Projectname:
Model-based and experimental approaches to compliance testing and packaging material development
Workgroup: Compliance of packaging material
Research Partner and Scientific Guidance:
IGF: 22760 N
Financing: BMWK
Duration: 2023 – 2025
Due to its good recyclability and biodegradability, paper is used for more and more food contact applications. Due to the broader field of application, the needs of functionalization, degree of specialization and requirements for barrier properties of the papers are also increasing. These developments confront the growing requirements for consumer protection, which are regulated by the legal basis with, in some cases, very low legal or guide limits for transfer of substances from packaging. Packaging materials made of paper and board are still tested mainly by conventional methods, in which the material is partially extracted by direct contact of the paper with water and / or solvents. As a result, the migration of individual substances can be overestimated compared to the migration onto a real food product. Testing with MPPO (modified polyphenylene oxide – simulant E for dry food according to the Plastics Regulation (EU) 10/2011) may also overestimate migration onto real foods due to the strong adsorbing properties of that simulant. Such tests have the potential to falsely classify materials as non-compliant with the requirements, therefore. In addition, those tests are costly and time-consuming.
In order to develop more realistic test conditions or theoretical prediction methods, a better and reliable quantitative understanding of the transport processes is required.
The MigPaP project aims to establish more realistic testing and prediction methods for the diffusion of chemical substances within and migration out of paper and board by deepening the understanding of mass transfer processes in paper and board and their influencing factors. The intended applications are on the one hand compliance testing and on the other hand development of new papers or packaging designs with improved barrier.
Within the scope of the project, the factors influencing migration will be investigated quantitatively. Their mutual interferences will be clarified by the help of mathematical models. Aim is to derive tools for developing multilayer papers and packaging structures and to realistically test their conformity either by experiment or calculated in a model-based approach. Prospectively in long term, the work shall be implemented into test standards and norms. Paper manufacturers shall receive planning tools for developing new products, e.g. with improved barriers against organic substances.
Papers or boards are fibrous materials enclosing air-filled pores. This allows transport processes of substances via the gas phase (fast) and through the fiber structure (slower) which are competing with each other. Furthermore, transport can be visualised as a sequence of adsorptions and desorption processes from the fiber. Influencing factors for the mass transport in the paper and the migration of substances from the paper into food are (i) substance properties such as polarity, but also (ii) properties of the fiber, the paper and its structure (fiber type, fiber morphology, fiber orientation, fiber surface, pore space, layer structure, board and cardboard structure, additives, fillers, …), as well as the ambient conditions (temperature, moisture). This complex interaction of influencing factors shall be simulated by realistic, three-dimensional mass transfer models (fiber-pore model). Experimental tests (migration, permeation of organic substances) on clearly defined and characterized papers and paper structures will be used to verify and parameterise the models. The complex model is required for understanding. It shall be simplified again in the end enabling the use of software solutions that are already applied for plastics by testing laboratories and in industry. The relevant influencing parameters shall be translated into an estimation equation for effective diffusion coefficients in the paper layer. The models for paper and board can be linked with those for migration or diffusion in food and plastic layers, including adhesives and printing inks. Thus, the entire packaging with filling material can be simulated. In parallel, more realistic experimental test conditions for determining food law compliance shall be derived and suitable simulants proposed. In addition, the appropriately validated models shall also be used in the sense of virtual prototyping for designing fibre based packaging solutions with, if necessary, suitable barriers.
The result are tools improving the compliance work of fibre-based packaging. Migration from and through paper-based packaging materials can be simulated thus much closer to reality. The development of new paper formulations or packaging designs with desired barrier properties can be facilitated.
The IGF project presented here by the Research Association of the Industrial Association for Food Technology and Packaging (IVLV e.V.) is funded by the Federal Ministry for Economic Affairs and Climate Action as part of the program for the promotion of industrial community research (IGF) based on a decision of the German Bundestag.