Preparation of Iron Oxide Shell Microcapsule
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概要
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The spherical particles of hydrated iron oxide, used as microcapsule shell, were prepared by "Inter-facial Reaction Method", in which the hydrated iron oxide was formed by the reaction of Fe (NO<SUB>3</SUB>) <SUB>3</SUB> aqueous solution emulsified in benzene with NaHCO<SUB>3</SUB> aqueous solution.<BR>The preparation of the spherical particles by using the surfactants of various HLB was examined in order to determine the best HLB range of surfactant for the formation of the spherical particles. The pH value of the reaction mixtures was measured during the reaction time in order to study the mechanism of the formation of the spherical particles. The differential thermal analysis curve, the X-ray diffraction pattern, the particle mean diameter, the specific surface area, and the pore volume distribution were measured to determine the properties of the spherical particles.<BR>The spherical particles of hydrated iron oxide were not crystalline and transformed to crystalline α-Fe<SUB>2</SUB>O<SUB>3</SUB> particles by heating at 500°C, of which shapes were also spherical. The particle mean diameter was about 0.9-1.0μm, the specific surface area was 400-450 m<SUP>2</SUP>/g, and the particle had many pores of 20-40Å in diameter on the surface. The spherical particles were formed in the HLB range of 4-7, by slower reaction (20-30min.) than in other HLB range (1-2min.). These results suggest that, in the HLB range of 4-7, the Fe (NO<SUB>3</SUB>) <SUB>3</SUB> aqueous solution microdrop has the stable protective layer of surfactant-benzene on the surface, and the protective layer maintains the sphere of emulsion and interferes with the reaction of Fe (NO<SUB>3</SUB>) <SUB>3</SUB> and NaHCO<SUB>3</SUB>.
- Japan Society of Colour Materialの論文