Brussels – ExxonMobil Chemical has developed what it says is a novel approach for formulating its Vistalon EPDM compounds for automotive sponge weatherseals.
The technology is said to produce a compound that can help to reduce the density of the sponge profile, while optimizing key properties such as long-term ozone resistance and sealing.
The compound combines an amorphous, high-diene EPDM rubber with a propylene-based elastomer, called Exxon IT0316, said a 29 June announcement from ExxonMobil.
“Using this new approach to tailor EPDM rubber compounds allows customers to reduce part cost while broadening their range of sponge profiles with differentiated properties,” said Thierry Hombert, global market development manager, specialty elastomers and butyl business at ExxonMobil Chemical.
The new formulation, based on metallocene polymerisation technology is said to enable developers to tailor properties through the precise control of the molecular architecture and co-monomer introduction.
Tests on a semi-industrial ultra high-frequency (UHF) extrusion line show that blowing-agent efficiency is optimised without compromising the sealing properties of the sponge profile, according to ExxonMobil.
“Compression load deflection (CLD) and compression set (CS) are maintained, and density can be reduced by 10 percent, which provides the potential to reduce costs,” it said. “ The uncured, soft-sponge compound also exhibits more green strength, improving weatherseal handling.
“Compounders can tailor the performance of the sponge weatherseal to produce a profile that has a similar density to an EPDM compound but with a higher CLD or a profile with a lower density but a similar CLD.”
– ERJ
