A core-shell composite pigment with rutile TiO₂ intensification for UV inhibition

Organic pigments generally have bright colors but poor ultraviolet (UV) resistance. To improve the UV resistance and extend the applications, a core-shell composite pigment with rutile TiO₂ intensification for UV inhibition is proposed by a facile sol-gel method in this work. A core-shell structure, with a homogeneous sol-gel TiO₂ shell containing additional nanosized rutile TiO₂ particles and with the pigment as the core, was established taking advantage of UV resistance of TiO₂ and binding ability of sol-gel. While the sol-gel TiO₂ shell alone has already shown obvious ultraviolet shielding effect, as tested over different sol-gel aging times and TiO₂ loadings, the UV resistance of the fluorescent pigments was further enhanced by binding the nanosized rutile TiO₂ in the sol-gel shell. At a sol-gel TiO₂ to rutile TiO₂ ratio of 2:1, the UV exposure time is extended about eight times compared with that of the original pigment and twice as that of the modified pigment with pure sol-gel TiO₂ for the same color change. Therefore, the novel core-shell composite pigment intensified with nanosized rutile TiO₂ particles is proved to be efficient in improving the UV resistance of organic pigments.