Corrosion protection powder coating free from critical ingredients

A new polyester-based corrosion protection powder coating without critical and label-required ingredients offers itself as an alternative to comparable expoxy resin products and also has the best edge coverage.

Many ingredients, as well as hardener components, have come under fire in recent years, as various of their ingredients have been classified as hazardous. This applies, for example, to ingredients such as TMA (trimellitic anhydride) or BPA (bisphenol-A), but especially also to products based on glycidyl esters. FreiLacke reacted to this classification at an early stage and developed new, non-declarable polyester paint systems with the "Freiotherm Powder Paint PS3005" (highly weather-resistant) and "Freiotherm Powder Paint PP3005" (polyester industrial grade) series. These are particularly suitable for industrial applications and for painting construction and agricultural machinery.

Primid is the trade name of a hardener that belongs to the chemical class of β-hydroxyalkylamides and shows its strengths particularly in the crosslinking of powder coatings. In addition to very good corrosion protection, the material offers high weathering resistance and excellent color stability. With the use of the primide hardener and its toxicologically favorable profile, FreiLacke's new polyester system does not require labeling: it is completely free of problematic components. Other advantages: Compared to epoxy resins, significantly less energy is required in the production of polyester coatings. This means that environmental protection is already taken into account in the formulation of this system. In addition, epoxy resins are mainly produced outside Europe, while the new polyester system eliminates the need for costly transport by sea. Last but not least, coaters thus circumvent the well-known price volatility of epoxy resins, which continues to fluctuate widely.

A small drop of bitterness: So far, the new coating system can only be used for standard curing conditions (10 minutes at 180°C object temperature). A variant for low-temperature applications (10 minutes at 160°C) for high-quality pretreatments is already in the works. The newly developed polyester-based powder coating was designed with the main focus on excellent corrosion protection properties. Freiotherm powder coatings based on PS3005 and PP3005 can be used in both single-coat and two-coat applications. "In two-coat form, the new coating system brings corrosion protection that almost reaches the level of a classic epoxy primer," explains Alexander Schelling, who is responsible for powder coating development at FreiLacke. "The advantage for the coater is that there is no need for a separate primer and the topcoat is simply applied twice." When using a topcoat with high pigmentation costs, however, the use of a separate primer still makes sense, he said. Freiotherm's PS3005 and PP3005 powder coatings are available on request in all surface finishes - smooth, fine-textured as well as coarse-textured - and in gloss levels from high-gloss to silk gloss.

In addition to excellent corrosion protection, the new system also offers very good edge coverage, which virtually rules out rust damage. "If edges and laser cuts are sufficiently rounded, the polyester coating can also be used in a single layer and, compared to classic industrial/façade powder coatings, brings a clearly noticeable added value in terms of corrosion resistance," emphasizes Jakob Zihsler from FreiLacke's powder coating development department.

PS3005 was developed in response to a specific customer inquiry from the agricultural and construction machinery sector. FreiLacke took this as an opportunity to revise the existing corrosion-optimized systems as a whole. "The development took around two years. We started the development proactively because we knew this would come our way," explains Zihsler. The aforementioned systems can also be modified according to customer-specific requirements. In the meantime, more than ten reference customers are already using the new systems in a wide variety of modifications. (OM-3/23)

Tab.1: The properties of the new polyester paint in comparison with epoxy and waterborne paints

Tab.2: Freiotherm PP3005/PS5205 compared to conventional polyester powder coatings