Freudenberg pioneers new ETU-free accelerator for chloroprene rubber

WEINHEIM, Germany—Sustainability considerations are affecting nearly every manufacturing industry, and the chloroprene rubber space is no different.

Freudenberg Sealing Technologies, one of four business divisions within Freudenberg Group, has developed an ethylene thioura (ETU)-free compound for cross-linking chloroprene rubber.

ETU is used industry-wide as an accelerator in the vulcanization process. Specifically, Freudenberg will use the new compound in seals and bellows.

"The innovation sets a benchmark for new elastomer compounds," Freudenberg said in a news release.

ETU, which has been used for decades, offers excellent low-temperature flexibility and resistance to greases and lubricants. However, it also can be toxic to fruit.

The replacement compound needed to meet these difficult standards, eliminating the toxicity, Freudenberg said.

To date, no one had developed an alternative to ETU for use in chloroprene rubber, Freudenberg said.

Until now.

And the first place the ETU-free went was the automotive segment, specifically in sealing bellows for joint seals in tie rods, control arms and wishbones—all moving components that require protection from "outside influences," Freudenberg said.

The chemists and engineers at Freudenberg Sealing also were charged with eliminating the harmful tetramethylthiuram disulfide.

To accomplish all this, Freudenberg had to consider current and future customer requirements before launching components containing the ETU-free material into production.

Methods in development of the accelerator included statistical design of experiments and thermal analysis, among others.

Processes helped figure out melting and crystallization temperatures, glass transition points and relaxation.

"The measurements have shown that one of the most important requirements, (such as) behavior in the low temperature range, is being met extremely well," Freudenberg said July 10.

This also is confirmed by feedback from customers in the automotive sector that are already using ETU-free sealing bellows for joint seals in tie rods, control arms and wishbones.

The ETU-free accelerator, the company noted, also reduces administrative work, as it eliminates the need for a reporting obligation for ETU use to a database within the European Chemicals Agency.

And this means everyone must report the chemical—from the manufacturer to the end customer.

In 2022, Freudenberg Sealing Technologies saw about $2.7 billion in sales. Freudenberg Group, which also includes nonwovens and filtration, household products and specialties, saw about $12.9 billion in net sales.