How does particle size affect the properties of inorganic pigments?

Analysis of the influence of particle size on the performance of inorganic pigments:

The performance of inorganic pigments is also significantly affected by the particle size, which is similar to organic pigments(Click to learn more: Basic knowledge of organic pigments-the decisive role of particle size), but also has important differences.

1. Optical properties (opposite to organic pigments)(See table above)

Hiding power and transparency: Inorganic pigments show the opposite law to organic pigments

Small particle size → high hiding power (improved light scattering efficiency)

Large particle size → high transparency (increased light transmission)

2. Same properties as organic pigments (See table above)

Coloring power: small particle size → high coloring power (large number of particles per unit mass)

Viscosity: small particle size → high viscosity (large specific surface area, strong interaction between particles)

Specific surface area: small particle size → high specific surface area

Addition amount: small particle size → Low addition (high coloring efficiency)

Difference in durability

Weathering stability: Inorganic pigments are generally better than organic pigments

Small particle size inorganic pigments still maintain good weathering resistance (stable crystal structure)

Large particle size inorganic pigments have the best durability (less environmental erosion surface)

Special performance

Density influence: Inorganic pigments generally have higher density

Small particle size is easier to settle (special dispersion technology required)

Large particle size has relatively good suspension stability

Refractive index: Inorganic pigments usually have higher refractive index

The influence of particle size on optical properties is greater than that of organic pigments

Application selection suggestions:

1. High hiding systems (such as architectural coatings) prefer small particle size inorganic pigments

2. Transparent effect requirements (such as automotive topcoat paint) choose large particle size inorganic pigments

3. Particle size classification technology (bimodal distribution) is recommended for balancing performance

Note: Typical inorganic pigments such as titanium dioxide and iron oxide pigments follow the above rules, but the specific performance will be slightly different due to differences in chemical composition.