Synthesis of vanillin-based flame retardant epoxy coating on wood surface

In this paper, a novel phosphate-containing epoxy reactive flame retardant (VB) was successfully synthesized by one step reaction using vanillin (VA) and benzene phosphorous oxydichloride (BPOD). The chemical structure of the VB was analyzed by FTIR, NMR (1H and 31P) techniques. The flame retardant epoxy coating was constructed on wood surface according to different phosphorus content. Compared to EP-0, the coating containing VB exhibited comparable the physical properties on wood. Besides, thermal stability and flame retardancy have been significantly improved at phosphorus content of 4.07 %. The char residue of EP-4.07 was obviously increased from 14.99 % (EP-0) to 47.08 % at 700 °C. Meanwhile, the EP-4.07-Wood presented a high limiting oxygen index (LOI) value of 32.9 % and passed UL-94 V-0 rating. Besides, the cone calorimeter (CONE) confirmed that the total heat release (THR) and smoke production (TSP) of EP-4.07-Wood were 47.95 MJ/m2 and 6.26 m2/kg, reduced by 50.8 % and 71.2 % compared to EP-0-Wood, respectively, thus to achieve superior flame retardancy and smoke suppression. The results of SEM and TG-IR exhibited that VB was responsible for flame retardant both in the gas and condensed phase. Hence, this study exhibited a continuable, environment-friendly strategy to construct flame retardant wood coating, which displayed enormous potential in wood application.