From Fundamentals to Applications: Understanding BPA-Non-Intent Resin Technology in Food Contact Metal Packaging Coatings

By Linqian Feng, Andrew Detwiler, Jeffrey Clauson, Abraham Boateng, Hongkun He, Goliath Beniah, Thilanga Liyana Arachchi, H. Chip Williams

Consumer and regulatory pressure to replace bisphenol-A (BPA)-based materials in food contact metal packaging coatings has increased in recent years. Regardless of the controversy around BPA, consumers expect canned foods to be free of substances perceived to have negative health impacts while maintaining current shelf life and flavor characteristics.

To address the market needs, formulators must innovate to deliver BPA-non-intent (BPA-NI) solutions that can meet or exceed the performance of BPA-based materials. This presents a challenge with regard to improving the resistance to food sterilization and stability during pack testing, and simultaneously balancing mechanical performance that allows the BPA-NI coating to withstand the aggressive canning process. One response to these technical challenges has been the development of BPA-NI polyester resin technology through innovation on a monomer basis.

This monomer innovation provides protective performance attributes such as resistance to corrosion and chemical attack, while enabling flexibility and adhesion through innovative resin and formula-tion design. Fundamental techniques such as electrochemical impedance spectroscopy (EIS) and cathodic disbonding were employed in combination with industrial fitness-for-use evaluations to demonstrate the improved protective barrier properties of novel non-BPA resins in formulated coatings.

In addition, hydrophobicity and interfacial properties were studied to understand the impact of resin structure on coating performance from both experimental and computational perspectives. Applying this suite of methods and analysis builds strong structure-property correlations as part of a resin development strategy for novel non-BPA resins in metal packaging coating applications.