ULTRAVIOLET RAY-BLOCKING COMPOSITE FINE PARTICLE, ITS PRODUCTION AND COSMETIC

摘要

PROBLEM TO BE SOLVED: To obtain ultraviolet rays-blocking composite fine particles having high transparency with visible light and light blocking property in ultraviolet ray area. SOLUTION: The composite fine particles having <=0.5μm average particle diameter are obtained by the following steps (a) to (c). (a) A mixed liquid containing a mixture of sol containing particles constituting mother particles having 0.001-0.3μm average particle diameter of primary particle or powder of the mother particle with a sol having 0.001-0.1μm average particle diameter, contaiining children particles in which band gap energy is smaller by >=0.2eV than particles constituting mother paricles or powder of the child particles is prepared and the mixed liquid is subjected to mill treatment and/or disperse treatment under high pressure to produce composite fine particles in which child particles and/or mother particles are aggregated. (b) The composite fine particles are coated with an inorganic material by sol-gel reaction method so as not to substantially have catalytic activity. (c) The treated composite fine particles are subjected to water-repelling treatment using a water-repelling agent and then, dried and/or pulverized to provide the objective fine particles, in which child particles are dispersed and fixed at a ratio of 0.1-85vol.% into the mother particles.