Anti-scorching Agent PVI (Chemical name: N-cyclohexylthiophthalimide, also known as CTP or PVIP) serves as a core processing additive in the rubber industry. By precisely capturing active vulcanization substances, it delays early cross-linking, providing comprehensive protection for sulfur vulcanization systems.
Here are the five core benefits of PVI that help manufacturers improve quality, increase efficiency, and reduce production losses.
1. Significantly Enhanced Processing Safety
PVI effectively inhibits the scorching phenomenon in various diene rubbers—such as Natural Rubber (NR), Styrene-Butadiene Rubber (SBR), and Nitrile Rubber (NBR)—during mixing, extrusion, and calendering.
- Wider Operation Window: It allows for processing at higher temperatures and faster machine speeds.
- Risk Reduction: By preventing localized overheating, it eliminates scrap caused by premature curing, drastically lowering production risks at the source.
2. Optimized Production Efficiency and Cost
With the robust anti-scorch protection of PVI, manufacturers can revolutionize their workflow.
- Single-Stage Mixing: It enables the transition from traditional two-step mixing to one-step mixing, shortening the mixing cycle by over 30%.
- Energy Savings: This streamlined process reduces energy consumption and equipment wear.
- Injection Molding: For injection vulcanization, PVI allows for higher injection temperatures and shorter curing cycles, significantly boosting equipment capacity while reducing labor and capital input.
3. Strengthened Compound Storage Stability
Adding PVI creates a safety buffer for unvulcanized rubber compounds during storage.
- Shelf Life Extension: It effectively prevents natural vulcanization (bin cure) at room temperature.
- Quality Assurance: It avoids hardening or cross-linking during storage, making it ideal for large-scale production involving long raw material turnover periods and reducing inventory losses.
4. Effective Waste Rubber Recovery
PVI offers a “regenerative” function for compounds that are slightly scorched or lack processing safety.
- Recycling: Through reasonable proportioning, scorched stock can be blended with fresh rubber and reused.
- Green Production: This capability significantly reduces the volume of waste rubber, improves raw material utilization rates, and helps enterprises achieve sustainable, green production goals.
5. Stable Vulcanizate Performance
While PVI powerfully delays scorching, it does not compromise the final quality of the rubber product.
- Physical Properties: It ensures that core indicators—such as tensile strength, elastic modulus, aging resistance, and compression set—remain unaffected.
- Compatibility: It poses no risk of migration or pollution. Aside from a negligible effect on pure white products, it is suitable for the vast majority of rubber product specifications.
Conclusion
In summary, Anti-scorching Agent PVI achieves multiple performance enhancements with a low dosage (0.1-1.5 phr). It is the critical additive for balancing safety, efficiency, and quality in rubber processing. It is widely applicable to the production of tires, hoses, seals, and other sulfur-cured rubber products.
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