FABRICATION OF FLAKE-LIKE BOEHMITE/CERIA OR ZINC OXIDE COMPOSITES FOR UV SHIELD COATING

摘要

It was discussed that flaked shaped particle with nano sized ceria (CeO_2) or zinc oxide (ZnO) synthesized by wetting process was possible to use as UV adsorption materials. Titanate aqueous solution (TNB-Lac) prepared by direct reaction of titanium tetra-n-butoxide (TNB) with lactic acid (Lac) in water shows characteristics of a polyanion and acts as a dispersant for preparing aqueous CeO_2 slurries. The isoelectric point (IEP) of CeO_2 particles shifted to lower pH with increasing concentration of TNB-Lac. Well-diesperesd CeO_2 slurries were obtained by modification of the surface changes on CeO_2 to adjust pH and addition of TNB-Lac concentration. On the other hand, the IEP of boehmite particles was at around pH 9.5. According to this result, the boehmite/CeO_2 or boehmite/ZnO pomposities could be synthesized by the electrostatic attraction between positively charged boehmite substrate and negatively charged CeO_2 or ZnO nanoparticles with 0.1 mmol/g TNB-Lac at around pH between 6 to 7. The synthesized particles were characterized by spectrophotometer and scanning electron microscopy. With boehmite/CeO_2 or boehmite/ZnO volume ratio 80/20, the boehmite was covered with CeO_2 or ZnO nanoparticles by microstructural observation. The silicon resin film including 5 mass% the synthesized composite with 20 vol% CeO_2 gave the equivalent UV shield ability, compared with the property of the film including nano-sized CeO_2.