Isobutylene-isoprene (IIR) Generally know as butyl rubber.
Chemical properties Butyl compounds have similar chemical resistance to ethylene propylene. They display excellent resistance to air, water, dilute acids and alkalis - plus aliphatic phosphate-ester hydraulic fluids, salt solutions, alcohols, glycols and silicone oils.
Resistance to hydrocarbons is poor: butyl must not be used with mineral oils.
Typical operating temperatures -35°C to +120°C continuous, or +150°C intermittent.
Fluid sealing duties Very low gas permeability makes butyl popular for vacuum and high pressure gas applications.
James Walker standard grades Supplied in grades of 60-70 IRHD.
