THERMOPLASTIC ELASTOMERS | MATERIALS
An expansion of applications for thermoplastic elastomers is supported by their advantages in haptics, weight reduction and
processing.Peter Mapleston looks at what’s new in TPEs
TPEs come to the aid of health and sustainability
Producers of thermoplastic elastomers (TPEs) continue to work on new developments that meet specific market needs. Among the highlights is a renewed emphasis on grades for over-moulding onto thermoplastics of various types, to provide hard/soft combinations in an increasing variety of consumer and technical applications. Thermoplastic polyurethanes (TPUs) are being processed in new ways. One major TPE supplier has developed innovative technology to enable parts that are light and strong. And numerous technology suppliers, whether it be in materials, moulds or injection moulding machinery, are pulling out the stops to create new solutions to combat Covid-19. TPEs have a long history of use in over-moulding
applications with harder thermoplastics. Elizabeth Ponte, Senior Product Marketing Manager, Teknor Apex Company, says that, until now, the classic example of an over-moulding application for TPEs has been the toothbrush, with its cushioning TPE grip over a rigid substrate. “The key attraction of this and other products with TPE grips and handles is ergonomics, combined with the stylish appeal of a two-tone finished part. But many new over- moulding applications require more from TPEs than a soft touch and good looks.” In automotive applications, over-moulding is
used increasingly for parts consolidation, which reduces production steps, part weight and costs, she says. One example she cites is an under-hood housing with an over-moulded TPE gasket. “Beyond the capability of adhesion to a rigid plastic, the TPE
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must provide low compression set for retaining its sealing function, plus resistance to high temperature and automotive fluids. In food storage containers whose rigid lids have over-moulded TPE seals, the TPE must be suitable for food contact and resistant to heat and hot water. And in over- moulded medical devices, the TPE component must be ISO-10993-5 compliant, have FDA- compliant ingredients, and be resistant to drugs and other fluids encountered in clinical settings.” Ponte goes on: “The expanding functionality
required of TPEs for over-moulding has accelerated the demand for custom TPE compounds, each of which meets specific application requirements and strongly adheres to a specific rigid substrate. While standard styrenic and vulcanizate TPEs generally adhere to polyolefins like PP and PE, they exhibit poor adhesion to polar engineering resins such as PC, ABS, nylons, polystyrenes, acrylics,
Left: Food storage
containers are an important and growing over-moulding application for TPEs
Main image: Haidlmair and Engel have collaborated on a mould solution for the production of TPE
components of reusable masks
IMAGE: TEKNOR APEX
IMAGE: ENGEL/HAIDLMAIR
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