Delamination

During the processing of coated tinplate and aluminium in the packaging industry delamination of the organic coating occurs intermittently. This affects adversely the visual appearance and the corrosion resistance of the product and can lead to the rejection of the material. Delamination can occur both during processing of the coated plates and further use of the packages. Up to now there is a lack of systematic investigations concerning the reasons for delamination of lacquer on metal surfaces in the packaging industry. Due to the application of different test methods for lacquer adhesion by the companies, the results of these tests are hardly comparable. Mostly the tests are carried out on unstressed plates, without considering further treatment (e. g. metal forming or sterilisation) and the later impact by the filling and the customer.

There are various reasons for delamination. One is the kind of surface treatment. Experiments with tin plate and aluminium have shown that particularly the metal passivation affects the wetting by the lacquer. It is assumed that the passivation layer also influences the lacquer adhesion. Other possible influencing variables are moisture content, texture and roughness of the metal surface as well as the protecting oil film. Last but not least the physical and chemical properties of the lacquer itself can affect its adhesion on the metal surface.

This project is based on the results of the former AiF project „wetting failures” and the investigations are performed in co-operation with different companies. At first an extensive literature and patent research is planned to determine and systematize the reasons for delamination. Furthermore investigations concerning the adhesion of lacquer on metal surfaces are planned including the examination of samples with delamination effects from the production of packaging companies. The aim of the research project is a quality improvement of coated packaging made of tin plate and aluminium. To enable a comprehensive study a research proposal will be presented to the AiF.