JEC COMPOSITES MAGAZINE - Issue #45 - November/December 2008 - 48

FEATURE “Automotive” compression mould with a textured bottom section using the inmould-coating process (IMC), followed by a layer of the elastic, wear- and tear-resistant polyurethane elastomer Baytec®. The above-mentioned polyurethane sandwich combining paper honeycomb, glass fibre mats and the spray system serves as the backing layer. With this version of the process, the laborious task of covering the trunk floors with fabric becomes redundant, leading to considerable cost savings. The resulting soft-touch surface has a high-quality appearance, is robust, and easy to maintain (Fig. 3). g…/… New sandwich composites: for lightweight construction in the automotive industry Polyurethane sandwiches combined with Trocellen foam Fig. 2: Trunk floor of the Volkswagen Tiguan. New thermoplastic honeycomb core A new process variant was recently added to the range of applications for polyurethane sandwich composites. The lightweight core elements used so far were mostly made of paper honeycomb, but a special thermoplastic honeycomb made from polycarbonate was developed for this purpose. The resulting polyurethane composites are insensitive to damp and moisture. They are therefore suitable for exposed applications inside and outside the vehicle bodywork such as backrests, seat shells and wind deflectors for trucks. The materials and process know-how for the new composites have been optimized, so that BaySystems is in a position to enter into application-specific cooperative development agreements with automotive system suppliers and OEMs. There is also another way to produce a soft-touch surface. Together with Trocellen®, a global supplier of cross-linked polyolefin foams, Bayer MaterialScience has developed sandwich composites that also have a marked sound-insulating effect. To manufacture these composite parts, a layer of closed-cell Trocellen® vertical polyethylene foam is placed in the mould, followed by the sandwich consisting of the honeycomb core and glass fibre mats sprayed with the polyurethane system. The entire composite is then compressed, whereby the polyurethane bonds the individual components permanently and durably to each other. Special surface treatment of the foam ensures excellent adhesion to the polyurethane sandwich. The high heat resistance and good resilience of the physically crosslinked foam means that it can also be used in a press. No additional adhesive is needed, not even when the composite is provided with a decorative facing layer like a highly scratchproof PVC surface (Fig. 4). Fig. 3: This polyurethane sandwich composite with a grained soft-touch surface was manufactured in a single processing step. Fig. 4: Sandwich composite element combining honeycomb core, glass fibre mats, polyurethane spray system and Trocellen® foam. Composites with a soft-touch surface The capabilities of the polyurethane sandwich lightweight construction process have now been considerably extended to include a number of new alternatives. Lightweight trunk floors for cars can be manufactured in a single processing step and produced directly with a coloured, textured soft-touch surface. An abrasion-resistant polyurethane coating is first sprayed into a Acoustic measurements clearly illustrate the sound-insulating effect of the composites. Figure 5 shows the measurements obtained on the window test rig for various composite structures. The simple sandwich combining paper honeycomb, glass fibre mats and the polyurethane system is compared with composites that have been additionally provided with one or two foam layers. Thus, the foam absorbs sound by an additional 4 dB. jec composites magazine / No45 November-December 2008

JEC COMPOSITES MAGAZINE - Issue #45 - November/December 2008

Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #45 - November/December 2008