Effects of fire-retardant additives for acrylic coating on flame-retardancy of painted poplar wood

Wood, as a renewable and environmentally friendly material, possesses unique mechanical, physical, and aesthetic properties that make it widely used in the construction, furniture, and decorative industries. However, wood is susceptible to degradation by various factors such as biological agents, weathering, and fire. Extensive efforts have been made to enhance the durability of wood, including the use of paints for protection against weathering and moisture. However, both wood and polymer-based paints are flammable. To address this issue, flame retardant materials have been incorporated into paint formulations to reduce flammability. This study aims to investigate the effects of flame retardants on the fire resistance and color changes of acrylic coatings applied to pine wood. In this research, the impact of flame retardant materials (zinc borate, di ammonium phosphate, nanosilica, and nanoclay) at concentrations of 10% and 20%, as well as their binary combinations (20%), in the structure of acrylic paint was examined for their fire resistance on colored pine wood. Subsequently, the tensile strength of the paint film, color changes of the wood samples, and their fire resistance were analyzed. The results of this investigation indicate that zinc borate and di ammonium phosphate did not have a discernible effect on the tensile strength of the paint film. However, the incorporation of nanoclay significantly increased the film's tensile strength, while the addition of nanosilica led to a notable decrease in this property. Among the tested samples, those containing zinc borate and di ammonium phosphate exhibited the least significant color changes. The introduction of flame retardant materials into the paint formulation resulted in improved fire resistance, with ammonium phosphate and nanoclay exhibiting superior performance in this regard. Importantly, there were no substantial differences observed between the 10% and 20% concentrations of the flame retardant materials across many of the conducted tests. Notably, the combination treatments of di ammonium phosphate-zinc borate and di ammonium phosphate-nanoclay demonstrated more effective outcomes concerning color changes and fire resistance. The findings of this study reveal that di ammonium phosphate and zinc borate had the least detrimental effects on the tensile strength of the paint film and the color changes observed in both the wood samples and the paint film. Furthermore, these two flame retardant materials exhibited superior performance in enhancing fire resistance. Therefore, it is strongly recommended to incorporate di ammonium phosphate and zinc borate as flame retardants in acrylic paint formulations specifically intended for use on wood surfaces