Synthetic resins are very important intermediate raw materials in industry, from the manufacture of coatings and composite materials to insulating foam and hard plastics. Today, resins are still produced mainly from petroleum derivatives. As part of its ambitious research programme on biopolymers, VITO wants to replace the fossil basic components of epoxy and phenolic resins with lignin, a biochemical compound that can be extracted from green by-products and waste streams. This not only reduces the climate and environmental impact of the resins, but also makes them less toxic.
Lignin is one of the most common organic materials on Earth and the most abundant natural source of phenolic compounds. It is mass produced as a by-product of, for example, the manufacture of wood pulp and paper. Most of this lignin is currently burnt, which means that the material is only valorised energetically.
That is a pity since lignin has much more potential as a so-called bio-aromatic. It can replace many aromatics of fossil origin in the chemical industry, such as the basic chemicals phenol and bisphenol A, which are found for example in synthetic resins. The latter are intermediate raw materials that have a wide range of applications in various sectors, from construction to mobility and transport to the plastics industry.
Ambitious biopolymer team
For years, VITO has been active in researching the use of lignin as a basic raw material for chemicals. It focuses, among other things, on the production of bio-based synthetic resins of two types: epoxy resin and phenolic resin. This not only increases the sustainability of these materials, but also makes the resins part of a broader circular value chain. After all, the lignin comes from secondary and waste flows. Finally, introducing recyclability in these resins is also our ambition.
The research into lignin is being carried out by an ambitious team of biopolymer researchers within the SPOT research group (Sustainable POlymer Technologies). The VITO team is working closely with the industry on this while also studying other bio-based side streams than lignin, such as hemicellulose. Furthermore, VITO is also part of the core of Biorizon, the Belgian-Dutch research consortium that aims to produce relevant bio-aromatics from lignin on an industrial scale - in order to achieve a sustainable and profitable 'green' chemical industry. Functional bio-aromatics will be produced from lignin at the LignoValue Pilot, a pilot installation that VITO is setting up and which is currently under construction and will be running at the beginning of 2022.
In the case of epoxy resin, the issue is replacing bisphenol A, a chemical that has built up a negative reputation in recent years due to its toxic effects on the environment and on human health (for example, it disrupts the hormone balance). Two years ago, VITO developed a new patented method to make epoxy resin completely bio-based from lignin and saturated fatty acids. "Lignin and lignin oil are therefore very good candidates to phase out bisphenol A over time," says Jaime Gracia Vitoria of VITO.
This year also saw the start of two new European projects on epoxy resin, both involving VITO's biopolymer SPOT team. "Some 320,000 tonnes of epoxy resin are produced in Europe every year," says Gracia Vitoria. "The introduction of bio-based raw materials will thus have a significant impact here, not least due to the wide range of epoxy resin applications." One of the projects is BBI LigniCoat, which focuses on the use of epoxy resin in metal coatings. This involves cutting the large lignin molecules into smaller pieces first (depolymerisation), after which these smaller aromatics can be used again in the resin synthesis processes. "In order to specifically investigate and improve this depolymerisation, a small reactor will soon be installed in our lab at VITO." In another project, VITO is working with various companies on the replacement of bisphenol A with lignin oil in epoxy resin for composite materials, in particular for car parts. "With these last two projects we are really moving out of the lab. We are taking an important step towards finding economically viable bio-based alternatives to bisphenol A in epoxy resin."
Demonstration phase
The other synthetic resin receiving strong attention from VITO is phenolic resin a material found in a wide range of applications, such as insulation foam, building materials, car parts and adhesives. Here the goal is to partially replace phenol, a basic chemical substance of fossil origin, in phenolic resin by lignin. To this end, the VITO biopolymer team is working together with industrial partners like INEOS, SBHPP and KINGSPAN and other knowledge institutions (UGhent – INCAT research group) within the framework of the BIORESAL project, which is supported by VLAIO and under the auspices of Catalisti (the Flemish spearhead cluster for innovations in sustainable chemistry). "We aim to replace at least 20 per cent of fossil phenol with lignin," says Gracia Vitoria. Again, VITO researchers are focusing mainly on the selection of lignin from by-products and waste streams, and on the chemical modifications required to reconstitute the bio-aromatics into long resin polymers.
The use of these biobased phenolic resins will be tested and evaluated in industrial foam insulation applications and in the production of molding compounds. Gracia Vitoria: "With BIORESAL we are currently aiming to scale up to a one-tonne production trial of lignin-based phenolic resin."
A third type of resin that VITO is researching - on a smaller scale - is synthetic resin based on acrylic fibres. Here, the researchers are still looking for possible applications, and for possible partners to cooperate with.
New partners are also welcome in the epoxy and phenolic resin research. Moreover, companies and organisations can always contact VITO with questions or suggestions about lignin and specifically about making synthetic resins more sustainable.
In the meantime, when it comes to the broad research landscape around lignin, VITO plays the role of spider in the web. Its researchers have an excellent view of the sources and availability of this bio-organic material. And the properties of this wonderful gift of nature, and how they translate into specific applications, hold few secrets for them. Finally, VITO researchers are also studying how applications can be recycled as much as possible.
More info
jaime.graciavitoria@vito.be