Provided are a novel titania fine-particle composite which has high transparency, high stability, and high ultraviolet-absorbing power and excellent redispersibility, and skin-care external preparations which contain the titania fine-particle composite and exert high ultraviolet protective effect. The titania fine-particle composite can be produced by adding one or more selected from among carboxylic acids and carboxylic acid derivatives represented by general formula (1), and polymers containing the carboxylic acids or carboxylic acid derivatives as a constituent monomer to an aqueous acid dispersion of titania fine particles, and neutralizing the resulting dispersion with an alkali to form a titania fine-particle composite composed of titania fine particles functioning as cores and the carboxylic monomer or polymer deposited on the surface of the cores. In the titania fine-particle composite, titania fine particles functioning as cores have a high degree of crystallization and the intermolecular interaction between titania fine particles and the carboxylic monomer or polymer is strong. Therefore, the titania fine-particle composite can be uniformly dispersed in a dispersion medium to attain high transparency and high stability. Further, skin-care external preparations which exert high ultraviolet protective effect can be produced by adding the titania fine-particle composite.
本发明提供了一种具有高透明度、高稳定性、高紫外线吸收力和优异再分散性的新型
二氧化钛细颗粒复合材料,以及含有该
二氧化钛细颗粒复合材料并具有高紫外线防护效果的护肤外用制剂。生产
二氧化钛微粒复合材料的方法是从通式(1)所代表的
羧酸和
羧酸衍
生物以及含有
羧酸或
羧酸衍
生物作为组成单体的聚合物中选择一种或多种添加到
二氧化钛微粒的
水性酸分散液中,然后用碱中和所得到的分散液,形成由作为芯的
二氧化钛微粒和沉积在芯表面的
羧酸单体或聚合物组成的
二氧化钛微粒复合材料。在
二氧化钛细颗粒复合材料中,作为核心的
二氧化钛细颗粒具有较高的结晶度,
二氧化钛细颗粒与羧基单体或聚合物之间的分子间相互作用很强。因此,
二氧化钛细颗粒复合材料可以均匀地分散在分散介质中,从而获得高透明度和高稳定性。此外,通过添加
二氧化钛细颗粒复合材料,还可以生产出具有高紫外线防护效果的护肤外用制剂。