Investigation of the network structure of new bisphenol A non-intent interior food can coatings using high-resolution solid-state 13C-NMR spectroscopy

Facing recent controversial debates about commonly used epoxy resins in food contact applications, an understanding of newly developed polyester-based BPA-non-intent (BPA-NI) interior food can coatings is necessary. So far, little is known about the polymer structure of the polyester-based blends which have been brought to the European market. We report a detailed study on a polyester-phenol blend model system suitable for interior can coating in terms of its mechanical properties such as high flexibility, very good adhesion and hardness. We employ vibrational spectroscopy (FTIR), thermoanalysis (DSC) and an in-depth high-resolution solid-state C-13-NMR analysis to reveal that an overall homogeneity on molecular scale of the two main components in the blend is sustained in the solid state. This is remarkable, taking into account the overall different characteristics of polyesters and phenolic resins and explains the exceptional material properties of this coating.