Butyl rubber (IIR)

Also called isobutylene-isoprene rubber (IIR), butyl is impermeable to gases, resistant to water, steam and weathering. A copolymer of isobutylene and a small amount of isoprene, this synthetic rubber is regularly used in precision engineering as rubber sealants and in the industrial sector [Industries] for everything from damp proofing and roofing to tyre inners and protective clothing.