Optimizing use of TPEs

North American demand for thermoplastic elastomers is forecast to rise 6% per year by 2007, reaching a market value of $2.7 billion, according to a recently released report by The Freedonia Group. The report notes that TPEs are continuing to displace thermoplastics and metals, especially in situations where recyclability, low toxicity, ease of processing and weight savings are important. Materials suppliers are helping to accelerate this demand with new lines and grades of TPEs that provide processors with hosts of benefits, including improved performance and ease of processing.

Specialty compounder RTP Company has introduced a new series of TPE compounds formulated for specific properties and optimized performance. The first commercial grades to be released, RTP 6002 and RTP 6003 have been specifically developed for improved bonding in two-shot or insert over-molded applications. Each product is optimized for bonding to a specific substrate. RTP 6002 is formulated for improved bonding to PC, ABS and PC/ABS, while RTP 6003 offers better bonding to PC/PBT and PC/PMMA. Both products offer processors a comfortable processing window.

“For a successful bond to occur during over-molding it’s critical to have the proper processing and design conditions,” says Paul Killian, RTP product manager for elastomers. “One of our goals during development was to offer products that have the widest possible processing window for the injection molder.”

Bayer Polymers is expanding its line of aromatic Desmopan thermoplastic polyurethanes with four new highly-transparent grades. The grades provide superior transparency, even with thick walls, as well as increased UV stability and a significantly lower yellow value.

The new TPUs, which can be injection molded or extruded, are primarily targeted for ski boots and sports and leisure footwear, applications for which good abrasion resistance is required. The new Desmopan TPU grades can also be enhanced with Bayer Polymers’ Fantasia colors and special effects technologies.

Atofina has launched two new thermoplastic elastomers for specific injection molding applications. Finaclear 636 has been developed specifically for the injection molding of transparent coat hangers. The new grade meets the American VICS standard which establishes optimum coathanger properties, such as flexibility and temperature stability. Finaclear 636 is always used in blends and can be diluted up to 40% in crystalline polystyrene.

Primarily used in blends of polystyrene, Finaclear 609 is particularly suited to the manufacture of food boxes and containers, transparent parts for unbreakable toys and desk accessories. The grade provides easy mold filling and mold release.

Advanced Elastomer System’s thermoplastic vulcanizate (TPV) plays a critical role in an award-winning industrial drum, Click Pack. The drums, manufactured by CurTec Netherland BV, are currently being used by pharmaceutical and chemical industries, and are available in 15-, 20- and 25-L sizes. The Click Pack screw lid provides an air- and water vapor-tight seal with an external double sealing rim. Santoprene TPV is used for the closure gasket inside the polypropylene lid. The lids are produced using two-shot injection molding with the TPV being permanently heat-welded to the lid during the molding process.

The braking system on General Motors’ next generation of mid size trucks is designed with a lightweight, self-retaining spacer made of DuPont Hytrel thermoplastic polyester elastomer. The spacer, designed and developed by Dephi Corp., helps significantly reduce assembly time, weight and offers performance advantages over the existing spacer.

“Helping to reduce component weight and improving design for assembly without sacrificing performance are crucial industry-wide goals,” said Michael Vermoesen, senior project engineer at Delphi.