LIGHTSCATTERING EFFICIENCY WHITE PIGMENTS - AN ANALYSIS OF MODEL CORE-SHELL PIGMENTS VS. OPTIMIZED RUTILE TIO2

The light-scattering efficiency of a white pigment is strongly depende nt on its refractive index and particle size. Rutile TiO2 is an effect ive opacifier because of its high refractive index. It efficiency can be further optimized by generating narrow particle size distributions near the optimum diameter. Recently, an alternative core-shell pigment was proposed as a means of increasing the light-scattering efficiency of TiO2. The proposed hybrid pigment would be prepared by coating a s hell of titania on spherical silica particles or some other low-refrac tive-index material. Theoretical calculations of the light-scattering efficiencies of these core-shell particles and solid TiO2 particles sh ow that core-shell particles are substantially less efficient light-sc attering materials than pure rutile, especially in the domain of titan ia coating thickness that can be realistically applied to a core mater ial.