木材接着に関する研究(第10報) : 材面調整後の経過期間と接着性との関係(その2)

The effect of surface aging prior to gluing on the wettability and gluability of wood have been investigated. For experimental materials, the heartwood of Shiinoki(Shiia sieboldi Makino), Kuri(Castanea crenata Sieb. et Zucc.)and Benimatsu(Pinus karaiensis Sieb. et Zucc.)were used. Immediately after machining the surface of lamina was exposed to the atomosphere but protected from the settling of airbone contaminate and exposure to light.
After a certain aging period, the wettability and gluability were determined. Ureaand resorsinol-formaldehyd resin adhesives, Polyvinyl acetate emulsion and casein glue were used for gluing. Some of the glued wood was treated with heat at 100℃ for 24 hours maintaining the moisture of wood at a constant level. The block shear strength test in air-dried condition was carried out on the treated and untreated specimens.
The results obtained are as follows :
1) The wettability and gluability did not vary with the lapse of aging period. It seemes that tannin in the wood of Shiinoki and Kuri affected the wettability and gluability.
2) The glue-joint strength of the heat-treated specimens was lower than the untreated specimens due to the deterioration of adhesives. Particularly, a remarkable degradation was observed on urea-formaldehyde resin adhesive.
3) The effect of aging period of lamina to the glue-joint strength of the heat-treated specimens showed a similar tendency in the case of the untreated specimens.
4) In the case of lamina of Shiinoki and Kuri stored for a long period, in the specimens glued with polyvinyl acetate emulsion or casein glue much delamination was observed. On the other hand, Benimatsu did not suffer delamination.