Isobutylene-isoprene copolymer

Isobutylene-isoprene copolymer (CAS 9010-85-9), commercially known as butyl rubber, is a synthetic elastomer produced by copolymerizing isobutylene with a small proportion of isoprene.

Where is Isobutylene-isoprene copolymer used?

• Tire industry: standard material for inner tubes and tubeless tire inner liners, where low air permeability determines performance and service life
• Automotive and industrial sealing: door seals, vibration dampers, HVAC gaskets relying on compression set resistance
• Pharmaceutical packaging: stoppers and closures for injectable drugs, meeting extractables and permeation requirements
• Halogenated derivatives such as chlorobutyl and bromobutyl extend use into faster-curing tire sidewall compounds and adhesives.

Good to know: Grades are differentiated by Mooney viscosity and isoprene content, with regular and halogenated variants for cure system compatibility. Pharmaceutical grades are subject to compendial specifications for closure applications.

Commercial specifications

• Grades differentiated by Mooney viscosity and isoprene content
• Regular and halogenated variants