PE+CaCO3 compounding with planetary roller extrusion
PE+CaCO3 filler masterbatch — polyethylene carrier loaded with 40–80% calcium carbonate by weight — is one of the highest-volume speciality compounding applications globally. CaCO3 masterbatch at 50–70% loading is used as a cost-reduction filler for blown film, cast film, raffia and tape, injection-moulded packaging, and geomembrane applications. The masterbatch is let down into processing compounds at 10–30% addition levels, effectively reducing the polyolefin content of the final product by 5–20% by weight.
The compounding challenge is specific: at 50%+ CaCO3 by weight, the compound behaves more like a ceramic paste than a thermoplastic melt. Viscosity is very high, sensitivity to shear is high, and the abrasive nature of CaCO3 accelerates wear in processing equipment. At 70%+ loading, torque demands approach the limits of standard processing equipment, and dispersion quality becomes the binding constraint — agglomerates that survive into the pellet appear as white flecks or stress concentrators in the downstream blown film.
Planetary roller extruders process PE+CaCO3 through repeated thin-film forming contacts between rollers and the grooved barrel, which distributes the CaCO3 through the PE matrix by a rolling-contact wetting mechanism rather than high-shear dispersive mixing. This distinction matters because high shear at very high loading levels breaks CaCO3 particles into fine dust that loses its aspect ratio advantage and contaminates the planetary roller lubrication system. The PLATEX by Takımsan’s rolling-contact mechanism at lower specific shear stress achieves the same dispersion outcome with less filler particle damage and lower equipment wear rates.
For comparison with other filled-compound applications, see WPC compounding and rigid PVC compounding. The PLATEX system overview covers the full processing architecture.
Why planetary outperforms twin-screw for PE+CaCO3
Torque stability at high loading: Co-rotating twin screw extruders at 70%+ CaCO3 generate cyclic torque peaks as CaCO3 agglomerates pass through the intermeshing screw gap. These peaks cause motor torque fluctuations of ±15–25% around the mean, which translates to output rate variability of ±5–10%. The PLATEX’s rolling-contact mechanism distributes load across multiple roller contact zones simultaneously, producing a far smoother torque profile — typically ±3–5% torque variability at 70% CaCO3 loading (estimated). This directly improves pellet uniformity.
Dispersion at extreme loadings: At 75–80% CaCO3, twin screw equipment requires high screw speeds that generate local shear heating, causing PE carrier degradation (yellowing, MFI shift, odour). The PLATEX achieves dispersion through prolonged film-contact wetting at moderate shear, maintaining PE carrier integrity even at 80% CaCO3 loading. PE yellowing index (ASTM E313) from PLATEX processing at 70% CaCO3 is typically ≤ +3 versus ≥ +6 for equivalent twin screw processing (estimated).
Equipment wear: CaCO3 is highly abrasive, particularly uncoated calcite at high loading. PLATEX planetary rollers and barrel liner are manufactured from hardened tool steel and are designed as replacement wear components. Wear rate on PLATEX at 60% coated CaCO3 is estimated at 3,000–5,000 hours between roller set replacement — replacement roller sets are stocked at Takımsan’s İstanbul facility via spare parts.
Energy efficiency: At 500 kg/hr on 60% CaCO3 in LDPE, PLATEX 155 total draw is approximately 60–70 kW. Twin screw equivalent at the same output and loading typically draws 75–90 kW. At 6,000 hours/year, the estimated difference is €9,000–12,000 at €0.10/kWh.
See PLATEX vs twin-screw for a full comparison across shear profiles and filler loading ranges.
Recommended PLATEX models
For PE+CaCO3 masterbatch production at 100–200 kg/hr, the PLATEX 100 (45 kW, PR 100) is the correct specification. At this scale, batch flexibility and rapid formulation changeover matter more than maximum throughput.
At 400–800 kg/hr, the PLATEX 155 (55 kW) is the standard production specification for CaCO3 masterbatch at 50–65% loading. At 600–1,100 kg/hr with 60–70% CaCO3, the PLATEX 165 (75 kW) is appropriate. For loading above 70% or throughput above 800 kg/hr, the PLATEX 185 (90 kW, PR 250 recommended) provides the torque reserve needed for sustained high-viscosity processing.
For formulation development — new CaCO3 grades, surface treatment evaluation, or new PE carrier grades — the PLATEX 80 lab extruder (max 45 kg/hr) provides direct scale-up data to any production PLATEX model.
Run your formulation in our lab
Send a 5–10 kg sample of your PE carrier and CaCO3 filler (specify coating type and surface treatment) to Takımsan’s İstanbul facility. Our team runs it on the PLATEX 80 lab extruder and provide a test report: torque profile, pellet bulk density, CaCO3 dispersion quality assessment (visual and SEM), and process recommendations for scale-up. Contact Takımsan to arrange a sample run.
