Reactive lignin replaces phenol

There is an active search for uses of a higher value than energy utilisation for the by-products of pulp mills. The wood product and adhesives industry, on the other hand, is looking for safer and environmentally more sustainable bio-based compounds to replace the phenol and formaldehyde used in resin glues.

The CatLignin technology developed by VTT – which won the resource scarcity category in the New Tree competition in Finland – enables the production of reactive lignin well suited for this purpose from the side streams of pulp production.

“The use of lignin in adhesives has been studied extensively. The problem with the currently commercially available lignins is that they are not reactive, like the phenols they should replace. This is why lignin can replace only a small part of the phenol used in adhesives without impairing the adhesive’s properties. The CatLignin technology, on the other hand, produces an entirely new kind of lignin with a consistent quality and more reactive chemical structure, which allows for a much higher degree of replacing phenol in adhesives,” says Senior Scientist Hanne Wikberg from VTT.

Tailored according to need

In CatLignin technology, the lignin is modified already at the pulp mill.

“The process can also be adjusted at the pulp mill in such a way that the properties of the reactive lignin are tailored according to the specific purpose of use,” says Senior Scientist Juha Leppävuori.

In the future, reactive lignins can ­substitute widely for fossil-based chemicals in the rubber and plastic industries and in composites.

“Reactive lignins also have antioxidative properties, meaning that they improve a product’s weather resistance,” says Wikberg.

Partners are needed

Only small amounts – bucketfuls – of Cat­Lignin have so far been manufactured, in VTT’s own reactor. The next step would be a pilot project which would generate enough lignin for the development of applications.

“We cooperate with adhesive manufacturers so that they can fit the new type of raw material into their recipes. We’ve also received encouraging messages from the forest industry, where many operators would be ready to replace all of their resin with a functional, bio-based material,” says Wikberg.

VTT is therefore actively looking for partners interested in developing reactive lignin into a commercial product.

“Our goal is to make reactive lignin commercially available by 2020,” says ­Leppävuori.

The CatLignin technology is being developed in the commercialisation project Creating Business from Research (TULI), funded by VTT and Tekes, the Finnish Funding Agency for Innovation.

Text by Katariina Krabbe,
Photo by Vtt