Preparation method and application of lactic acid-based environment-friendly plasticizer

The invention relates to a preparation method and application of a lactic acid-based environment-friendly plasticizer, and belongs to the fields of fine chemical synthesis, environment-friendly plastic additives and plastic additive application. Lactic acid, 2-ethylhexanoic acid and diethylene glycol monobutyl ether are used as main raw materials, diethylene glycol monobutyl ether-lactic acid-2-ethylhexanoate is prepared through two-step esterification reaction, excessive lactic acid is added in the first-step esterification reaction, obtained molecules contain oligomeric lactic acid chain segments, and the compatibility of the plasticizer and PVC is further improved. The diethylene glycol monobutyl ether-lactic acid-2-ethylhexanoate plasticizer prepared by the method is light in color, low in viscosity and good in compatibility with PVC, and compared with di (2-ethylhexyl) terephthalate and acetyl tributyl citrate, the diethylene glycol monobutyl ether-lactic acid-2-ethylhexanoate plasticizer can endow PVC w