Increasingly plastic and medium density fiberboard substrates are being used in industry; metal substrates are disappearing. Powder coatings must develop new technologies so they continue to perform to consistently high standards.
AkzoNobel aims to replace areas where liquid coatings are currently used. One of the challenges to this is the high curing temperatures needed for traditional powders since these can adversely affect MDF and plastic.
There are two different techniques.
The first uses low-bake powders that are special formulations, usually a hybrid powder of epoxy polyester. Intended only for indoor applications they are available in a range of some 15 colors including metallic shades.
Jörg Walther, Market Manager Furniture – Europe West says, “The process for low-bake powders is to pre-heat the MDF component to slightly raise the temperature, spray with powder, then have a couple of minutes under IR heat before a final ten minutes in the conventional oven”. The finish has a fine texture but it is not high gloss.
The alternative is to use UV curing where the component is pre-heated using IR about ten minutes and then cured for up to a minute. Walther remarks, “With these coatings it is possible to obtain a high gloss finish that can be polished.
Similar innovations are being developed in the automotive industry. “The process is much quicker – it only takes a couple of seconds 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 polyester coating applied to an engine block requires four coats to achieve 120 microns thickness but this can be achieved with a single powder coating.
Now AkzoNobel is looking at reducing the particle size to give an even finer finish. Kersten remarks, “There is potential for significant growth here”.