Influence of pulping process on the emission of formaldehyde and volatile organic acids from pulps and medium density fibreboards (MDF)

Cold water extracts from pulps produced by the chemo-thermomechanical technique (CTMP process) contain higher amounts of formate and acetate ions compared to cold water extracts from pulps produced by the thermo-mechanical process (TMP process). The CTMP shows a higher emission of acetic acid than the corresponding TMP. However, the release of formic acid is lower than that from TMP due to the higher pH-value of CTMP. Furthermore, the release of formaldehyde from CTMP is lower than that from TMP due to Cannizzaro reaction catalysed by alkali. Moreover, binderless fibreboards from CTMP are significantly lower in the formaldehyde release compared to binderless boards from TMP. The use of MUF-resin increases the formaldehyde release of the boards from TMP and CTMP. Furthermore, MUF-bonded boards from TMP and CTMP are of higher pH-value and lower emission of formic and acetic acid.