Bromobutyl Rubber (BIIR) 

Brominated X_Butyl® is produced in a continuous process by reacting Butyl Rubber with bromine. Halogenation allows co-vulcanization and improved compatibility with other diene rubber types, in addition to improvements in the vulcanization rates, states of cure and reversion resistance. 

Many of the properties of Halobutyl vulcanizates are virtually identical, regardless of the halogen employed. With Bromobutyl Rubber however, the brominated sites are more reactive, resulting in faster cure and better adhesion to unsaturated rubber types. The versatility of halobutyl rubber has led to a significant growth of its use in a diverse range of tire and non-tire applications.

Key Properties  

Brominated X_Butyl® consists predominantly of saturated polyisobutylene. The halogen functionality makes it more reactive to cure systems, compared to Butyl Rubber. Provided that compounds based on brominated X_Butyl® are correctly formulated and processed, the vulcanizates have excellent resistance to weathering, ozone and hot air, very good resistance to acidic and basic chemicals, very low permeability to gases and liquids, high damping and low-temperature flexibility, balanced with good processing properties. 

In summary: 

· high impermeability to gases

· improved weather and ozone resistance

· improved chemical resistance

· good cure versatility

· faster cure rate with lower amount of curatives

· good cure compatibility with unsaturated rubber types

· high heat resistance




These would include articles which need low permeability to gases and liquids, e.g. tire innerliners, hoses, seals and membranes. Furthermore, Brominated X_Butyl® is material of choice for pharmaceutical closures due to its cleanliness and good resealing properties. Rubber articles needing good resistance to chemicals, weathering and ozone, such as tank linings, conveyor belts and protective clothing also benefits from the unique properties of Brominated X_Butyl®




Brominated X_Butyl® combines the unique properties of polyisobutylene (impermeability, damping, chemical and weathering resistance) and the possibility of cure with a broad range of systems. Bromobutyl is known for its good cure compatibility with unsaturated rubber types.

Product Portfolio
X_Butyl® Halogen content[mol%] Mooney[MU]   Density[g/cm3] 
BB 20301.8320.93
BB 20401.8390.93
BB X21.8460.93