Designing Alternate Cure Systems to Eliminate Restricted Substances for ECO, ACM and AEM Polymers

The development of high-temperature and bio-fuels applications for fuel systems has increased the demand for ECO, AEM, and ACM polymers. These, along with the more conventional chlorinated polymers, are difficult to process and cure effectively using standard cure system strategies. Historically, several, products have been used to crosslink these polymers that are now either restricted or could be restricted for use by international regulations such as REACh. In the past restrictions have been placed on the use of lead and thiourea cure systems. Now DOTG (N, N’ iOTolylguanidine) is potentially being targeted for restriction or elimination. Due to these present and upcoming regulations, Original Equipment Automotive Manufacturers have implemented their own “Restricted Substances Material Specifications” to help insure compliance with the upcoming international initiatives. These RSMS now regulate the use of any products containing lead and will soon regulate the use of other curatives and additives that could include both thioureas and DOTG. Previously Rhein Chemie has shown data for the elimination of both lead and thiourea from compounds containing chlorinated polymers. Recent evaluations have shown that Rhein Chemie has also developed a strategy for the elimination of DOTG as well. This paper will review the previous data and introduce new data showing that alternatives can be compounded to eliminate these restricted or potentially restricted substances. These new products can be used to develop compounds that are now both processable and meet the demanding performance of current and potentially future specifications without using certain curatives and additives that are restricted or might be restricted in the future. This paper will show examples of how to develop alternate cure systems for these polymers using non-restricted curatives.