LAUSR

The quality of press-formed paperboard trays and its effect on the leakproof heat-sealability of the lidding film is known to depend on the quality of the sealed trays and the parameters of the sealing process. In this study, the elevation of the sealing pressure and its effect on the leak-proof heat-sealing of press-formed trays with reduced surface quality were investigated. Trays with varying quality were manufactured and heat-sealed with a lidding film, using three different sealing pressures. The quality of the sealed trays was evaluated using oxygen content measurements, leak detection by a coloring solution, and microscopic analysis. The results showed that using a higher, elevated pressure resulted in a lower oxygen content in the packages during the analysis. The results also showed that even a high sealing pressure was not enough to achieve a leakproof seal if the quality of the sealed trays was not in a satisfactory level, for example as a result from a low forming force.