Safe, sustainable and high performance adhesives and coatings from industrial softwood bark

Informazioni relative al progetto

SuperBark

ID dell’accordo di sovvenzione: 101112447

DOI

10.3030/101112447

Data della firma CE 22 Maggio 2023

Data di avvio 1 Settembre 2023

Data di completamento 31 Agosto 2027

Finanziato da

• Food, Bioeconomy Natural Resources, Agriculture and Environment

Costo totale

€ 4 687 071,75

Contributo UE

€ 4 468 890,75

Coordinato da

TEKNOLOGIAN TUTKIMUSKESKUS VTT OY
Finland

Periodic Reporting for period 1 - SuperBark (Safe, sustainable and high performance adhesives and coatings from industrial softwood bark)

Periodo di rendicontazione: 2023-09-01 al 2025-02-28

Sintesi del contesto e degli obiettivi generali del progetto

Many consumer products used in our daily life contain adhesives and coatings formulated with fossil and harmful chemicals that pose significant risks to human health and the environment. Therefore, there is an urgent need to develop bio-based adhesives and coatings with improved sustainability and safety profile that also achieve the performance required by industry and consumers.
The main objective of SuperBark is to use natural components from softwood bark, an abundant side stream from forest industries, to develop ≥ 95% bio-based adhesives and coatings for wood-based panels and food packaging paper. This will be achieved by applying a multidisciplinary approach that includes:
a. Extraction of tannins and other polyphenolic compounds from industrial softwood bark using a patented alkaline process, followed by recovery of polyphenols from the alkaline extracts using membrane separation technologies.
b. Utilization of bark-based polyphenols for development of 4 different adhesive formulations for plywood, particleboard, and medium density fibreboard (MDF).
c. Conversion of cellulose-rich bark residues, left after extraction of polyphenols, into cellulose nanofibrils (CNF) that are used as functional components in coatings for plywood and packaging paper.
d. Combination of digital technologies in process design, system dynamics modelling, and data analysis to evaluate technical, socio-economic, and market opportunities, and accelerate the adhesive and coating developments.
e. Application of Safe and Sustainable by Design (SSbD) principles, from the bark extraction to the development of adhesives and coatings and their application to the end products, which are then validated for recyclability and/or biodegradability in relevant environments.
f. Active communication and dissemination activities to increase awareness of relevant stakeholders and ensure the exploitation of the technologies and solutions developed in the project.
The results from SuperBark will provide clear impact by contributing to diversification of the bio-based adhesives and coatings portfolio with improved safety, sustainability, and circularity compared with existing fossil-based products. This will be achieved by validating the alkaline fractionation of bark and use of bark-based fractions in adhesive and coating formulations with ≥ 95% bio-based content, with application in the furniture, construction, transport, and packaging sectors. Eventual industrial replication of bark fractionation processes and the consequent availability of bark-based components on the market will further diversify the bio-based product portfolio. Moreover, bio-based formulations with bark-based components will eliminate the need for fossil and hazardous chemicals typically used in adhesives and coatings, and will promote the recyclability and/or biodegradability of wood panels and packaging paper products.

Lavoro eseguito dall’inizio del progetto fino alla fine del periodo coperto dalla relazione e principali risultati finora ottenuti

The main activities performed during the first reporting period (M1-M18) of SuperBark were related to the production of bark-based components, the preliminary testing of bark components in adhesive and coating formulations, and the implementation of SSbD methodology and process modeling.
Alkaline extractions of European softwood barks from Finland (i.e. Norway spruce and Scots pine) and Türkiye (i.e. Calabrian pine) were conducted under mild and harsh conditions, and the polyphenols in the alkaline extracts were recovered by membrane separation and acid precipitation. The spruce bark residue from harsh alkaline extraction conditions was used, either as such or after mild bleaching, as raw material for fibrillation into CNF.
Resin formulations to be applied as adhesives in wood panels were developed with mixtures of bark-based polyphenols and commercial tannins, with different crosslinkers. The formulations were initially optimized regarding i.e. mixture composition, dry solids, viscosity, curing parameters, etc, and selected resins were tested in lap joint tests to evaluate their mechanical performance.
Coating formulations were developed for wood products and packaging paper. Wood coating formulations were based on commercial bio-based binders and bio-based fillers, including unmodified and chemically modified bark CNF. Alternatively, a polyphenol-based resin combined with overlay paper was also studied as coating for plywood. Barrier coating formulations based on starch and containing bark-based CNF were developed and applied to four different commercial packaging papers.
The different processes developed in SuperBark and their system boundaries were established for implementation of the SSbD methodology, which was tailored to the project needs. Data collection and the first iterations of the assessment (safety and environmental sustainability) were performed, with analyses of hotspots based on safety and sustainability profiles. A techno-economic analysis was performed for the scenario in which bark extraction is integrated into a wood panel mill, the bark polyphenols are extracted for use in adhesives, and the bark residue is burned for energy.
Diffusion models for system dynamics were built and included performance criteria (technical, economic, safety) of the bio-based solutions, with the importance of each criterion assessed by an analytical hierarchy process. Preliminary data analysis on bark extraction was carried out to find functional relationships for integration of equations in the data assessment of the SuperBark value chains.

Progressi oltre lo stato dell’arte e potenziale impatto previsto (incluso l’impatto socioeconomico e le implicazioni sociali più ampie del progetto fino ad ora)

Alkaline extraction of softwood barks resulted in polyphenol yields over 25% of the bark dry mass, which are significantly higher compared to yields from conventional water extraction processes. The polyphenols in the alkaline extracts were recovered by membrane concentration with reasonable flux and yield, but their purity was lower than for acid precipitated polyphenols due to a higher content of carbohydrates and ash. Spruce bark residue from harsh extraction conditions, especially after oxygen delignification, was easy to fibrillate and formed uniform and strong hydrogels comparable to wood-based CNF grades.
Mixtures (50-50%) of bark-based polyphenols and commercial tannins were successfully used to synthesize non-isocyanate polyurethanes and other resin types with promising mechanical properties, but optimization of formulation and pressing parameters is still necessary. Addition of bark-based CNF to coating formulations improved the scratch and abrasion resistance of wood, and also provided barrier properties against grease and oil to low-grammage papers with low coating weights. Further optimization of coating formulations is however necessary.
The technical solutions in SuperBark are built upon state-of-the-art SSbD assessments and any new developments with relevance to the project work are continuously monitored. Techno-economics of bark extraction was completed for the first scenario, and the analysis indicated that the total production costs (inc. OPEX and CAPEX) of the bark-based polyphenols were close to the price level of commercial polyphenols. The structure of the system dynamics model for bark utilization was built to illustrate the mass flows to polyphenols and CNF, and the processes were integrated in a plant producing wood panels. Initial data analysis in SuperBark identified key correlations between extraction conditions, polyphenol properties, and adhesive formulation parameters.