China Aluminum Industry Network – Over the past few decades, electrostatic powder coating has been primarily used for metal surfaces since its introduction in the 1960s. While many manufacturers and equipment suppliers have claimed that this technique can also be applied to non-metallic surfaces, no industrial products have ever been realized. However, in the late 1990s, with advancements in both powder coatings and spraying technology, it became possible to apply electrostatic powder coating to non-conductive materials. Recently, companies such as Yu Dong Gao Ting Shi and Eluda in the UK have made significant progress in applying this method to medium density fiberboard (MDF), achieving industrial production success. This article explores the latest developments in MDF powder coating and highlights how these innovations are helping to advance electrostatic powder coating technology in China.
Electrostatic powder coating is a process where dry powder is applied to a surface using an electric charge, followed by baking to form a durable finish. The key elements involved include the object being coated, the powder itself, the spray gun, and the curing equipment. Understanding these components helps in grasping the overall process and its potential applications.
When selecting objects for powder coating, economic factors play a major role. While metals have traditionally been the primary choice, wood and plastic are also being considered. At present, plastics are not ideal due to temperature constraints. Wood, especially MDF, has become a preferred option. This is because wood is hygroscopic and can absorb or release moisture depending on environmental conditions. By controlling the moisture content of the wood, it can be made to behave more like a conductor, making it suitable for electrostatic application. MDF, in particular, is a widely used, environmentally friendly material with strong industrial potential.
Recent advances in powder coatings have led to the development of low-temperature curing powders. For example, some coatings now cure at 120°C for 20 minutes, which opens up new possibilities for applications that require less heat. Although these powders still face challenges such as storage stability, they are expected to improve in the near future. In MDF applications, UV-curable and ultra-low temperature curing powders are commonly used. Companies like DSM have developed UV-curable powder coatings based on maleic acid and vinyl ether, while Eluda uses epoxy/polyester hybrid powders that cure at around 150°C.
Significant improvements have also been made in electrostatic powder spraying equipment. Traditional corona charging systems limited the use of this technique to conductive materials. However, new technologies such as Total Energy Controlled (T.E.C.) charging allow for effective application on non-conductive surfaces. This system automatically adjusts voltage and current based on the distance between the spray gun and the object, ensuring consistent powder charge and efficient coverage.
For ultra-low temperature curing, special drying tunnels are used to eliminate volatile compounds from MDF under controlled conditions. Unlike UV curing, which involves melting the powder with infrared light before curing with UV lamps, this method ensures stable curing temperatures throughout the process.
Since the late 1990s, industrial-scale electrostatic powder coating of MDF has been successfully implemented. In August 1999, the UK launched the first fully automated MDF powder coating line. It is expected that in the next few years, MDF powder coating will see rapid growth. Future improvements will focus on further developing low-temperature and UV-curing powders, diversifying paint types, and upgrading spray guns and curing equipment to enable dual functionality for both metal and MDF. As this technology continues to evolve, it's likely that other non-metallic materials will soon enter the electrostatic powder coating market as well.
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