Monitoring of Polyurethane Penetration into Alumina Coating by Raman Spectroscopy

Polyurethanes are extensively used as adhesives and sealants in laminated packaging, aluminum (Al) foils, cans, sheets, etc. Usually PUR is obtained from hydroxy-terminated macrodiols and isocyanates. Adhesion of PUR to metals has great importance for the recycling of metallized multi-layer packaging. In this study, Raman spectroscopy was used to evaluate the penetration of PUR components into anodic Al coating, since many Al foils are partially anodized to enhance durability and adhesion.