Influence of moisture content on the formaldehyde release of particle- and fibreboards bonded with tannin-formaldehyde resins

Abstract

The main objective of this study was to evaluate the influence of moisture content on the formaldehyde release of particleboards and medium density fibreboards (MDF) bonded with tannin-formaldehyde (TF-) resins. The results revealed that increasing the moisture content in the TF-bonded boards elicited a decline in the content of extractable formaldehyde (perforator values according to EN 120). This is an opposing behaviour to the general state of knowledge related to the influence of moisture content on the formaldehyde content (EN 120) of particleboards and MDF bonded with urea-formaldehyde based resins. Moreover, the TF-bonded panels showed a decrease in the gas analysis values (EN 717-2), flask values (EN 717-3) as well as formaldehyde emission measured in the 1 m(3)-chamber (EN 717-1). EN 120 (now also pr EN ISO 12460-5, 2013) does not take into consideration that boards bonded with other binders rather than aminoplastic resins may behave differently at different moisture contents. Insofar, it leaves no leeway to consider different binders systems.