The Quest for Cobalt‐Free Alkyd Paint Driers

Abstract

AbstractPaint formulations, based either on organic solvents or on water, often contain alkyd resins that depend on catalysts for their oxidative curing. Cobalt carboxylates are the most widely used to date, but the use of these compounds is under pressure because classification as carcinogens under the REACh system is probable, and as a consequence there is great interest in the development of alternative driers to cobalt‐based ones. A variety of manganese and iron carboxylates have been studied as paint drying catalysts in the last two decades, but these often show drawbacks with respect to activity, level of application, colour of the paint drier or cost in use. More recently, several reports on active manganese and iron paint driers containing polydentate ligands have been published. In particular, one iron‐based catalyst, identified originally for stain bleaching in laundry cleaning, shows good paint drying activity at very low dosage levels, outperforming cobalt carboxylates in a wide range of applications.