Titanium Dioxide Pigment for Paints & Coatings
Titanium dioxide (TiO2) is by far the most suited white pigment to obtain whiteness and hiding power in coatings, inks and plastics. This is because it has an extremely high refractive index and it does not absorb visible light. TiO2 is also readily available as particles with the right size (d ≈ 280 nm) and the right shape (more or less spherical) as well as with a variety of post-treatments.
However, the pigment is expensive, especially when the volume prices of systems are used. And, there always remains a need to develop a full-proof strategy to obtain the best results in terms of cost/performance ratio, scattering efficiency, dispersion… while using it in coating formulations. Are you searching for the same?
Explore the detailed knowledge of TiO2 pigment, its scattering efficiency, optimization, selection, etc. to achieve the best possible white color strength and hiding power in your formulations.
All About Titanium Dioxide Pigment
Titanium dioxide (TiO2) is the white pigment used to give whiteness and hiding power, also called opacity, to coatings, inks, and plastics. The reason for this is two-fold:
oTiO2 particles of the right size scatter visible light, having wavelength λ ≈ 380 - 700 nm, effectively because TiO2 has a high refractive index<
oIt is white because it does not absorb visible light
The pigment is expensive, especially when volume prices of systems are used. Most paint and ink companies buy raw materials per weight and sell their products by volume. As TiO2 has a relatively high density, ρ ≈ 4 g/cm3, the raw material contributes substantially to the volume price of a system.
Production of TiO2 Pigment
A few processes are used to produce TiO2 pigment. Rutile TiO2 is found in nature. This is because the rutile crystal structure is the thermodynamically stable form of titanium dioxide. In chemical processes natural TiO2 can be purified, thus obtaining synthetic TiO2. The pigment can be made from ores, rich in titanium, that are mined from the earth.
Two chemical routes are used to make both rutile and anatase TiO2 pigments.
1.In the sulfate process, the titanium-rich ore is reacted with sulfuric acid, giving TiOSO4. Pure TiO2 is obtained from TiOSO4 in several steps, going via TiO(OH)2. Depending on the chemistry and route chosen, either rutile or anatase titanium dioxide is made.
2.In the chloride process, the crude titanium-rich starting material is purified by converting titanium to titanium tetrachloride (TiCl4) by using chlorine gas (Cl2). The titanium tetrachloride is then oxidized at high temperature, giving pure rutile titanium dioxide. Anatase TiO2 is not made via the chloride process.
In both processes, the size of the pigment particles as well as the post-treatment is adjusted by fine-tuning the final steps in the chemical route.
Post time: May-27-2022