It’s December 2015 when Tjalling Chaudron’s phone rings. On the other end is a former colleague now working for a research organisation in Canada. The conversation is about something that sounds familiar: lignin – and the possibility of using it as adhesive in plywood.
“I’d just started as a product developer at Moelven and I remember how fascinated I was. When we hung up, I immediately wrote it down as a development project,” says Tjalling Chaudron, head of product development at Moelven Wood.
Ten years later, Moelven Vänerply has begun mixing lignin powder into the adhesive that bonds their structural plywood together.
“It feels absolutely fantastic that we’ve managed to make this transition. It’s been a major undertaking for all parties involved. The main advantage is that we’re reducing our contribution to carbon dioxide emissions, whilst we’ve managed to demonstrate through third-party verification that the plywood board still maintains the same performance and quality.”
Vänerply was founded in Otterbäcken over 50 years ago and produces plywood from Swedish softwood. Annual capacity amounts to approximately 90,000 cubic metres. In 2011, the company became part of the Moelven Group.
Five years ago, RISE started a research project with the goal of developing 100 per cent fossil-free building boards and elements. For Moelven Vänerply, the project became an opportunity to test the bio-based glue line in controlled conditions – before industrial production began.
“We quickly saw that mixing lignin into the adhesive worked very well. It has high performance in terms of strength and is naturally water-resistant. In the long term, I think we can incorporate more lignin.”
Hot commodity
A softwood tree consists of approximately 30 per cent lignin. The substance is also found in other landbased plants – like grass, straw and stems. It’s during pulp and paper production that the lignin is separated from the cellulose fibres. For every tonne of pulp, 200 kilos of lignin can be extracted.
The material’s unique properties are attracting interest.
“We’ll see more and more products containing lignin in the coming years. There’s an incredible amount of it and the applications are numerous. You can mix it into everything from batteries to carbon fibre and plastic bags. It would work well as a binder in paint too,” says Tjalling Chaudron.
Another company investing in lignin is Södra, which has invested two billion kronor in its sulphate lignin plant in Mönsterås. The facility is expected to be completed in 2027.
More research needed
It’s no coincidence that structural plywood is first out. The product requires a waterproof glue line, and the traditional phenol-formaldehyde adhesive is already dark in colour. Since lignin is also brown, neither aesthetics nor application area are affected – whilst performance is maintained.
“Interior plywood doesn’t have the same water-resistance requirements, and light-coloured glue lines are often used there to enable painting in pale colours. To use lignin in interior applications as well requires further research into colour treatment,” says Tjalling Chaudron.
When new bio-based raw materials are to be incorporated into products, it’s an advantage if existing machinery can be retained. Moelven Vänerply has adapted its production to the lignin-based adhesive.
“You have to expect that bio-based materials behave differently to fossil-based ones. We needed to adjust temperature and humidity in the factory, and saw that lignin cures faster, which gives a somewhat tighter production window. Long-term, the ambition is for the adhesive to be completely fossil-free, but we’re not quite there yet. More research is needed.”
By switching from fossil raw materials to bio-based ones, Moelven Vänerply has reduced its contribution to both carbon dioxide emissions and chemical substances.
“For us, it’s not about being greenest here and now, but about being relevant in the long term too. When we analysed the environmental impact of production, it turned out that the adhesive played a central role. By influencing this particular step, we’re taking an important stride towards an increased proportion of renewable raw materials,” says Tjalling Chaudron.
Text: Gustav Schön Photo: Malin Hildén, Moelven
