The invention relates to a method for preparing ultra-high
rare earth composite oxide ultraviolet screening agent, which is characterized by comprising the steps of: formulating raw materials, including
salt solution of the
rare earth and oxides of two elements in IIIB-IIB, into
mixed solution with the
rare earth ion concentration of 0.05mol / L to 2mol / L, wherein the rare earth salt in the
mixed solution accounts for 40%-80% by
mass percent, adding surface dispersant for
dissolution, wherein the adding amount of the surface dispersant accounts for 0.1-3% of the
mixed solution by
mass percent, then adding precipitating agent with the concentration of 0.1mol / L to 4mol / L to react under vigorous stirring at 50 DEG C to 90 DEG C until pH value reaches 6.5 to 7, filtering and washing the reactant,
drying the reactant for 6 to 24 hours at 70 DEG C to 110 DEG C, converting the dried reactant to precursor
powder with the particle size lower than 2 microns, and heating the precursor
powder to 900 DEG C in a gradient manner through 300 DEG C and then preserving heat for 30 to 180 minutes to obtain the ultra-high rare earth
composite oxide ultraviolet screening agent with the particle size of 20 to 300nm. The method has the advantages of: low cost, excellent quality, high efficiency, great easiness for industrial production, strong screening within the
ultraviolet range from 100nm to 400nm, high thermal and
chemical stability, no
toxicity, no
odor and great
solvent resistance.