Peelable packaging systems are being increasingly used not only for foods but also for medicinal products. They facilitate product handling and minimize the risk of contamination, in particular for sterile products. Important for safe and consumer-friendly easy-opening is a low opening force, with the proviso that the packaging must remain sealed during storage and transport. On opening, no cracking or so-called angel hair must appear in the packaging.
The objective of the research project is to develop a tool for advance calculation of the force required to open peelable packaging. This tool will be used in the design and development phase using CAD data of the sealing seam contour. The tool takes account of the packaging structure as well as the place and direction of the force application during the opening process.
The calculations are based on descriptions of crack initiation and crack propagation in the sealing seam during the opening process as a function of the packaging film structure (support layer and peel layer). The sealing conditions and seam formation are also taken into account. Structure-property correlations are being drawn up based on peel tests and structural analyses. These allow the relationship between the polymer structure, the adhesion mechanisms, and the resulting crack formation processes to be described. The geometrical conditions during the peeling procedure (length of the peel line, opening direction) are also being studied and compared to classical tests on film strips. The calculation tool being developed to determine the opening force as a function of various parameters will subsequently be available for development projects with industry.