INNOVATION | AUTOMOTIVE
A Plexiglas PMMA moulding compound from
Evonik has been used in the curved Hella taillights of Opel’s Crossland X, providing an intense, evenly distributed red light. The new Crossland X from Opel aims to combine the properties of a SUV with the elegance and functionality of a sedan and is the first model to sport a newly developed LED taillight made by Hella. Evonik says that the taillights act as an interface between the boot lid and roof lines, making the brand’s signature double-curve motif clearly visible along both components. When lit, its arrow-like shape is a uniform red, but even when the lights are off, the curved lines are still easy to see. “This application was the first time that we combined light-diffusing additives with the signal colour red,” says Jörg Stricker, head of Global Key Accounts Automotive at Evonik. “Plexiglas 8N 3V219 dispers- es light more evenly than other moulding com- pounds, making it even better for use with LEDs.” LEDs, while popular in the automotive industry for their energy efficiency, place considerable demands on light-diffusing taillight covers. Stricker adds that LEDs emit a powerful point light, and that quickly leads to undesired differences in brightness known as hotspots, meaning that the material used for covering them has to do a good job of diffusing light. Due to the customised Plexiglas moulding compound, taillight covers can now be positioned more closely to the LEDs without resulting in hotspots. This means the taillight as a whole can be much flatter and, as a result, take up less space in the body of the car. In addition, Evonik says that the moulding compound makes the red of the light guide look even more intense. The red shade itself likewise places demands on the material used. Because colours used in taillights are standardised all over the world, manufacturers have to be able to adjust the colour of the material with tremendous precision. Plexiglas starts out completely colour- less, meaning that it can be coloured to any signal colour required. It does not alter optical properties like light transmission or diffusion. The compounds are stable in the presence of UV light and heat, which means the precise colour of the taillight covers remains unchanged for the life of the car. Initz, a joint venture between SK Chemicals and
Teijin of Japan, has developed a chlorine-free PPS (polyphenylene sulphide) resin that resolves headlamp haze. The company has commercialised its Ecotran PPS compounds in collaboration with Hyundai Mobis, a global automotive parts supplier. PPS is an engineering plastic that has been increasingly replacing metals for lightweighting reasons in the automotive industry for all cars and
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trucks, but particularly for electric vehicles. PPS is considered a super engineering plastic as it is highly resistant to both heat and corrosive chemi- cals. Initz produces PPS resin by using environmen- tally-friendly techniques that generate no by-prod- ucts and few gases and impurities. Initz says that its high-performance PPS address-
es the root cause of lamp haze, a major car headlight problem. The problem occurs because plastic parts inside headlamps begin to generate gas when the internal temperature rises to over 200°C. Upon cooling the gas solidifies and adheres to the interior of the lamp. The resultant film hinders light projection. The condition not only reduces the performance of the vehicle, but also the appearance and light distribution value (light transmission and diffusion). Many global automotive parts manufacturers
have previously addressed the problem by focusing on the design of the internal structure of the headlamps as no other solution resolved the fundamental problem. A headlamp holder needs to be highly resistant not only to high heat but also to humidity, which is generated due to the tem- perature gap between the inside and outside of the headlamp. A headlamp holder must also be rigid enough so that internal parts are not loos- ened by strong vibration. Working closely with Hyundai Mobis, Initz says that it has succeeded in resolving the lamp haze issue by incorporating glass fibres using specially formulated resins to produce the new material.
CLICK ON THE LINKS FOR MORE INFORMATION: �
www.kraussmaffei.com �
www.engelglobal.com �
www.ach-solution.com �
www.milacron.com (Mold-Masters) �
www.ikv-aachen.de �
www.evonik.com �
www.skchemicals.com
September 2018 | INJECTION WORLD 57
Above: Plexiglas moulding compound from Evonik has been used for the taillights of the Opal Crossland X SUV
PHOTO: OPAL
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