Two new bonding and material technologies have been introduced to expand the use of hybrid plastic/metal composites for automotive applications.

Two new bonding and material technologies have been introduced to expand the use of hybrid plastic/metal composites for automotive applications. Such hybrids have been made by overmolding stamped sheet metal with injection molded plastic (typically nylon). Up to now, it has been usual practice to mechanically lock the two materials together by injecting plastic through holes in the metal. Bayer MaterialScience, Pittsburgh, now says it can improve the joining of hybrid materials by using thermoactivated adhesives based on its Dispercoll U polyurethane dispersions. A 100-micron layer of the water-based PUR dispersion is first applied to the metal insert and dried. Later, during injection molding, the hot melt of the thermoplastic material activates the adhesive to bond to the plastic. Good initial strength is achieved at 70 to 80 C and a crosslinking reaction ensures final bond strength. Tel: (412) 777-2000 . PTDirect: 468PT Meanwhile, Lanxess Corp., Pittsburgh, is extending the definition of such overmolded "hybrids" by replacing the metal with thermoplastic composite sheet, creating an all-plastic part. Lanxess is working with Bond-Laminates GmbH in Brilon, Germany, which makes Tepex reinforced sheet from glass, carbon, or aramid fabric embedded in nylon. The sheet is first thermoformed and then reheated to just below its melting point before being encapsulated with more nylon via injection molding. Because the sheet is preheated, good adhesion is said to result. Lanxess maintains that the process is economical because tooling investment for thermoforming is less costly than for metal, particularly in small- to medium-size production. Lanxess: (412) 809-1000/PTDirect: 411NZ . Bond-Laminates: +49 2961-96628-0/www.bond-laminates.com

Bayer MaterialScience
100 Bayer Rd. Pittsburgh, PA 15205-9741
Phone (412) 777-7677 Fax (412) 777-4478