A Lignin Adhesive System for Flakeboard Production

A new renewable adhesive system based on pulpmill effluent is described for flakeboard production. The system involves base activation of wood flake surfaces with 3N sodium hydroxide, followed by application of methylolated kraft lignin. The lignin was methylolated by refluxing in a basic solution of formaldehyde. Aspen laboratory flakeboards bonded with this system had superior dimensional stability as measured by water absorption and thickness swelling (water-soak) when compared to phenol-formaldehyde (PF) control samples. Although the internal bond strength was lower for the lignin bonded flakeboards, it was well above accepted standards (ANSI). The modulus of elasticity was 35 percent higher than the PF controls and the modulus of rupture was equivalent to the PF bonded flakeboards. The base activated-lignin adhesive system for bonding flakeboards may be a viable alternative to conventional PF resins if the costs of phenol were to rise or if supply problems develop and if the bonding temperature and time can be reduced to conform to conventional methods.

You must be logged in to download any documents. Please login (login accounts are free) or learn how to Become a Member