Table of Contents

Why Processing PVC is Different from Other Plastics Calcium Carbonate in PVC: The Good, The Bad, and The Gritty CPE: The Secret Weapon for Balanced PVC-CaCO₃ Formulations Pairing CPE with CaCO₃: A Match Made for UPVC Pipes, Profiles, and More Choosing the Right Ingredients: A Quick Guide Conclusion

Overview

When you’re working with PVC, you know it’s not just another plastic. Its quirks—like particulate flow and stubborn heat management—make processing a puzzle. Add calcium carbonate (CaCO₃) to the mix, and things get even trickier. But what if there was a way to balance cost, performance, and processing ease? Enter chlorinated polyethylene (CPE)—a game-changer that complements CaCO₃ in PVC formulations. Let’s dive into how CPE bridges the gap between challenges and solutions.

Why Processing PVC is Different from Other Plastics

Think of melting PVC like trying to melt a bag of marbles instead of butter. While butter melts smoothly, PVC behaves more like tiny grains (90-250 µm in size) that need to break down into even smaller particles (about 1 µm) to blend properly.

or PVC to form a strong and durable product, these tiny particles must fuse together. This fusion happens when small crystal-like structures in the PVC melt at temperatures between 105-250°C, allowing their molecular chains to tangle and create a solid structure.

The challenge is that PVC doesn’t conduct heat well. This poor heat flow leads to uneven heating and hot spots, so processors rely on mechanical force (shear stress) to generate the extra heat needed for proper fusion. If the grains don’t fuse completely, the final product may have weak points, making it more likely to fail.

Calcium Carbonate in PVC: The Good, The Bad, and The Gritty

CaCO₃ is a staple in PVC formulations. It’s cost-effective, improves processing, and can enhance certain properties—if used wisely

The Good:

• Fine particles (~1 µm) boost impact strength and surface finish.
• Acts as a “friction agent,” generating heat to aid PVC fusion.
• Coated CaCO₃ (e.g., stearic acid) reduces metal adhesion in UPVC, ideal for extrusion.

The Bad:

• Larger particles (>1 µm) disrupt PVC chain entanglement, weakening tensile strength.
• Overloading CaCO₃ (high phr) risks brittle products.
• Dolomitic CaCO₃ (with MgCO₃) can wear down equipment faster.

The Gritty:

CaCO₃ doesn’t melt. It relies on friction to contribute heat—a double-edged sword. Too much friction? You risk degradation. Too little? Fusion stalls.

CPE: The Secret Weapon for Balanced PVC-CaCO₃ Formulations

This is where chlorinated polyethylene (CPE) shines. As a versatile impact modifier, CPE tackles the shortcomings of CaCO₃ while amplifying its benefits. Here’s how:

A. Better Fusion, Fewer Headaches

• CPE’s flexible polymer chains act as a “bridge” between PVC and CaCO₃ particles.
•  During processing, CPE:
  • Enhances melt elasticity, helping PVC grains fuse evenly.
  • Reduces the risk of incomplete fusion caused by CaCO₃’s interference.
  • Lowers processing temperatures by improving heat distribution—key for PVC’s poor thermal conductivity.

B. Impact Strength That Lasts

• CaCO₃ can make PVC rigid but brittle. CPE counters this by:
• Absorbing and dispersing energy (like a shock absorber).
• Maintaining ductility even at high CaCO₃ loadings.

C. Processing Made Smoother

• CPE’s lubricating properties:
• Reduce melt viscosity, easing flow in twin-screw extruders.
• Minimize shear stress, lowering the risk of thermal degradation.

Pairing CPE with CaCO₃:

A Match Made for UPVC Pipes, Profiles, and More

Let’s get practical. Suppose you’re formulating UPVC for window profiles. You need:

• Cost savings: High CaCO₃ loading (20-30 phr).
• Surface smoothness: Fine GCC (~1 µm).
• Durability: Impact resistance against weather and stress.>

Enter Suntek CPE:

• Compatible with coated CaCO₃ to reduce friction and extruder wear.
• Compensates for CaCO₃’s rigidity, ensuring profiles withstand impact without cracking.
• Works synergistically with GCC’s bulk density to maximize extruder output.

Pro Tip: For abrasive dolomitic CaCO₃, pair with a higher CPE grade to offset equipment wear and maintain product integrity.

Choosing the Right Ingredients: A Quick Guide

CaCO₃ Type:

• GCC: Cost-effective, high bulk density. Ideal for UPVC with Suntek CPE.
• PCC: Lower density, better for niche applications.

Particle Size:

Aim for ~1 µm GCC for UPVC. Avoid “chunky” fillers.

CPE Selection:

Suntek offers tailored CPE grades for high CaCO₃ formulations.

Conclusion

Smarter PVC Processing Starts with Suntek CPE

In the dance of PVC, CaCO₃, and additives, CPE is the partner that keeps everything in rhythm. It turns compromises (cost vs. performance) into synergies, ensuring your products are tough, smooth, and cost-efficient.

At Suntek, we’ve spent years perfecting CPE formulations that meet the real-world demands of PVC processors. Whether you’re extruding pipes, molding profiles, or pushing the limits of filler loading, our CPE solutions are designed to deliver.

Ready to optimize your PVC-CaCO₃ mix? Let’s talk about how Suntek CPE can elevate your next product.