Choosing Calcium Carbonate for Masterbatch and PVC: Coated vs Uncoated, Particle Size and Buying Checklist

If you produce filler masterbatch, compounds or PVC parts, the useful question is not simply “which mesh should I buy?” The right grade must deliver acceptable dispersion, appearance and production economics in your own resin and line. This guide explains which specifications to request, when to evaluate coated calcium carbonate and how to test a sample before a bulk order.

Quick answer: coated or uncoated calcium carbonate?

In polyethylene and polypropylene formulations, surface-treated grades may help disperse the mineral filler. Coating alone, however, does not guarantee the performance of the finished product. For PVC, the choice also depends on formulation, mixing conditions and part requirements. Compare samples under equivalent process conditions and decide on product quality and total cost. For the surface-treatment mechanism, see our guide to coated calcium carbonate.

Define the finished product before choosing a grade

A thin film, a PVC pipe and an injection-moulded part have different requirements. Record the carrier resin, target filler loading, product thickness and colour, process, temperatures and customer acceptance criteria. A supplier can then suggest a grade for testing. A visually attractive powder can still be unsuitable for the application.

Seven specifications to check when buying calcium carbonate for masterbatch and PVC

1. Particle size: mesh alone is not enough

Mesh is a common market label, but the particle-size distribution is more useful for technical selection. For sensitive applications, ask for D50 (median particle size), D97 or D98 (the upper size of most particles), and the test method. Oversized particles or agglomerates can create problems in film, part surfaces or line filters. A direct mesh-to-micron conversion is not a reliable way to compare suppliers without a consistent measurement method.

2. Surface treatment and resin compatibility

For coated grades, the treatment agent and coating consistency matter. In non-polar PE and PP, test a surface-treated sample alongside an uncoated one. If a special treatment is claimed, request its identity and supporting test data. Coatings from different suppliers are not interchangeable across all applications.

3. Brightness and impurities

For white masterbatch and colour-sensitive products, check brightness, colour tone and relevant impurities such as iron, together with the test methods. A single brightness value cannot predict the colour of a formulation containing resin, pigments and additives. Compare the finished article against your reference sample.

4. Moisture and storage

Powder moisture and storage conditions may affect feeding, mixing and the finished product. Specify moisture content, measurement method, packaging and warehouse conditions. Bags or jumbo bags must match your transport route and unloading equipment.

5. Consistency between batches

One sample is not enough for continuous production. Ask for the analysis of the actual shipment, batch identification, agreed tolerances and a process for handling deviations. Record measurable acceptance criteria in recurring supply agreements.

6. Behaviour on the line

Compare dispersion, filter pressure, feeding stability, surface appearance and relevant mechanical properties in production trials. Results depend on resin, additives, loading and equipment. Do not assume that benefits reported for another grade will apply to yours without testing.

7. Total cost, not only the price per kilogram

Consider freight, material loss, energy use, scrap rate and the amount of saleable product alongside powder price. A cheaper grade is not necessarily more economical if it causes downtime or rejects. Final price also depends on grade, order volume, packaging and delivery location.

Starting points for different applications

• PE and PP filler masterbatch: define carrier resin, target loading, particle size and whether a coated grade should be tested. Compare dispersion and processing.
• Film and packaging: coarse particles, agglomeration and surface defects can matter more. Check D97/D98, filter behaviour and film defects in a production trial.
• Injection-moulded parts: compare surface, colour, impact performance and dimensional behaviour with a reference part. A grade suitable for film is not automatically suitable for moulding.
• PVC pipe and profile: evaluate particle size, moisture, processing and part properties in your real formulation. Choose coated or uncoated material by trial.

What documents and samples should the supplier provide?

Request proposals using one consistent technical specification:

• Product name and form: micronized powder, coated or uncoated;
• Particle-size range and, when available, D50 and D97/D98 with the test method;
• Chemical analysis, brightness and moisture with method and test date;
• Treatment type and level if a coated grade is proposed;
• A representative sample, shipment certificate of analysis and batch number;
• Minimum order quantity, recurring supply capacity, packaging, origin and delivery destination.

A three-step sample trial before bulk purchasing

Step 1 — technical screening: review datasheets and samples for particle size, moisture, brightness and consistency. Step 2 — line trial: run candidates with the same formulation, equipment and processing conditions. Record predefined metrics such as filter pressure, surface quality and scrap. Step 3 — purchasing decision: compare saleable output and total cost, then record acceptance limits in the order.

Grades to review from Alvand Giti

Alvand Giti lists micronized calcium carbonate, mesh 230–2000, for evaluating applications including masterbatch and PVC. You can also review the industrial calcium carbonate product page and 0.2–1 mm granular grade. Do not substitute coarse granules for masterbatch powder without a technical review. Confirm availability of a coated grade, shipment analysis and pricing when requesting a quotation.

Frequently asked questions

Which mesh should I use for masterbatch?

There is no universal mesh number. Specify the finished application, resin, product thickness and tolerance for coarse particles. For sensitive products, compare D50 and D97/D98 as well.

Is coated calcium carbonate always better?

No. Surface treatment can support dispersion in some polymer formulations, but its effect depends on coating chemistry, particle size and processing. A side-by-side trial is the basis for choosing.

Does mesh 230–2000 mean every listed grade suits PVC and masterbatch?

No. It is a range of grades to investigate. Check the shipment analysis and test each proposed grade in the intended finished product.

What information is needed for an accurate quotation?

Provide the finished product, resin, target grade or size, coated or uncoated preference, monthly volume, packaging and delivery city. Share a target specification or reference sample when available.

Technical references and quotation

This guide follows the approach used in international technical literature for grade selection, particle-size control and trials in the real formulation. Specifications of the products cited below are not specifications of Alvand Giti products. Further reading: Omya on highly filled masterbatch and an example datasheet reporting D50, upper particle size and moisture.

To request a grade proposal for your line, send your application and order volume through the Alvand Giti contact page or call +98 918 305 2513. Make the final selection after reviewing the actual shipment analysis and testing a sample.