Pierre Moulinié, Godwin Suen, Paul Nowatzki, Elizabeth Ponte, Long Zhang – Teknor Apex
Thermoplastic elastomers (TPEs) and polycarbonates (PCs) offer an interesting combination of rigid and soft materials for housings and interfaces in wearable applications. However, strong adhesion between TPE and PC materials is critical to achieve durable devices that can withstand repeated use. A recent study conducted by Covestro and Teknor Apex, “Adhesion of TPEs on Polycarbonates for Medical Wearables,” examined the adhesion and chemical resistance of medical grade resins that are candidates for wearable applications. In the study, the team evaluated the adhesion of newly introduced TPE grades designed specifically for overmolding on various medical grade PC substrates. The adhesion was examined in the context of two-shot molding by measuring the force required to pull apart the PC and TPE layers. Excellent chemical resistance is also a must have for wearable devices, in which repeated cleaning or contact with skin creams or lotions has been known to cause chemical attack on plastics. The study also examined the chemical resistance of the TPE and PC substrates to isopropyl alcohol and suntan lotion.