The invention discloses a preparation method of
ultraviolet light absorber UV-PS as indicated in the formula (I). The preparation method comprises the steps of 1, mixing ortho-
nitroaniline with
hydrochloric acid, then adding
sodium nitrite, and conducting a reaction for 1-3 hours with the temperature preserved; adding
urea for a reaction, so that a diazonium
salt solution is obtained; 2, mixing and dissolving first
solvent, an auxiliary agent and tert-butylphenol, lowering the temperature, adding the diazonium
salt solution, adding alkali, and preserving the temperature for 1-3 hours; 3, conducting purification for the first time on a
mixed solution obtained in step 2, so that azo matter as indicated in the formula (II) is obtained; 4, mixing the azo matter, alkali and second
solvent for a reaction, raising the temperature to 60-70 DEG C, adding glucose, conducting
backflow for 2-4 hours, and adding acid; 5, conducting purification for the second time on a
mixed solution obtained in step 4, so that an intermediate as indicated in the formula (III) is obtained; 6, mixing the intermediate, third
solvent and an auxiliary agent for a reaction, raising the temperature to 80-85 DEG C, adding
zinc powder, conducting a reaction for 2.5-3 hours, and adding adsorbent; 7, conducting purification for the third time on a
mixed solution obtained in step 6, so that the
ultraviolet light absorber UV-PS as indicated in the formula (I) is obtained. According to the preparation method of the
ultraviolet light absorber UV-PS, a fractional-
step method is adopted, reactant in each step can fully react, the yield of products of all steps is guaranteed, and the yield of a final product is remarkably raised.