Butyl (isobutylene, isoprene rubber) is produced by many companies in different types and varies widely in isoprene content. Isoprene is necessary for proper vulcanization. Butyl has a very low permeability rate and good electrical properties.
Up to approximately 121 °C (250°F)
Down to approximately -59°C (-75°F)
Hot water and steam up to 121 °C (250°F)
Brake fluids with glycol base
Polar solvents, e.g. alcohols, ketones and esters
Poly-glycol based hydraulic fluids (HFC fluids) and phosphate-ester bases (HFD R fluids)