In this age of lightweighting vehicles to meet ever stricter Corporate Average Fuel Economy standards in the automotive industry, carbon fiber is looking to come out a big winner. Carbon-fiber-reinforced polyurethane (PUR) composites offer huge potential for reducing vehicle weight and, thus, CO2 emissions. Covestro (Leverkusen, Germany), formerly Bayer MaterialScience, has developed a new Baydur matrix system for carbon-fiber structural components that has three times the energy absorption potential of comparable resins. It is therefore able to provide an extremely high level of occupant safety in the event of a collision.
Automakers and direct suppliers also benefit from high productivity, because the components are manufactured efficiently using the high-pressure resin transfer molding (HP-RTM) process. “We developed the polyurethane system with high-profile partners in the automotive industry and optimized it for the latest requirements,” explained Detlef Mies, expert for RTM composites at Covestro. “Our partner ThyssenKrupp used it to manufacture prototypes at its Composites Technical Center in Dresden. They have performed extremely well in material testing.”
Carbon-fiber content is approximately 54% by volume. The HP-RTM process has proved effective for manufacturing robust composite parts in volumes in the low hundreds of thousands. Wovens or fabric with oriented carbon fibers are first laid in the open mold, which is then closed. In a matter of seconds, the low-viscosity PU system is injected into the closed mold under high pressure. Given the high reactivity of the PU system, the composite cures rapidly and fully, and the component can be demolded and processed over a short period of time. Cycle times are just a few minutes and achieve consistently high quality.
Various PU matrix materials from Covestro are already being used successfully to manufacture composite materials via RTM, pultrusion and other process technologies. Material data are available on request.
Covestro will be showcasing prototypes at Fakuma in Friedrichshafen, Germany, from October 13 to 17, 2015.