Renewable bio-based coatings deliver strong performance
Coatings are widely used across a range of industries to enhance material properties, protect surfaces and ensure consumer safety. They are used for example to boost the durability and corrosion resistance of vehicles, improve fire retardancy of furniture, and provide antiviral and antimicrobial properties to household goods. Given their ubiquity, it is important that coatings are produced as sustainably as possible, as well as being non-toxic and recyclable. This is not always the case, with fossil-based coatings still on the market. Furthermore, there is growing regulatory pressure on the coatings industry to diminish the content of volatile organic compounds to improve indoor and outdoor air quality, by shifting from solvent-borne systems to waterborne ones. A key challenge for the industry is achieving this, without impacting performance or putting consumers at risk.
Sustainable coatings with defined properties
The goal of the LIGNICOAT(opens in new window) project was to address this, by putting Europe at the forefront of producing technically, economically and environmentally viable renewable coatings. LIGNICOAT received funding from the Circular Bio-based Europe Joint Undertaking(opens in new window), a public-private partnership. “Our main objective was to develop new, more sustainable coatings with defined and targeted properties,” explains LIGNICOAT project coordinator Aitor Barrio from TECNALIA(opens in new window) in Spain. “For this, we focused on lignin as an abundant, bio-based raw material for the development of lignin-based resins.” Lignin is an organic polymer that, along with cellulose, forms the chief constituent of wood. It is in fact second to cellulose as the most abundant organic material on Earth. The idea was that by combining this natural polymer with water in different ways, coatings with anticorrosion, antiviral-antimicrobial and flame-retardant properties could be derived.
Functionalities for different resins
From the beginning, the main challenge was finding effective and efficient ways of modifying lignin, in order to incorporate functionalities needed in different resins. While lignin has long been identified as a renewable biomaterial with lots of potential, finding ways of exploiting this has proven to be tricky. “Through teamwork, we were able to formulate different coatings with targeted applications,” says Barrio. “These include bio-polyurethane coatings for flame retardancy of wood, bio-alkyd coatings for anticorrosion in metals, and bio-epoxy for coil coating.” The team also developed bio-additives based on hop extractives and thymol for antiviral and antimicrobial coatings used for wood and metal protection. All the coatings were validated following standardised tests, and compared with fossil alternatives.
Sustainable solution for resin and coating manufacturers
The project team was successful in modifying lignin intermediates, and validating these at pilot scale. Next steps include scaling up the different processes, building up the supply chain and conducting further research into potential applications. Barrio and his team are also interested in further increasing the lignin and bio-based(opens in new window) content of coatings.
Keywords
LIGNICOAT, bio-based, fossil-based, renewable, coatings, bioresin, sustainable
