Precision Scorch Control: PVI (CTP) Solutions for High-Performance Hoses & Seals
In the manufacturing of precision rubber goods—specifically hydraulic hoses and automotive seals—”scorch” (premature vulcanization) is the primary enemy of profitability. For high-specification products, even a minor variance in processing stability can lead to high rejection rates and wasted material.
PVI Antiscorching Agent (N-(cyclohexylthio)phthalimide, or CTP) is the industry standard for securing the processing window. It delays the onset of cure without altering the final vulcanization characteristics.
To meet the varying needs of our clients—from traditional open-mill workshops to fully automated extrusion lines—we offer PVI in two distinct forms: Standard Powder and Advanced Granules.
Dual Forms: tailored for Your Production Line
1. PVI Powder: The Cost-Effective Standard
Best for: Open Mill Mixing, Compression Molding, Small-to-Mid Sized Batches.
Our PVI Powder is the classic solution for traditional processing environments.
- Broad Compatibility: Perfectly compatible with Natural Rubber (NR), Nitrile (NBR), and other diene rubbers used in hoses and seals.
- Economic Performance: A small dosage (0.1–0.4 phr) significantly extends scorch safety, neutralizing risks caused by temperature fluctuations in open mills.
- Cost Control: Delivers high performance at a price point that keeps standard industrial seals and hoses competitive.
2. Granular PVI: The Automated, Dust-Free Upgrade
Best for: Automated Weighing Systems, Continuous Extrusion, High-Precision Automotive Parts.
As regulations on factory dust (VOCs) tighten and production speeds increase, Granular PVI is the preferred choice for modern facilities.
- EHS Compliance: The advanced granulation process eliminates airborne dust, protecting worker health and helping facilities pass environmental audits.
- Precision Dosing: The uniform granules flow freely, allowing automated feeders to dose with an accuracy of ±0.01 phr.
- High Dispersion: In internal mixers, granules disperse 30% more efficiently than powder, preventing “specks” in critical surfaces like high-pressure hydraulic hose linings.
- Storage Stability: Resistant to caking and moisture absorption, with a shelf life of over 12 months.
Technical Specifications
Manufactured to strict quality standards to ensure consistent scorch protection.
| Property | PVI Powder | Granular PVI |
| Appearance | White/Gray-white powder | White uniform granules (Dust-free) |
| Active Content | ≥ 96.0% | ≥ 97.0% |
| Initial Melting Point | ≥ 89.0°C | ≥ 89.0°C |
| Heating Loss | ≤ 0.50% | ≤ 0.50% |
| Ash Content | ≤ 0.10% | ≤ 0.10% |
| Toluene Insoluble | ≤ 0.50% | ≤ 0.50% |
| Bulk Density | 0.55–0.65 g/cm³ | 0.65–0.75 g/cm³ |
| Sieve Residue (100 mesh) | ≤ 0.20% | ≤ 0.10% |
Proven Results: Case Studies in Hoses & Seals
Our PVI series is currently in use by major manufacturers to solve specific processing pain points.
Case 1: Automotive Sealing Systems (Precision NBR)
A manufacturer of high-end automotive seals struggled with dimensional instability and scorch defects.
- The Fix: Integrated 0.2 phr PVI Powder into the NBR formula.
- The Result:
- Mooney Scorch Time ($t_{10}$) extended from 4.0 to 7.5 minutes.
- Scorch defect rate dropped from 4.2% to 0.9%.
- Dimensional tolerance pass rate improved to 98.2%.
- The additive did not affect oil resistance or compression set, securing OEM certification.
Case 2: High-Pressure Hydraulic Hoses (Automated Extrusion)
A hose manufacturer using an automated line faced issues with dust pollution and inconsistent dosing, leading to scorch spots on inner liners.
- The Fix: Switched to Granular PVI (0.3 phr) in a Natural Rubber/SBR blend.
- The Result:
- Zero dust pollution in the mixing room.
- Dosing accuracy stabilized at ±0.01 phr.
- Extrusion qualification rate rose from 88% to 97.8%.
- Green compound storage life extended from 10 to 30 days, reducing material waste.
Case 3: General Industrial Hoses (Cost Reduction)
A mid-sized factory using open mills faced high scrap rates due to unstable temperature controls during summer months.
- The Fix: Added 0.4 phr PVI Powder.
- The Result:
- Stabilized the process against temperature spikes.
- Reduced rubber compound waste by 15%.
- Increased overall production efficiency by 20% while maintaining low raw material costs.
Which Form is Right for You?
- Choose Granules if you are running a smart factory, require strict dust control, or manufacture safety-critical automotive parts (EVs, hydraulics).
- Choose Powder if you operate traditional open mills and prioritize cost-performance for general industrial goods.
We provide comprehensive technical support to help you adjust your formula for maximum efficiency.
Contact us today for a free sample and a consultation on optimizing your cure system.