RecyBa

Projectname:
Investigation and comparative evaluation of the effect of aluminium and aluminium oxide evaporation on the properties of recycled polypropylene films

Workgroup: Packaging materials

Research Partner and Scientific Guidance:

  1. Fraunhofer-Institut für Verfahrenstechnik und Verpackung IVV Freising, Nelly Freitag

Financing: IVLV e. V.
Duration: 2024

The design of flexible packaging for improved recyclability is predominantly associated with a mono-material structure of the films. In the food sector, the increasing use of OPP//PP and OPE//PE will replace traditional non-recyclable composites such as PET//PE in the coming years. Organic and inorganic coatings, for example, provide a sufficient barrier for product protection and should account for less than 10 % of the film weight for a mono-material design. While the layer thicknesses for barrier polymers are in the micrometre range, barrier layers in the nanometre range can be achieved with inorganic coatings. This makes metallisation or vapour deposition of metal oxides an attractive alternative.

The aim of this IVLV project is the comparative evaluation of the film properties of recycled polypropylene films with inorganic vapour deposited layers. While the Recyclass protocol works with a dilution of the film to be analysed, this project will look at the barrier film alone in order to be able to derive statements about the influence of the vapour deposition. The focus here is on the mechanical and optical influences. Furthermore, the processing properties of the film extrusion process (temperature, pressure, throughput) are to be analysed in order to identify deviations from the extrusion of virgin material. In this way, the effects of the inorganic coatings on the actual recyclability can be assessed and conclusions can be drawn about the recyclability of a composite. In addition, statements can be made about the reuse of such a recyclate. The vapour-deposited PP films under consideration are obtained from the pool of IVLV members. Mechanical recycling and renewed film production are carried out at the Fraunhofer IVV.

The results obtained in this project create a basis for a better understanding of the recycling of barrier films with thin inorganic barrier layers. While barrier polymer combinations have already been investigated to some extent, this does not yet apply to the same extent to inorganic barrier layers. They potentially offer an opportunity to provide suitable protection for the packaged product or to enable the reuse of recyclate in new packaging. If the project results are positive, this will lead to a need for further research and fields of research into functional barriers on an inorganic basis. If the project results are negative, there will also be a need for research into suitable alternative barrier layers. Such objectives can be defined within the framework of this project and prioritised in consultation with the companies. The aim here is rapid implementation in follow-up projects (IGF procedure).