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BAYER POLYMERS' POLYURETHANE SYSTEMS AND PROCESSING TECHNOLOGIES COMBINE TO MEET AUTOMAKER NEEDS
Bayer Polymers has responded to this need by offering the Baypreg® F polyurethane system that is a combination of polyurethane chemistry adapted to work best with natural fibers and processing technology - NafpurTec™ - developed by Bayer's Hennecke Machinery unit. The Baypreg F polyurethane system can produce a cost-effective composite part; in some designs, such as door panels, the Baypreg F natural fiber composite can cost less than other substrate systems. Parts made using Bayer's system can be found in vehicles from Audi, BMW and Mercedes-Benz. These parts include door panels, spare tire covers, load floors, sunshades and various interior trim pieces. Other application possibilities include interior rear parcel shelves and exterior light truck tonneau covers. The Baypreg F system utilizes different combinations of reinforcing mats and honeycomb cores to manufacture interior composite parts for vehicles. The resulting parts provide good strength and light weight - as much as 45 percent lighter than equivalent parts made with conventional injection molding materials. Superior Capabilities, Less Cost 'Natural fiber reinforced polyurethane parts can often surpass glass-reinforced materials' properties and provide a cost-effective alternative,' said Terry D. Seagrave, market channel manager for NAFTA Automotive Composites at Bayer. 'For the auto industry, this approach is finding success in interior applications to help meet the continuing demand for lighter weight vehicles while maintaining quality.' The Baypreg system uses a natural fiber mat of flax and sisal in equal amounts, although other fibers such as hemp also work effectively. The mat is supplied in widths suitable for the parts being made, and weighs from 700 to 1,200 grams per square meter. The mat is first dried to be sure the moisture content is below 3 percent, then cut to size. The cut mat is then sprayed on both sides with the polyurethane mixture, using a high-pressure metering device and self-cleaning mix heads, and placed in a heated mold. The closed mold shapes the part and the heat cures the polyurethane. The Baypreg process uses metal molds due to the high pressing force, the temperature used to cure the polyurethane (about 130 degrees Centigrade), and the use of mold release additives in the mixture that are effective only in metal molds. Examples of parts made with this technique include interior door panels with wall thicknesses of 1.5 to 2 mm. A similar approach is used for making parts with an aluminum or paperhoneycomb as a core or spacer to create a sandwich panel composite. Either natural fiber mats or glass fiber mats form the two outer surface layers, and the entire 'sandwich' is sprayed with the polyurethane mixture and placed in a mold. The closed mold forms the part and the heat cures the polyurethane, although this takes somewhat longer due to the insulating properties of the honeycomb core. Representative parts made with this technique include sunshades and spare tire covers. Bayer's Baypreg polyurethane system, combined with Hennecke's NafpurTec equipment, produces strong, high-quality parts that are significantly lighter than competing materials. http://www.bayermaterialscience.com
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