THERMOPLASTIC ELASTOMERS | MATERIALS
TPE producers are designing new materials, such as elastomer hybrids, and refining established materials to meet precise needs in automotive, medical and consumer applications. By Peter Mapleston
Tailoring with TPEs
Advances in compounding technology are making it easier to create thermoplastic elastomers (TPEs) that better meet the needs of individual applica- tions. Overall performance is improving too, with more progress being made in compounds that bond well with all sorts of thermoplastics in two-component injection moulding. Kraiburg TPE has developed thermoplastic elastomer hybrid technology, or TEH. This allows it to compound TPEs made from more diverse combinations of elastomers and thermoplastics than before using TPV (thermoplastic vulcanizate) technology. The company says TEHs are “a new performance class for thermoplastic processors.” It has implemented new compounding equipment to make the products and currently has capacity of around 100 tpa on a pilot line. “The concept for bigger lines is there,” it says. Thermoplastic elastomer hybrids are quite
different from TPVs, which are in most cases com- pounds of polypropylene and partially vulcanised EPDM. “TPVs are good for temperatures up to 100-120°C and they have little oil resistance,” says a representative. “We can select other elastomers to take long-term temperature resistance up to around 150°C and also provide resistance to oils and grease.” In this case, the elastomers are fully crosslinked. Hardnesses range from 55 to 80 Shore A. The new materials are said to be particularly suitable for use in internal combustion engine compartments, in heat management of drives and batteries for electric vehicles, as well as in lubrication and cooling systems of machines, process technol- ogy and buildings. Applications include seals and
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gaskets, plugs and connectors, lids and covers. Frieder Vielsack, Head of Advance Development
at Kraiburg TPE, says the compounds can not only be used as an alternative to common crosslinked rubber solutions, but they also offer appealing options for multi-component applications when bonded with technical plastics such as polyamides and thermoplastic polyesters. Vielsack says there has long been a need for a uni-
versal soft TPE solution capable of replacing rubber, showing high temperature resistance and chemical resistance. “Numerous so-called super-TPEs or super-TPVs entered the market and then gradually disappeared again,” he says. He cites “super-TPVs” based on acrylate rubber as one example. “There are many reasons why these develop- ments were not able to really establish themselves on the market. It is noticeable, however, that these thermoplastic elastomers are each based on only one specific raw material. Attempts were repeat- edly made to satisfy the needs of as many applica- tions as possible with one TPE class and its special raw-material base. The desired ‘universal solution’ failed to materialise.” Kraiburg TPE’s objective was to combine
different thermoplastics and different elastomers using only a single manufacturing technology “and thus to achieve the maximum possible number of combinations with a low level of complexity in production technology,” says Vielsack. He points out that the unique structure of the Kraiburg Group, which includes an operation making synthetic rubber (Gummiwerk Kraiburg) as well as Kraiburg TPE, has proved very useful in tackling this issue.
Main image: Precision and customisation are growing features in TPE materials
� May 2019 | INJECTION WORLD 17
PHOTO: SHUTTERSTOCK
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