Industrial production of pine tannin-bonded particleboard and MDF

This article reports on the industrial particleboard and MDF production and trial results obtained over a period of nine years using pine tannin adhesives in Chile. The industrial panels obtained clearly showed that pine tannin extract, a renewable raw material, can be industrially used as an adhesive to manufacture particleboard and medium density fiberboard (MDF) of excellent quality and of very low formaldehyde emission, and this at a reasonable cost. The technology revealed itself suitable both for very old multi-daylight particleboard lines and for more modern single daylight MDF lines. Panels were manufactured initially with addition of small percentages of pMDI to the pine tannin adhesive. Later, adhesive formulations in which pine tannin alone without pMDI was used still showed good results. Industrial results where either paraformaldehyde or hexamethylenetetramine was used as hardener are reported. In the former case the panels satisfied with ease the E1 formaldehyde emission class of European norms. In the case of either pMDI-added adhesives, or hexamine-hardened adhesives without pMDI the emission was lower than the requirements of the F**** Japanese standard.