Introduction
Calcium carbonate (CaCO₃) is one of the most commonly used fillers in the plastics and rubber industries. It is widely used to improve material performance while also reducing production costs.
Although many people are familiar with calcium carbonate as a filler, fewer people fully understand the different types of calcium carbonate and their specific properties.
Depending on the production method and particle structure, calcium carbonate can generally be classified into the following types:
- Ground Calcium Carbonate (GCC)
- Precipitated Calcium Carbonate (PCC)
- Nano Calcium Carbonate
- Coated (Active) Calcium Carbonate
1. Ground Calcium Carbonate (GCC)
Ground Calcium Carbonate (GCC) is the most commonly used form of calcium carbonate. It is produced by physically grinding natural limestone or other calcium carbonate ores into fine powder.
Key Characteristics
- Appearance: white powder
- Bulk density: 0.8–1.3 g/cm³
- Whiteness: 89–93%
Applications
GCC is widely used as a cost-effective filler in:
- PVC products
- Rubber products
- Coatings and paints
- Construction materials
Its main function is to reduce production cost while improving rigidity and dimensional stability.
2. Precipitated Calcium Carbonate (PCC)
Precipitated Calcium Carbonate (PCC), also known as light calcium carbonate, is produced through a chemical synthesis process.
Production Process
- Limestone is calcined at high temperature to produce calcium oxide (CaO) and carbon dioxide (CO₂).
- Calcium oxide reacts with water to form calcium hydroxide (Ca(OH)₂).
- Calcium hydroxide reacts with carbon dioxide to produce precipitated calcium carbonate.
- The material is then filtered, dehydrated, and ground to obtain the final product.
Key Characteristics
- Bulk density: 0.5–0.7 g/cm³
- Whiteness: 92–95%
Applications
PCC provides higher purity and better whiteness than GCC and is commonly used in:
- Plastics
- Paper manufacturing
- Coatings
- Rubber products
3. Nano Calcium Carbonate (CCR)
Nano Calcium Carbonate is an ultra-fine form of precipitated calcium carbonate with extremely small particle sizes.
Key Characteristics
- Particle size: 20–100 nm
- Bulk density: approximately 0.28 g/cm³
Applications
Because of its extremely small particle size and high surface area, nano calcium carbonate is used in:
- High-performance plastics
- Rubber reinforcement
- Advanced composite materials
Unlike ordinary fillers, nano calcium carbonate can also provide reinforcement effects, improving mechanical properties such as strength and impact resistance.
4. Coated (Active) Calcium Carbonate
Active Calcium Carbonate, also known as coated calcium carbonate, is produced by surface modification of calcium carbonate particles using organic substances.
Common coating agents include:
- Stearic acid
- Coupling agents
Key Characteristics
The main difference between active (coated) calcium carbonate and ordinary calcium carbonate is its hydrophobic surface.
This modification improves:
- Compatibility with polymers
- Dispersion in plastics and rubber
- Processing performance
Applications
Coated calcium carbonate is widely used in:
- PVC products
- Plastic masterbatches
- Rubber materials
- Composite materials
Comparison of Calcium Carbonate Types
| Type | Production Method | Bulk Density | Main Function |
|---|---|---|---|
| GCC | Physical grinding | 0.8–1.3 g/cm³ | Cost reduction filler |
| PCC | Chemical precipitation | 0.5–0.7 g/cm³ | High whiteness filler |
| Nano CaCO₃ | Ultra-fine precipitation | ~0.28 g/cm³ | Reinforcement and filler |
| Coated CaCO₃ | Surface modified CaCO₃ | Varies | Improved compatibility and reinforcement |
Conclusion
Calcium carbonate plays an important role in plastics and rubber manufacturing. While GCC and PCC are primarily used as fillers to reduce cost and improve basic properties, nano calcium carbonate and coated calcium carbonate can also provide reinforcement effects, enhancing the overall performance of polymer materials.
Understanding the differences between these types helps manufacturers choose the most suitable calcium carbonate for specific applications.
