Wood Fireproofing Coatings Based on Biobased Phenolic Resins

Different formulations of phenolic resins based on two natural products, namely, lignin and tannins, were implemented as biobased fireproofing coatings for wood. Moreover, inorganic nanoparticles were included as additives for improving the thermal resistance of the coatings. The biobased coating formulations were first characterized for their structure and thermal properties via Fourier transformed infrared (FTIR) and thermogravimetric analyses (TGA). Then, their fireproofing performance was assessed over a softwood and a hardwood species. Various parameters were studied, such as the heat released during combustion, the integrity of the samples, and the flames’ propagation. Furthermore, their performance regarding the mentioned parameters was evaluated with respect to two different commercial formulations (top-ranked fireproofing coatings). It was confirmed that the risks derived from the exposure of wood to fire were significantly reduced after the application of the biobased coatings: the heat release during combustion was reduced, a protective effect was achieved concerning wood integrity, and the propagation of the flames was significantly delayed. Besides, these parameters displayed a better performance on beechwood compared to maritime pinewood. Finally, it was observed that the results obtained by the biobased coating formulations RA and RB were comparable to those achieved with the used commercial fireproofing coatings.