Relative humidity and moisture impact on décor polyethylene adhesion

Sammanfattning: Adhesion is the force keeping different materials together. In packaging materials this is important due to the many layers needed to protect its content. Retaining the packaging integrity is necessary to keep the long term storage capabilities of the packaging. This thesis will focus on the outermost interface for adhesion in Tetra Pak packaging material. The interface in this case is polyethylene film laminated on a coated paperboard where moisture has been found to have an impact on adhesion levels, potentially causing problems to arise in filling machines and with end product. By using standardized methods for measuring adhesion and moisture content, a strong relationship between the two was found and investigated. By mixing different compositions of clay coating it was possible to relate adhesion results to moisture content in the coating rather than in the board. It was also possible to relate commercial supplier board contents to adhesion results. A small series of atomic force microscope experiments were tried and seems like a promising tool for future investigation. No correlations were found between production settings and material properties for the samples investigated in this study.