Abstract: To study the synergistic effect of MB on the flame retardancy and smoke suppression properties of intumescent fire-retardant coatings, the properties of the coatings with different contents of MB were analyzed by cone calorimeter test, cabinet method test, tunnel method test, thermogravimetric analysis (TGA), Fourier transform infrared (FTIR) spectroscopy, and scanning electron microscopy (SEM). The results showed that a proper content of MB could improve flame-retardant and smoke suppression properties of the intumescent coatings. The optimum mass fraction of MB corresponding to the best synergistic effect is 5%, which makes the flame spread rating value decrease to 11.9 and the expansion ratio reach 48.4 and that the addition of MB promotes the formation of more thermostable P-O-C, B-O-P and C=C structures in the char residue that improve the high-temperature thermal stability and char-forming ability of the coatings, thus exhibiting a more compact and intumescent char as well as high flame-retardant and smoke suppression efficiencies.

Key words: intumescent fire-retardant coating, melamine borate (MB), thermal stability, flame retardancy, smoke suppression