Method for preparation of graft modified ammonium polyphosphate with ultra-low hydroplaning and resistance to hydrolysis and application thereof

A method for preparation of graft modified ammonium polyphosphate with ultra-low hydroplaning and resistance to hydrolysis, wherein firstly amino silane is hydrolyzed under the condition of ammonia water, and hydrolyzed mixture is added into a reaction equipment which has been put into phosphorus pentoxide, diammonium hydrogen phosphate and melamine for the reaction, comprising the steps of:

• (1) putting amino silane into the reaction equipment, under nitrogen protecting and stirring, adding ammonia water solution in droplet at room temperature, after finishing dropping, controlling reaction temperature of the reaction equipment between 25° C. and 100° C. and reacting for 1˜10 h to form a preparation liquid;
• (2) adding phosphorus pentoxide, diammonium hydrogen phosphate and melamine into the reaction equipment, adjusting revolving speed of the reaction equipment, protecting with nitrogen, heating to 60˜150° C., then speeding up the revolving speed, increasing nitrogen flow, spraying preparation liquid obtained from (1) at upper portion of the reaction equipment evenly and slowly, after finishing the spraying, maintaining the reaction temperature of the reaction equipment between 60° C. and 150° C., after 0.1˜6 h, starting switching nitrogen to introduce ammonia gas, raising the reaction temperature of the reaction equipment to 250˜320° C., if the temperature is higher than 320° C., switching ammonia gas to introduce nitrogen, when the temperature is lower than 300° C., again switching nitrogen to introduce ammonia gas, at this time ammonia flow is less than the ammonia flow at the beginning;
• (3) when the temperature of the reaction equipment is lower than 280° C., adding melamine through a inlet, and setting oil temperature of the reaction equipment at 220˜280° C., maintaining the temperature for 1˜6 h, lowering the temperature, discharging and obtaining graft modified ammonium polyphosphate;
• wherein, concentration of the ammonia water solution in (1) is 25%, the ratio of mole of water in the ammonia water solution and alkoxy in amino silane is 1˜1.5:1, and the mass ratio of amino silane and phosphorus pentoxide in (2) is 0.01˜0.15;
• the ratio of mole of phosphorus pentoxide and diammonium phosphate in (2) is 1˜1.5:1, the mass ratio of melamine and phosphorus pentoxide is 0.001˜0.025;
• the mass ratio of melamine in (3) and phosphorus pentoxide in (2) is 0.01˜0.1.