The SuperBark project, a four-year research and innovation action funded by the CBE JU to accelerate the market entry of bio-based adhesives and coatings, has recently passed its midterm. The main goal of SuperBark is to develop safe, sustainable, and functional adhesives and coatings for wood panels and packaging paper using softwood bark as a raw material.
During the first half of the project, extensive work has been carried out to extract and recover polyphenolic compounds (e.g., tannins) from bark using an alkaline extraction technology developed by VTT. Alkaline extractions under different process conditions have been performed on the barks of Nordic tree species such as spruce and Scots pine, as well as on Calabrian pine bark from Türkiye. The bark residues remaining after the extraction of polyphenols have been used to produce various grades of cellulose nanofibrils (CNF).
Both the bark-based polyphenols and CNF intermediates have been thoroughly characterized and distributed to project partners for the development of adhesive and coating formulations for wood panels and packaging paper. Based on feedback, specific alkaline extractions of spruce and Calabrian pine bark have been piloted to produce larger quantities of polyphenols and CNF for material upscaling and testing.
The outcomes from the two years of work have validated the alkaline extraction technology as a suitable process for extracting polyphenols from softwood bark with high yield. Nonetheless, the quality of industrial bark streams requires special attention, as the presence of impurities (i.e., wood particles, sand, stones) is detrimental to the extraction and fibrillation processes. The recovery of polyphenols using membrane separation technologies also requires further development to ensure that high-purity polyphenols are obtained.
After the initial screening of the bark-based intermediates, several adhesive and coating formulations have already demonstrated promising performance and are currently being optimized to meet the required targets in terms of bio-based content (>95%) and end-product performance. The technical work is closely linked to safe- and sustainable-by-design (SSbD) and techno-economic evaluations to ensure that the developed processes and products comply with safety and sustainability standards while remaining economically feasible for eventual market uptake.
The SuperBark project is progressing at full speed and remains on track to achieve its objectives and expected impacts—namely, diversifying the range of bio-based adhesives and coatings on the market with improved safety and sustainability profiles. Looking ahead, the second half of the SuperBark project will be pivotal in demonstrating that bark-based components can replace fossil-based and often harmful chemicals in the manufacture of adhesives and coatings for wood panels and packaging paper—without compromising product performance.
About the Author
Marc Borrega, originally from Spain, now resides in Finland and works as a senior scientist and project manager at VTT. As project coordinator for SuperBark, he facilitates collaboration, monitors project progress, and represents the consortium. His work includes extracting polyphenols from bark, formulating bio-based adhesives, producing nanocellulose, and assessing the extraction process economically. His research background aligns with SuperBark’s aim to refine industrial bark into chemical components for bio-based products.