Butyl Rubbers (IIR)

Properties and Applications

Butyl rubber (also known as isobutylene-isoprene, IIR) is a synthetic elastomer produced by low temperature cationic copolymerization of isobutylene with about 0.5 to 2 percent 1-methyl-1-butenylene (isoprene) using Lewis catalysts. This type of elastomer has unique physical and chemical properties.

Due to its low level of unsaturation, it can withstand prolonged exposure to heat, oxygen, and ozone. It also has exceptional low gas and moisture permeability which makes it ideal for inner tubes and high pressure/vacuum applications under demanding conditions. Its very low resilience makes it also suitable for shock absorption and vibration damping applications. Other typical applications include diaphragms, gaskets, O-rings, seals, wire and cable insulations, off-road tires, weather stripping and bottle closures. Lower molecular weight grades find uses in pressure sensitive adhesives (PSA), caulks / sealants, hot melts, and heavy-duty lubricants.

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