The combination of reducing agents/iron as environmentally friendlier alternatives for Co-based driers in the drying of alkyd paints

Ascorbic acid and several ascorbic acid derivatives, in combination with iron salts, have been tested in alkyd emulsions, alkyd resins (or varnishes), and in a high gloss white paint formulation. We have found that the combination of iron salts with reducing agents forms an excellent drier, in terms of film hardness and particularly total drying time, compared to a commercial Co drier and a new Mn-based alternative. The effect of two nitrogen donor ligands, N,N-bis(2-ethyl-5-methyl-imidazol-4-ylmethyl)aminopropane (BIAP) and 2-ethyl-4-methylimidazole (Im), to the mixture reducing agent/iron was also studied in a high gloss white paint formulation. Outstanding total drying time of just 2.2 h was observed for the combination of ascorbic acid 6-palmitate, iron and imidazole.