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:

• Good performance properties.
• Dispersion in varieties of organic liquids and water.
• Hiding powder
• Resistance for discoloration by heat reduction.
• Chalk resistance.

Organic surface treatments improves:

• Dispersion in water-based and oil-based coatings.
• Its usage value in coating formulation by varying combinations.
  
  

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:

• Unique in its properties.
• It combines high degree of transparency with a high refractive index of visible region spectrum.
• Highly bright and opaque coating surface is achieved with minimum film thickness.
• It promotes hiding effectively.
• Titanium dioxide is used in an appropriate size which is slightly less than half wavelength of scattered light. Particle size ranges between 0.2 to 0.3 microns in diameter.
• Titanium oxide has great scattering power and show power for red, blue and green light. For 0.2 micron particle size scattering wavelength is maximized. From 0.25 to 0.3 microns size scattering of blue light decreases rapidly whereas green and red light remains unchanged.
• An undertone phenomenon is also observed for titanium dioxide in which increase in particle size increases blueness.
• Coating opacity and scattering efficiency is achieved by increasing volume concentration of titanium dioxide.
• Titanium dioxide contributes in light scattering in color pigments with 50% reflectance.
• Metal oxide contaminants are removed from titanium dioxide pigments during the production process to achieve the desired color status.
• Proper and correct measures are taken to improve the gloss power of titanium dioxide to achieve a shiny surface.
• Correct selection enhances the weather ability of titanium dioxide pigment coatings.
• Titanium dioxide pigments are photochemically active and sometimes promote degradation which is controlled by inorganic surface treatments.
• Titanium dioxide is durable in powder coating and it provides excellent over brake yellowing resistance.