Rubber Accelerators

Robac SRM102, a Novel Safe Accelerator for Curing Polychloroprene and Other Elastomers
 

Summary
Robac SRM102 is a novel safe accelerator designed to replace ethylene thiourea (ETU) as the main curative in polychloroprene rubber (CR). In general, the majority of unsaturated elastomers (such as natural rubber) require sulfur or a sulfur donor to cross-link the polymer chains. However, CR undergoes cross-linking differently and the most effective accelerator system for CR traditionally utilises ETU in combination with zinc oxide (ZnO). ETU, is however, classified as a CMR (Carcinogenic, Mutagenic, toxic to Reproduction) and as a consequence has been included in the list of substances of very high concern (SVHC). Substances identified as SVHC, such as ETU, will eventually be included in the REACH Authorisation list and can not be placed on the market or used after a certain date. As a consequence, there has been a need to replace ETU for many years.

This paper initially provides a brief background of how Robac SRM102 was designed. Following on from this, the physical properties achieved using Robac SRM102 as a curative in CR are discussed and compared with ETU. Technical data presented herein includes rheological, tensile, heat aged and compression set values. The versatility of Robac SRM102 is then demonstrated in a range of other polymer matrices, including specialised saturated polymers (e.g. epichlorohydrin) and unsaturated elastomers (e.g. natural rubber). Evidence provided in this paper demonstrates that Robac SRM102 is an excellent replacement accelerator for ETU in CR and can also be used as an effective curative in other polymers.