Exploring Traditional and Novel Cure Systems for Halobutyl Rubber for Medical Applications

Butyl rubber is a copolymer of isobutylene with small amounts of isoprene (typically <3 mol%). In order to increase the crosslinking reactivity of butyl rubber to match with other highly unsaturated elastomers, halogenated butyl rubber (bromobutyl and chlorobutyl) was developed. High impermeability to gases and liquids, low temperature flexibility, and broad damping characteristics are just a few of the many unique properties of butyl rubber which make it ideal for a diverse range of consumer end products including tire inner liners and tubes, chewing gum and pharmaceutical closures.

Comparison of the cure reactivity of chlorinated and brominated butyl rubber and their versatility in responding to a wide range of curing systems will be discussed from a mechanistic, compounding and physical property point of view.

Both traditional cure systems such as sulphur and resin, as well as non-traditional and novel cure systems such as dioxime and difunctional phosphines will be highlighted in order to provide options for customers seeking alternative cure systems for improved properties and manufacturing efficiency.

In addition, a new generation of halogenated butyl rubber with reduced extractables that is being developed by ALRANXEO for the pharmaceutical industry will be discussed.