Tanninformaldehydharze aus den Rindenextrakten von Fichte (Picea abies) und Kiefer (Pinus sylvestris): Einsatz der Rindenextrakte als Bindemittel und Bindemittelzusatz in Holzwerkstoffen

Bark extracts from sproce and pine obtained with water or organic solvents were used as adhesives partly as binder additives, for manufacturing wood based boards. For plywood the extracts replaced about 60% (pine extracts) or 80% (spruce extracts) of PF-resin. The addition of more than 20% of extract reduced the wet bonding strength. Extracts were further used together with cold setting PRF-resin as adhesive for solid beech boards. They could replace the resin up till 30% without falling the boiling-water-resistance below the minimum values of DIN 68602. The mechanical properties of partieleboards bonded with unmodified extracts were low. The addition of PF-resin of düsocyanate as fortifier increased the strength values and reduced thickness swelling