Zum Sorptionsverhalten von Holzspanplatten. Tl.3: Untersuchungen an mit Phenolformaldehydharzen gebundenen Spanplatten

Preliminary investigations showed that alkaline phenol-formaldehyde resins (PF-resins) were by far more hygroscopic than wood, whereas “neutral” and acid cured PF-resins were less hygroscopic than wood. Accordingly, the course of the sorption isotherm at 20°C of particleboard bonded with an alkaline PF-resin was much steeper than that of softwood, whereas the corresponding sorption isotherm of particleboard bonded with a “neutral” PF-resin was above 40% rel. humidity flatter than that of softwood, and the hygroscopicity of particleboard bonded with an acid cured PF-resin was even lower. Moreover, in the cured state “neutral” and acid cured PF-resins proved less hygroscopic than a corresponding urea-formaldehyde resin (UF-resin). Therefore, partial substitution of UF-resin by “neutral” PF-resin in particleboards led to a slight decrease in the equilibrium moisture content of the boards