In order to improve the weather resistance and chemical stability of TiO2, and to improve the dispersion of TiO2 in various media, the surface treatment of TiO2 is usually carried out. Inorganic surface treatment is to form a uniform colorless or white inorganic oxide film on the surface of TiO2 particles to block the photoactive point of TiO2 and improve weather resistance. Organic treatment is to coat a layer of organic oxide film or surfactant on the surface of TiO2, so that the TiO2 particles remain in a dispersed state and can be better compatible and uniformly dispersed in an organic medium. For the surface treatment of TiO2, generally inorganic surface treatment first, followed by organic surface treatment. Inorganic surface-treated materials generally use SiO2 (silica), Al203 (alumina), ZrO (zirconia), ZnO (zinc oxide).
SiO2 is ubiquitous in nature. Pure SiO is colorless and transparent crystal, called “quartz”. It is an important material for optical instruments and an important component of granite, gneiss, quartzite, sandstone and other rocks. SiO2 is insoluble in water and acid, but soluble in alkali. It is used to manufacture chemical vessels, glass and refractory materials.
Al203 (white powder, insoluble in water, with different crystal forms). Among them r-Al203. Soluble in acid or alkali, it is a typical amphoteric oxide, the main raw material for smelting metal aluminum, can also be used as an adsorbent. o1-A1203. It is generally not corroded by chemicals and exists in the form of corundum in nature. Corundum is second only to diamond in hardness, and can be used to make drills, grinding wheels, files and bearings. A1203. It is also an important refractory material and filler.
The rutile TiO2 produced by the sulfuric acid method is generally treated with alumina / silica / zirconia, and its content is 2.23%, 1.55%, 0.77% in order. The rutile TiO2 produced by the chlorination method can only be surface-treated with alumina / silica. High abrasion resistance, high gloss and good tinting strength, high hiding power and excellent outdoor weather resistance. Al203 is simply used. The surface-treated TiO2 has better dispersion, but the weather resistance is insufficient. With SiO2 connected to the surface treated with Al2O3, the weather resistance can be greatly improved, but the content of TiO2 is reduced and the coloring strength is reduced.