Preparation method of three-source-in-one expansion type fire retardant

The invention belongs to the technical field of materials, and particularly relates to a preparation method of a three-source-in-one expansion type fire retardant, which comprises the following specific steps: adding 1-10g of polyving akohol into 5-30g of water, stirring at the temperature of 90 DEG C, dispersing uniformly, then adding 5-80g of phosphoric acid into the system, continuing to stir to raise the temperature to 60-150 DEG C, reacting for 0.5-3.5 h, reducing the temperature of the system to 50 DEG C, then adding the mixed liquor of 5-84g of melamine and 50-300g of solvent, reacting for 0.5-2h at the temperature of 60-120 DEG C, cooling, filtering and drying to obtain white 'three-source-in-one' expansion type fire retardant powder. The expansion type fire retardant has good flowability and low water solubility, and can be used for the fire retardance of plastics, rubber, wood, fabrics, coating and the like.