Optimization of EPU Composite Cooling Coating With Environmental Suitability

Thermal reflective cooling materials offer zero-energy cooling under sunlight but face durability challenges in complex environments. While improvements for single factors are well-documented, further studies on durability under multiple environmental factors are needed for large-scale application. In this study, a polyurethane-modified epoxy (EPU) resin was first synthesized, followed by the fabrication of a composite cooling coating (EPURC) using TiO₂ and radiative powders. The optical properties and cooling performance confirmed that the optimized proportion of cooling fillers realized the maximum synergistic cooling effect of solar reflection and infrared emission. Therefore, when the temperature of the controlled black iron plate reached 60°C, EPURC achieved a temperature reduction of 13.8°C. Based on this, the comprehensive durability evaluation including shear resistance, water resistance, acid resistance, alkali resistance and UV resistance was further explored through cooling performance. Except for abrasion for 60 min, EPURC influenced by multiple factors could all achieve a strong cooling ability above 10°C. Although a heavy abrasion could weaken cooling performance to a certain extent, EPURC still showed a shear resistance due to the excellent toughness of EPU binder. These findings proved that EPURC could be applied in complicated work conditions and satisfied the need for practical applications.