Cobalt blue is a high-performance composite inorganic pigment composed of cobalt oxide (CoO) and aluminum oxide (Al₂O₃), forming a stable spinel structure through high-temperature calcination. Its unique crystalline structure and chemical composition grant it excellent weather resistance, chemical stability, high thermal stability, and superior tinting capabilities, making it widely used in coatings, plastics, inks, ceramics, glass, and building materials.

I.Structural Analysis and Chemical Stability

I.I Crystal Structure and Performance Impact

Cobalt blue has a spinel crystal structure, formed by cobalt oxide and aluminum oxide in octahedral and tetrahedral coordination, ensuring its chemical stability and physical durability. This unique crystalline arrangement provides:

• Outstanding Optical Properties: Selective absorption in the visible light spectrum, giving it a stable and saturated blue hue.
• High Thermal Stability: The structure remains stable above 1000°C without significant decomposition or discoloration.
• Exceptional Chemical Resistance: Insoluble in water and most organic solvents, with high resistance to acids and bases.

I.II Thermal Stability and Weather Resistance Mechanism

The thermal stability of cobalt blue is attributed to its spinel phase, which remains intact even at extreme temperatures. Its weather-resistant properties include:

• UV Stability: Effectively reflects or absorbs UV light, preventing photodegradation and ensuring long-term color retention.
• Oxidation Resistance: Maintains chemical inertness in both oxidative and reductive atmospheres, making it suitable for outdoor and harsh environments.
• Acid and Alkali Resistance: Remains chemically stable across a wide pH range, making it ideal for industrial coatings and construction materials.

II. Dispersibility and Application Techniques

The surface characteristics and particle size distribution of cobalt blue significantly affect its dispersibility in various mediums:

1. Coating Applications:
   Suitable for both water-based and solvent-based coatings; high-shear dispersion equipment is recommended to minimize agglomeration and enhance dispersion stability.Low oil absorption (15-25 g/100g) helps maintain coating mechanical properties and gloss.
2. Plastic Coloring:
   Twin-screw extrusion or high-speed blending is used to ensure uniform pigment distribution and improved color consistency.Compatible with PVC, PP, PE, ABS, and other polymers, providing high-temperature-resistant coloration.
3. Ink Applications:
   Suitable for solvent-based and UV-curable inks, offering low migration properties ideal for packaging printing.Surface modification treatments may be required in water-based inks to improve hydrophilicity and wettability.

III. Key Application Areas

1. Coatings Industry:
   Automotive coatings, architectural coatings, industrial anti-corrosion coatings.
2. Plastics Industry:
   Suitable for PVC, PP, PE, ABS, and thermoplastic applications.
3. Ink Industry:
   High-quality packaging printing inks, screen printing inks.
4. Ceramics & Glass Industry:
   Ceramic glazes, glass coloring agents.
5. Other Applications:
   Building materials, textile dyeing, artistic pigments.