FUNDAMENTALS INFLUENCING POWDER COATING FREE-FLOW BEHAVIOR

Powder coatings are a paint system consisting of solid micronized particles, ranging in size on average from sub-micron to <200 µm. Typically, these coatings are applied by air-conveying the coating and applying by electrostatically charged spray onto grounded metal substrates and heat curing.

To effectively transfer and spray these coatings in a consistent, reliable manner using compressed air, free-flow additives are added during manufacturing of the paint. Fumed alumina and silica are some of the commonly used additives for this purpose due to their ability to fluidize the powder and allow flow in an almost frictionless manner, while preventing clumping during storage and transport. These materials are still able to allow electrostatic charge to the particles during spray application allowing efficient deposition onto the metal substrate.

These important additive effects are generally accepted but not always well understood, as they balance a variety of influencing factors including electrostatic attraction of particles, reducing the effect of moisture introduced during manufacture (in the milling and sieving stages) and the effects of compaction under pressure (by its own weight) and vibration during transport. Differences in powder coating compositions can also affect additive performance.

This presentation explores these influencing factors closer and how to leverage them to provide improvements to free-flow properties, using established and newly developed analytical methods to quantify and provide insight on how these free-flow additives affect powder free-flow rheology, storage stability, transfer efficiency and the faraday cage effects while maintaining product performance and quality.

About Our Speaker: Bernhard Resch
Bernhard Resch is a Technical Manager with Evonik Corporation’s Coating Additives Business Line. He has extensive powder coatings experience having worked for over 25 years in various functions at TIGER Drylac and Akzo Nobel before joining Evonik. His experience in managing production and labs, as well as formulating powder coatings, and trouble-shooting customer problems gives him a broad understanding of powder coatings raw materials, manufacturing, and application. He has a degree in Chemical Industrial Engineering from Austria.