Hydrolysebeständigkeit von formaldehydarmen bzw. formaldehydfrei verleimten Spanplatten

Industrial and laboratory particleboards were stored in humid air respectively in water of different temperatures with subsequent reconditioning to assess the influence of same on the bonding strength (internal bond) and the difference between particleboards bonded with formaldehyde-free resins respectively with resins of low formaldehyde content manufactured according to different processes. Also the changes in thickness and moisture content were taken into consideration. Particleboards bonded with PMDI resins proved to be more resistent to hydrolysis as UF-bonded ones although there might be considerable differences between different manufacturers. The development of "UF-E1 resins" compared to UF-resins of higher formaldehyde content did not lead to a remarkably higher sensibility to hydrolysis caused by moisture or water respectively. In this respect the processes for the manufacture of particleboards of low formaldehyde content do not differ from each other. The irreversible thickn ess swelling proved to be more appropriate for the assessment of the resistance to hydrolysis and the related long-term behaviour than the internal bond.