Due to enhanced government regulations and insurance company pressure, hospitals continuously seek to further reduce the level of Hospital Acquired Infections (HAIs). Every single day hospitals are using more aggressive solvents and disinfectants in order to obtain thoroughly cleaned devices. Medical device manufacturers respond to this trend by delivering materials that have better chemical resistance to the newer, more stringent disinfectant agents and systems launched in the marketplace.
Durable medical device enclosures have to withstand more potent cleaners every single day. Styron’s broad Emerge portfolio offers customers several options to choose from depending on their specific needs. (photos: Styron R&D)
Compared to the traditional polycarbonate (PC) or polycarbonate/acrylonitrile-butadiene-styrene copolymer (PC/ABS) materials, next generation device enclosure materials need to provide for a higher level of resistance to these cleaning fluids, wipes and sprays. The use of ever more potent cleaners has, in addition to a better bacteria-kill response, a more pronounced stress crack effect on plastics. On top of this disinfectants development there is a cleaning-time reducing trend to consider in which medical professionals gradually move away from ‘spray-and-cloth’ type cleaning towards cleaning with lower contact time pre-applied and packaged non-woven wipes and cloths. This also requires an increased focus on more potent or higher concentration of functional cleaner components such as benzalkonium chlorides, other alkyl-aromatic ammonium chlorides and functional carrier fluids like diethylene glycol butyl ether and alkyl alcohols.
Styron has developed a comprehensive next generation portfolio of medical device enclosure materials marketed under the Emerge brand. The material is said to provide improved chemical resistance against the most frequently used hospital cleaners, for instance, Wexcide, Cavicide, Virex TB. Furthermore, these materials afford the required structural, aesthetic and haptics features that modern medical devices demand.
Next series of blood pumps are designed for high quality high stiffness, aesthetics and haptics whilst withstanding ever more potent cleaners.
Emerge PC/PET 9000 series: setting the new chemical resistance standard
A new addition to Styron’s portfolio of Emerge products is the line of polycarbonate polyester blends specifically designed for high end durable applications such as medical device enclosures. This line of products encompasses impact modified blends of polycarbonate and semi-crystalline polyester catering to a range of enclosure rating definitions including UL. Emerge polycarbonate/polyethylene terephthalate (PC/PET) 9100CR, is an enhanced performance material designed to set the new standard for UL94 HB rated enclosure parts. This grade features good chemical resistance and low temperature impact as well as ease of processability, including thermoformability. Building from this a UL94 V0 rated product, it was also developed to allow for stringent flame retardancy requirements for mains wall-powered devices. Both materials are fully ISO 10993 biocompatibility certified.
Both Emerge PC/PET 9100 CR (left) and Emerge PC/PET 9500 CR (right) are said to have improved chemical resistance versus incumbent solutions. (source: Styron)
Moreover an additional technology was developed by Styron to enhance performance – captured in a new product line marketed with the ‘TGR’ extension – which is said to provide chemical resistance against the harshest cleaners such as Virex TB at higher strain levels (>1.5% strain). These TGR products – which perform as well as the amorphous polyamides for chemical resistance – are suited for applications demanding high stress crack resistance in current and future devices.
Emerge 9100TGR is said to provide chemical resistance against the harshest cleaners. (source: Styron)
Completing the PC/PET line of products under the Emerge designation are the Emerge PC/PET reinforced series, targeted at applications requiring high stiffness. Whereas glass fibre is a proven way to stiffen Emerge PC/PET products, it does not always bring good aesthetics. To improve the design flexibility for customers requiring such materials, Styron has developed a new mineral filler technology allowing for an improved product stiffness-toughness balance whilst providing good aesthetic qualities for moulded parts.
Emerge PC/ABS 7700 Advanced Resin: superior processability and chemical resistance
The new Emerge PC/ABS 7700 Advanced Resin was designed to be used for a broad range of applications, including powered medical device enclosures. This is an ignition-resistant PC/ABS blend which does not contain chlorine or bromine additives. Styron’s proprietary mass polymerised ABS resin is key to the formulation providing good colour and moulding process stability. Styron says that the resulting good processability of this resin allows designers and moulders to produce thin-wall parts whilst the improved thermal stability allows processing across a broad temperature range. Due to the UV performance housings are said to maintain their integrity and appearance under exposure over time.
Emerge Reinforced Elastomer 1000 series: combining high chemical resistance with increased haptic qualities
Styron’s new-proprietary polymer formulation technology, Emerge Reinforced Elastomer (RE), is characterised by a nano structured semi-crystalline morphology. This provides a multitude of advantages over conventional micro morphologies in the areas of mechanical performance, durability and product aesthetics. Its soft touch haptics can be tuned to meet specific customer requirements. Styron claims that Emerge RE closes the performance gap between moulded thermoplastics and soft paints in terms of scratch and mar durability leading to an improved economic solution versus painting, elastomer over-moulding or TPU moulding.
Emerge RE’s nano semi-crystalline morphology to allow for haptics tuned to specific needs (source: Styron)
The Emerge RE 1000 series comprises various different products, filled and unfilled, that are tailored to meet stiffness and material hardness criteria set by customers for their applications. Designers can specify Emerge RE for a low gloss soft feel still obtaining good structural performance (with a 3,300MPa flexural modulus, 85 shore D), but also use another grade of Emerge RE for soft overmoulded skins or buttons (with a 20MPa flexural modulus, 25 shore D). Functionality is also added to the unfilled super soft Emerge RE range to allow overmoulding onto dissimilar materials such as polypropylene (PP), polyamide (PA) and polycarbonate (PC) in three distinct products. The Emerge RE range is claimed to be ideally suited to frequently handled and/or transported medical devices, patient trolleys, hospital bed cladding, lighting and alarm buttons. Such medical devices require an outstanding resistance to cleaning and disinfection fluids. Emerge RE is effective against harsh cleaners such as Virex TB, and is resistant to UV, discolouration and infusion of water based colour bodies. The company claims that these properties and features make the Emerge RE 1000 series superior to TPU, soft Polyester and PBT-polyol block copolymer TPEs.
Emerge RE 1000 series comprises different grades to meet specific stiffness and hardness criteria. (source: Styron)
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