Calcium tripolyphosphate: An anticorrosive pigment for paint

The objective of this work was to evaluate the performance of calcium tripo lyphosphate in anticorrosive paints. Its anticorrosive properties were stud ied in pigment suspensions an solventborne paints with 10% and 30% of the p igment by volume and a pigment volume concentration/critical pigment volume concentration (PVC/ CPVC)equal to 0.8. The behavior of paints formulated w ith epoxy and alkyd resins was assessed by acccelerated (salt spray cabinet and humidity chamber) and electrochemical tests (corrosion potential, ioni c resistance, and polarization resistance). Calcium tripolyphosphate was pr oven to inhibit steel corrosion when incorporated in a paint film. Good pro tection was achieved employing only 10% by volume of the pigment, instead o f 30%, as was suggested in the case of phosphates. The anticorrosion protec tion afforded by alkyd paints was impaired when the pigment content was inc reased. Epoxy paints seemed fo be less sensitive to the pigment content.