The effect of the pH value of water-based coatings on different metal substrates

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It’s not the case that the higher the pH value, the more stable it is, and the less corrosion it causes to the metal substrate. Water-based coatings using different resin systems exhibit varying pH values of their paint films on different metal substrates, such as carbon steel. In water-based alkyd and epoxy ester coatings, a pH value of around 4 or 5–5 provides relatively stable protection against flash rust corrosion. This indicates that certain metal carbon steel substrates are sensitive to alkalis. Therefore, acidic systems are more suitable for the coating protection of metal carbon steel substrates. Galvanized steel sheets and cold-rolled steel sheets are both suitable metal substrates for coating with alkaline paints for protection. These materials help to maintain an electrical charge balance with 2,2-N-dimethylethanolamine in aqueous systems, thereby ensuring that the electrical charge potential of the metal substrates is roughly equal to that of the aqueous acrylic amino topcoat. Achieve a balance in the potential space, so that the resin in the aqueous system can be adsorbed onto the metal substrate in an appropriate and rapid manner to form a hydrocarbon film. Thereby achieving corrosion-resistant protection.