New TPEs Provide Material Flexibility

TPEs offer the formulation freedom to match or exceed the properties of many thermoset offerings for healthcare devices and equipment. Advances in TPE compounding science have helped these versatile materials make significant inroads into a variety of healthcare sectors. The desirable combination of design freedom, system cost benefits, and improved performance characteristics is fueling strong growth of TPEs in a wide range of medical applications.

Designers and manufacturers of medical devices face challenges that are driving the adoption of next-generation thermoplastic elastomers (TPEs). The materials give designers new flexibility for processes such as part consolidation. Their user-friendly properties often make them preferable to thermoset rubbers, which can be cumbersome and coarse. Also, TPEs can be molded using the same injection molding and blow molding equipment as traditional materials, allowing them to be integrated into the manufacturing process rather than requiring separate operations for creation and assembly, as is the case for thermoset parts. Further, TPEs enable techniques such as overmolding on a variety of substrates.

WHAT ARE TPES?

Thermoplastic elastomers are generally low-modulus, flexible materials. They can be stretched repeatedly to at least twice their original length at room temperature and return to their approximate original length when stress is released.1 Originally, thermoset rubbers such as styrene butadiene rubber (SBR), latex, and polyisoprene were used in applications requiring such elasticity. In many situations, injection-moldable TPEs have replaced these rubbers.

TPES AND THE MEDICAL INDUSTRY

TPEs have been used for several years in the medical industry. They were initially adopted as replacements for SBR, latex, and polyisoprene. Those materials did not offer design freedom, and TPEs had similar stress-strain performance. TPE materials can also be easily extruded, which makes them appropriate for tubing and elastic bands. Characterized by softness and suppleness, TPEs also appeal to consumers and are therefore popular for many healthcare products used in a home setting.

Early TPE formulations were considered for thermoset stopper replacement in syringes but failed to meet performance requirements. New formulations and other advances, however, have improved performance of TPEs for stopper applications. As TPE technology has evolved, these materials are being considered for overmolded designs to enhance the feel, ergonomics, and aesthetics of the final part.

Desirable attributes such as softness and ease of molding provide opportunities for TPE use in medical applications such as orthopedics, surgical equipment, syringe plungers, needle shields, face masks, resuscitator and breathable bags, and home-use medical devices. With new formulations, these materials help to address regulatory, performance, design, and cost requirements.

ENHANCED DESIGN

From a design standpoint, TPEs can enable part consolidation to eliminate potential points of failure. Instead of having multiple components mechanically joined together with fittings that could leak or break, TPE overmolding can create a single seamless assembly.

The design flexibility of TPEs also helps manufacturers achieve device miniaturization and improved usability. They can be molded using a high-pressure injection molding process, which helps in thin-wall molding and complex geometries. The combination of hard and soft TPEs (dual-durometer products) enables additional functionality. Although thermoset rubbers may need reinforcing fillers that limit physical attributes such as clarity and density, TPEs do not require such fillers. They can be reinforced using plastics, which allows them to maintain a low specific gravity, as well as clarity and translucence.

REDUCING COSTS

In most medical devices, raw materials make up only a portion of the final product cost. There are also costs associated with assembly, quality assurance, validation, and the overall manufacturing process. Although the raw-material price of TPEs on average could be 50% higher than thermosets, TPEs help reduce overall costs by reducing or eliminating scrap, enabling part consolidation, and improving quality. In comparison with thermosets, TPEs can reduce finished part cost by up to 30% through processing efficiency, elimination of secondary processes and their associated materials, and fewer rejects from contamination.6 Further, the ability to process TPEs using conventional molding equipment makes these materials an attractive choice.

CONCLUSION

Source:https://www.mddionline.com/new-tpes-provide-material-flexibility