In the BioActiveMaterials project, active coatings were developed on paper and, from these, initial demonstrators of typical packaging materials (sealed bags, wrapping paper). In addition to the functionality of the coated papers, their recyclability was also investigated.
Functional properties by combining protein layers and waxy coatings
At Fraunhofer IGB, we have developed various biobased coatings that provide a barrier to oxygen, water vapor and mineral oils as well as possessing antioxidant and antimicrobial properties. For this purpose, combinations of different protein layers and waxy coatings containing natural waxes such as carnauba, beeswax or candelilla wax as well as natural antioxidants were investigated. The latter serve to stabilize the films and can provide additional protection of the packaged goods through their antioxidant and antimicrobial properties.
Long-term stable dispersions for production of homogeneous coatings
For the production of homogeneous coatings, protocols were developed for the formulation of long-term stable and easily processable aqueous dispersions. Papers coated with these dispersions were produced on a pilot coating line of the project partner.
Effective barrier to oxygen, water vapor and mineral oils
The investigation of the barrier properties of the best combinations showed 5 cm³/(m²*d*bar) for the oxygen transmission rate and 500 g/(m²*d) for the water vapor transmission rate. A good barrier effect was measured with regard to mineral oils.
Printing on the coated papers is possible.
Long-term resistance to water, on the other hand, is not yet given; further optimization is necessary for this.
Alternative: Edible coatings by spraying
Alternatively, the wax-containing dispersions developed could also be applied directly to foodstuffs – as edible coatings. This is to be investigated in further joint efforts.