing uses of Sugi and other woods of low quality.Neutral or weakly acidic aqueous solution of hydroxymethylphenol monomers which contains little amounts of free phenol, formaldehyde and condensation products is desirable for the improvement of wood. The resins which have been provided by resin makers are not good for the purpose. It needs to establish reasonable reaction procedures for the synthesis of hydroxymethylphenol monomers. Therefore, reaction kinetics of the hydroxymethylation of phenol under the catalysis of sodium hydroxide was investigated. The seven reactions taking place competitively in the process of hydroxymethylation of phenol were analyzed by use of a computer simulation technique, and rate constants and energies of activation for the seven reactions were determined. The result indicates that free (unreacted) phenol decreases as the NaOH/phenol molar ratio increases and as the reaction temperature is lowered.Impregnation of Sugi columns and squares with a neutral 10% aqueous solution of hydroxymethylphenol monomers effectively suppressed the cracking after drying and heating. Fences and benches were manufactured for trial and were exposed to out-doors. There are no problem so far. Face-layr densified Sugi squares impregnated with the resin are light in weight and have sufficient hardness. The use as table tops is expected.