Synthesis of phosphazene modifiers to improve the fire resistance of epoxy coating materials

Phosphazene modifiers based on hexachlorocyclotriphosphazene and various ratios of phenol and bisphenol A were synthesized and used to increase the fire resistance of epoxy coatings. The structure of all modifiers was confirmed by NMR spectroscopy and it was shown that all products represent the mixtures of hexa- and pentasubstituted cyclotriphosphazenes. All the modifiers were mixed with epoxy resin and the obtained coatings were studied. The addition of phosphazene modifiers did not affect coating properties such as adhesion, impact strength and elasticity. On the other hand, the modifiers led to an increase in the fire resistance of the coatings. It was shown that increased bisphenol A content led to a decrease in fire retardant efficiency. The best results were shown with modifier having phenol/bisphenol A ratio of 5:1 at a concentration in epoxy resin of 5 wt%.