Synergistic effect of graphene oxide and ammonium biborate tetrahydrate for flame retardancy of amino resin coatings

A transparent intumescent flame retardant coating was prepared using melamine formaldehyde resin (MF) as the film-forming resin, phosphoric acid-pentaerythritol (H3PO4-PER) as the intumescent flame retardant system, and graphene oxide-ammonium borate (GO-ABT) as the flame retardant synergists, and applied to the surface of wood-plastic composite (WPC). The transparency, flame retardancy, and thermal stability of the flame retardant coatings were investigated and the flame retardant mechanisms of GO and ABT were analyzed. The results showed that the addition of 0.4 (wt%) GO and 4.0 (wt%) ABT coating had the best overall performance. After curing, the surface of the coating was smooth and flat, no whitening and cracking and other undesirable phenomena. Its overall light transmittance was greater than 80 %, and the surface pattern of the substrate was clearly visible. The addition of flame retardant synergists of GO and ABT significantly improve the flame retardant performance of the coating, with a maximum flame resistance time of 37 min. Meanwhile, the total heat release and total smoke release of the coating with 0.4 % GO and 4.0 % ABT decreased by 33.23 % and 39.43 % respectively compared with the control sample, and the carbon residue increased by 94.97 %, demonstrating good flame retardant and smoke suppression effects.