Moisture-proof bionic coating for PPC packaging – BionicBarrier

Graphic representation of the BionicBarrier project with a paper cup holder and a water-repellent coating of grape marc
Graphical representation of the production and recycling cycle of packaging with bionic barrier coating

Condensation impairs the integrity of PPC packaging

Paper, paperboard, and cardboard (PPC) are important packaging materials due to their low cost and good mechanical stability. These materials are often used as transport packaging for foods as part of a cold chain and as such there is a risk of condensation forming and subsequently damaging the packaging and food products. The packaging can soften and lose its mechanical stability.

Mineral oil based barrier layers impair recyclability

In order to guarantee the stability of the packaging and thus optimal product protection, PPC substrates are often coated with mineral oil based water barrier layers made of wax or plastics. A consequence of this is that these coated PPC materials cannot be easily recycled. For a biobased circular economy, new solutions are needed to provide effective moisture barriers and easy recyclability.

Plant cutin barrier layer facilitates recycling processes

The objective of the BionicBarrier project is to develop a water-repelling bionic coating based on plant cutin. Cutin is a natural polymer formed from fatty acid monomers. It protects certain parts of plants, such as the leaves and fruit, from drying out and forms a mechanically stable matrix. It is hence a biobased and biodegradable water-barrier. So following nature's way, a cutin-based coating will be developed to guarantee the dimensional stability and tear resistance of PPC packaging, the longevity of the laminates, the protection of the products, and the stability of the printing inks. The coating will be applied to the substrates as a water-based formulation, namely free of solvents that are harmful to health. In addition, the coating will be able to be readily removed from PPC substrates in subsequent recycling processes. The raw material for the coating is not in agricultural competition with the foods and will only be sourced from waste materials that hitherto have had no high-value use.

Fraunhofer scientists develop cutin-based coatings

The Fraunhofer IVV scientists will investigate the enzymatic extraction of cutin from the skins of pressed grapes. By controlling the process, it will be endeavored to optimize the chemical and hence physical properties of the cutin for its use as a coating for packaging. Then, via melt emulsification or a solution precipitation reaction, a water-based cutin suspension will be prepared. The scientists will evaluate various types of emulsifying agents. A further development step will be to set and measure the optimal cutin particle size in order to maximize the stability of the dispersion for minimal emulsifier use. The dispersion will then be applied to cardboard and parameters such as the Cobb value (water absorption) and mechanical stability will be determined. The recyclability of the coated packaging will be first of all evaluated on a laboratory scale. It is planned to test the concept on an industrial scale in further projects.

Project term: 2018 to 2019
Project management
/project funding:
Forschungszentrum Jülich (FZJ)
/Federal Ministry of Education and Research (BMBF)