Influence of resin content and pulping temperature on the formaldehyde release from medium density fibreboards (MDF)

Increasing the binder content from 12?% to 20?% in medium density fibreboards (MDF) using a slightly melamine modified (3?% melamine) UF-resin of a molar ratio F:U of 1:1 causes a decrease in the formaldehyde release from the boards prepared under the same conditions. The formaldehyde emanation was measured using the perforator (EN120) and the flask method (EN 717-3) after a reaction period of 3?h and 24?h. The results apply for boards made from thermo-mechanical pulps (TMP) prepared by pulping wood at 140?°C and 175?°C. The pulping temperature of wood also impacts the formaldehyde release from MDF prepared therefrom. Ascending the pulping temperature from 140?°C to 175?°C has a positive, but less significant influence on the formaldehyde release compared to that of increasing the binder content from 12?% to 20?%. Insofar, it becomes evident from the results that the conclusions drawn in the literature pertaining to the influence of resin content in case of high molar ratio resins do not necessarily apply to low molar ratio resins.