Professional Protection with Water-Based Emulsions

New Trends and Standards in Industrial Metal Coatings

One of the major topics in today's industrial metal coatings market is environmentally sustainable products, compared to the properties of conventional products. BASF has developed various technologies over the years to meet different demands. The reasons for the successive development of new technologies are based on many factors; regional market preferences, existing application systems, substrate selection and environmental pressures can be listed as the key factors among these. Formulation Principles

Film Formation

When a water-based coating is applied to a heat-conductive metal, rapidly evaporating solvents quickly cool the surface. This rapid temperature drop on the surface can lead to a decrease in MFT and consequently result in weak paint film formation. Weak paint film can allow water and moisture to penetrate, reducing corrosion resistance. Therefore, the solvents used in the formula are expected to form film on metal surfaces at low temperatures. These solvents vary depending on the emulsion. To ensure good film formation under various conditions, plasticizers should be used in the formula together with appropriate solvents. Sometimes plasticizers can be used to improve the barrier properties of the paint film.

Stabilization with Anti-corrosive Pigments

Stabilization problems can occur when anti-corrosive pigments such as zinc phosphate and zinc oxide are used together with acrylic emulsions. Although emulsions are neutralized with ammonia, this may not be sufficient to provide stabilization for many anti-corrosive pigments. Depending on the type of anti-corrosive pigment, neutralization with amine at a rate of 50-100% may be required. Various amines are being tested to evaluate shelf stability and the film's moisture and corrosion resistance.

Auxiliary Resins

Acrylic emulsions are often used together with resins such as epoxy, polyurethane or alkyd to adjust application and performance properties. Compatibility and stabilization are critical factors in the selection of auxiliary resin. Good results are obtained with alkyd and epoxy compatible with water-based systems and their esters.

Corrosion Resistance

In order to test long-term outdoor durability, accelerated tests are conducted on various equipment, and these tests generally produce reliable results. Corrosion tests that typically include condensation following salt spray are more effective than salt spray alone. Although many companies have their own test methods, salt spray corrosion tests conducted according to EN-ISO 12944 are accepted as industry standards.