An ultra-low infrared emissivity composite coating with outstanding mechanical properties and salt water resistance

An ultra-low infrared emissivity composite coating with outstanding mechanical properties and salt water resistance was prepared by using epoxy resin, flake Al powders, KH560 and dioctyl phthalate (DOP) as resin matrix, functional pigments, and modifiers, respectively. The effects of Al powder addition, silane coupling agent types, silane coupling agent addition, and DOP addition on the coating performance were discussed. In addition, the salt water resistance of the coating under the optimal formulation conditions was examined. The results show that when the addition amount of Al powder is 50 wt%, the coating has lowest infrared emissivity (0.025) and glossiness (20.7) properties. By adding a certain amount of KH560 and DOP to the coating formulation, the mechanical properties of the coating can be significantly improved by enhancing the bonding strength between the resin matrix and the pigment, and between the resin matrix and the substrate. When the content of KH560 and DOP in the coating are both 7 wt%, the coating has ultra-low infrared emissivity (0.053), low glossiness (17.3), and outstanding mechanical properties (adhesion strength is grade 1, flexibility is 2 mm, impact strength is 50 kg.cm) at the same time. After the coating with the best formulation was corroded by salt water for 21 days, the emissivity, glossiness, and mechanical properties of the coating had limited changes, which showed that the prepared coating had good salt water resistance.