Enhancing the durability of fire-retardant epoxy coatings through an eco-friendly self-stratification approach

Developing durable fire-retardant coatings is crucial for enhancing the safety and longevity of structural materials. This research investigates how trusted fire-retardant agents, aluminum hydroxide (ATH) and ammonium polyphosphate (APP), perform in the context of a new self-stratifying fire-retardant epoxy-acrylic coating. The coating system comprises a DGEBA-based epoxy resin and an isobutyl methacrylate homopolymer as the binder. SEM-EDX, ATR-FTIR, and contact angle were employed to investigate self-stratification, microstructure, and fire-retardant distribution. The fire retardancy of the coatings was evaluated before and after aging using furnace tests to assess their durability. Our results demonstrated that incorporating ATH and APP did not disrupt the stratification process in the epoxy-acrylic coating, successfully obtaining a type-I stratified structure. It was also found that the fire retardants predominantly localized in the epoxy-rich layer adjacent to the substrate. Notably, the fire resistance of the self-stratified coatings was similar to that of conventional double-layer coatings, with APP-containing coatings exhibiting superior fire performance compared to those containing ATH. Furthermore, the self-stratified coatings maintained comparable durability and resistance to aging as conventional double-layer coatings. This study underscores the technical feasibility of developing self-stratified fire-retardant epoxy-acrylic coatings with comparable fire performance and durability to traditional double-layer systems. The findings contribute valuable insights into designing eco-friendly and effective fire-retardant coatings, highlighting the potential for optimizing material performance through this innovative technique.