Author : Chalerm Mahittikul

Summary : Four experiments were conducted to determine the properties of tangal (Ceriops tagal (Perr.) C. B. Rob.) tanbark extract for use as adhesive for plywood and particleboard. The predominant compounds identified in both monomeric and polymeric polyphenols with the amount of 63% and 58%, respectively, there was flavonol with resorcinol A nucleus and pyrogallol B nucleus. Chemical analysis of tangal bark showed 40.5% solubility in hot water (unleached). The yield of tangal bark extract under six-stage countercurrent process was 232.4 kg/ton of air dried bark with efficiency of 85.5% (based on total solid of raw material and spent material). The tannin content of bark was 26.1%; tannin formaldehyde precipitate from the bark, 47.2%; and the tannin to non-tannin ratio of the bark, 1.6:1. The 3-ply white lauan (Pentacme contorta (Vid.) Merr. & Rolfe.) plywood was glued with unfortified tangal tannin formaldehyde with 5% paraformaldehyde, 10% tangal bark flour and 1% phenol solution (based on total dry weight of tannin powder) with the final pH of 5.7. The final glue bond quality passed the Type 2 bond (PHILSA, R1975).