The Technical Role of Calcium Carbonate in uPVC Profiles: Why Precise Dosage Matters

In uPVC profile manufacturing, material formulation determines more than appearance—it defines mechanical strength, weatherability, service life, and processing performance. Among all components, calcium carbonate (CaCO₃) is one of the most influential. At Haitec Profile, we adopt a strictly controlled CaCO₃ dosage to ensure every profile meets global performance standards.

1. CaCO₃ as a Structural Enhancer — Not Just a Filler

When used within an optimal range, calcium carbonate improves rigidity and dimensional stability. However, excessive dosage leads to brittleness, poor impact resistance, and chalking. This makes precise control essential. Typical Industry Range: 8%–18%. High-quality uPVC profile manufacturers generally maintain CaCO₃ within 8–18% depending on product type, climate, and performance requirements.

Haitec Profile maintains a scientifically defined CaCO₃ window to ensure:

Higher modulus of elasticity

Stable profile geometry during extrusion

Controlled shrinkage rate

Improved welding strength

2. Mechanical Performance: Strength, Impact Resistance, Durability

Tensile & Impact Strength

Fine-particle CaCO₃ (1–2 μm) disperses evenly within the polymer matrix, enhancing:

Tensile strength

Notched impact resistance

Load-bearing capability for large frames

However, when CaCO₃ exceeds 20%, these properties begin to decline sharply. That is why Haitec enforces strict upper limits in its production protocols.

Screw Holding Force

Optimized CaCO₃ content ensures excellent screw retention for hardware installation—critical for casement and sliding systems.

3. Surface Quality and Processability

Fine CaCO₃ Improves:

Surface gloss

Smoothness

Weldability

Color uniformity

Haitec uses high-purity CaCO₃ with controlled particle distribution, preventing:

Surface chalking

Exposed particles after weathering

Uneven weld lines

Our surface roughness (Ra) remains consistently within ≤0.8 μm, ensuring premium appearance and sealing performance.

4. Thermal and Weathering Performance

Correct CaCO₃ dosage enhances thermal stability while maintaining low thermal conductivity—an essential attribute of uPVC.

Excessive CaCO₃, however, increases:

Thermal expansion

UV-induced brittleness

Powdering and early aging

Haitec profiles undergo repeated UV, humidity, and thermal cycling tests to guarantee long-term performance in extreme climates.

5. Haitec's Material Engineering Standard

To deliver globally reliable uPVC profiles, Haitec ensures:

Controlled CaCO₃ dosage (strictly within engineered limits)

High whiteness, low-impurity CaCO₃

Uniform dispersion enabled by high-torque twin-screw extrusion

Compliance with ISO 9001, CE, and region-specific performance standards

This results in:

Balanced mechanical strength

Long-term weather resistance

Stable extrusion performance

Higher product lifespan in harsh environments

Conclusion: Precision Formulation Defines True Quality Calcium carbonate plays a fundamental role in uPVC profile engineering, but only when used in the correct structure and dosage. Haitec Profile’s strict control of CaCO₃ ensures every product achieves the required balance of strength, durability, thermal efficiency, and long-term stability—making our profiles trusted worldwide.