Why Particle Size Matters in PVC

When calcium carbonate is incorporated into a PVC compound, the particles must be adequately dispersed throughout the polymer matrix.

Particle size influences several aspects of the formulation:

• Dispersion of the mineral filler
• Surface appearance of the finished PVC product
• Melt processing behavior
• Filler loading capability
• Mechanical properties
• Processing stability

In general, finer particles provide a greater specific surface area. This means that more polymer, processing aid, or surface treatment may be required to effectively wet and disperse the particles.

Therefore, smaller particle size does not automatically mean better performance.

The optimum grade depends on the PVC formulation, processing equipment, required loading level, and final product specification.

D50 and D97 – What Do They Mean?

Two particle-size parameters commonly used in calcium carbonate specifications are D50 and D97.

D50 represents the particle diameter at which 50% of the particles are smaller and 50% are larger.

D97 represents the particle diameter below which approximately 97% of the particles fall.

For PVC manufacturers, looking at both parameters is more informative than considering only one particle-size value.

For example, two calcium carbonate products may have a similar D50 but significantly different D97 values. The second product may contain a larger proportion of coarse particles, which can affect dispersion and surface quality.

Therefore, suppliers should provide a reliable particle-size distribution rather than only stating that a product is "fine calcium carbonate."

Calcium Carbonate for PVC Pipes and Profiles

Rigid PVC pipes and UPVC profiles have different formulation requirements.

For pressure pipes, drainage pipes, electrical conduits, window profiles, and other extrusion products, calcium carbonate selection should be evaluated together with:

• PVC resin type
• Stabilizer system
• Lubricant system
• Impact modifier
• Processing aid
• Filler loading
• Extrusion temperature
• Screw configuration

A calcium carbonate grade that performs well in one formulation may not necessarily provide the same results in another.

Why Consistency Is Critical

For large-volume PVC production, consistency between batches is often more important than achieving an exceptionally fine particle size.

Variations in:

• Particle size distribution
• Moisture
• Whiteness
• CaCO₃ content
• Surface treatment
• Mineral impurities

can change processing behavior and may require adjustments to the formulation.

This is why PVC manufacturers should evaluate calcium carbonate based on both technical specification and batch-to-batch consistency.

Tan Ky Mineral – Vietnam Calcium Carbonate Manufacturer

Tan Ky Mineral is a Vietnam calcium carbonate manufacturer and supplier producing calcium carbonate powder from selected white limestone.

For PVC customers in India, we can discuss calcium carbonate grades based on the customer's actual application rather than recommending one universal specification.

When evaluating a new grade, we recommend comparing:

1. D50 and D97
2. CaCO₃ content
3. Moisture
4. Whiteness
5. Particle-size distribution
6. Surface treatment, where applicable
7. Performance at the customer's actual loading level

This application-based approach helps PVC manufacturers select a calcium carbonate grade that is technically suitable and commercially efficient.

Tan Ky Mineral – Vietnam Calcium Carbonate Manufacturer & Supplier for PVC Applications

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