Titanium dioxide（Tio2） is a white compound used as an important pigment in the coating industry which is quite efficient because it scatters visible light resulting in increased brightness, whiteness and opacity. Due to these characteristics it is widely used in the paints and coatings industry.
Titanium dioxide has two commercial crystal structures. One is anatase tio2 and the other is rutile tio2. Rutile titanium dioxide pigments are preferred over the former due to better efficiency in scattering the light. They are also more durable and stable as compared to tio2 anatase pigments.
The appearance of titanium dioxide is determined by particle size and surface composition coated. Physical, chemical and photochemical properties entirely depend on these two characters. Titanium dioxide pigments are dispersed accordingly due to their insolubility in coating vehicles. On a commercial scale, titanium dioxide coated with organic and inorganic surface modifiers. Inorganic surface modifiers are forms of alumina and silica precipitates.
Inorganic surface treatments:
Organic surface treatments improves:
Whatever it is solvent or water-based paint, Titanium dioxide(Tio2) coated in paints is not only cover and decoration, the most important is to improve the physical and chemical properties of coatings, enhance chemical stability, and improve hiding power, tinting strength, anti-corrosion , Light resistance, high durability, enhancing paints strength and adhesion to prevent cracks, avoiding the transmission of ultraviolet light and moisture .So titanium dioxide in paint can effectively delay aging, extending to the life of the paints.
Titanium dioxide pigment coated surfaces absorb light at the bottom but the top surface having a high refractive index will bend light and it will appear white, opaque and bright. This absorption and emission phenomena helps a lot in imparting a color.
Diffraction takes place when light or a wave bends away from its original path. Light often bend behind the object when it passes by the object. Light bending is insignificant for large objects until incident light wavelength approaches the object’s dimension.
In case of titanium dioxide, this pigment bends light 4 to 5 times as compared to the original light falling on the object. Particle size of the pigment also affects the diffraction process. Diffraction from small sized particles is due to electromagnetic resonance between light and the particle.
Titanium dioxide coatings systems employ well controlled sized and spaced particles for better functioning of pigments.
PROPERTIES OF TITANIUM DIOXIDE:
Harmony Tio2 properties is used in the coating industry due to the following reasons: