Biocompatible thermoplastic compounds for use in medical devices

A series of biocompatible styrenic-based thermoplastic elastomer (TPE) compounds suitable for use in medical devices has been developed to provide healthcare designers and engineers additional TPE material options that make it easier to obtain regulatory approval for medical components and devices.

Global custom engineered thermoplastics compounder RTP Company has introduced RTP 2700 S MD Series materials that have been pre tested for compliance with ISO 10993-5/10/11 biocompatibility standards and are available in hardness ranging from 30 to 80 Shore A. Having ISO 10993 biocompatibility testing compliance makes these materials ideal candidates for many healthcare applications because the formulations have been pretested for cytotoxicity, irritation and acute systemic toxicity. The inclusion of these materials will make it possible for OEMs to advance the design and function of their medical devices. These biocompatible TPE compounds offer a number of advantages to medical device applications including gamma and EtO sterilizability. They can be processed via multi-shot over molding, with inherent bondability to polypropylene substrates, to add "soft touch," ergonomic features for molded-in stoppers, seals and masks. Good flexibility is maintained over their entire 30 to 80 Shore A hardness range and these products are cost competitive when replacing alternative medical grade TPE materials such as thermoplastic vulcanizate (TPV) or olefinic-based thermoplastic elastomer (TEO). Naturally translucent, these TPE compounds are fully colorable with RTP Company's companion EMD Series color products - which offer biocompatibility compliance to precolored resins and color masterbatches. These materials have a very neutral color and are appropriate for use in many Class I and II medical devices. Applications for RTP 2700 S MD Series TPEs range from drug delivery systems, that require multi-shot over molding for ergonomics and cost efficiency, to disposable devices that require good needle stick and reseal performance, tear strength, or compression set properties. These materials will also benefit other applications such as surgical tools that require slip-resistance when moist and color identification for accurate tool identification. They can also be used in respiratory care requiring materials that offer a high degree of clarity and low tack for contact with patient's skin. The mechanical property versatility and processing flexibility of these biocompatible TPE compounds, along with easing FDA approval for medical devices in which they are used, will allow greater innovation that will ultimately lead to improved products and procedures to advance medical treatment.

A transparent medical elastomer gel available in free-flowing pellets is the softest compound in Tecknor Apex�s Medalist® product range, enabling designers to achieve added comfort in skin-contact and other sensitive applications requiring molded-in seal areas or cushions. Medalist MD-447 is so ultra-soft that it could not be measured accurately on the Shore A hardness scale used for other Medalist elastomers, the softest of which has a Shore A rating of 5. Subjected to the Shore OO test for ultra-soft materials, the new compound has a rating of 25. The new compound avoids handling problems sometimes posed by exceedingly soft materials in pellet form. To qualify as a Medalist medical elastomer, the new gel compound has been formulated and manufactured under the same stringent standards as other Medalist products. Based on a standard hydrogenated styrenic block copolymer, this is free of latex, phthalates, or animal-derived components, and complies with FDA, California Proposition 65, CONEG and REACH requirements for medical applications. The range provides the broadest selection of high-purity elastomers available to medical manufacturers. They utilize multiple polymer chemistries and technologies to achieve desired functional properties. Shore a hardnesses range from 5 to 87. Clear, translucent and opaque grades are available for injection and blow molding, multi-component molding and extrusion of tubing, profiles, films and coatings. The compounding plant that produces this range of medical elastomers is now certified under the international ISO-13485 standard for quality management in medical manufacturing. ISO-13485 specifies systems for consistent compliance with regulatory and customer requirements and includes provisions for risk management, sterile manufacturing and traceability. Developed for device manufacturers, ISO-13485 is not an essential standard for a compounder.

Over the years, medical product designers and manufacturers have come to rely on Bayer to provide technically advanced medical grade plastics like TPU that can help meet the critical design, manufacturing and end-use performance parameters of a variety of medical applications. The company's Texin and Desmopan families of thermoplastic polyurethanes are plasticizer-free thermoplastic elastomers offering high elasticity and resilience, excellent abrasion resistance and high tensile and tear strength. From soft and comfortable to the patient's skin to hard and resistant to wear and tearing, these thermoplastic polyurethanes are remarkably versatile medical grade plastics. These medical grade elastomers offer excellent strength and elastic properties, even at minimal wall thickness. They also feature elastic memory, with the ability to maintain tension and resist leaking at joints. Both elastomer product lines include medical grades with proven biocompatibility. These medical grade urethanes have been used in a range of medical device applications including Thin-walled flexible tubing, catheters, connectors, luers and stopcocks, films and fabric coatings, component housings, soft-touch grips. These TPUs can be injection molded or extruded. Without the use of plasticizers, they bridge the gap between thermoplastics and rubber. Medical grades of Texin and Desmopan TPU range in Shore hardness from soft and supple 85A to tough and durable 70D. Desmopan DP 9370A softens at body temperature while still maintaining its properties for such uses as monitor sensors, gowns and breathable wound dressings. These medical grade polymers can be an ideal alternative to PVC and silicone. Chemical resistance is also a key property of these medical grade urethanes that resist lipids, cleaning and disinfecting agents. These grades withstand a variety of sterilization methods, including ethylene oxide gas, gamma irradiation, dry heat and E-beam. During sterilization using steam autoclaving or boiling water techniques, polyurethane materials may hydrolyze to their corresponding precursor diamines (for example, aromatic polyurethane based on diphenylmethane diisocyanate [MDI] may hydrolyze and produce methylene dianiline [MDA]). This condition needs to be considered by the device manufacturer in defining sterilization conditions.