The Registration, Evaluation, Authorisation & restriction of CHemicals (REACH) board added DDM to its candidate list of Substances of Very High Concern (SVHCs), and Attwater quickly moved to address the issue. Diaminodiphenylmethane (DDM) is a catalyst used in epoxy resins and was previously a key ingredient in the original B42, a fine-weave scoured cotton epoxy laminate which can be easily machined to a fine finish. This grade exhibits good anti-track properties, coupled with high mechanical and electrical strength. Finding a compliant replacement took several iterations of B42, and the process of replacing it was not straightforward as common alternative catalysts are not suitable due to their performance being affected by the natural water content in the cotton. Matt D’Arcy, Attwater’s technical development engineer, explained: “Several formulations were tried, including the use of an advanced additive used in the manufacture of high-performance bearing materials. After the first few developments we saw positive signs as it became clear that the use of a new cotton cloth improved the results significantly. “Eventually, altering the percentage resin content on the new cloth gave test results that were well within BSEN requirements, and now our popular B42 product is even more effective than before.” www.attwater.com
