Polycarbonate resins for lighter LED automotive headlights

27/09/2017 09:28 AST

Plastics-maker SABIC has released new materials for customers producing LED automotive lighting parts. The LEXAN HF4010SR resin is a polycarbonate material which enables the development of complex headlight bezels with enhanced aesthetics.

While current high-end LED headlamps weigh close to six kilograms with up to 200 components, SABIC has engineered the new LEXAN resin to address customers seeking to produce complex headlamp bezels with enhanced styling, but at a lighter weight and at a lower overall system cost. When designing injection-molded parts, a low draft angle is important because it enables greater styling freedom as well as a larger optical surface. However, the lower this angle, the more problems arise with parts sticking in the mold, creating scuff marks and potentially even resulting in a part with cosmetic defects.

The LEXAN HF4010SR resin was designed to allow designers to target draft angles between 0.5 and 1.0 degrees lower than the recommended draft angle for PC tools (typically between 3 and 5 degrees). Bezels that are injection molded in LEXAN HF4010SR can be directly metallized (no need for priming) and gloss and reflectivity performance under high temperature environments are both very good. The material has a unique wide processing window and high flow. Parts perform in environments requiring a maximum constant use temperature of up to 130°C.

SABIC says potential cost savings up to $2 per vehicle can be achieved by avoiding the use of complex tools, potentially enabling faster molding, part integration and weight-out. LEDs are relatively cold light sources, but LED headlamps can still generate considerable amounts of heat. SABIC has added new grades to its existing LEXAN high flow XHT portfolio: LEXAN XHT1171, XHT2171 and XHT3171, that provide particularly high flow for high temperature PC resins.

A recent molding study carried out by SABIC indicated that a bezel molded in LEXAN XHT2171, for example, could weigh 37 percent less than a bezel in a rival PBT material, thanks to possible reductions in wall thickness and the lower density.

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