Compounds- Butyl

Butyl (IIR)

Butyl GasketsButyl rubber is a synthetic rubber, a copolymer of isobutylene with isoprene. Butyl rubber is a good choice for shock absorption and has exceptionally low gas and moisture permeability and outstanding resistance to heat, aging, weather, ozone, chemical attack, flexing, abrasion, and tearing. It is resistant to phosphate ester based hydraulic fluids, and has excellent electrical insulation performance. Butyl is not recommended for use when in contact with petroleum oils and fluids.

Both o-rings and gaskets can be made from Buna materials.

Names: Butyl, IIR, Isobutylene Isoprene Rubber

Compound Info
ASTM D1418 Designation IIR
ASTM D2000/SAE J200 Type, Class AA, BA, CA
Hardness (Shore A) 40-90
Color black
Thermal Properties
Min Temp. -70°F (-56°C)
Max Temp. 250°F (121°C)


Chemical Resistance
Chemical Resistance
Esters, Alkyl Phosphate, Aryl Phosphate
Alcohols, Inorganic acids, aldehydes
Alkalies (both dilute & concentrated)
Not compatible
NOT compatible
Mineral oils
LP gases & fuel oils, petroleum (both aromatic & non-aromatic)
Hydrocarbon fuels, Halogenated solvents
Mineral oil, silicone oil, and poor oil resistance 

Disclaimer: These are general guidelines only. All materials should be tested in your application.