Multicomponent molding and coextrusion are coming to thermoplastic elastomers - and the technologies will spur much greater use of TPES in the huge automotive market, according to consultant Robert Eller.
Automotive is already the largest consumer of TPEs, accounting for 40-50 percent of total TPEs used worldwide, said Eller, president of Robert Eller Associates Inc. of Akron, Ohio.
TPEs are growing rapidly in automotive sealing, where they are displacing rubber by offering potential cost savings, Eller said during a TPE Conference in Cologne.
He credits Jyco Sealing Technologies of Dexter, Mich., for its use of thermoplastic vulcanizate seal for the 2007 Dodge Ram pickup truck - the first time TPV penetrated into a dynamic body-seal application.
More automotive breakthroughs are coming for TPEs, he said. Eller listed hose and tubing, boots and bellows, constant velocity joints and even belts. One example, a coextruded crank-case ventilation hose, uses an outer layer of flexible TPV over an inner layer of nylon.
Two-shot injection molding of TPEs got its start in a classic consumer product, the soft-touch toothbrush. A two-shot razor is another common example. But brand-new two-shot and even three-shot applications include much larger parts like interior car door panels. A two-shot injection process can be used to mold the three-layer trim part, forming a TPE skin, foam and substrate.
Eller said TPE instrument panels are coming. Injection molded TPE and foam will compete with thermoformed instrument panel skins, he said.
Studies by Robert Eller Associates show a trend for shortening the path between TPE production and the final assembled car part. ``We see the growth of in-house compounding, by the automotive Tier 1s, of TPEs,'' Eller said.
Eller also outlined the rapid globalization of the TPE industry, especially as it spreads into China, the world's fastest-growing auto market. Most major TPE compounders have established operations in China, and these big players serve multinational customers there.
A new class of domestic Chinese compounders has emerged, to supply lower-cost, more-basic TPEs to Chinese processors. Eller said they will improve to become global competitors eventually.
Companies from Japan, Korea and Taiwan also have set up beachheads of TPE production in China, he said. Eller called India ``the next big growth market for TPEs,'' with demand driven by automotive and consumer products.
North America remains a key TPE market, though the region is growing more slowly, he said. He predicts that, largely because of the weak U.S. dollar, Western European and Japanese resin companies will keep up a strong flow of capital investment and technology into North America.
Allod Werkstoff GmbH & Co. in Burgbernheim, Germany, compounds specialty TPEs, with an emphasis on joining TPEs to engineering plastics, rubber and glass and other materials.
Allod has developed adhesion-modified TPEs under its Allruna line for applications such as molding TPE end caps onto rubber parts or molding a TPE gasket over a glass mirror, said Ger Vroomen, marketing and sales director.
The firm is developing modified TPE materials that do not use any primer of special adhesive. The next big challenge is TPE adhesion to large sections of glass, he said. Possible applications included fixed rear windows for cars, and components for refrigerators. Currently, those types of parts require assembly of separate components in a separate step, Vroomen said.
GLS Corp. of McHenry, Ill., has developed two TPEs that adhere to a large number of resins, including polypropylene, polystyrene, high-impact PS, polycarbonate, PET, ABS, PC/ABS, copoly- ester and polymethyl methacrylate, said John Simons, GLS business manager for Europe.
``We finally have a universal product that bonds to a lot of the engineering plastics in the industry,'' Simons said.
Houston-based Kraton Polymers LLC also is working on the adhesion issue. Jeff Southwick, global research manager, said an experimental Kraton with improved overmolding adhesion is in the pilot plant stage.
``We think we've got a raw material that's really tailor-made for overmolding compounds,'' he said.
Smithers Rapra Technology Ltd. of Shrewsbury, England, sponsored the TPE conference, held in October.