Filler Masterbatch (Calpet) & Calcium Carbonate for Plastics in Indonesia: A Buyer's Guide

In short: Filler masterbatch — known in Indonesia as calpet — is a pellet containing roughly 70–85% calcium carbonate (CaCO₃) that is blended into resin to lower cost while adding stiffness and whiteness. In woven sacks, converters typically load 5–30% calpet (up to ~40% for coarse tape). Because calpet costs far below virgin resin, replacing part of the resin lowers raw-material cost — though the net saving is smaller than the share replaced, and only if particle size, whiteness, and loading are chosen correctly. This guide explains how to pick the right grade for your application.

Calpet is the Indonesian industry term for calcium filler masterbatch — from "calcium pellet". It is a plastic granule containing:

• Calcium carbonate (CaCO₃) — typically 70–85% by weight. This is the mineral filler that replaces part of the resin.
• Carrier resin — PP or PE, which binds the CaCO₃ powder into a pellet that feeds into the machine like ordinary resin.
• Additives — around 2–3%: PE wax and stearic acid (a coating/lubricant) for dispersion and processing.

Converters use calpet as pellets (rather than loose CaCO₃ powder) because pellets are easy to dose, blend evenly, and are dust-free on the production floor.

CaCO₃ content varies by application. Film grades actually run lower CaCO₃ (more carrier) so thin film does not tear easily; woven-sack and injection grades are usually higher, 80–85%. (The overall commercial range can be as wide as 60–90% depending on grade.)

Three terms that are often confused:

Bottom line: filler masterbatch for plastics uses GCC — bulk cost-filling is its job. PCC is not "better"; it is for a different purpose (specialty/reinforcement). For an Indonesian converter looking to lower cost on sacks, film, or pipe, the path is GCC — as calpet (if you don't have your own compounding line) or as GCC powder (if you do).

For white or light products — white packaging film, sheet, household goods — the whiteness of the CaCO₃ determines the final appearance and how much expensive white pigment you can save.

Two technical points matter:

1. Whiteness is not the same as brightness. Brightness (the paper-industry standard ISO 2470) measures reflectance at a single wavelength of about 457 nm; whiteness measures reflectance across the full visible spectrum — closer to what the eye judges. A good spec sheet lists both as separate figures. When comparing grades, make sure you compare the same measurement basis.
2. Practical tiers: ≥90% is the quality floor; ≥95% whiteness is common for masterbatch grade; high-quality natural GCC (e.g. from certain marble deposits) reaches 97–99%.

Titanium dioxide (TiO₂) substitution: TiO₂ is a whitening pigment far more expensive than CaCO₃. High-whiteness CaCO₃ does not replace TiO₂ entirely (TiO₂ gives opacity that CaCO₃ does not), but a high-whiteness grade lets you cut part of the TiO₂ in many white applications — a real source of cost saving.

Supply position: Indonesia's domestic GCC is generally available at mid-level fineness and whiteness. For the very fine + high-whiteness grade (approaching 98%, coated) needed for white film and premium masterbatch, imported premium grade fills a gap domestic production does not yet serve.

Fineness is usually given as D50 (microns) — the median particle size. "Mesh" (e.g. 800, 1250, 2000) is often used as a marketing label, but below ~400 mesh physical sieving no longer applies, so treat mesh figures as an indication of fineness, not an exact size. For precision, look at D50 in microns.

On dispersion (two levers often merged by mistake): finer particles give a smoother surface and thinner-gauge capability — but they also cost more and demand more wax/coating. Adequate coating is what makes a fine grade actually disperse well; without coating, fine grades agglomerate more easily. So fineness and coating are two separate things — choose both to suit the application, not "as fine as possible." Coarse particles / grit cause film tears and screen blockage.

Coated = the CaCO₃ surface is treated with stearic acid (around 1% for fine GCC, rising to 2–3% for ultrafine grades — the dose tracks particle surface area, not a fixed number). Coating makes the surface organophilic and so more compatible with PP/PE: better dispersion, lower moisture pickup, less agglomeration. Uncoated is cheaper and adequate for low loadings / non-critical applications. For thin film, high loadings, or products that demand a smooth surface, coated is generally worth the cost. (A detailed guide on when to choose which: see our coated vs uncoated article.)

This is the most commonly misunderstood figure. Distinguish two things:

• CaCO₃ content inside the calpet: ~70–85%.
• Loading of calpet into resin: how much calpet you blend into virgin resin at your machine.

Typical loadings (as a percentage of masterbatch, not CaCO₃):

High loadings (approaching 40%) demand a suitable resin MFI and draw ratio — test on your own line before raising the load.

Because calpet is ~80% CaCO₃, a 25% masterbatch load means only ~20% actual CaCO₃ in the finished product. Always state which basis you mean when talking to a supplier.

Cost logic (illustrative): suppose calpet costs about half the price of virgin resin per kilogram. At 25% loading, raw-material cost falls by about 12% (0.25 × 50%). But remember: because calpet is only ~80% CaCO₃, part of "the 25% you replaced" is still resin (the carrier) — so the real saving is smaller than simply "replacing 25% of the resin," and its size depends on the price spread between calpet and resin (if the spread narrows, the saving shrinks). The real saving also only materialises if tensile strength, dispersion, and surface quality stay within acceptable limits — loading too much to save money can raise costs through product rejects and customer complaints. (How to calculate the saving per scenario: see our loading & cost-saving article.)

A fair question — and the answer is not simply "yes." CaCO₃ raises stiffness (modulus) and lowers cost; whether it makes a product brittle or tougher depends on loading, fineness, dispersion, and coating:

• Excessive loading, poor dispersion, or particles that are too coarse → stress concentration and crack-initiation points → impact strength falls, the product turns brittle.
• A fine, well-coated grade at the right loading → can maintain impact toughness within acceptable limits.

So "filler makes plastic brittle" is only true if the grade or loading is wrong. With the right grade and loading, this is manageable. (A discussion of the mechanism and how to avoid it: see our article on filler and brittleness.)

Vietnam is a leading source of premium GCC (coated, high-whiteness) entering Southeast Asia. To import into Indonesia:

• Tariff (ATIGA): Vietnam-origin GCC and filler masterbatch can qualify for a 0% preferential tariff under ATIGA (HS 2836.50.90 for GCC powder; HS 3824.99.99 for filler masterbatch) — provided the rules of origin are met and a Form D certificate of origin is supplied. (Form D is for intra-ASEAN goods; do not confuse it with Form E, which is for China-origin goods under ACFTA — relevant if you also import resin from China.) Without Form D, the MFN rate applies. Always confirm the current HS code and rate via INSW (insw.go.id) and your customs broker (PPJK) before contracting.
• Why one import partner simplifies things: a converter importing resin from China (Form E) and filler from Vietnam (Form D) manages two certificate-of-origin regimes at once — one partner handling both removes a point of customs error.
• HS classification: filler masterbatch is generally classified as a chemical preparation under HS 3824.99, not under the PP resin heading (3902). This matters: some PP imports (heading 3902, e.g. PP homopolymer and PP block copolymer) currently carry anti-dumping duty in Indonesia for certain origins — so a PP-carrier filler masterbatch wrongly classified under 3902 could be charged a duty it should not. Confirm the correct classification (3824.99) with your PPJK; verify the current code on INSW.
• Anti-dumping: as of June 2026, no Indonesian anti-dumping/safeguard measure was identified on calcium carbonate or filler masterbatch itself. For comparison, India imposed anti-dumping duty of up to USD 75/MT on Vietnam-origin filler masterbatch (Notification 37/2025-Customs (ADD), HS 3824.99, 24 December 2025) — Indonesia is not known to have a similar measure. Confirm current status via KADI (kadi.kemendag.go.id) before committing.
• SNI: some product categories require standards conformity; verify with your PPJK for your specific application.

For ACFTA and Form E context (China-origin resin), see the ACFTA & Form E guide for Indonesia.

The parameters that determine fit:

• CaCO₃ purity (%) — higher means fewer impurities.
• Whiteness (%) — make sure the measurement basis (whiteness vs brightness) is consistent when comparing.
• Particle size (D50, µm) — match to the application (see table above).
• Coating (coated/uncoated) and stearic-acid level.
• Oil absorption — affects how much you can load before flow suffers.
• Top cut / largest particle — coarse particles are the main cause of film tears.

The CoA-versus-TDS methodology for spotting an off-spec lot applies to filler as it does to resin: compare the lot's certificate of analysis against the grade's technical data sheet before the container ships.

The main considerations, beyond price:

• Lot-to-lot consistency — stable whiteness, D50, and purity from shipment to shipment.
• Carrier compatibility — the calpet carrier (PP vs PE) suits your resin and process.
• Technical support — a supplier who can help match grade to application and resolve dispersion problems.
• Documentation — per-lot CoA, Form D for Vietnam origin, SNI conformity where relevant.
• Supplier consolidation. Handling a mineral supplier separately from a resin supplier means two relationships, two payment terms, and two FX exposures; one partner for both simplifies the paperwork (see the Form D + Form E point above).

Kantor Materials supplies both — China-origin resin and premium GCC/filler we source directly from Vietnam — handling sourcing, quality, and documentation as one relationship. For more technical needs (engineering compounds or specialty grades), the same sourcing channel applies.

What is calpet?

Calpet is the Indonesian industry term for calcium filler masterbatch — pellets containing a high proportion of calcium carbonate (CaCO₃) blended into plastic resin (PP or PE) to lower raw-material cost while adding stiffness and whiteness. The name comes from "calcium pellet".

How much CaCO₃ is inside filler masterbatch?

Typically 70–85% by weight, with the rest carrier resin plus 2–3% additives such as wax and stearic acid. Film grades usually run lower CaCO₃ (more carrier, so thin film does not tear); woven-sack and injection grades can reach 80–85%. The CaCO₃ content inside the calpet is different from the percentage of calpet you load into resin.

How much calpet do you load into resin?

It depends on the application. PP woven sacks are typically 5–30% (around 15% or less for fine denier; up to ~40% for coarse tape). PE blown film is 5–20%. Injection is 10–30%. These figures are the masterbatch percentage of the final blend — not the CaCO₃ percentage. Because calpet is ~80% CaCO₃, a 25% load means only ~20% actual CaCO₃ in the product.

What is the difference between coated and uncoated calcium carbonate?

Coated means the particle surface is treated with stearic acid (around 1% for fine GCC, higher for ultrafine) so it becomes organophilic — easier to disperse in PP/PE, absorbs less moisture, less prone to agglomeration. Uncoated is cheaper and adequate for low-loading or non-critical applications. For thin film and high loadings, coated is generally better.

What is the import duty on calcium carbonate from Vietnam into Indonesia?

Under ATIGA, the preferential tariff for Vietnam-origin GCC and filler masterbatch is 0% — provided the rules of origin are met and a Form D certificate of origin is supplied (not Form E; Form E is for China-origin goods under ACFTA). Without Form D, the MFN rate applies. Confirm the current HS code and rate via INSW and your PPJK.

Does Indonesia produce its own calcium carbonate?

Yes — there are domestic limestone-based GCC producers, but domestic supply is generally at mid-level fineness and whiteness. For the very fine, high-whiteness premium grade (approaching 98% whiteness, coated) needed for white film and quality masterbatch, imported premium grade remains the option.

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Have a specific filler or resin requirement? Tell us — product type, application, the whiteness/mesh you need, and volume — and our team will respond with a matching grade (including high-whiteness coated grade), an indicative CFR price, and documentation.

See also: Indonesia Plastics Industry & Polymer Demand 2026 · Importing Polymers from China to Indonesia · ACFTA & Form E Guide for Indonesia.