BASF Demonstrates PBT Grade for Headlights Featuring Extremely Low Outgassing

The new Ultradur® High Gloss B4570 is one of the numerous new engineering resins from BASF making their appearance at the trade fair FAKUMA 2011 being held in October in Friedrichshafen, Germany.

Compared to existing PBT grades (PBT: polybutylene terephthalate) for headlight bezels, this material offers not only high gloss. It is specifically characterized by its extremely low outgassing at temperatures up to 160°C over an extended period of time. Like related resins in the Ultradur family, the new material can be metallized without difficulty and is immediately available in Europe and Asia.

A fogging test developed by Toyota is considered one of the most challenging when it comes to formation of deposits on headlight lenses. When the outgassing of the new Ultradur® High Gloss B4570 from BASF is compared with that from conventional PBT grades in this test, the result is a so-called haze value of 2.2 and a clarity value of 88 on a glass plate after 24 hours at 160°C. Both values together characterize the new plastic as having minimal outgassing. It is thus very well suited for reflectors and bezels in the challenging designs of modern headlights where the lenses are expected to remain clear. 2011 Foto: BASF

When standard PBT grades that outgas at high temperatures are used for reflectors or bezels of especially hot headlights, fogging of the lens may result and reduce the light output of the headlight. On the one hand, automobile headlights have now become design elements with complex aesthetic forms.

At the same time, the space in which the headlight must fit has become smaller. Both effects can lead to rising temperatures, which cause outgassing of the bezel material.

The substances released during outgassing condense on the clear headlight lens and cause fogging. With the new Ultradur® High Gloss, hardly any outgassing can be detected even at very high temperatures. The material expands the PBT product line for headlights from BASF, which to date consisted of Ultradur B4520 for standard applications, Ultradur B4560 with optimized release characteristics and Ultradur S4090 with especially good flow properties and a minimal tendency to warp.

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