噴霧乾燥法による紫外線遮蔽性複合微粒子の生成とその光学特性 [in Japanese] Preparation of Ultraviolet Shielding Composite Fine Particles by the Spray Dry Method and Their Optical Properties [in Japanese]
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超微粒子の凝集を抑制し光学機能を発現させる為に, 無機微粒子の中に無機超微粒子を分散・固定化させた構造をもつ複合微粒子, すなわち超微粒子複合化粉体を考案した.具体的には, 工業的製造が可能な噴霧乾燥法を用いて, SiO<SUB>2</SUB>ゾル, TiO<SUB>2</SUB>ゾルの混合物を出発原料としてTiO<SUB>2</SUB>/siO<SUB>2</SUB>複合微粒子の生成を種々の条件にて行い, 粒子径が0.48～0.59μmの球状微粒子が得られた.生成された微粒子の微細構造を電子顕微鏡を用いて観察したところ, TiO<SUB>2</SUB>超微粒子がSiO<SUB>2</SUB>微粒子 (超微粒子の凝集体) 中に分散・固定化していること, また噴霧液濃度の増加により生成粒子径も増大し, 生成粒子径と液滴径との間に相関があることがわかった.次にその光学特性を評価した結果, 本複合微粒子はTiO<SUB>2</SUB>超微粒子が有する可視光の高透明性および紫外線の高遮蔽性を発現し得ることがわかり, 今後は, 高透明性紫外線遮蔽剤として, 化粧品, 塗料分野などへの応用が期待される.
We have proposed composite fine particles, i.e. composite powders of ultra-fine particles, to show the optical function of ultra-fine particles by preventing them from aggregating. They have the structure where optically functional ultra-fine particles are dispersed and fixed in transparent inorganic fine particles. For instanse, spherical TiO <SUB>2</SUB>/SiO<SUB>2</SUB> composite fine particles with diameters from 0.48 to 0.59 im were prepared by the spray dry method from an aqueous solution of SiO<SUB>2</SUB>sol and TiO<SUB>2</SUB> sol under various experimental conditions. It was confirmed by an electron microscope that the microstructure of prepared particles was composed of SiO<SUB>2</SUB> fine particles with TiO<SUB>2</SUB> ultra-fine particles being dispersed and fixed in them. Moreover, it was found that the particle diameter was increased at higher concentration of nebulized solution, and it was primarily concerned with the droplet diameter. The prepared particles showed the optical properties of TiO<SUB>2</SUB> ultra-fine particles which had a high transparency in the visible range and a high shielding ability in the ultraviolet range. Accordingly, it is expected that prepared composite fine particles are applicable to cosmetics, paints, and other products as ultraviolet shielding agents with a high transparency.
- Chemical engineering
Chemical engineering 23(2), 237-242, 1997-03-10
The Society of Chemical Engineers, Japan