[Technical Workshop] Troubleshooting Common PVC Product Defects: From "Fish Eyes" to Yellowing
Expert Solutions for PVC Processing Challenges
PVC processing is a systematic engineering of "formulation + process." Any single issue in the production chain can lead to defective products. This article focuses on the most common problems and their solutions.
Problem 1: "Fish Eyes"
Phenomenon: Small, fish-eye-like particles appear on the product surface that haven't been uniformly plasticized.
Root Causes:
- Processing temperature too low
- Insufficient material mixing
- Poor plasticizer absorption capability of the resin itself
Solutions:
- Increase processing temperature appropriately
- Optimize mixing process and extend mixing time
- Choose PVC grades with better plasticizer absorption (such as SG-5)
Problem 2: Yellowing/Degradation
Phenomenon: Products turn yellow, darken, or even become brittle during processing or use.
Root Causes:
- Processing temperature too high or residence time too long, causing PVC thermal decomposition
- Insufficient heat stabilizer dosage or inappropriate selection
Solutions:
- Reduce processing temperature or increase screw speed to minimize residence time
- Check and increase heat stabilizer dosage
- Ensure use of high-quality, thermally stable PVC resin
Problem 3: Product Brittleness
Phenomenon: Low impact strength of finished products, prone to cracking.
Root Causes:
- Over-plasticization
- Insufficient plasticizer or impact modifier dosage
- Excessive filler (such as calcium carbonate) content
Solutions:
- Optimize process to avoid excessive shear
- Adjust formulation by increasing plasticizer or impact modifier ratio
- Reduce filler content or use coupling agents for surface treatment
Conclusion: Quality Raw Materials Are Half the Success
Choosing a PVC resin with low impurities, excellent thermal stability, and uniform particle size is the foundation for avoiding the above problems. At SuDao Chemical, we provide high-quality PVC resins that meet the most demanding processing requirements.