Improving the performance of acrylic-epoxy ester hybrid coatings with phosphate monomers

There is a growing interest in environmentally friendly coatings from the paint and coating industries, with water-borne acrylic-epoxy ester hybrid resins emerging as prominent candidates. Despite their eco-friendliness, these resins exhibit poor mechanical and anti-corrosion properties. These two essential properties can be improved by grafting new functional materials into the hybrid resin. In this work, we introduced a novel phosphate ester functional monomer (hydroxyethyl methacrylate ethyl phosphate (HEMAPE)) to traditional water-borne acrylic-epoxy esters through free radical polymerization. Initial results reveal a substantial enhancement in the dispersion stability of the modified water-borne acrylic-epoxy esters in aqueous environments. The cured coating derived from this modification significantly improves the mechanical strength and anti-corrosion characteristics of the coating. Notably, X-ray Photoelectron Spectroscopy (XPS) analysis further explains the improved performance whereby it confirms the formation of phosphate chelates within the cured modified coatings, facilitated by HEMAPE, which effectively chelates with metallic ions originating from the corrosion products on the steel substrate. These chelates adhere to the metal surface, impeding further corrosion reactions and thereby optimizing the corrosion protection performance of the coating. This modification approach, characterized by its simplicity of preparation and overall improved coating performance, could be employed in paints for metal corrosion protection. The phosphoric ester designed in this manuscript not only enhances the mechanical properties of acrylic-epoxy ester hybrid coatings but also, through chelation with metal, significantly improves the coating's corrosion resistance.