Thermoplastic Elastomers for Medical Pump Valves

Medical device manufacturers have traditionally used thermoset silicone rubber to mold pump valve inserts. However, these inserts are often hampered by inefficient designs and a manufacturing process that is time-consuming and costly, as it involves several labor-intensive assembly steps.

To address these issues, PolyOne developed the GLS thermoplastic elastomer (TPE) created in a two-shot molding process to eliminate assembly operations.

The custom-formulated grades PolyOne creates are based on Dynalloy OBC and Versaflex TPEs to facilitate two-shot molding. PolyOne conducts compatibility testing to confirm that the new grades will bond chemically with the rigid engineering thermoplastic substrate required in these applications.

The custom grades are formulated with multi-functional capabilities, so that they can replace several different hardness grades of silicone rubber. The TPE materials also provide better tension set, improved compression and enhanced permeability compared to silicone rubber. In addition, the new TPE grades boast lower extractables because, unlike thermoset silicones, they require no cross-linking. These materials also offer quick set-up on standard two-shot molding equipment along with faster cycle times for higher productivity.

Eliminating a multi-component process cuts the need for assembly operations, offering as much as $50,000 in savings to medical device OEMs annually. This savings is achieved because several assembly steps are removed because the TPE custom formulations deliver multi-functional capabilities.

Secondly, the lower specific gravity of the TPEs cuts overall part weight by 15 to 20 percent and reduces associated freight costs for further savings.

In addition, these custom materials result in major scrap rate reductions, providing savings of up to $40,000 annually. The regrind also offers recycling benefits that are not available with thermoset silicone rubber.

In total, the use of custom TPE pump valve inserts can create more than $100,000 in operational savings by reducing manufacturers' costs for assembly, freight and scrap.

Joe Kutka, is technology launch manager, PolyOne GLS Thermoplastic Elastomers.