Polycarbonate makes automotive inroads


The BMW i3 has one of the highest level of polycarbonate (PC) usage of any vehicle according to Bayer MaterialScience (Leverkusen, Germany), with more than 25 kg of safety, interior and exterior components, among others, utilizing the material.

These include air bag covers molded from PC/ABS and structural components to protect the vehicle's battery. "For the most demanding safety applications PC blends offer an unique balance of accurate part dimensions and constant ductile behavior over the whole temperature range" notes Markus Steilemann, head of Bayer's Polycarbonates Business Unit. Steilemann was speaking to PlasticsToday at the recent Chinaplas show in Shanghai.

For example, a moveable trim part of the BMW 5GT model is molded using a DirectCoating/DirectSkinning (DCDS) process developed jointly with machine builder KraussMaffei. In this process, the PC core is molded in one cavity, then the surface is flooded in-mold with PU in a second cavity to produce the final part with a soft surface. A variant of the process can form a rigid PU coating on the PC core instead of a soft foamed skin.

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