Synthesis of hexa‐allylamino‐cyclotriphosphazene as a reactive fire retardant for unsaturated polyesters

A phosphazene derivative, hexa‐allylamino‐cyclotriphosphazene (HACTP), was synthesized through the aminolysis of hexa‐chloro‐cyclo‐triphosphazene with excess allylamine. HACTP is a soluble light‐brown crystalline solid, which melts at 90°C. It was reactive after melt but decomposed at 236°C. When it was incorporated into the resin formulations of unsaturated polyesters, it acted as a reactive flame retardant. The oxygen index was increased from 20.5 to 25.2, rating from the flammable to self‐distinguishable scale.