E4S Awards - Lanxess

Lanxess topped the E4S table with its project to develop rubber anti-degradant, labelled Vulkanox 4060, which is said to offer an alternative to the use of 4-N- (4-methylpentan-2-yl)-1-N-phenylbenzene-1,4-diamine (6PPD) in tires.

Developed to protect against oxygen, ozone and cracking, 6PPD is used in almost all commercial tires, especially in the tire sidewalls and the tread compounds.

On reaction with oxygen and ozone in the environment, however, 6PPD can transform into 6PPD-quinone, found to be acutely toxic to coho salmon – possibly via entry of tire wear particles into aquatic environments.

Based on lab results, Lanxess believes that Vulkanox 4060, which contains n,n’-dicyclohexyl-1,4-phenylene diamine is a potential 6PPD replacement.

The rubber stabiliser, it stated, “shows similarly strong antioxidant and antiozonant performance results in rubber tests, while having a more favourable product safety profile.” 

For use in compounds based on diene rubbers such as NR, BR, SBR and blends, Vulkanox 4060 “offers very good protection against oxidation, ozone attack, and flex cracking,” the company added.

In testing, aged for 28 days at 60°C, the tensile strength of a reference compound was reduced by about 22%, whereas in compounds with CCPD the tensile strength reduced by only 13% – similar results to those seen with 6PPD.

Among other claims, Lanxess said the new product exhibits: “Exceptional resistance to oxidative aging; very good ozone protection; shields rubber surfaces from ozone-induced damage; and enhances flex cracking resistance.

The company noted that the chemical structure of Vulkanox 4060 also has the potential to form quinones: the quinone formation from para-phenylene-diamines (PPDs) is an integral part of the rubber protection against ozone.

OECD Guideline 203 standardised testing of the toxicity of the potential ozonation product CCPD-quinone to coho salmon was completed “with no mortality or abnormal behaviour observed.”

While the performance and safety profile is still being tested, Lanxess said it is targeting global registration of Vulkanox 4060, with a roadmap covering studies of all potential human health and environmental safety concerns of related chemicals – as required under EU REACH.

CCPD is being produced in pre-commercial scale at Lanxess facilities, with plans to “ramp-up the production in the next years, which goes hand in hand with different product safety studies.”