To ensure product protection, paper-based packaging often requires a barrier layer which is currently typically achieved using fossil-based polymers or harmful chemicals such as per- and polyfluorinated alkyl substances (PFAS). These substances are of very high concern due to their toxicity, persistence in the environment, and tendency to accumulate in living organisms. As a result, their use is increasingly being restricted across the globe.
In the SuperBark project, we are developing an innovative, sustainable alternative to PFAS-based barriers. Our approach focuses on bio-based coatings enhanced with nanocellulose—renewable materials derived from plant fibers. By combining biodegradable components with advanced performance, we aim to create paper packaging solutions that meet functional barrier requirements while minimizing environmental and health impacts.
Coating process. Photos: Urška Kavčič, ICP – Pulp and Paper Institute
Towards bio-based barrier coatings
Barrier coating in the food packaging is of great interest, especially in the era of transition from plastic to fibre-based packaging materials. Plastic materials are effective in terms of barrier properties; however, fibre-based packaging materials (like paper and cardboard) when coated with appropriate coating formulations, can be a great sustainable substitution for fossil-based materials. Barrier properties of current papers are mainly achieved with PFAS that are harmful for nature, so to withstand these challenges in the field of barrier packaging materials and to be in line with packaging and packaging waste regulation, the SuperBark project aims to develop at least 95% bio-based barrier coatings that will reduce the use of harmful fossil-based substances while maintaining barrier properties.
Bio-based barrier coatings containing bark-based nanocellulose
The aim of WP4 of the SuperBark project is to develop coating formulations containing bark-based nanocellulose. Pulp and Paper Institute (ICP) in collaboration with Goričane Papermill and VTT, which produces and provides bark-based nanocellulose, aims to develop coating formulations for packaging papers that provide barrier properties against moisture, grease, oil and oxygen.
In the first year and a half, many different coating formulations based on starch and containing bark-based nanocellulose were developed and applied on different base papers produced in Goričane Papermill. The addition of CNF significantly improved the moisture barrier properties of the base papers, particularly in higher humidity environments. Additionally, oil and grease barriers were tested, and grease resistance of coated papers was at the highest level (KIT 12). Further adjustments will be performed to increase also the oxygen barrier that is the most challenging among tested barriers.
While the mechanical and converting properties of the packaging are as important as barrier ones, the developed coated barrier papers will be analysed regarding these properties too. The final goal of the project is to develop a coating containing bark-based nanocellulose that will enhance the barrier properties of base papers produced by the Goričane papermill while also allowing them to be processed into various types of paper-based packaging.
SuperBark project results will enable Goričane papermill to broaden the portfolio of their barrier papers with bio-based coated barrier papers that are recyclable in standard paper waste streams and biodegradable, thus contributing to the circular economy.
1-2) Preparation of 100% biobased coating formulation with unbleached bark-based nanocellulose. 3-4) Preparation of 100% biobased coating formulation with bleached bark-based nanocellulose. Photos: Urška Kavčič, ICP – Pulp and Paper Institute
1-2) Uncoated paper (KIT 1 – no grease resistance, the drop stains the paper surface). 3-4) Paper coated with the developed coating formulation containing bark-based nanocellulose (KIT 12 – great grease resistance, the drop does not stain the paper surface). Photos: Urška Kavčič, ICP – Pulp and Paper Institute
Urška Kavčič, WP4
ICP (Pulp and Paper Institute) is contributing its expertise in fiber and packaging material development, barrier coating formulation, and end-of-life assessment. ICP is responsible for developing and testing functional coatings, evaluating their performance on various paper substrates, and ensuring that the final packaging solutions meet environmental and circular economy standards.
To learn more about the work in WP4, contact Urška Kavčič at urska.kavcic@icp-lj.si or WP4 leader Boris Forsthuber at b.forsthuber@holzforschung.at.