The invention discloses a preparation method of an
ultraviolet light absorber UV-360. The preparation method comprises the following specific steps: subjecting
hydrochloric acid, o-
nitroaniline and
sodium nitrite to reacting to obtain a diazonium solution; stirring and dissolving water,
petroleum ether, nekal and p-tert-octylphenol, adding the diazonium solution, carrying out a
coupling reaction, and performing spin-
drying to obtain an o-nitroazo compound; carrying out alkalization reaction on water, caustic soda liquid,
methanol, glucose, hydrazine
hydrate, caustic soda flakes, aluminum
powder,
toluene and a conjugate, and reserving a
toluene layer; subjecting water,
hydrochloric acid,
zinc powder and the
toluene layer to an acidic reaction, and reserving the toluene layer; carrying out decoloration reaction on the toluene layer,
activated carbon and carclazyte, conducting filtering, and carrying out a reaction with
methanol to obtain UV-329; carrying out
condensation reaction on di-n-
propylamine,
paraformaldehyde, trimethylbenzene and UV-329, and adding
methanol for
crystallization to obtain a crude UV-360 product; and subjecting the crude UV-360 product to reacting with trimethylbenzene, performing filtering, and carrying out a reaction with methanol to obtain a finished UV-360 product. According to the preparation method, industrial
wastewater, washing
wastewater and a filtering
solvent generated in the preparation process are distilled and reused, so the characteristics of zero
discharge of the industrial
wastewater and low use amount of the
solvent are realized.