Metal ion modified melamine polyphosphate as well as preparation method and application thereof

The invention discloses metal ion modified melamine polyphosphate as well as a preparation method and application thereof. The preparation method comprises the following steps: mixing polyphosphoric acid and melamine to react, and then adding a metal oxide to react to generate a prepolymer; adding melamine and an acid catalyst into the prepolymer, and carrying out heating reaction in a protective gas atmosphere to obtain a mixture; and washing the mixture with an alcohol aqueous solution to remove the acidic catalyst, and drying to obtain the metal ion modified melamine polyphosphate, wherein the pH of 10wt% suspension at 25 DEG C is 5.5-7.0, the dissolved mass is less than or equal to 0.2 g/100ml water at 20 DEG C, and the thermal weight loss temperature of 0.5% is greater than or equal to 320 DEG C. Melamine condensation compounds melem and melam are generated in metal ion modified melamine phosphate molecules through in-situ catalysis, and the generated metal ion modified melamine polyphosphate molecules c