Powder design for UV-attenuating agent with high transparency for visible light

To design high-performance ultraviolet (UV)-attenuating agent for dispersion type of functional paints and/or cosmetic powders, nano-meter size of zinc oxide (ZnO) powder was immobilized onto the surface of 4 μm square size of crystalline sheet (H-ilerite: synthetic polysilicic acid (PSA)). A high-speed elliptical-rotor-type powder mixer (HEM) was applied for exfoliating in a sheet one by one from the PSA agglomerates without breakage of the original shape and for arranging the ZnO in the mono-particle layer on the sheet during dispersing the self-coagulative ultra-fine ZnO. The critical operating conditions of the HEM were determined by an observation of the morphological change of PSA. Optical characteristics of the compounded powder (ZnO-PSA) were evaluated in the form of suspension dispersed into polymer medium. The UV-attenuating effect was confirmed in the UVA region (320–400 nm) and the heat treatment after immobilization was one of the effective methods to get higher transparency for visible light.