Potential use of metalworking fluid as surface additive for improving surface properties, technological properties, and formaldehyde emission of fiberboard

This study investigated the potential use of metalworking (cutting) fluid as an surface additive in the production of medium density fiberboard (MDF). The cutting fluid was sprayed on the mat surface of the fiberboard at different loading levels, of 3.5 g/m2, 7 g/m2, and 14 g/m2 (5 wt% or 10 wt% concentration levels) before the hot pressing. Some physical and mechanical properties of the resulting MDF specimens were carried out according to European standards. The bending strength and bending modulus, internal bond strength improved with the addition of the cutting fluid into the surface layers while the thickness swelling and water absorption decreased. This might be related to the fact that there was no hydrophobic chemical used in the production. The improvement in the adhesive bond between the fibers may be explained by the enhanced heat transfer from surface to the core layer of the MDF. The formaldehyde emission of the MDFs decreased with the incorporation of the cutting fluid. It was estimated that the crosslinking of the UF resin increased due to the higher thermal conductivity of the cutting fluid. The preliminary findings of the present study showed that the cutting fluid used in the metal industry could be efficiently used as surface additive in the production of the MDF.