Synthesis of acrylic-modified water-reducible alkyd resin: improvement of corrosion resistance in painting formulations

In this study, we investigated the effect of organosilane monomer on the adhesion strength and corrosion protection of the water-reducible alkyd coatings. For this purpose, firstly, alkyd resin was synthesized and modified with acrylic monomers by changing organosilane monomer content in the range of 4-16 wt% in all acrylic monomer compositions. Then, the carboxyl groups on the hybrid resins were neutralized with a base and the coating recipes were formulated using these water-reducible resins. The chemical structure and composition of the synthesized polymers were confirmed using H-1-NMR and FTIR spectroscopies. Mechanical properties of coatings applied on the cold-rolled steel surfaces were investigated via crosshatch adhesion, pendulum hardness, gloss, impact, and conical mandrel bend tester. According to the results, it can be said that water-reducible acrylic-modified alkyd coatings offer a good balance of hardness and flexibility. Then, the line was scratched parallel to the coating system and the surface coating properties of the coated panels, such as the adhesion strength after being exposed to humidity and corrosion resistance, were comparatively investigated. The best results for corrosion resistance and adhesion strength were obtained with the coating which was formulated with the resin having organosilane monomer of 8 wt% in all acrylic monomer mixtures. As the organosilane monomer amount increased to 16 wt%, the coatings' corrosion resistance and adhesion strength decreased. As a result, it was observed that organosilane modification is significantly effective in improving the adhesion strength and corrosion resistance of water-reducible alkyd coatings. However, increasing the amount of silane monomer may reverse the positive results obtained. This study also reveals significant results about the correlation between the adhesion strength and corrosion resistance of coatings by presenting visual results.