The many positive properties of plastics are used for packaging. They are convincing due to their simple production and low weight. At the same time, they perform their main task — the protective effect on the packaged goods — excellently: they protect food from contamination, simplify its transport, are difficult to break, in many cases allow a view of the product and significantly extend its shelf life. Good packaging can therefore make a major contribution to saving resources and reducing food waste. To further increase the recyclability of packaging, four Fraunhofer institutes are working in an ongoing project to develop a monomaterial film with all the properties needed for product protection.
In recent decades, the advantages of plastic packaging have helped it become more widespread and an indispensable part of everyday life. At the same time, however, packaging waste also contributes significantly to the accumulation of plastics in the environment. If waste is not disposed of adequately, its long persistence hides the risk of accumulation of the corresponding materials in the environment, with negative effects on wildlife and even humans.
Monomaterials replace multilayer films
Single-grade disposables, can be well separated and recycled in the recycling loops, provided they are disposed of correctly. More problematic are so-called multilayer films, which are made up of several polymer layers that are practically inseparable from each other. Due to their outstanding properties, such composite films are mainly used for packaging in the food sector, e.g. pre-packaged cheese, sausage or snacks. For these materials, the only practical option at the end of the product life cycle is thermal recycling, which, however, is not an ecologically desirable solution — although it is preferable to disposal in simple landfills or even shipment abroad. The focus of current developments is therefore on monomaterials. Initial approaches for replacing multilayer films are already being offered on the market for selected applications.
Monomaterial films with tailored product properties
The recycling of plastic packaging, also in the sense of the circular economy and an associated equivalent use as the original product, is therefore also the focus of a currently ongoing project of the Fraunhofer-Gesellschaft. The consortium consists of the Fraunhofer Institutes for Organic Electronics, Electron Beam and Plasma Technology FEP in Dresden, for Silicate Research ISC in Würzburg, for Process Engineering and Packaging IVV in Freising and for Environmental, Safety and Energy Technology UMSICHT in Oberhausen.
Under the coordination of the Fraunhofer IVV, the four institutes are conducting research to develop a completely recyclable monomaterial film that meets all the requirements of the packaging industry. These include mechanical properties, e.g. to ensure the stability of stand-up pouches, as well as requirements for the barrier effect with regard to gases, vapors and aromatic substances. The central idea of the project is to separate the property profile of the polymer granules to be extruded from the subsequent product properties of the film by specifically modifying the film material afterwards. Compared with the solutions already available, it is possible to increase the stiffness as required and thus save material. For this purpose, technologies are used which can be applied in-line to the film extrusion and therefore do not reduce its productivity. This enables the production of recyclable films while maintaining previous production costs.
