Tannin‐based bio‐adhesives for the wood panel industry as sustainable alternatives to petrochemical resins

Abstract The development of natural‐based adhesives is a key aspect in reducing the consumption of fossil resources, in adapting to legislation on the use of formaldehyde and in ensuring the sustainability of the wood panel industry. This study focuses on five alternatives for tannin‐based adhesives (tannin‐paraformaldehyde, tannin‐glyoxal, tannin‐hexamine, tannin non‐isocyanate polyurethane (NIPU) with ammonium hydroxide and tannin NIPU with HDMA bio‐adhesives) as potential proposals for the substitution of synthetic adhesives currently used: Urea‐formaldehyde (UF), Phenol‐formaldehyde (PF) and melamine urea formaldehyde (MUF). Modeling and simulation tools were used for the conceptual design of the reaction stage of the bio‐adhesives due to the lack of real data from industrial scale production systems. The life cycle assessment methodology was used to identify the environmental impacts associated with the production processes of these bio‐adhesives. The results obtained showed that tannin NIPU bio‐adhesive with ammonium hydroxide has the best environmental profile, although the other alternative bio‐adhesives also show good environmental profiles compared to synthetic adhesives. Sensitivity analyses have been carried out after evaluating the main hot spots in the production processes. In all of them, reductions of the environmental impacts have been observed, with the replacement of DMC by EC and the reduction of energy consumption being the options that showed the greatest improvements.