The strong, non-toxic and fire-resistant eco-friendly glue is made using lignin, a structural component of wood and by-product of the pulp industry. Although it is responsible for giving wood its tough, strong structure, currently only 2–5 per cent of the lignin produced is used. These rest is typically burned for energy after wood is processed.
Aalto University’s solution can be created in a few minutes, significantly faster than the 10 hours previously needed for chemical-intensive pre-treatments. The purified kraft lignin and chemical reaction used to make the adhesive require no additional heating of the raw material and thus greatly reduce energy consumption.
Glued wood panels such as plywood and chipboard are an increasingly common feature of walls, ceilings and flooring during construction.
“It is important to overcome the disadvantages of wood-based panel adhesives and develop the new innovation into a commercial product,” said doctoral researcher Alexander Henn. “This would enable a shift towards more wood-based construction, as a strong and heat-resistant adhesive made from natural materials makes construction truly ecological and safe.”
The lignin content of previous adhesives has been around 20–50 per cent, whereas the Aalto University innovation has a lignin content of over 90 per cent. The researchers also point out that lignin can be used as a raw material for applications such as coatings and composites.