IIR - synthetic rubber with excellent chemical resistance
What is butyl rubber (IIR)?
Butyl rubber (IIR, Isobutene Isoprene Rubber) is a synthetic rubber that is characterised primarily by its low gas permeability and very good chemical resistance. It is produced by copolymerising isobutylene with small amounts of isoprene. The low isoprene content enables vulcanisation, while the high isobutylene content is responsible for the dense, saturated polymer structure.
These properties make IIR particularly suitable for the production of Moulded rubber parts, where impermeability, weather resistance and chemical resistance are paramount, e.g. for seals, membranes or closures.
Also in rubber compounds such as Metal composite parts butyl rubber is used, especially when a reliable seal or barrier function is required within a composite material. Here, adhesion to neighbouring materials and a reliable connection are decisive quality features.
What are the properties of butyl rubber (IIR)?
- Very low air and gas permeability, ideal for gas and airtight applications
- Excellent chemical resistance to many acids, alkalis and polar chemicals
- High resistance to weathering, ozone and ageing without additives
- Good electrical insulating properties, suitable for high-voltage applications
- Temperature resistant from approx. -60 °C until +130 °C
- High damping properties, reduces oscillations and vibrations
- Limited oil and fuel resistance, therefore not suitable for media rich in mineral oil
What areas of application & material combinations of butyl rubber (IIR) are there?
IIR is preferably used in products that need to be air or gas-tight. Typical applications include inner tubes for tyres, sealing membranes, pharmaceutical stoppers or protective films. In combination with halogenation (e.g. chlorobutyl, bromobutyl), adhesion to other materials can be improved, which makes it suitable for use in Rubber-plastic composite parts or as an inner layer in tyres.
