Solvay Engineered Polymers Inc., in a new marketing approach, is pitching its thermoplastic olefins for the carrier component on automotive door window belt-line seals made of thermoplastic vulcanizates.
The carriers in TPV seals typically are made of rigid polypropylene to keep the inner and outer belt-line seals in place. Traditional seals made from ethylene propylene diene monomer use metal carriers.
But as the seals move to TPVs, designers must take into account the thermal expansion of the seal and carrier, said Derrek D. Greenberg, TPE market development representative for the Auburn Hills-based firm.
Solvay's Sequel and DexFlex grades exhibit less expansion over a broad temperature range, the company claims, making shrinkage less of an issue.
As a material family, TPOs also have greater melt strength than PP, giving them good resiliency for secondary bend or ``sweep'' steps, he said.
``Because of its elastomeric properties, TPO is more flexible for secondary steps, but still has high modulus in application,'' said Jim Haseley, Solvay TPE market development manager.
With its TPOs, Solvay claims to be the first materials supplier to market an entire package of sealing materials.
The TPOs complement its slip coats, gloss coats, Respond TPV and Thermoplastic Rubber Systems Inc.'s Nexprene TPV materials.
``When you've got one raw material supplier supplying all of the materials, they take responsibility for compatibility,'' Haseley said. ``It's really important that the seal, carrier and gloss coat adhere to one another.''
The supplier already has General Motors Corp.'s approval to use its TPO materials in carrier applications and now is beginning testing with at least half a dozen Tier 1 and 2 suppliers.
For carrier applications, the main interest in TPOs is low coefficient of linear thermal expansion and the material's ability to provide high modulus, Greenberg said.
The weight and recyclability aspects of TPOs are similar to PP, but there is a 5-10 percent cost premium with TPOs, Haseley said.
Traditionally, TPOs are more expensive than talc-filled PP, but the price is merited if higher performance is required, he said.
``We see a need in the market for some of those things in a carrier material.''
Solvay expects to hear soon whether it has won a contract to supply the carrier material to a Tier 2 extruder for a domestic vehicle program, Haseley said.