Visual appearance durability as function of natural and accelerated ageing of electrophoretic styrene-acrylic coatings: Influence of yellow pigment concentration

Organic coatings are extensively used in many fields of engineering such as automotive or architectural industries for protection of the metallic structure against corrosion and to deliver visual aspects to the coated item. High quality paints either for outdoor or indoor applications require longer stability of their visual appearance alongside maintenance on the corrosion protection ability. In the present work, the total color variation and corrosion protection efficiency of waterborne styrene-acrylic paints loaded with different contents of organic yellow pigment has been studied. The paints have been deposited via cathodic electrodeposition on cold rolled steel. The visual aspect's stability of the paints was monitored as function of field exposure wherein the painted panels were naturally aged throughout one solar year in the alpine environment of Trento − northern of Italy. Color measurements were conducted according to the CIEL*a*b* color standard and gloss measurements alongside FT-IR spectroscopy were used to assess variations on the surface topography and chemical structure of the coated panels. It has been observed that solar radiation, the relatively humidity and temperature played a role on the surface roughness as well as on the lightness aspects of the coated panels. The electrochemical impedance spectroscopy outcomes revealed a dependency of the barrier properties of the paints with the pigment concentration. Superior barrier properties were verified for the paints with pigment content lower than 1.0 wt.%.