Method of producing ultraviolet protective agent composition, and ultraviolet protective agent composition obtained thereby

A method of producing an ultraviolet protective agent composition, which comprises at least

• step (a) of precipitating iron oxide microparticles by mixing with a microreactor an iron oxide raw material fluid containing at least Fe3+ ion, and an iron oxide precipitation fluid containing at least a basic substance, and
• step (b) of dispersing the above precipitated iron oxide microparticles in a dispersion medium to obtain a dispersion of the iron oxide microparticles,
• wherein:
• the iron oxide is α-hematite,
• a primary particle diameter of the iron oxide microparticles is less than 25 nm, and more than 90% of the iron oxide microparticles are single crystals,
• the iron oxide microparticles of single crystals are microparticles in which lattice strips are observed in one direction in the electron microscopic observation, and
• a haze value of the dispersion of the iron oxide microparticles is 2.0% or less, and a transmittance of the dispersion of the iron oxide microparticles for the light of the wavelengths of 200 to 420 nm is 2.0% or less.