ABSTRACT
Sophisticated noise control techniques are in great demand for modem automotive interiors. The increasing use of cell phones and newly emerging voice control applications as well as the greater perceived comfort of a quiet vehicle interior fuels this demand [1]. Classical noise control measures such as dash insulators, carpeting, seating and other acoustically absorptive interior parts are already in wide use. However, cavity filling PU foams are a relatively new class of sound abatement materials [2], [3]. These foams reduce the propagation of noise through the hollow spaces in the vehicle body shell [4].
Bayer Corporation has developed a PU foam system, which will be marketed by Orbseal to Automotive OEM’s. It expands to 5000% of its initial volume. The low-density foam resulting from the high expansion rate allows for a complete acoustic seal and provides material savings of up to 30% while still meeting OEM requirements on Insertion Loss. The new foam system was specifically designed to meet OEM demands for robustness and safety when dispensed on an assembly line in a paint shop general assembly application. As a result, this foam provides a low foam surface temperature (<137 °F) and a rapid viscosity build up to overcome sagging problems. The emission of residual MDI during the foaming process is extremely low even though the foam is produced using a 1:1 mixing ratio.
