High-Efficiency Processing Safety Solution for Rubber Compounds
Product Name: Scorch Retarder PVIP
Chemical Name: N-Cyclohexylthiophthalimide
CAS No.: 17796-82-6
Equivalent to: PVI / CTP
Manufacturer & Supplier:
Qingdao Chengda Huili Import and Export Co., Ltd.
Website: https://ctp-pvi-chem.com
1. Product Overview
PVIP (also known as PVI or CTP) is a high-performance scorch retarder designed for sulfur-vulcanized rubber compounds.
It effectively delays premature vulcanization during mixing, storage, and processing, while maintaining normal cure speed and final physical properties.
PVIP is widely used in:
- Tires
- Rubber hoses
- Conveyor belts
- Industrial rubber goods
- High-temperature extrusion compounds
2. Mechanism of Action (Technical Principle)
PVIP selectively reacts with active accelerators at processing temperatures, temporarily suppressing vulcanization.
- Below 130 °C:
→ Accelerator activity is inhibited → improved scorch safety - Above 150–170 °C (vulcanization stage):
→ PVIP decomposes rapidly → normal curing proceeds
📌 This explains why PVIP provides excellent scorch delay without extending T90 cure time.
3. Typical Technical Data (ASTM / ISO Reference)
| Property | Typical Value | Test Method |
|---|---|---|
| Appearance | Pale yellow to off-white powder | Visual |
| Melting Point | ≥ 140 °C | ASTM D127 |
| Loss on Heating | ≤ 0.5 % | ASTM D5668 |
| Ash Content | ≤ 0.3 % | ASTM D1506 |
| Purity | ≥ 98 % | HPLC |
| Solubility | Insoluble in water | — |
4. Scorch Safety Performance Data
Example: NR + CBS Sulfur Vulcanization System
Test Method: ASTM D5289 (Moving Die Rheometer)
Test Temperature: 125 °C
| Formulation | PVIP Dosage (phr) | Scorch Time T5 (min) | Increase |
|---|---|---|---|
| Control | 0 | 6.5 | — |
| With PVIP | 0.2 | 11.8 | +81 % |
| With PVIP | 0.3 | 15.2 | +134 % |
📊 Key Result:
Significant expansion of processing safety window with minimal effect on cure time (T90 ±5%).
5. Effect on Final Physical Properties
Test Standards:
- Tensile strength: ASTM D412
- Hardness: ASTM D2240
| Property | Without PVIP | With 0.2 phr PVIP | Change |
|---|---|---|---|
| Tensile Strength (MPa) | 22.5 | 22.1 | −1.8 % |
| Elongation at Break (%) | 480 | 475 | −1.0 % |
| Hardness (Shore A) | 65 | 65 | No change |
📌 PVIP does not negatively affect mechanical performance when used at recommended dosage.
6. Application Suitability (Material Compatibility)
| Rubber Type | Suitability | Performance |
|---|---|---|
| NR | ✔✔✔✔✔ | Excellent |
| SBR | ✔✔✔✔✔ | Excellent |
| BR | ✔✔✔✔ | Very good |
| NBR | ✔✔✔✔ | Very good |
| EPDM (Sulfur cured) | ⚠ | Limited |
| Peroxide curing systems | ✖ | Not suitable |
| TPE / TPU | ✖ | Not required |
7. Recommended Dosage
| Accelerator System | PVIP Dosage |
|---|---|
| CBS / TBBS | 0.1 – 0.3 phr |
| MBTS (DM) | 0.2 – 0.4 phr |
| Multi-accelerator systems | ~0.2 phr |
📌 Dosage should be optimized via Mooney Scorch (ASTM D1646) or MDR testing.
8. Processing & Application Benefits (Production Data)
| Production Stage | Improvement After PVIP |
|---|---|
| High-temperature mixing | Scorch risk ↓ 40–60 % |
| Extrusion stability | Line stoppage ↓ ≥30 % |
| Compound storage | Shelf life extended 24–72 h |
| Batch consistency | Significantly improved |
9. Packaging & Storage
- Packaging: 25 kg paper bag / PE inner liner
- Storage: Cool, dry, well-ventilated area
- Shelf Life: 12 months under proper storage
10. Why Choose Qingdao Chengda Huili PVIP?
- Stable purity & consistent scorch performance
- Suitable for export-grade rubber products
- Reliable supply for industrial & tire applications
- Technical support based on real compound data
🌐 Official Website: https://ctp-pvi-chem.com
11. Summary
PVIP (PVI / CTP) is not a universal additive—but it is the most effective scorch retarder for sulfur-vulcanized unsaturated rubber compounds.
When applied correctly, it delivers:
- Strong scorch protection
- Stable curing behavior
- No compromise in final properties