Ultraviolet rays are one of the important components of sunlight, and their wavelengths can be divided into three bands. Among them, UVC is a short wave, which is absorbed and blocked by the ozone layer, cannot reach the ground, and has no harmful effect on the human body. Therefore, UVA and UVB in ultraviolet rays are the main wavelength bands that cause damage to human skin.
Hongwu Nano’s titanium dioxide (TiO2) nanopowder has small particle size, high activity, high refractive properties and high photoactivity. It can not only reflect and scatter ultraviolet rays, but also absorb them, thus having stronger blocking ability against UV rays. It is a promising physically UV-shielding protectant with superior performance.
The anti-UV ability of nano TiO2 is related to its particle size. When the particle size of titanium dioxide nanoparticle is ≤300nm, the ultraviolet rays with wavelengths between 190 and 400nm are mainly reflected and scattered; when the particle size of titania nanopowder is <200nm, the UV resistance is mainly reflected and scattered. The sun protection mechanism of ultraviolet rays in the mid-wave and long-wave regions is simple covering, and the sun protection ability is weak; when the particle size of TiO2 nano powder is between 30 and 100nm, the absorption of ultraviolet rays in the medium-wave region is significantly enhanced, and the shielding effect on ultraviolet rays is the best. Well, its sun protection mechanism is to absorb ultraviolet rays.
To sum up, titanium dioxide nano particle has different sun protection mechanisms for different wavelengths of ultraviolet rays. When the wavelength of ultraviolet rays is relatively long, the shielding performance of nano titanium dioxide TiO2 depends on its scattering ability; when the wavelength of ultraviolet rays is short, its shielding performance depends on its absorption ability. That is to say, nano titanium oxide’s ability to shield ultraviolet rays is determined by both its absorption capacity and scattering capacity. The smaller the primary particle size, the stronger the UV absorption ability of nano titanium dioxide powders.
Experiments show that Hongwu Nano’s nano rutile titanium dioxide TiO2 has better UV shielding properties than nano anatase TiO2. Nano TiO2 has good application prospects in anti-UV finishing of cotton fabrics and in anti-ultraviolet coatings on insulating glass.