Flame retardancy through alkaline lignin in acrylic resin coatings for plywood - News and insights for the European coatings industry

New study shows how lignin enhances the fire-retardant properties of water-based acrylic emulsions.

A recent study published in the Journal of Coatings Technology and Research investigates the effectiveness of intumescent coatings based on water-based acrylic resin and alkaline lignin for flame retardancy on plywood. Testing various lignin concentrations (1%, 3%, 5%, and 10%), the researchers found that a 5% concentration optimally promoted a stable, protective char layer during combustion. This moderate amount of lignin significantly reduced flammability, providing enhanced protection.

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Using advanced analysis techniques such as Fourier-transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR), the research team explored the chemical structure of the intumescent coatings. They confirmed that carbon-phosphorus bonds were especially stable and fire-resistant with a lignin concentration of 5%. Higher concentrations, however, reduced the protective effect due to weakened char formation.

The study highlights the importance of natural fire retardant additives like lignin as a sustainable alternative to synthetic additives. By using targeted concentrations, high fire protection can be achieved without compromising material integrity.

Source: Journal of Coatings Technology and Research, Volume 21, pages 611–622 (2024)