Application of platelet aluminum oxide in pearlescent pigment substrates
Platelet aluminum oxide is the mainstream substrate for high-end pearlescent pigments, often referred to as alumina pearlescent flakes or flake-shaped α-alumina substrate. Compared to natural mica and glass flakes, it has uniform thickness, no impurities, and is physically and chemically stable. It is widely used in cosmetics, industrial coatings, plastics, and high-end pearlescent printing, relying on its regular two-dimensional flake structure to achieve directional reflection.
I. Basic Material Characteristics
1. Artificial single-crystal wafer shape, controllable thickness, regular diameter, and uniform aspect ratio; natural mica has uneven thickness and inherent black spots and mineral impurities.
2. High temperature resistance, acid and alkali resistance, solvent resistance; does not deform during high-temperature calcination when coated with metal oxides, resulting in a uniform coating.
3. Smooth and dense surface; strong adhesion of titanium dioxide and iron oxide coatings, preventing coating peeling; chemically inert, does not react with pigments, additives, or resins.
4. Good light transmittance, moderate refractive index, capable of forming regular multi-layered interference reflections; delicate luster, without stray light.
II. Three Main Types of Pearlescent Pearlescent Products
1. Silver-White Series (Most Common): Rutile titanium dioxide coated on flat alumina. Advantages: Clean, cool white luster, non-yellowing; minimal batch-to-batch color variation; UV resistant, does not yellow outdoors. Applications: Foundation, loose powder, automotive paint, plastic casings, printing inks.
2. Metallic Colored Pearlescent (Gold, Red, Brown, Green): Inner layer TiO₂, outer layer coated with iron oxide and chromium oxide. Utilizing the smooth surface of alumina, the color is uniform and saturated, without the discoloration often seen in natural mica; acid and alkali resistant, stable and colorfast in nail polish, makeup, and industrial anti-corrosion paints.
3. Interference Iridescent Pearlescent (Color-Changing Pearlescent): Multi-layer oxide film, relies on light interference to change color with angle. Flat alumina has high flatness and clean, transparent interference colors; glass flakes are brighter and shinier, while mica is darker. Alumina balances fineness and color saturation, and is often used in high-end cosmetics, high-end curved plastics, and high-end packaging printing.
Zhengzhou haixu abrasives co.,ltd,manufacturer and supplier of platelet aluminum oxide for many years,the sizes and its PSD are as follows:
| SIZE | D0（um) | D3（um) | D50（um) | D94（um) |
| #500 | <64.2 | 35.4-39.8 | 23.8-27.2 | 15-17 |
| #600 | <50.4 | 28.1-32.3 | 19.2-22.3 | 13.4-15.6 |
| #700 | <40.1 | 24.4-28.2 | 16.1-18.7 | 9.6-11.2 |
| #800 | <32.0 | 20.9-24.1 | 13.1-15.3 | 8.2-9.8 |
| #1200 | <25.2 | 14.8-17.2 | 9.4-11 | 5.8-6.8 |
| #1500 | <20.3 | 11.8-13.8 | 7.6-8.8 | 4.5-5.3 |
| #2000 | <16.3 | 8.9-10.5 | 5.9-6.9 | 3.3-3.9 |
| #3000 | <12.5 | 6.6-7.8 | 4.3-5.1 | 2.55-3.05 |
| #4000 | <10.0 | 4.8-5.6 | 2.8-3.4 | 1.5-2.1 |