Leverkusen - Sandwiched between a decorative skin and a carrier, Bayfill® foam systems from Bayer MaterialScience AG comply with strict safety requirements while also providing high levels of comfort in vehicle interiors. Furthermore, quick-hardening systems mean that molded parts can be produced even more economically. Whereas the polyurethane filling foams used previously take up to 180 seconds to harden, Bayfill® systems from Bayer MaterialScience enable demold times of around one minute, considerably shortening production cycles.
To comply with the vehicle manufacturers' specifications, ever lower emissions are required in the passenger compartment. One method for determining volatile organic compounds (VOCs) and the fogging behavior of materials is VDA 278. This requires a VOC value below 100 ppm, with a FOG guide value of 250 ppm. The semi-rigid foams made of the polyurethane raw materials Bayfill® VP.PU 52IF16 and Desmodur® 44V20LF meet these requirements and are currently used in the Mercedes Benz C Class.
Passenger airbags are increasingly being integrated into instrument panels. The component contains an invisible laser perforation, which enables the airbag to inflate with complete reliability. The semi-rigid foams must be extremely tear-resistant to avoid particulate matter from being dispersed when the airbags are deployed. For the instrument panel of the Mercedes Benz A Class Bayer MaterialScience has therefore developed a foam with a considerably higher elongation at break than previous systems. The foam is made from the polyurethane raw materials Bayfill® VP.PU 54IF25 and Desmodur® VP.PU 58IF06.
The optimized elongation behavior ensures that the tear occurs along the perforated line when the airbag is deployed both at low (-30°C) and high (80°C) temperatures. Additionally, the thermal foam stability has been improved, enabling sharply delimited small-diameter perforation channels during laser treatment. This prevents the perforation from being visible on the decorative layer.
It was also important that the instrument panels are softer and more comfortable to the touch than before. The compressive strength of the A Class foam was adapted to meet this requirement. Instrument panels made from Bayfill® VP.PU 54IF25 and Desmodur® VP.PU 58IF06 exhibit comfort you can feel.
JR Interiors GmbH & Co. KG uses the innovative wet-in-wet process to produce the instrument panels at its plant in Germany. Immediately after the polyurethane decorative layer is sprayed into the mold using a special technique, robots pour in the semi-rigid foam system. As it cures, the foam forms a stable, resilient bond between the skin and the carrier. The hallmark of the tear-resistant Bayfill® system is its enhanced adhesion to the external skin. It also complies with DaimlerChrysler's rigorous specifications in terms of its aging resistance.
We are pushing development forward," says Josef Beuth, an instrument panels expert at Bayer MaterialScience. We are now testing a Bayfill® system in which the isocyanate components can also be stored at comparatively low temperatures. This system has enabled us to further improve emission behavior. The VOC and FOG values of the foam are now below 50 ppm."
Pic shows - Greater passenger safety and comfort: Instrument panel with a layer of Bayfill® polyurethane foam from Bayer MaterialScience.