Toward glueless technical timber
The glues used in engineered timber manufacture contain formaldehydes that raise environmental and sanitary concerns. A European group of researchers is working on ways to eliminate the use of these petrochemical derivatives. Meanwhile, some promising innovative alternatives are reaching the market.
The group’s project, called “Towards adhesive free timber buildings” (AFTB), involves researchers from the universities of Liverpool, Galway, Dresden, and Lorraine along with the Wallonia timber economy office (OEWB).
Its objective is the manufacture of glue-free engineered timber products.
One cubic metre of glued timber uses 5kg of phenol-resorcinol-formaldehyde (PRF) and 1kg of melamine-urea-formaldehyde (MUF) glues. Given that Europe makes roughly 5m cubic metres of engineered timber every year, this becomes a sizeable issue. The alternative being tested is CLT panels assembled with wooden dowels.
Manufacture of these dowels is under way. Their strength will be tested and if the results are satisfactory, they will be used in the manufacture and assembly of panels. The project’s outcome is expected in 2020.
Manufacturers are also getting in on the act, with other alternatives at the commercialization stage. In early 2018, Stora Enso launched a lignin resin to replace the glues used for plywoods, OSB (oriented strong board), glulam, CLT, and insulating materials. So far, not much has been made of this biosourced material (lignin is a natural component of timber), but it could be an effective substitute for petrochemical derivatives.
Another solution expected to make an appearance in 2019 comes from Evergreen, specialist in industrial process and materials research. It involves replacing glues by an additive to resin derived from rapeseed protein. The battle against VOCs, the main culprits of indoor air pollution, has taken a winning turn.