N-(cyclohexylthio)phthalimide (PVI/CTP): The Standard for Scorch Control
Dual-Form Solutions for Traditional & Automated Rubber Processing
In rubber vulcanization, “scorch” (premature curing) is the primary bottleneck preventing higher production speeds and lower scrap rates. N-(cyclohexylthio)phthalimide—widely known as PVI or CTP—is the industry’s most effective pre-vulcanization inhibitor.
By chemically intercepting sulfur-active free radicals, PVI provides a precise “safety window” during mixing, calendering, and extrusion. It delays the onset of cure without altering the final vulcanization rate or the physical properties of the finished product.
Whether you operate a traditional open mill or a fully automated smart factory, our Powder and Granular grades offer the specific handling characteristics your process requires.
Which Form Fits Your Production Line?
We offer two distinct physical forms to match your equipment and Environmental, Health, and Safety (EHS) goals.
1. PVI Powder: The Economic Standard
Best for: Open Mills, Small Batch Mixing, Cost-Sensitive Applications.
Our PVI Powder is the classic choice for general rubber goods. It is a white/gray-white crystalline powder designed for rapid integration.
- Universal Compatibility: Excellent solubility in Natural Rubber (NR), SBR, NBR, and CR.
- Cost-Effective: Requires only low dosages (0.1–0.4 phr) to stabilize processing temperatures.
- Ease of Use: Ideal for manual weighing and open mill mixing where high-tech feeding systems are not required.
2. Granular PVI: The Dust-Free Upgrade
Best for: Tire Manufacturing, Automated Dosing, Precision Seals, Clean-Room Standards.
As regulations on factory dust (VOCs) tighten, Granular PVI is becoming the standard for high-end manufacturing. Produced via an advanced wet-granulation process (binder-free), these granules solve the “dust problem” entirely.
- EHS Compliance: Eliminates airborne dust, protecting worker health and helping facilities pass environmental inspections.
- Precision Dosing: The free-flowing granules allow automated feeders to achieve accuracy within ±0.01 phr.
- Superior Dispersion: In internal mixers, granules break down and disperse 30% more efficiently than powder, preventing “white spots” in critical components like tire sidewalls.
- Storage Stability: Resistant to caking and moisture absorption, with a shelf life exceeding 12 months.
Technical Specifications (GB/T 24801-2019)
Our product is manufactured under strict quality control systems to ensure consistent purity and performance.
| Property | PVI Powder | Granular PVI |
| Appearance | White/Gray-white powder | White uniform granules |
| Purity (HPLC) | ≥ 96.0% | ≥ 97.0% |
| Initial Melting Point | ≥ 89.0°C | ≥ 89.0°C |
| Heating Loss (70°C) | ≤ 0.50% | ≤ 0.30% |
| Ash Content | ≤ 0.10% | ≤ 0.10% |
| Toluene Insoluble | ≤ 0.50% | ≤ 0.50% |
| Sieve Residue (100 mesh) | ≤ 0.20% | ≤ 0.10% |
Chemical Data
- CAS Number: 17796-82-6
- Molecular Formula: $C_{14}H_{15}NO_{2}S$
- Solubility: Soluble in acetone, benzene, toluene; insoluble in water.
Proven Performance: Industrial Case Studies
Our PVI/CTP is currently driving efficiency in major rubber sectors. Here is how our clients are using it:
1. Radial Tire Manufacturing (Granular Application)
A major tire producer utilized our Granular PVI (0.3 phr) in their tread compound (NR/BR blend) to combat scorch during high-speed mixing.
- Result: Mooney Scorch Time ($t_{10}$ at 130°C) extended from 4.2 to 7.8 minutes.
- Impact: Scorch waste reduced by 18%; automated feeding efficiency improved by 25%.
- Bonus: Improved adhesion between the rubber and brass-coated steel cords when used with sulfenamide accelerators.
2. Precision Oil Seals (Powder Application)
A manufacturer of NBR seals for heavy machinery faced high rejection rates due to dimensional variations caused by pre-curing.
- Result: Adding 0.2 phr PVI Powder extended the processing safety window significantly.
- Impact: Dimensional tolerance pass rate increased from 91.5% to 98.2%.
- Quality: Zero impact on oil resistance or thermal stability properties.
3. Industrial Hoses (Cost Efficiency)
A hose manufacturer using open mills struggled with temperature fluctuations in summer, leading to burnt stock.
- Result: A dosage of 0.4 phr PVI Powder stabilized the compound against heat history.
- Impact: Production efficiency rose by 20%, and raw material waste dropped by 15%.
Why Partner With Us?
The global market is shifting. While Powder PVI remains the cost-leader for traditional goods, Granular PVI is essential for the future of green, smart manufacturing. We provide both, ensuring you have the right material for your specific machinery and budget.
Ready to secure your processing window?
Contact our technical team today for a free sample or a consultation on dosage optimization for your specific rubber grade.