What is butyl rubber (IIR)?

Butyl rubber (IIR) is a co-polymer of isobutylene and isoprene, usually consisting of 95 – 99 % isobutylene and only 0.8 – 5 mole percent isoprene. Compared to other elastomers, IIR has a high resistance to heat, ozone and chemicals, chemicals– and ageing resistance. In addition, IIR has a very low permeability to liquids and gases. Chlorine and/or bromine atoms can also be incorporated to improve the above-mentioned properties.