Interior/exterior | automotive
Plastics are being used to cut weight and to brighten the appearance of today’s top selling cars. Peter Mapleston explores some of the enabling material and process developments
Plastics make lighter work
“Let there be light” seemed to be a common theme across many material supplier stands highlighting automotive interior and exterior applications at K 2016—and in several injection moulding equipment demonstrations too. And light in both senses of the word, including new ideas for taking weight out of cars and trucks as well as new concepts for application of highly transparent plastics. At the same time, the trend towards deeper, darker, and ever more shiny black continues. This article picks out some of the development highlights. In lightweighting, for example, polypropylene is
already prized for its low density but LyondellBasell is pushing the envelope further with new grades of its Hifax TPO containing reduced levels of talc for parts such as bumper covers. Klaus Klemm, Customer Project Manager, Advanced Polyolefins points out that talc is added to improve stiffness and strength, so taking some away required development of new resins based on its Catalloy technology to compensate. Hifax TKC 461X, which has just 12% talc versus the normal 20-30% to save around 7% in weight, is used in the BMW i8 hybrid electric car while the new Audi A4 uses the Hifax TKC 435X grade with just 9% talc for an even bigger saving. On the LyondellBasell stand at K2016, the company
showed an interior trim part that appeared to have a textile covering but in fact came straight out of the mould without the need for any in-mould or post-mould decoration. The part was moulded in Softell Textile, which contains various fillers and is described as a
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scratch resistant, low gloss compound with high impact strength. Customers – Mercedes Benz said to be among them – have started to qualify Softell Textile for upcoming models. LyondellBasell says other Softell soft-touch materials
are already being used in car interior applications such as dashboards and door panels against solutions such as painted ABS. “Due to their morphological structure, finished parts produced using Softell compounds do not form sharp edges and splinters in crash tests, even at low temperatures,” the company claims. Several independent compounders are also focusing
on talc content reduction to cut weight in PP-based materials for auto applications. At Sweden-based compounder Polykemi, for example, Development Manager Henrik Eriksson says its own high performance talc reinforced PP homopolymer compounds provide weight savings in the order of 10-15% with a minimum of technical risk and no additional cost compared to mainstream compounds based on prime resins. Polykemi is targeting non and semi-visible interior parts as well as some applications under the hood. “Some other suppliers promote compositions with
exotic fillers and reinforcements, which can only be implemented if the car makers are willing to pay extra for this sort of weight saving,” Eriksson says. “We have made sure that our lightweight materials are cost-com- petitive.” He says that to date, two carmakers have moved from PP compounds with 40% talc to Polykemi
November/December 2016 | INJECTION WORLD 13 Main image:
Steering wheel covers
produced by
Covestro using its one-step
DirectSkinning decorative moulding technique
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