New TPEs Adhere Better to Nylon than Other Over-Molding TPEs and Make Possible Insert Molding Even over Unheated Substrates

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In Addition to Lower-Cost Insert Molding, Tekbond® 6700 Series Compounds Process Equally Well in Two-Shot Molding and Exhibit Similarly Strong Adhesion to Nylon

CHICAGO, June 23, 2003: Thermoplastic elastomer (TPE) compounds that achieve stronger bonds to nylon than currently available TPEs for over-molding enable manufacturers of handles, grips, and other parts to use insert molding rather than more complex and costly two-shot processes, it was announced at NPE 2003 by the Thermoplastic Elastomer Division of Teknor Apex (Booth 9755). The compounds also process well in two-shot molding, according to Edwin Tam, Senior Market Manager for consumer products.

Unlike competing styrenic TPE alloys and thermoplastic vulcanizate (TPV) elastomers formulated for nylon over-molding, the new Tekbond® 6700 Series compounds bond well to glass-filled and unfilled nylon 6 and 6/6 even when the substrate is at room temperature, Tam said. This eliminates the need for pre-heating substrates. While both TPEs and nylon are hot during two-shot over-molding and form a strong bond, this process requires costlier equipment and tooling than insert molding.

“Tekbond 6700 compounds enable molders to take on short-run jobs without the big investment entailed by two-shot molding,” Tam said. “And since these new TPEs bond equally well to nylon in both insert and two-shot molding, processors who employ both techniques need to stock only one compound.”

Recommended applications for the new compounds include grips, handles, and other “soft-touch” or over-molded components in appliances, automotive, mechanical goods, and power and hand tools. Compounds in an earlier Tekbond series, the 6000, are already in use with glass-reinforced nylon for power tool grips produced by two-shot molding. The 6700 series is based on “completely different” polymer technology from that in the 6000 series, Tam said.

The new Tekbond 6700 Series includes Shore A hardness grades of 45, 55, and 65. In insert-molding tests with a competing styrenic-alloy over-molding TPE of similar hardness, Tekbond grade 6700-65 exhibited up to three and a half times the bond strength with nylon. All three new compounds show excellent adhesion to nylon even after immersion in brake and transmission fluids, Tam said. In addition, they exhibit a wider processing window than comparable TPVs, and their lighter natural hue permits lower loadings of colorant.

Tekbond 6700 Series TPE compounds are available in natural, pre-colored, and UV-stabilized grades.