The Effect of Particle Properties of
Titanium Dioxide on Pigment Performance
The influence of particle characteristics on pigment performance has the following three aspects:
1. The influence of particle size on pigment performance
For a certain wavelength of light, when the pigment particle size is half wavelength, the scattering rate of light is the highest, that is, the opacity is the highest. The wavelength of visible light is 0.4-0.7μm, so theoretically the best particle size of pigment particle is 0.2-0.35μm. if the particle size is too small, the diffraction of light will occur, which leads to the decrease of opacity. And the pigment performance is very much related to the scattering coefficient. When the scattering coefficient is the highest at 0.2μm particle size, the pigment has the best achromatic power and covering power, and the best whiteness and gloss. However, the performance of various pigments sometimes contradict each other, such as the weather resistance decreases when the particle size becomes small, so for some pigments with high weather resistance requirements, the particle size should be appropriately large.
2. The effect of particle size distribution on pigment performance
Excellent pigment performance of titanium dioxide, its particle size distribution width should be as narrow as possible, that is, the particle size between 0.2-0.3μm to account for the majority, and 0.lμm below and 0.37μm above almost does not exist.
3. The influence of particle shape on the performance of pigment
The particle shape of pigment also has influence on light scattering, generally when the particle is round, the scattering rate is the highest, and the pigment performance is the best for the round and regular particles. So we should avoid angular particles as far as possible, because not only its optical performance is poor, but also when it is stacked together, the space volume is large, and the corresponding oil absorption is high.
