Epoxy plasticizer as well as preparation method and application thereof

The invention discloses an epoxy plasticizer as well as a preparation method and application thereof. The preparation method comprises the following steps: step 1-1): mixing reactants and a water-carrying agent, continuously introducing nitrogen under the liquid level, and heating to 125-128 DEG C; the reactants comprise sorbic acid, C4-C8 monocarboxylic acid and glycerol, and the molar ratio of the sorbic acid to the C4-C8 monocarboxylic acid to the glycerol is (0.27-0.77): (2.25-2.75): 1; (1-2) heating to 130-140 DEG C, then adding a catalyst, heating to 150-190 DEG C, and carrying out constant-temperature reaction for 8-10 hours; reacting to obtain unsaturated glycerol sorbate mixed ester; the catalyst accounts for 0.1-3% of the total mass of reactants; step 2-1): mixing unsaturated glycerol sorbate and phosphoric acid, reacting at 50-70 DEG C for 4-8 hours, and dropwise adding a formic acid and hydrogen peroxide mixture 30-60 minutes after the reaction is started; the mass percentage of the phosphoric aci