Michael Bednarik has a poster hanging in his Akron office detailing all the weatherseals that go on a vehicle.
``The nice thing about that is, somewhere in the world on a car ... every one of those seals is made in [thermoplastic vulcanizates],'' said the ExxonMobil Chemical Co. global weatherseals manager for the firm's specialty elastomers business.
That wasn't the case until recently, said Bednarik, who also uses the poster as he speaks with customers around the world so they can discuss the parts using a common language.
The company's Santoprene TPV - developed and evolved over the years by ExxonMobil's Advanced Elastomer Systems LP business - broke the last dynamic seal barrier when the material was commercialized as the primary door seal for the Dodge DR pickup truck platform, he said.
Bednarik said the TPV was first used for a dynamic seal application - for things on a vehicle that open and close - on a glass-run channel window seal in 1986 for a Rover made in the United Kingdom. That was followed by other seals, such as for fixed windows, quarter-length windows, sunroofs and doors.
The primary door seal was difficult to master, he said, mostly because the performance criteria for the application are so high. ``As the doors are opening and closing, there's long life on those,'' he said. ``They take up a good deal of space and they've got very significant loading. That is the seal of the door, and also probably one of the biggest seals on the car weightwise.''
ExxonMobil has been working extensively on developing TPV grades for corner molding, where two extruded profiles come together.
The firm worked on the first materials about a decade ago and more recently has been making TPVs for the application that are slippery, with a nice coefficient of friction, and that slide up and down with the glass.
He said the supplier also is preparing to commercialize its B200 series of Santoprene that will have high bond strength to rubber, where the TPV corner would connect two ethylene propylene diene monomer strips. Having a hybrid system allows the end-product maker to take advantage of the fast cycle times of TPVs for the injection molded corner and eliminate the need for most, if not all, trimming.
That could mean a 20-30 percent cost savings per corner using existing equipment, Bednarik said. ``It's been an area we've concentrated on a lot with these corner molding grades because the economics are there for people, the performance is there and the acceptance in the marketplace is now there.''
TPVs have grown faster in automotive body sealing than typical TPE growth, the ExxonMobil official said, though he couldn't provide exact statistics.
``Out of the seven to eight big car companies in the world, all except a couple of the Europeans have major platforms with TPE seals on them for windows,'' he said.
And for those that favor EPDM over TPVs, ExxonMobil is positioned to serve those customers as well with its Vistalon line of materials. ``We look at it as a business, and most [original equipment manufacturers] buy both EPDM and TPVs,'' he said.
``We're not playing favorites. We're trying to serve the market as the market needs to be served.''
ExxonMobil's automotive weather-sealing business is close to being split evenly among North America, Asia and Europe, with programs ongoing with all big weatherseal makers, he said.
ExxonMobil also is moving forward in its alliance with Woburn, Mass.-based Trexel Inc. to develop a foam TPV to be used in conjunction with Trexel's MuCell microcellular foam process. ExxonMobil soon will commercialize a foam extrusion line designed to work with Trexel's machinery in producing automotive weathersealing.