Engineered Materials Group
llR and Butyl
Little Known Low Permeability Options for Drug Delivery and Blood Collection Applications
Part Two of Two-part Series
Part 2 In the Series:
IIR and Butyl Life Science Material Offerings, Leakage Types & Case Studies
As stated in part one of this article series, rubber materials are some of the first materials that come to mind for use in medical devices. However, when working with certain applications, such as syringe stoppers, plungers for infusion therapy applications, closure seals for drug vials and blood collection containers, low permeability is necessary. In the second part of this two-part blog based on material from our webinar, A Short Overview of Butyl Rubber and Its Applications, specific examples are shown where the butyl rubber polymer family offers what is needed for those situations―both high density and low permeability. Part two focuses on Life Sciences offerings, types of leakage and butyl case studies. Part one covered the butyl family―including Bromine and Chlorine, as well as chemical resistance.
For Life Science applications in particular, butyl is known for its low permeation and ozone resistance, as well as its biological inertness. And, because both BIIR and CIIR can be vulcanized with sulfur-less cure systems, low extractables from the materials are possible.
Parker has a variety of llR materials available for Life Science applications, including these compounds:
- B0612-70 for low compression set, vacuum (70 Shore A Durometer)
- B0318-70 for general purpose (70 Shore A Durometer)
- B8885-70 for high voltage switch, vacuum (70 Shore A Durometer)
- WB3025-45 for low metals for blood chemistry (45 Shore A Durometer)
- WB3326-50 for flush stoppers (50 Shore A Durometer)
- WB3252-45 for insulin pumps (45 Shore A Durometer)
Leakage problems
Let’s discuss leakage and why this issue is important. Normally, we have two different types of leakage. First, we have tangential leakage, which is material or fluid going around the seal. Tangential leakage is normally much more significant over short periods of time. Over long periods of time, however, permeation becomes a greater factor.
Examples of permeation rates can be seen in samples from our O-ring handbook. You can see big differences between butyl and other materials, especially silicone, a commonly used material in medical applications.
Common applications for butyl are not limited to just life sciences. In general, popular applications range from vacuum blood stoppers, insulin pump sealing elements, flush syringes, pre-filled syringes, vacuum sealing of high voltage equipment to aerospace vacuum sealing. For many of these applications, in addition to permeation, low fragmenting and self-sealing capabilities are also required.
Butyl case studies
Now let's look at five examples of llR used in different applications.
Vacuum Blood Collection Stoppers. The benefits here are not only vacuum sealing, but also low friction during needle insertion. Additionally, when the needle is removed, the stopper re-seals reliably and there is low particle fragmentation. BIIR and CIIR materials are often preferred not only because of their low gas and vapor permeation, but also because of their good biocompatibility and low extractables. For customers with a special requirement, we do have an extremely low metal material that can be used in sensitive analytical applications.
Flush Syringe Tip. Here we use Parker compound WB3326-50 gray. It’s a 40-durometer material. Why BIIR? We use this material because of its low gas and vapor permeation, as well as low extractables. The exposure to saline over a long period of time has minimal impact, which is valued by the customer.
Insulin Pump Sealing Component. The Parker compound WB3252-45 gray is used. Here again we see that not only is the long-term sealing function needed, but that we also have good biocompatibility with the fluids that are being sealed, as well as low extractables. In this situation, there was long-term insulin contact, and it was assembled into wearable insulin delivery devices.
Drug Delivery. This example is a novel wet/dry autoinjector for the epinephrine market. It uses ZB629, which is a halobutyl blend. ZB629-40 is also USP <381> Type 1 compliant, and again it was designed for low gas and moisture permeability, as well as good sealability and biopharma compatibility.
High Voltage Switchgear. And then finally, our last case study is not for Life Sciences, but we thought it would be interesting to point out. It is for our material B8885-70, used in a high voltage switchgear. For those familiar with that market, sulfur hexafluoride gas (SF6) is a very potent and persistent greenhouse gas. Therefore, our customer is replacing that gas with vacuum. Using CllR provided long-term sealing, low permeation and long-term compression set resistance.
In summary, we hope you can take away the following points:
- Although a very mature technology, butyl rubber offers some unique properties useful for many sealing applications
- It is well suited for applications where low permeation of water vapor and air is required
- Halogenated butyl materials (chloro and bromo butyl) offer improvements in processing, blending and toxicity
- While our review of butyl materials was focused on life science applications, other applications include industrial vacuum sealing
Related information:
Watch the on-demand webinar replay on this and other Parker Engineered Materials Group topics: On-Demand Webinar Replays
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