Dispersion stability, adhesion strength, and anti-corrosion properties of water-born polyester resins

In this study, a water-reducible polyester resin curable with melamine resin was synthesized and characterized to be used as a strong automotive base-coat. The main goal is to produce a resin with improved properties compared to similar products. Glycidyl neodecanoate was used as the key polyol monomer. The presence of polyester index peaks in the FTIR test, along with the results of the TGA, DSC, and GPC tests, was a testament to the controlled confirmation of water-based polyester synthesis. Due to the zeta potential value (−50.28 mV) for the PS3 sample (trimethylolpropane, adipic acid, glycidyl neodecanoate, and trimellitic anhydride monomers), this sample had less accumulation and instability separation than other samples. Samples were compared with commercial paint to evaluate the quality of the paint. The synthesized samples and the commercial sample were applied to the steel substrate. A pull-off test was used to check the adhesion strength to the substrate. The adhesion strength of the PS3 sample was recorded 4.3 MPa on steel sheet and 2.30 MPa on electrodeposition layered steel. Electrochemical impedance spectroscopy test showed that the samples PS1 and PS3, after 15 weeks of immersion in 3.5 wt% sodium chloride solution, provided resistances of 4.59 × 109 and 2.45 × 109 Ω cm2. Also, digital images taken from the surface of the samples in the salt spray test revealed that PS3 and in the next stage, PS1 after one month of exposure to corrosive environment, showed better corrosion resistance than other samples.