CaZn stabilizers (Calcium-Zinc stabilizers) are widely used in modern PVC cable formulations due to their environmental friendliness, regulatory compliance, and excellent long-term performance. They have become the mainstream alternative to traditional lead-based stabilizers in power cables, communication cables, automotive wiring, and building cables.
However, in real production, many manufacturers encounter practical problems when using CaZn stabilizers for the first time or when switching from lead systems. These problems are not caused by the stabilizer itself, but by formulation design, processing conditions, and compatibility issues.
Understanding these common problems helps cable manufacturers optimize formulations, reduce defects, and achieve stable product quality.
1. Insufficient Thermal Stability
One of the most common issues is that PVC compounds show lower thermal stability after switching from lead stabilizers to CaZn systems.
This usually appears as early discoloration, black spots, or material degradation during extrusion. The root cause is that CaZn stabilizers have a different stabilization mechanism and often require a more balanced formulation system.
If the co-stabilizers, antioxidants, and lubricants are not properly matched, the CaZn system may not fully protect PVC under high processing temperatures.
This problem can be solved by using cable-grade CaZn stabilizers and optimizing the additive package rather than simply replacing lead stabilizers at the same dosage.
2. Poor Initial Color and Yellowing
Some manufacturers report that PVC cables show slight yellowing or unstable initial color when using CaZn stabilizers.
This is mainly related to zinc soap activity and insufficient color masking agents. CaZn systems are more sensitive to processing temperature and shear compared with lead systems.
If extrusion temperature is too high or residence time is too long, color stability may decrease.
Optimizing processing conditions and selecting CaZn stabilizers with improved color retention formulas can effectively solve this issue.
3. Plate-Out and Equipment Contamination
Plate-out refers to the accumulation of stabilizer residues on screws, dies, and molds during extrusion.
This problem is more likely to occur if the CaZn stabilizer system has an unbalanced lubricant structure or poor compatibility with other additives.
Plate-out leads to surface defects, unstable output, and increased cleaning frequency, which directly reduces production efficiency.
Using high-quality CaZn stabilizers with optimized internal and external lubrication systems can significantly reduce plate-out problems.
4. Reduced Mechanical Properties
Some cable producers find that after switching to CaZn stabilizers, PVC compounds show lower tensile strength or reduced flexibility.
This is usually caused by plasticizer compatibility issues or insufficient long-term stabilization. CaZn systems interact differently with plasticizers compared with lead systems, so the original formulation may no longer be optimal.
Without proper formulation adjustment, PVC may lose elasticity faster during aging tests.
This issue can be resolved by adjusting plasticizer type, stabilizer dosage, and antioxidant system to maintain mechanical performance.
5. Lower Processing Window
Compared with lead stabilizers, CaZn systems generally have a narrower processing window.
This means that PVC compounds become more sensitive to temperature fluctuations, screw speed, and shear force.
If processing parameters are not well controlled, degradation may occur more easily.
This requires better process control and more stable extrusion conditions, especially for high-speed cable production lines.
6. Incompatibility with Certain Fillers
Another common problem is poor compatibility between CaZn stabilizers and certain inorganic fillers, such as calcium carbonate or recycled materials.
In some formulations, fillers may absorb part of the stabilizer, reducing its effective concentration and leading to insufficient thermal stability.
This problem is more obvious in high-filler or recycled PVC cable compounds.
Using surface-treated fillers and increasing stabilizer efficiency can help maintain performance.
7. Higher Cost Per Unit Compared to Lead Systems
From a procurement perspective, some manufacturers feel that CaZn stabilizers have a higher unit cost than traditional lead stabilizers.
Although CaZn systems often require lower dosage or provide higher added value, the initial material cost may appear higher.
However, when considering environmental compliance, export requirements, and long-term regulatory risks, CaZn stabilizers are usually more cost-effective over the full product lifecycle.
8. Formulation Adjustment Is Often Required
A very common mistake is directly replacing lead stabilizers with CaZn stabilizers without changing the formulation.
This often leads to multiple problems such as poor thermal stability, unstable color, and processing difficulties.
CaZn systems require:
Different lubricant balance
Different antioxidant structure
Different plasticizer compatibility
More precise dosage control
Successful application depends on complete formulation redesign, not simple substitution.
9. Inconsistent Quality Between Suppliers
Not all CaZn stabilizers on the market have the same performance.
Different suppliers use different raw materials, zinc content ratios, and co-stabilizer systems. This leads to inconsistent thermal stability, processing behavior, and aging resistance.
Choosing experienced and specialized CaZn stabilizer suppliers is crucial for stable cable production.
10. Insufficient Long-Term Aging Performance
In some cases, PVC cables perform well in short-term processing but fail in long-term aging tests.
This usually means the stabilizer system lacks sufficient antioxidant or long-term acid scavenging capacity.
For cables with high service life requirements, such as power and automotive cables, long-term aging performance must be validated through accelerated aging tests.
How to Avoid These Problems
Most CaZn stabilizer problems can be avoided by:
Using cable-specific CaZn stabilizers
Optimizing full formulation, not only stabilizer
Controlling processing temperature and shear
Matching stabilizer with plasticizer system
Selecting reliable suppliers with technical support
Conducting thermal and aging performance tests
Conclusion
CaZn stabilizers offer clear advantages for PVC cable production, including environmental safety, regulatory compliance, and long-term sustainability. However, they also require more precise formulation design and process control compared with traditional lead systems.
The most common problems when using CaZn stabilizers in cables include insufficient thermal stability, color issues, plate-out, reduced mechanical properties, and narrower processing windows. These issues are not inherent defects of CaZn stabilizers, but rather formulation and application challenges.
With proper material selection, formulation optimization, and supplier support, CaZn stabilizers can deliver stable processing performance and excellent long-term aging resistance, making them the most reliable choice for modern PVC cable manufacturing.
