Anticorrosive Pigments

Anticorrosive Pigments

Corrosion is defined as the deterioration of metal through chemical or electrochemical reaction when exposed to air, moisture, chemicals or other agents in its environment. Corrosion is not merely an aesthetic problem, but also an important safety issue. The corrosion reaction of iron is shown as follows:

4 Fe + 3 O2 + 2 H2O → 2 Fe2O3. H2O

Metal tends to react with its surrounding environment. Oxygen continuously attacks iron in order to be reduced (OH-) by requesting electrons. The active site where metal damage occurs is the anode, which is where the metal passes into solution as metal ions. Thus electrons are released (oxidation). At the cathode, electrons are consumed as a result of reaction with the environment. Water carries (OH-) ions and brings them into contact with iron ions (in the presence of excess oxygen).

Typical aggressive agents acting on an organic coating exposed to the external environment can be listed as: water, SO2, NaCl, U.V. Along with these, oxygen, pH, temperature, dissimilar metals, soluble salts, metal composition, and the stability of the oxide film on the metal surface are factors affecting corrosion.

The most common method of protecting metal is coating it with paint containing anticorrosive pigment. In this way, corrosion inhibitors protect the metal against these effects through pH control, anodic inhibition, and cathodic inhibition mechanisms.

The most widely used products for this purpose are zinc phosphates. However, they exhibit poor adhesion and low performance in accelerated tests.

Since zinc phosphates could not meet the developing market and sector demands, Nubiola conducted studies on pigments that could be used in both water-based and solvent-based systems and would demonstrate higher performance, and as a result developed modified zinc phosphate pigments and zinc-free anticorrosive pigments. The new generation anticorrosive pigments obtained by improving the properties of standard zinc phosphate Nubirox N2 are as follows:

Nubirox SP: Zinc phosphate with smaller particle size. It is white in colour. Due to its low particle size, it offers higher performance compared to standard zinc phosphates. It is recommended for use in both water-based and solvent-based systems, particularly in thin film applications. Figure 1. Comparison of Nubirox SP with Zinc Phosphate

Figure 2. Comparison of Nubirox 102 with Zinc Phosphate Figure 3. Comparison of Nubirox 106 with Zinc Phosphate

Nubirox 301: It has a calcium strontium phosphosilicate structure. Since it contains no zinc, it can be used in systems where environmentally friendly coatings are desired. It is white in colour. It can be used in systems where zinc phosphates are reactive (such as polyurethane). It is suitable for both water and solvent-based systems.

Nubirox 302: It has an organofilic calcium strontium phosphosilicate structure. It is white in colour. Its performance has been improved through surface treatment. It can be used in acidic systems. It can be used in direct application on metal.

Nubirox FR-10: A product specifically used to prevent rust formation on the metal surface during the application of water-based paints and inside the metal container (in-can) containing the paint.

Nubirox 102-106-213-301-302 products do not require labelling. They have not been classified as hazardous to physical and human health, nor to the environment. Therefore, they do not contain any labelling elements.