Ingenious Innovations for Shifting Substrates
Increasingly plastic and medium density fibreboard substrates are being used in industry. Not one to sit still in the face of change, AkzoNobel Powder Coatings has developed new technologies that perform consistently to high standards on these substrates.
Currently the domain of liquid coatings, powder has now become a viable option. The initial barrier to powder coating substrates such as MDF and plastic, was the effect on them of the high curing temperatures needed for traditional powders. Not any more. There are now 2 different techniques. The first uses low-bake powders that are special formulations, usually a hybrid powder of epoxy polyester. Intended for indoor applications they are available in a wide range of colours including metallic shades. Jörg Walther, Market Manager Furniture - Europe West says, “The typical process for low-bake powders is to pre-heat the MDF component to achieve conductivity, spray with powder, then have a couple of minutes under IR heat before a final 10-20 minutes under 130-140 °C in the conventional oven”. Depending on the powder
formulation the finish ranges from coarse to very fine texture. The alternative is to use UV curing powder technologies, where the component is pre-heated, then, after spraying, the powder is melted using IR for about 2 minutes and cured under UV for a few seconds. Walther remarks, “With these coatings it is even possible to obtain a high gloss finish when polished afterwards. Similar innovations are being developed in the automotive industry.
“The process is much quicker – it only takes a couple of minutes and the surface melts quickly and evenly to give a smooth finish”, remarks Jens Kersten, Manager Centre of Expertise - Automotive Europe. AkzoNobel’s powder coatings are used on a vast array of components in the automotive industry. A liquid solvent coating applied to a plastic part requires four coats to achieve 120 microns thickness - this can be achieved with a single powder coating. Now AkzoNobel is looking at reducing the curing temperature and melt viscosity to give an even finer finish. Kersten remarks, “There is potential for significant growth here”.