TPV Performance Advantages Over Widely Used Non-Crosslinked TPEs Are Available For First Time At Very Low Hardness Levels

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Very Soft Uniprene® Compounds Introduced at NPE 2003 Exhibit Better Mechanical Properties at High Temperatures and Greater Chemical Resistance than Styrenic TPEs

CHICAGO, June 23, 2003: A new series of Uniprene® compounds makes the outstanding performance of thermoplastic vulcanizate (TPV) elastomer compounds available for the first time at very low hardness levels, it was announced today at NPE 2003 by Teknor Apex, Thermoplastic Elastomer Division (Booth 9755).

While the softest conventional TPVs are rated at around 45 durometer on the Shore A hardness scale, three grades in the new Uniprene 2000 Series have durometers of 15, 25, and 35, according to Keith G. Saunders, Program Manager. “Until now, manufacturers who needed exceptional softness in applications like grips, gaskets, and weatherstripping were limited to non-crosslinked thermoplastic elastomers [TPEs] such as those based on styrene block copolymers [SBCs],” Saunders said. “The new Uniprene compounds not only provide comparable softness but perform better at elevated temperatures.”

The outstanding rubber-like properties of TPVs are attributable to their highly crosslinked elastomer component (typically EPDM rubber), which is finely dispersed in a thermoplastic such as polypropylene. “TPVs generally provide a higher-performance alternative to non-crosslinked styrenic or olefinic TPEs,” said Saunders, who noted that Teknor Apex will price Uniprene 2000 Series compounds at about 25% more than SBCs of comparable durometers.

New Uniprene® Grades Are Tough and Rubber-Like at Both Temperature Extremes
“Uniprene 2000 Series compounds exhibit brittle points below -60 °C,” Saunders said, “and they are the only super-soft TPEs that also provide the elasticity and outstanding performance that distinguishes TPVs at elevated temperatures.”

In terms of compression set, a key measure of rubber-like elasticity, the new Uniprene grades outperform standard SBCs of comparable hardness at elevated temperatures.
(Compression set is roughly defined as the extent to which a test sample does not recover its original shape after being deformed, with lower values indicating greater elastic recovery.)

The table below summarizes these property advantages.

Property	15 Shore A Compounds		25 Shore A Compounds
	Uniprene® 2005	SBC	Uniprene® 2012	SBC
Compression set, 22hr., % 23ºC 70ºC 100ºC	10 22 54	11 45 90	11 23 44	12 42 60
Continuous use temperature, ºC	105	90	105	90

Other advantages over comparable-hardness TPEs cited by Saunders include greater resistance to solvents and oils, improved abrasion resistance, and a softer, dryer feel. “In natural form, Uniprene 2000 Series compounds have a very light color, are easily colorable, and do not require pre-drying,” Saunders said. “They exhibit a processing viscosity that is ideal for most injection molding applications, and in over-molding and two-shot operations they adhere well to most olefinic and styrenic substrates.” The compounds can also be extruded or coextruded.