Powder coating on wood
Since the 1960s, powder coatings have revolutionized the finishing industry by providing superior, durable, and environmentally friendly topcoats, especially for metal products (such as appliances, auto parts, sporting goods, and countless other products).
The technological advancement, application and curing methods of powder coatings have also brought the advantages of powder coatings to heat-sensitive substrates. Powder coatings are now used in various products that were impossible a few years ago.
In the thermal substrate market, one of the biggest breakthroughs in powders is in medium density fiberboard (MDF), which is a composite panel that binds wood particles and synthetic resin together. MDF has a low porosity and a uniform surface, so it is very suitable for powder coating applications. MDF products include office furniture, kitchen and bathroom cabinets, doors, store fixtures and display racks, barbecue trays, and ready-to-install furniture for offices and homes.
Powder coatings are revolutionizing the MDF market because it provides design freedom that other finishing methods and lamination processes cannot. Powder coating can provide beautiful, durable and seamless surface effects for every color of the rainbow. Moreover, powder coatings can protect MDF products from debris, stains, spills and scratches.
Meeting the challenges of thermal substrates
Some wood and wood products (such as MDF) have sufficient moisture content and consistent moisture content to provide electrical conductivity and can be coated directly. Compressed air can be used to clean wooden parts that need to be polished to remove any contaminants from the surface. To enhance electrostatic attraction, wood can be pretreated with a spray solution that provides a conductive surface. The part is then preheated to the desired coating temperature. When the powder is applied, this temperature will dissolve or partially melt the powder and help the powder adhere to the part, causing it to melt slightly when impacted. Uniform plate surface temperature can achieve higher transfer efficiency and consistent appearance. For powder applications, an electrostatic charge is applied from the spray gun to deposit the powder on the MDF surface. The powder material used for MDF may be a heat-cured product of UV-cured powder. Thermosetting powders rely on infrared ovens that combine infrared and convection heating, convection ovens or hybrid ovens. The heat can melt the powder, so it will flow into the flat film and eventually solidify or crosslink into the final film.
Using a specially formulated UV-curable powder, the melt and flow can be separated from the curing process, and the powder can be cured with very little heat. After the part enters the infrared or convection oven, the coating melts and flows for two to ten minutes, and then exposes the board to ultraviolet light for only a few seconds to finally cure and harden the finish. Then cool the parts naturally or in the cooling channels, and then remove them from the coating line.
Powder coating meets the needs of MDF products
Many office furniture manufacturers are moving from standard shapes (such as squares and rectangles) to more rounded corners and contoured edges, with internal round and oval shapes to allow computer wires to pass through. They also provide seamless desktop paint and various colors and effects. Powder coatings can adapt to these shapes, while other lamination techniques relying on edge banding methods cannot. Moreover, powder spraying is a one-step process that does not require continuous coating or long drying times.