Surfactants as corrosion inhibitors for zinc pigment

A lamellar zinc pigment reacts in aqueous alkaline media (e.g. water-borne paints) with the evolution of hydrogen. This corrosion reaction can be inhibited by certain surfactants. The most important structural part of the examined surfactants is the hydrophilic group; only anionic phosphate or phosphonate hydrophilic groups are effective corrosion inhibitors. Surfactants with carboxylate, sulfonate, amphoteric, cationic and non-ionic hydrophilic groups are ineffective. There seems to be also an influence of the hydrophobic group of the surfactants because a partial ester of phosphoric acid with a fluorinated hydrophobic group was the most effective corrosion inhibitor in this study.