Automotive OEMs demand increase for extruded TPV weather seals, interior TPE applications

Thermoplastic elastomers (TPEs), mainly thermoplastic polyolefins (TPOs) and thermoplastic vulcanizates (TPVs) are already a mainstay in today’s automobiles.

But according to one industry insider, most of the innovations are not coming from plastics processors, the Tier One suppliers, or the automotive OEMs — especially in the case of the Big 3 — but from the materials suppliers.

However, this probably doesn’t come as a surprise to most processors supplying the automotive industry.

If a processor realizes cost savings with a new material, manufacturing process or design, the OEM demands the cost savings be passed along to them. This has provided little incentive for processors to innovate, especially when demands for cost reductions have left them with fewer or no resources to devote to research and development (R&D)

“The automotive OEMS aren’t against innovation per se, just that if, in the end, it will cost them anymore than what they’re already paying, they’re not interested,” said John Caccese, a plastics industry marketing consultant in Lords Valley, Pa. “Even if it costs the same, they still expect continual cost and/or productivity give-backs that wind up stifling the effort to bring innovation to the market.”

However, processors need to stay abreast of developments in automotive applications for TPEs, especially when the market continues to grow. Then, when an OEM requests an extruded TPV weather seal, they can quickly adapt, or if an RFP for such a product comes along, it can be pursued confidently.

“TPEs and TPVs have been in automotive for 20 to 25 years. We are really starting in on the next generation of products,” said Scott Israelson, global strategic marketing manager, automotive, Santoprene Specialty Products Group of ExxonMobil Chemical (known as Advanced Elastomer System, LP in North America), in Detroit, Mich.

Cost reduction is a leading driver in the automotive market, and that is shaping new developments in TPEs, he added. Automotive OEMs are moving to modular assembly systems for parts consolidation, especially for applications like car doors, weather seals and for under-the-hood components, Israelson said.

“The low hanging fruit of material substitution (with TPEs) has reached the saturation point, but now with cost being a stronger driver, it’s forcing new innovations,” Israelson explained.

Materials suppliers have responded to this need by improving processability for faster cycle times, improving bonding technology to allow TPEs to better adhere to other materials, and through colour-matching paint and colourants for TPEs with automotive OEM palettes. And as long as the automotive industry continues to heavily invest in TPEs, the incentive to improve TPEs for automotive applications will continue.

An analysis of the worldwide market for TPEs by the Freedonia Group in Cleveland, Ohio shows the automotive industry is the biggest user of the materials.

“Motor vehicles will remain the largest market for TPEs at the global level,” the study said. “The sustained solid gains forecast for TPEs in this market are attributable to the development of new products for exterior panels (e.g. body seals) and interior (e.g., instrument and door panel skins) applications at the expense of ethylene-propylene-diene monomer (EPDM) and polyvinyl chloride (PVC).”

Of all available TPEs, TPVs are experiencing the strongest growth rate, Israelson noted. In fact, extruded TPV body seals, or weather seals, is rapidly become the ‘Holy Grail’ for TPVs in automotive.

SEALING THE DEAL

Traditionally made of EPDM rubber, TPV weather seals have been commonplace in Europe for quite some time. North America’s market has just been picking up in the past couple of years, said Jim Haseley, marketing manager, TPV at Solvay Engineered Polymers in Auburn Hills, Mich.

“There are sub-segments within the weather seal market that we’re just beginning to penetrate,” Santoprene Specialty Products’ Israelson said. “We’re targeting foam seals around the trunk and door, and we’re seeing a lot of growth in corner molding applications.”

TPV corner molding applications have gained traction due to the existence of better bonding materials that allow TPVs to adhere well to the injection-molded corners, he noted. Benefits to automotive OEMs include better esthetics than rubber, and weight reduction, as well as recyclability, he added.

Solvay, for example, offers corners that are bondable to either TPVs or EPDM. In fact, Solvay’s Haseley said weather seals are the firm’s primary focus for TPVs and it is positioning itself as a one-stop-shop where processors can purchase an all-TPE ‘system’ for each component of a weather seal. These materials can be co-, tri- or quad-extruded as per the application’s requirements.

“If the profile extrusion needs a rigid carrier or a structural part, we would offer our filled high-modulus TPOs,” he said. These weather seals would generally be co-extruded with a TPV, which would provide the sealing function.

LONG AND LEAN

However, the high-flow and super high-flow grades streaming onto the market, have given TPEs a boost for long skinny parts like exterior ear dams below bumper fascia, and roof gaskets. Roof gaskets injection-molded with TPV can be used for sealing and scratch-resistance when placd under a roof rack, Haseley said

Improved materials are not the only piece of the puzzle enabling a wider adoption of TPEs. Santoprene Specialty Products’ Israelson said the emergence of robotic extrusion could open the door for more innovative co-extruded applications.

GETTING THE INSIDE STORY

TPEs, especially TPOs, have also driven their way into the hearts of automotive OEMs, in interior applications.

However, it’s not just the soft-touch properties — although esthetically pleasing – responsible for adoption of TPEs inside the car; there is a practical reason as well.

Consolidating materials so they can be recycled together is spurring automotive OEMs to turn to TPOs and TPVs and leave PVC behind, Solvay’s Haseley said.

Interest in recyclability has been driven globally by strict regulations from the E.U., which make manufacturers fiscally responsible for recycling the products they make.

Additionally, the prevalence of coloured TPEs for applications like interior cosmetic trim welts, thin mats and coin trays are increasing.

BUILDING THE FUTURE

Arkema is also not sitting still when it comes to improving the colour of TPE parts, but that’s just one of the many possibilities with its new BlocBuilder technology — and it’s not limited to applications for TPEs.

Using controlled radical polymerization technology, BlocBuilder provides an inexpensive way to develop acrylic block copolymers, opening the door for a new generation of acrylic-based thermoplastic elastomers (TPEs). Essentially, it’s a nitroxide-based reaction controller and a free radical initiator bundled together in one molecule.

Unlike acrylic-based TPEs that are commercially available, those developed using BlocBuilder would be tri-block copolymers, said Mike Mendolia, manager of commercial development for controlled radical polymerization technologies at Arkema.

Plus, BlocBuilder can be used to create TPEs with properties tailored for specific applications.