Study on corrosion resistance of epoxy ester coating cross-linked by a new type of titanium ion curing agent

With the environmental pollution caused by solvent-based coatings gets worse and worse, it is urgent to improve the anticorrosion property of waterborne coatings. As we all know, the coating showed better corrosion resistance because of the adding of curing agent. And tetra-n-butyl titanate is a coupling agent with excellent properties. But the waterborne epoxy coatings' feature of hydrolyzing easily limits its development. This study aimed to investigate the protection performance of the epoxy ester coatings with titanium ion curing agent (EC). To obtain excellent water resistant coatings, butyl titanate improved by ethylene glycol and triethanolamine is used as curing agent (ranged from 2 to 8 wt%) for epoxy ester resin. The chemical structures of the prepared coatings were analyzed by Fourier transform infrared spectroscopy (FTIR). And field emission scanning electron microscope (FESEM) was used to observe the coatings' surface morphologies. The corrosion resistance of the coatings was also examined by means of electrochemical impedance spectroscopy (EIS), surface topography and Copper-accelerated acetic acid-salt spray testing (CASS). From the FTIR spectra it was observed that demonstrated peak shift and changed in intensity with the adding of titanium ion curing agent. The corrosion resistance of the epoxy ester coating cured with titanium ion curing agent increased obviously. Its impedance reached 108 Ω cm2, and it still remained as high as 107 Ω cm2 even after immersion in 3.5 wt% NaCl solution for 40 days. Not only that, but the coating showed better corrosion resistance than other coatings when the curing agent's dosage increased to 5%. In addition, the observation of surface topography and CASS test confirmed with the results obtained from EIS.