Preparation and characterization of solvent-free anti-corrosion polyurethane-urea coatings

Metal corrosion can cause severe damage to metal facilities, leading to huge economic loss. Anti-corrosion coating is considered to be effective and economic for the protection of metal facilities. Herein, a series of polyurethane-urea coatings were prepared with aromatic isocyanate, amino terminated polyether, castor oil-based polyol and polyaspartic resin as reactants and conductive mica powders as filler. The effect of isocyanate index on the chemical structure, static conductivity and corrosion resistance of the polyurethane-urea coatings were studied, and the micromorphology of the coating layers were observed. With the increase of isocyanate index, the cross-linking degree of the coating increased, while the compactness and electrostatic conductivity decreased, which was caused by the generation of carbon dioxide bubbles in the coating layer. Electrochemical impedance spectroscopy and salt spray test indicated that as the isocyanate index increased, the anti-corrosion ability of the polyurethane-urea coating on the flawless area increased, but that on the defect area decreased. The polyurethane-urea coatings prepared with isocyanate index of 1.0-1.1 possessed good corrosion resistance and electrostatic conductivity. The findings conceivably provided a new strategy to prepare solvent-free anti-corrosion coatings for the protection of metal and metallic facilities and promote the rapid development and practical application of anticorrosive materials.