In order to disperse titanium dioxide (TiO
2) powders (0.2μm) well in emulsion systcm, a surface modification of Nylon 12 powders (5μm) were applied.TiO
2 and Nylon 12 powders were mixed to modify the surface of Nylon 12 powders with an automatic ceramic mortar. The strong adhesiveness of TiO
2 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. TiO
2 powders were dispersed in neither water nor liquid paraffin, but Nylon 12 powders were dispersed well in the both solvents. TiO
2 modified Nylon 12 particles (TiO
2, 33%) showed the physicochemical properties, especially wettability, of both TiO
2 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% TiO
2 powders were aggregated but 1% of the modified particles (0.3% as TiO
2) 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 TiO
2 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.
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