Über die Eignung von thermo-mechanischem und chemo-thermo-mechanischem Holzstoff (TMP und CTMP) aus Buchen- und Kiefernholz für die Herstellung von mitteldichten Faserplatten (MDF). Tl.2. Eigenschaften von MDF aus Buchen-Faserstoff
Medium density fibreboards (MDF) were made from beech in laboratory and pilot plant scale from thermo-mechanical (TMP) and chemo-thermo-mechanical pulps (CTMP) using both melamine reinforced urea-formaldehyde resin (UF-resin) and diphenylmethane diisocyanate polymers (PMDI). The physical-mechanical and chemical properties of the boards were evaluated. From the results the following conclusions can be drawn: Both TMP and CTMP led, on using UF-resin, to MDF with very high mechanical properties. Pulping temperature seems to have an influence on the mechanical properties of the boards, prepared from TMP and CTMP. Increasing the pulping temperature from 150 øC to 170 øC negatively affects the mechanical board properties, whereas the properties of MDF from CTMP increases by elevating the maximum pulping temperature from 150 øC to 170 øC. The pulping chemicals in the CTMP-process (Na2SO3 and/or NaOH) decrease the formaldehyde release from the boards. MDF made from CTMP release more than 4 ti mes acetic acid than MDF from TMP. The release of formic acid is quite different, it is in MDF, made from TMP higher than in MDF from CTMP. MDF with very high mechanical properties can also be made from beech pulps (TMP) using PMDI. PMDI in combination with a formaldehyde scavenger in the middle layer and UF-resin in the surface layer leads to boards with very low formaldehyde release.