Effect of resination technique on mechanical properties of medium density fiberboard

Abstract

Effects of different resination techniques relative to the mechanical properties of commercially produced thick medium density fiberboard (MDF) were investigated. The amount of urea-formaldehyde resin (11 wt%) applied to the wood fibers was gradually decreased in the blowline (11, 10.5, 10, and 9.5 wt%), while it was gradually increased in the short-retention blender (0, 0.5, 1, and 1.5. wt%). The internal bond strength of the MDF boards considerably improved as the amount of the resin applied to the fibers in the short-retention blender was increased to 1.5 wt%. In particular, the increase in the IB strength was most pronounced as the resin content increased from 1 to 1.5%. The edge and face screw withdrawal resistances increased by 7.7 and 7.9% as the amount of the resin applied to the fibers in the blender was increased. Similar values were also observed for the flexural properties. Overall, the total resin content in the production of thick MDF can be decreased as blender resination, a means of post-dryer resin addition, is incorporated into the blowline resination technique.