Lear Corp. has developed two new poly-mer materials to be used in some of Lear's future interior-trim products including door panels, pillars, and trunk trim. With properties that the company claims offer optimized occupant safety potential, these ultra-lightweight and recyclable polymers could save vehicle manufacturers both weight and money. Because they are composed of natural fibers that are replenishable, the two polymers are also environmentally friendly.
The two innovative polymers, natural fiber acrylic and natural fiber polypropylene, were developed at Lear's Manufacturing Operation Division's development center in Ebersberg, Germany, where materials development focuses on vehicle safety and weight reduction.
"With these two new polymers, Lear is addressing key material needs for European vehicle manufacturers, who want to reduce weight while contributing to passive safety," said Randall Carron, President International Operations for Lear Corporation.
The natural fiber acrylic polymer has been developed specifically for automotive door panel trim, package tray, and trunk applications. A "modular binder system" allowing stiffness and impact resistance to be varied according to need offers flexibility for customers. The lightweight properties of the acrylic polymer also could make it suitable for a range of other automotive interior applications in the future.
"In our extensive testing we have reached a record low weight savings of greater than 40% when compared to conventional injection molded substrates," said Armin Schwaighofer, Material Development Engineer, Lear's Manufacturing Operations Division. "The bending strength of this polymer has proven to be very high, which puts it among the very best in the market right now."
Selected after months of research, the unique formula consists of acrylics and up to 70% of plant fibers. According to Lear, it also offers an improved environment for production workers compared with glass-fiber-based polymers.
The natural fiber polypropylene is made from plants that are combined with polypropylene. In this natural fiber, Lear replaced the flax fiber with kenaf, hemp, and jute. Additional improvements in mechanical properties were achieved with the use of coupling agents that improve the chemical bonding of the fiber and polypropylene. Lear claims that the new material's enhanced elasticity provides high impact resistance. This new "elastic" environment could mean improved occupant safety by eliminating potentially sharp edges caused by conventional brittle panels that may fracture during an accident.
"Broken interior panels in accidents can sometimes be serious. Our tests have shown that, in an accident, interior door panels furnished with our natural fiber polypropylene are more 'impact friendly,'" said Ulrich Probst, Vice President and General Manager, Lear's Manufacturing Operations Division.
Significant cost savings are achieved through the thermoplastic properties of the polypropylene, which allow the material to be reheated. Simplified manufacturing has been made possible whereby the natural fiber polypropylene is covered with the actual surface material in just one step.
Jean L. Broge
AEI September 2000
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