Updated: Freudenberg claims ETU-free elastomer advance

Weinheim, Germany – Freudenberg Sealing Technologies (FST) has announced a new development for the vulcanisation of chloroprene rubber that eliminates the need for ethylene thiourea (ETU) as an accelerator.

The development, the company claimed 10 July, “sets a benchmark for new elastomer compounds,” and meets the strict requirements of the automotive industry.

ETU accelerators have been used to cure chloroprene rubber for decades: enhancing low-temperature flexibility and resistance to media such as greases and lubricants.

However, due risks identified regarding reproductive toxicity and damaging effects on fruit, use of the chemical should today be avoided where technically and economically feasible.

According to FST, there had been no alternatives to ETU that offer a similar performance or even met the requirements – until the company’s new development.

The company cited an “already successful” applications of ETU-free products: an automotive sealing bellows for protecting moving parts, including from leakage of lubricants.

In eliminating ETU and other potentially harmful accelerators – particularly additional use of tetramethylthiuram disulfide – FST said its development team addressed increased requirements placed on its new compounds, intended for series production.

The challenges, it said, included delivering “significant low-temperature flexibility after targeted aging, compatibility with greases and lubricating additives in direct contact with the sealing bellows, and resistance to hydrolysis.”

Feedback from automotive customers using the ETU-free sealing bellows for joint seals in tie rods, control arms and wishbones “confirm that the new material has much more stable values at low temperatures than other products on the market,” continued FST.

Another advantage is the considerable reduction in administrative work, according to the company.

Since the start of 2021, the European Chemicals Agency has placed complex reporting requirements on all products containing specific quantities of ‘substances of very high concern’ across the supply-chain.

With its new development, FST stated “the additional reporting requirement is eliminated, and reporting can be carried out as before via the existing and globally standardised exchange and management system IMDS.”