Diethyl phosphinate fire retardation agent preparation method

The present invention relates to a preparation method of a diethyl phosphinate fire retardation agent for a polymer material, wherein the diethyl phosphinate fire retardation agent does not contain monoethyl phosphinate. The preparation method comprises that: hypophosphorous acid and/or hypophosphite, an organic acid and an organic solvent are subjected to a reaction under a condition of ethylene gas introduction, the obtained material and an initiation system formed by an initiator, an auxiliary initiator and an organic solvent are subjected to a reaction to obtain monoethyl hypophosphorous acid-free diethyl hypophosphorous acid and organic acid sodium, and the diethyl hypophosphorous acid, the organic acid sodium and a metal compound are subjected to a reaction to obtain the monoethyl phosphinate-free diethyl phosphinate fire retardation agent. With the preparation method, a hypophosphorous acid and/or hypophosphite conversion rate can be 100%, and the finally obtained diethyl hypophosphorous acid and the salt thereof do not contain the monoethyl hypophosphorous acid group.