The ESP 9, latest generation of Bosch's electronic stability program (ESP), is part of the safety package in many vehicles today. Its control housing is molded from the especially hydrolysis-resistant Ultradur B4330G6 HR from BASF: This special compound from the PBT family satisfies the very demanding requirements faced by engineering plastics in hot-humid environments.
Severe test conditions
The new UltradurB4330G6 HR retains its material properties such as high strength, elasticity and impact strength during long-term testing at 85°C and 85% relative humidity. It withstands test periods of over 5000 hours without noticeable characteristics of aging. This is several times longer than the hydrolysis-resistant PBT used to date. Many materials compared already show significant degradation after only one third of this time.
As unremarkable as the housing for the new ESP 9 electronic stability program control module from Bosch may appear, the requirements to be met by the housing material are extremely challenging. The new, especially hydrolysis-resistant PBT grade (PBT: polybutylene terephthalate) from BASF offers very high reliability: Ultradur® B4330G6 HR can withstand 5000 hours at 85°C and 85% relative humidity without noticeable decreases in its material properties, remains stable during processing, and is suitable for both laser welding and laser marking. Photo: BASF - The Chemical Company, 2011.
Severe test conditions for electronic components in automobiles are no longer unusual today. As the result of continual downsizing, the operating temperature under the hood has increased continuously. In addition, electronic components from global suppliers are used in automobiles worldwide and for this reason must pass tests based on all international standards and test conditions.
Processing stability - laser marking - laser welding
An additional benefit of the hydrolysis-resistant Ultradur is its stability during processing. Its rheological behavior, i.e. its flow characteristics, remain stable even after longer residence times in an injection molding machine. This is not something that can be taken for granted, as many additives that are used to improve the hydrolysis resistance can reduce the flowability quite considerably, with flowability worsening as the residence time and processing temperature increase.
The material is also suitable for laser marking and acts as a very good absorbing partner during laser welding. Suitability for laser marking is of special importance for the ESP 9 from Bosch, since considerable information about the component must be entered in the data matrix code on the plastic by means of a laser. At the same time, laser weldability is necessary in order to seal the cover (also molded from Ultradur) tightly after the electronics have been installed. Ultradur B4330G6 HR is available from local production in Asia, Europe and the NAFTA region