Effect of the composition of new bisphenol A non-intent coatings for the insides of tins

Inner coating of an open tin can
© Fraunhofer IVV - Angela Störmer

The insides of tins that are used for food products have been coated with epoxy (EP) lacquers for more than 40 years. One of the starting materials for these coatings, bisphenol A (BPA), is a topic of current public debate due to its estrogenic effect. Coating and raw material manufacturers are developing alternative coatings which do not intentionally contain BPA (so-called BPA non-intent (BPA-NI) coatings). Initial studies have shown promising results for polyester-based coating systems.

The situation for tin manufacturers is being made even more difficult by the fact that tinplate manufacturers are no longer able to use chromium passivation systems. This is due to the coming into force of the European REACH regulation (Registration, Evaluation, Authorization, and Restriction of Chemicals). Tinplate manufacturers are therefore currently having to develop Cr(VI)-free post-treatment processes. Tin manufacturers and users are now faced with a situation whereby both the coating and tinplate itself are changing. This requires the development of new, technically reliable solutions.

The aim of this research project is to systematically study the effect of the coating formulation on the functional properties of the coating. In particular, the effect on the adhesion and interaction with different tinplate substrates will be investigated. In order to monitor the quality of the coating, optimum test methods will be developed. In addition, test routines for predicting the suitability and stability of the coatings to sterilization processes and long-term storage will be developed and validated. The suitability of coatings for tins for food products can currently only be determined by storage tests.

Project term: 2014 to 2017
Project management
/project funding:
Federation of Industrial Research Associations AiF (via the Forschungsgesellschaft für Pigmente und Lacke e.V. (FPL) and Industrievereinigung für Lebensmitteltechnologie und Verpackung e. V. (IVLV))
/Federal Ministry for Economic Affairs and Energy BMWi