DISPERSIONS

摘要

An oil dispersion which is substantially transparent to visible light comprises an oil, particles of zinc oxide having an average size of from 0.005 to 0.15 micron and an organic dispersing agent. The solids content of the dispersion is at least 30 weight per cent, its extinction coefficients at 308 nm (E(308)) and 360 nm (E(360)) wavelengths are both at least 9 litres per gram per centimetre and the ratio E(360):E(308) is in the range 0.75:1 to 1.5:1. A method of preparing the dispersion is also described in which the ingredients are milled together in the presence of a particulate grinding medium until the required particle size and optical properties are obtained. The dispersions are useful in sun-screening preparations and especially those products designed to provide a balanced protection from UVA and UVB radiation.