Effects of Inhibitors on Corrosion Resistance of Acrylic–Amino Resin Coatings in Alkaline Solution for Industrial Measuring Tapes

During industrial construction, steel measuring tapes are frequently exposed to alkaline cement environments, leading to rapid degradation of protective coatings and corrosion of the steel substrate. In this study, acrylic–amino resin composite coatings incorporating three different inhibitor systems (RZ/ZMP, RZ/ZPO, and RZ/ZPA) were prepared, and their corrosion resistance in alkaline media was systematically evaluated. The microstructure and composition of the coatings were characterized by SEM, EDS, and XRD, while surface wettability was assessed by water contact angle measurements. Corrosion protection performance was investigated using potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and long-term alkaline immersion tests. The results show that the incorporation of inhibitors significantly enhances the corrosion resistance of the coatings. Compared with the inhibitor-free acrylic–amino resin coating, the corrosion current density of the RZ/ZPA coating decreases by approximately 1.9 times, while that of the RZ/ZPO coating decreases by about 1.7 times. EIS analysis further reveals that the RZ/ZPO/acrylic–amino resin coating exhibits the highest coating resistance (1.41 × 107 Ω·cm2), which is approximately 4.2 times higher than that of the inhibitor-free coating and 188 times higher than that of the steel substrate, indicating the strongest ion-blocking capability. Based on combined electrochemical parameters and long-term alkaline immersion behavior, the corrosion resistance of the coatings increases in the following order: acrylic–amino resin coating < RZ/ZPA < RZ/ZMP < RZ/ZPO. Overall, the synergistic effect of multiple inhibitors significantly improves both the electrochemical corrosion resistance and long-term alkaline durability of acrylic–amino resin coatings.