In-plane Wetting in Packaging Material and its Consequences for Cap Performance

Abstract: Aseptic packaging solutions enable long time storage without refrigeration and are an important part of securing food supply globally. The package material consists of multiple layers: A paperboard for robustness, polymers for adhesion as well as shielding the board from liquid, and a barrier protecting the product. This thesis consists of two parts regarding in-plane wetting into the paperboard. The first part is investigating the current test method evaluating in-plane wetting by the raw edges due to the aseptic hydrogen peroxide bath during production. In the aseptic process of the filling machine, packaging material is exposed to sterilizing hydrogen peroxide which can penetrate the raw edges of the material where the paperboard is exposed. If this is extensive enough, breakage of the material can lead to the need to halt production for cleaning the machines. Later in the filling process, residual water can also cause soaking of the material by the edges or where the cap is to be attached (around the pre-laminated hole) if defects are present in the décor layer. The second part of the thesis aims to investigate a possible correlation between the amount of in-plane wetting around the pre-laminated hole and the amount of force needed for cap detachment. For the investigation regarding in-plane wetting around the raw edges due to the hydrogen peroxide bath, promising results that eventually might lead to a chemical exchange were obtained and observations regarding how the existing test set-up could be optimized were made. For the second part of the thesis, the results indicate that there exists a correlation between the amount of in-plane wetting around the pre-laminated hole and cap detachment force when measuring on material with board still soaked. The force needed decreases for increasing amount of wetting which somewhat correlates with the expectations. For material that had been dried before cap application, no clear trends were found.