AMINE-FREE CATALYST SYSTEMS FOR AUTOMOTIVE INSTRUMENT PANELS

The requirements, composition and performance of modem automotive instrument panels have been thoroughly examined. In particular the antagonistic behaviour of conventional semi-rigid PU foam with the decorative skin cover made from either an ABS/PVC vacuum formed sheet or slush moulded PVC powder was investigated. Extended exposure to high temperatures of such composites has been shown to result in staining and embrittlement of the skin material. ICI Polyurethanes, in conjunction with ICI EVC, has carried out an extensive programme of work to identify the mechanisms of discoloration and embrittlement. This paper summarises the results and shows the importance of PVC stabilizers, pigments and plasticizers and the use of amine catalysts in the polyurethane foam as the critical factors. Although amine-free catalysts were known the resulting polyurethane foams did not have the right balance of foam structure, physical properties and processing characteristics. Thus a novel amine-free catalyst system was developed which gave excellent staining resistance whilst maintaining the other foam properties and giving the required processing characteristics.