Zur Feuchtebeständigkeit und Hydrolyseresistenz von mitteldichten Faserplatten (MDF). Tl.3: Kriechverhalten und Formstabilität

Medium density fibreboards (MDF), prepared from thermomechanical (TMP) and chemo-thermomechanical (CTMP) pulps using phenolformaldehyde (PF), melamin urea phenolform-aldehyde (MUPF) and tanninformaldehyde (TF) resins as well as adhesives based on 4,4-diphenylmethandiisocyanates (PMDI) as binders and both the blow-line and blender technique as gluing method, were tested as to the creep behaviour and dimensional stability. The results reveal: TMP-boards bonded with PMDI (6 %) and MUPF-resin (14 %) have much lower creep factors than those bonded with pf-resin (8 %). The creep factor of boards bonded with TF-resin (14 %) lies in-between. Furthermore, using the blow-line technique leads to boards with much higher creep resistance, lower creep factors than those prepared from fibres glued by the blender process. Evidence has also been adduced that the dimensional stability of MDF prepared by using PF-resin is much lower than those made by using MUPF-resin or PMDI adhesive.