抄録
In order to disperse titanium dioxide (TiO2) powders (0.2μm) well in emulsion systcm, a surface modification of Nylon 12 powders (5μm) were applied.TiO2 and Nylon 12 powders were mixed to modify the surface of Nylon 12 powders with an automatic ceramic mortar. The strong adhesiveness of TiO2 powders to the surface of Nylon 12 powders was confirmed by an X-ray analysis and a scanning electron microscopic observation. The dispersibility of the particles was tested in water, liquid paraffin and emulsions. TiO2 powders were dispersed in neither water nor liquid paraffin, but Nylon 12 powders were dispersed well in the both solvents. TiO2 modified Nylon 12 particles (TiO2, 33%) showed the physicochemical properties, especially wettability, of both TiO2 and Nylon 12 powders, so the modified particles were dispersed well in liquid paraffin but not in water. In O/W type emulsion, only 0.3% TiO2 powders were aggregated but 1% of the modified particles (0.3% as TiO2) were dispersed well. On the other hand, in W/O type emulsion larger amount of the modified particles (5%) were dispersed well. It is concluded that the surface modification of Nylon 12 powders is a good method to disperse TiO2 powders well in emulsions, and especially W/O type emulsion containing the modified particles was suggested to be applicable to sun screen agents because of its good shielding effect from ultraviolet light.
