🧩 IIR – Butyl Rubber
(A high-density synthetic elastomer known for its extremely low permeability to gases and fluids. It features excellent resistance to aging, ozone, and chemicals, remaining elastic at temperatures as low as –50 °C.)
🔹 What is IIR
IIR is the “sealing champion.” At ReplastMD, we treat this material as the ultimate gas barrier. Its compact molecular chains provide excellent insulation against both gases and vibrations. It is the preferred choice for tire inner liners, vacuum gaskets, and brake membranes where maintaining pressure is critical. While it excels in contact with air and steam, it is not suitable for contact with mineral oils.
🔧 Composition & Properties
- Polymer Base: Isobutylene-isoprene copolymer.
- Density: ~ 0.92 – 0.94 g/cm³.
- Operating Range: -50 °C to +100 °C.
- Gas Permeability: Extremely low (best in class).
- Visuals: Soft, smooth, dense black rubber; matte finish.
🚗 Where it is used in the automotive industry
| Component | Example parts | Observations |
| Tire Inner Liners | All Manufacturers | Excellent air retention properties |
| Vacuum Gaskets | VW, Toyota, Renault | No pressure loss in vacuum systems |
| Brake Membranes | Hyundai, Peugeot | Flexibility combined with gas isolation |
| Acoustic Sealing | BMW, Mercedes | High-density sound and thermal insulation |
🔧 Welding and Bonding Methods
| Method | Optimal Temp | Observations |
| Chemical Bonding | ✅ Recommended | Universal rubber adhesive (Loctite® 406 + 770 primer) |
| Local Vulcanization | ✅ Ideal | Possible with butyl-based repair compounds |
| Hot Air | ✅ 100 – 130 °C | Easy to weld via superficial reactivation |
💡 ReplastMD Recommendation: Repair using professional rubber adhesives and hot air at ~120 °C for activation. IIR is the ideal choice for parts requiring absolute airtightness and acoustic insulation, but it should never be used in contact with fuels or oils.