Titanium dioxide (chemical formula: TiO₂, white solid or powdered amphoteric oxide, molecular weight: 79.9, is a white inorganic pigment with non-toxic, best opacity, best whiteness and brightness, and is considered to be the world today A white pigment with the best performance. Titanium white has strong adhesion, is not easy to undergo chemical changes, and is always white. It is widely used in coatings, plastics, papermaking, printing inks, chemical fiber, rubber, cosmetics and other industries. Its melting point Very high, it is also used to make refractory glass, glaze, enamel, clay, high temperature laboratory utensils, etc.
1) Relative density
Among the commonly used white pigments, the relative density of titanium dioxide is the smallest. Among the white pigments of the same quality, the surface area of titanium dioxide is the largest and the pigment volume is the highest.
2) melting point and boiling point
Since the anatase type will change to a rutile type at high temperatures, the melting point and boiling point of the anatase type titanium dioxide are virtually non-existent. Only rutile titanium dioxide has a melting point and a boiling point. The melting point of rutile titanium dioxide is 1850 ℃, the melting point in air is (1830 ± 15) ℃, and the melting point in rich oxygen is 1879 ℃. The melting point is related to the purity of titanium dioxide. The boiling point of rutile titanium dioxide is (3200 ± 300) ° C. At this high temperature, the titanium dioxide is slightly volatile.
3) Dielectric constant
Titanium dioxide has excellent electrical properties because of its high dielectric constant. When determining certain physical properties of titanium dioxide, the crystalline direction of the titanium dioxide crystals must be considered. The anatase type titanium dioxide has a relatively low dielectric constant of only 48.
Titanium dioxide has the properties of a semiconductor, and its electrical conductivity increases rapidly with increasing temperature, and it is also very sensitive to anoxia. The dielectric constant and semiconductor properties of rutile-type titanium dioxide are very important to the electronics industry. This property can be used to produce electronic components such as ceramic capacitors.
According to the Mohs hardness scale, the rutile titanium dioxide is 6 to 6.5, and the anatase titanium dioxide is 5.5 to 6.0. Therefore, in order to avoid abrasion of the spinneret, anatase is used in the extinction of the chemical fiber.
Although titanium dioxide is hydrophilic, its hygroscopicity is not very strong, and the rutile type is smaller than the anatase type. The hygroscopicity of titanium dioxide has a certain relationship with the size of its surface area. The large surface area and high hygroscopicity are also related to the surface treatment and properties.
7) Thermal stability
Titanium dioxide is a substance with good thermal stability.
Titanium dioxide particle size distribution is a comprehensive index, which seriously affects the performance of titanium dioxide pigments and product applications. Therefore, the discussion of hiding power and dispersibility can be directly analyzed from the particle size distribution.
The factors that affect the particle size distribution of titanium dioxide are more complicated. The first is the size of the original particle size of the hydrolysis. By controlling and adjusting the hydrolysis process conditions, the original particle size is within a certain range. The second is the calcination temperature. During the calcination of metatitanic acid, the particles undergo a crystal form conversion period and a growth period. The appropriate temperature is controlled so that the growing particles are within a certain range. The last is the crushing of the product. Usually, the modification of the Raymond mill and the adjustment of the speed of the analyzer control the crushing quality. At the same time, other crushing equipment can be used, such as universal mills, jet mills and hammer mills.