New Azo Dyes-Based Mg Complex Pigments for Optimizing the Anti-Corrosion Efficiency of Zinc-Pigmented Epoxy Ester Organic Coatings

Abstract

This work addresses the possibilities of using synthesized novel magnesium complex dyes in zinc pigmented organic coatings based on epoxyester resin to reduce the zinc content in these coatings while maintaining or increasing the anticorrosive efficiency of them. The magnesium complexes Mg-Dye-I (C34H26MgN8O6), Mg-Dye-II (C26H19MgN3O5), Mg-Dye-III (C17H10MgN2O3), and Mg-Dye-IV (C25H18MgN4O6) with a series of azo carboxylate ligands were prepared from the diazo-coupling reaction of anthranilic acid with 5-methyl-2-phenyl-3-pyrazolone (Dye I; C17H14N4O3), anthranilic acid with naphthol AS-PH (Dye II; C26H21N3O5), anthranilic acid with 2-naphthol (Dye III; C17H12N2O3), and 2-amino-5-nitrophenol with naphthol AS-PH (Dye IV; C25H20N4O6). The synthesized novel magnesium complex dyes were characterized by analytical methods. Model coatings containing these dyes at pigment volume concentrations (PVCs) = 1, 3, 5 and 10% and zinc at a ratio of pigment volume concentration/critical pigment volume concentration (PVC/CPVC) = 0.60 were formulated to study the inhibitory properties of the individual synthesized magnesium complex dyes. Model coatings containing inorganic pigments (MgO and Ca-Mg-HPO4) at PVCs = 1%, 3%, 5% and 10% and zinc at PVC/CPVC = 0.60 were also formulated. The coating pigmented only by zinc at PVC/CPVC = 0.60 was prepared as a standard organic coating. Corrosion resistance was also evaluated by potentiodynamic polarization studies and electrochemical impedance spectroscopy. The properties of organic coatings were also tested using other standardized and derived corrosion tests. In addition, the mechanical properties of the studied organic coatings were determined using standard tests. The aim of the work was to verify the possible synergistic efficiency of novel magnesium complex dyes by improving the mechanical, anti-corrosion, and chemical properties of zinc pigmented organic coatings.

Preparation and Testing of Anti-Corrosion Properties of New Pigments Containing Structural Units of Melamine and Magnesium Cations (Mg2+)

“…The stability of the complex is ensured by hydrogen bonds between the two compounds. Magnesium was chosen be cause of its proven positive effect on the anti-corrosion properties of many types of pig ments, and it is also more environmentally acceptable than zinc [34,35].…”

Inhibition Effect of Triphenylmethane Dyes for the Corrosion of Carbon Steel in CO2-Saturated NaCl Corrosion Medium

“…Most dyes contain complex molecular structures with both hydrophilic and hydrophobic segments that are associated with many donor centers that interact with the metallic species, which is essential for the corrosion mitigation effect [ 7 , 8 ]. There are some literature studies that show that many dye series have excellent anticorrosive properties for many metal/electrolyte combinations because of their abundant electron-donating sites as polydentate and chelating ligands [ 9 , 10 , 11 ]. Triphenylmethane dyes are compounds with abundant phenyl ring structures which generally have strong interactions with the metal surface [ 12 ].…”

Improving the Protection Performance of Waterborne Coatings with a Corrosion Inhibitor Encapsulated in Polyaniline-Modified Halloysite Nanotubes

“…To prevent this process, many anticorrosion technologies have been developed. Among these, organic coatings over metal surfaces offer an efficient and economical solution to this problem [1,2]. Traditional coatings are organic solvent-borne, which makes them harmful to the environment due to their high content of volatile organic compounds (VOCs).…”