| Property | Value |
|---|---|
| Temperature range | -50 °C to +120 °C |
| Hardness | 40–80 Shore A |
| Best at | Gas impermeability, damping, steam, acids and bases |
| Contains fluorine | No |
Impermeability is the whole argument
Butyl is roughly ten times less permeable to air than natural rubber. For a bladder, a diaphragm, or a tank liner, that is not an incremental improvement, it is the difference between a part that holds pressure for years and one that needs topping up. This is the single reason butyl is specified, and no other general-purpose family comes close to it.
The same structure makes it a genuinely good damping material. Butyl has low resilience, which is a weakness in a mount that must return energy and a strength in one that must absorb it. Vibration isolators for sensitive equipment often use butyl for exactly the reason natural rubber is rejected for them.
How we compound and test it
Butyl cures slowly and it is sensitive to contamination from sulfur-cured compounds run before it, which is a real risk on a shared mixing floor. Run sequencing and documented cleaning between blocks is how we manage that, and it is why we can show evidence that the batch you bought was not compromised by the batch before it.
Halobutyls, chlorobutyl and bromobutyl, cure faster and co-cure with other diene rubbers, which matters when butyl has to bond to a different compound or to metal. We select between regular and halogenated butyl on what the part has to stick to.
The two mistakes buyers make
The first is putting butyl anywhere near petroleum oil. It swells badly. A bladder that is perfect for compressed air is the wrong part for a hydraulic accumulator, and the two look identical on a drawing.
The second is expecting resilience. Buyers sometimes specify butyl for a mount because it is weather-resistant and then are surprised that the part feels dead. That deadness is the damping, and it is not a defect. If the part needs to spring back, the family is wrong.
Typical uses
- Pressure tank bladders and bags
- Diaphragms and vapour barriers
- Tank and pipe linings for acids and bases
- Steam service seals and gaskets
- Damping mounts for sensitive equipment