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Citroën Cactus with unpainted “Airbumps” from BASF.

Plastic 'Airbumps' protect Citroën exterior

For its quirkily styled new Cactus, Citroën uses UV-stable thermoplastic polyurethane (TPU) for unpainted exterior cladding called “Airbumps” to give protection against low-speed impacts and scratching.

PSA Peugeot Citroën worked with chemical company BASF and Swiss company Rehau on the development of the Cactus’ TPU exterior detailing.

BASF optimized its new grade Elastollan AC 55D10 HPM (High Performance Material) for unpainted application on the car to create the air-filled “cushion bumpers” called Airbumps, fitted to the sides, front, and rear of the car. Rehau makes the side Airbumps, Faurecia (France) the front and rear.

BASF states that the injection-molded Elastollan HPM can be pigmented (in black, brown, light or dark gray colors), so does not require painting. The material has long-term durability and meets required levels of haptics and appearance. The new TPU grade adds to its established characteristics via what BASF describes as “outstanding surface properties even at low wall thicknesses.” It is scratch, UV, and weather resistant, is easy to clean, and has a high service temperature of 120 to 150°C (248 to 302°F).

The injection-molded Elastollan component is mounted on a polycarbonate and ABS (acrylonitrile-butadiene-styrene) support shell to form flexible cavities that can be dented but are able to bounce back into shape. The mounting properties of HPM facilitate tight assembly that conventional trim materials such as polypropylene typically do not have, according to BASF.

The company adds that previous automotive applications for Elastollan were for underhood cable sheathing, and in the cabin for door handles, gearshift/transmission selector knobs, and cupholder linings.

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