Pharmaceutical stoppers in grey, orange, and purple

Pharmaceutical stoppers and seals  

Achieve a high level of cleanliness and gas/moisture barrier in pharmaceutical stoppers and seals

More than 90 percent of antibiotic, infusion and biomedical stoppers made in Europe, the United States and Asia are based on halobutyl rubber. Exxon™ halobutyl rubber is ideal for stoppers and seals because of its high cleanliness and chemical resistance as well as low permeability to air, gases and moisture.

Because halobutyl rubber is chemically inert and nonpolar, absorption of drugs or water is low. Studies indicate that bromobutyl rubber-based stoppers have much lower drug turbidity than regular butyl stoppers.

Another option for high-end applications is Exxpro™ specialty elastomer, a brominated isobutylene paramethyl-styrene terpolymer (BIMSM). It is the cleanest elastomer available from ExxonMobil that is suitable for pharmaceutical applications. Exxpro specialty elastomer-based stoppers have been shown to exhibit similar drug turbidity performance in comparison to a coated stopper.

Applications and benefits

Exxon halobutyl rubber offers a number of other advantages over natural rubber and other synthetic rubbers in pharmaceutical packaging, including:

  • Chemical and biological inertness
  • Low extractables due to low level of additives and high curing efficiency
  • Resistance to heat, ozone and oxygen
  • Good self-sealing and fragmentation performance
  • Vulcanizable by low level of sulfur-free and/or zinc-free curatives

Product solutions

  • ExxonMobil Chemical Butyl Rubber Plant

    Butyl rubber

    Exxon™ butyl rubber is the foundation of today’s butyl rubber technology. It is a copolymer of isobutylene and a small amount of isoprene. The primary properties are excellent air-barrier performance, good flex fatigue and vibration damping.

    Learn more
  • ExxonMobil branded Tire


    Exxon™ bromobutyl rubber is derived from halogenating butyl rubber with bromine in a continuous process. It is structurally similar to Exxon™ chlorobutyl rubber and produced through the same halogenation process.

    Learn more
  • Rack of tires made with Chlorobutyl

    Chlorobutyl rubber

    Exxon™ chlorobutyl rubber is derived from halogenating butyl rubber with chlorine in a continuous process. It is structurally similar to Exxon bromobutyl rubber and produced through the same halogenation process.

    Learn more
  • BIMSM Pharma Stoppers

    Specialty elastomer for pharmaceuticals

    Exxpro™ specialty elastomers, brominated isobutylene paramethylstyrene terpolymers (BIMSM), provide a super-clean solution and cost-effective alternative to expensive coated stoppers.

    Learn more

Featured resources

View highlighted news, events, technical papers and case studies below. To see our full collection of resources, browse our Library.
  • ExxonMobil Chemical Library icon

    Exxpro™ Specialty Elastomer Grade 3433

    Model formula for pharmaceutical closure Exxpro Specialty Elastomer Grade 3433.

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  • ExxonMobil Chemical Library icon

    Gradeslate: 80 years of leadership in butyl technology

    Reference the list of ExxonMobil Chemical’s butyl rubber gradeslate, including grades and typical applications.

    Read more
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