Why is white corundum added to the production of UV coating topcoat?
Adding white corundum (mainly aluminum oxide) to UV coating topcoat is mainly to improve the comprehensive performance of the coating through its unique physical and chemical properties. The following are the specific reasons and mechanisms of action:
1. Enhance wear resistance and hardness
The Mohs hardness of white corundum is as high as 9.0 (slightly lower than silicon carbide and diamond) .Adding it to UV coating topcoat can significantly improve the scratch resistance and wear resistance of the coating. It is especially suitable for high friction scenes such as floor paint and industrial equipment coating.
Mechanism of action:
White corundum particles are evenly distributed in the coating to form a rigid skeleton structure, disperse external stress, and reduce coating loss caused by friction.
2. Optimize adhesion and coating stability
White corundum powder can fill the tiny pores in the coating and improve the bonding strength between the coating and the substrate. The particles of white corundum powder are uniform in shape, and the mechanical bite effect is enhanced by increasing the surface roughness to prevent the coating from peeling off.
Experimental verification:
Adding white The UV coating adhesion test of corundum increased by 20%–30%, especially on smooth substrates such as metal and ceramic.
3. Improve gloss and texture
White corundum powder (such as 800#, 1000#) is white and translucent crystal, which does not affect the transparency of UV coating. Its high reflectivity can enhance the gloss of the coating, and at the same time, the surface fineness can be controlled by adjusting the particle size (such as 120 mesh, 180 mesh) to meet the requirements of matte or high gloss.
4. Enhance anti-slip and weather resistance
White corundum forms a micron-level raised structure on the surface of the coating to increase friction, which is especially suitable for anti-slip scenes such as floors and stairs. At the same time, its chemical inertness (acid and alkali resistance, UV resistance) can delay the aging of the coating and maintain stable performance in outdoor or high humidity environments.
5. Improve chemical resistance and high temperature resistance
The melting point of white corundum is as high as 2050°C, and it remains stable during the UV curing process and will not decompose due to high temperature or ultraviolet radiation. Its strong resistance to organic solvents, acids and alkalis (pH neutral) can protect the substrate from corrosion and extend the life of the coating.
Typical applications:
Power battery UV insulation coating: replaces traditional PET “blue film” and provides higher dielectric strength and chemical resistance;
Chemical equipment anti-corrosion coating: resists acid and alkali medium erosion.
6. Key points of technical selection of white corundum
Particle size selection:
120-180 mesh: Enhance wear resistance and anti-skid (floor paint, industrial channel);
800-1000 mesh micro powder: Improve surface smoothness (high-end furniture, electronic product coating).
Addition ratio:
It is recommended to account for 2%-5% of the total weight of the coating. Excessive amount may lead to decreased fluidity or increased cost.
Process adaptation:
Fully stirred to ensure uniform dispersion to avoid agglomeration affecting the curing effect.
Summary: White corundum plays the role of “multifunctional enhancer” in UV topcoat. By improving core properties such as wear resistance, hardness, adhesion, and taking into account gloss, anti-skid and weather resistance, it becomes the preferred additive for industrial protection and high-end decorative coatings. In the future, with the expansion of UV coatings in new energy and electronic fields (such as power battery insulation coatings), the high performance characteristics of white corundum will further release potential.