Innovations in the Powder Coating World
The powder coating industry has experienced a resurgence in innovation in the past several years. According to expert chemist Roger van Duin, “Many of the disadvantages to the use of powders that had existed have been eliminated or minimized through formulation and equipment development.”
Chemical engineers are developing new materials and processes to meet the emerging needs of the manufacturing sector. Here are just a few of the latest trends and developments:
Powder on Plastic
Manufacturing processes are evolving, which means methods and materials to coat manufactured goods are also evolving. Lighter-weight materials in fabrication continue to displace traditional substances like steel and aluminum. As a result, coating technology has been advancing to meet the finish required for these new materials.
Plastics encompass a wide spectrum of materials and processes. And the unique characteristics of each product will determine the most appropriate coating technology. For instance, some conventional powder technology is suitable for high-temperature plastics, the only requirements being that the plastic surface is conductive and adhesive. This is rather easily achieved.
Powder resins formulated from renewable chemical resources are currently being tested at many research facilities. Scientists have been incorporating derivatives of soybean oil, corn, sugar cane and cellulose into polyester resin chemical chains – so far, with limited success. They have not yet been able to develop a bio-based polymer that is acceptable to the coatings industry. Right now, the lab-synthesized products are more expensive and less durable than their petroleum-based counterparts. Nevertheless, research continues in this area and it is hoped that a more viable product will soon be found.
Recent advances in robotics design and software have made the technique much more affordable to a wider market. High-quality units now sell for less than $50,000, making them accessible to mid-range finishers like never before. And the robotics software is much more user friendly, as well. Without the high capital cost and need for a full-time robotics engineer, this technology has officially been introduced into the powder coating mainstream.
Non-conductive substrates have traditionally presented a bit of a problem, particularly for novice coaters. But chemical engineers have recently developed new conductivity solutions that allow for excellent transfer efficiency of powder coatings, and they are now available to the coating industry. These new solutions will enable researchers to explore even more novel approaches to finishing a wide variety of plastics.
Many of the new powder coatings can be cured at temperatures as low as 250°F. The advent of these low-curing-temperature systems has significantly opened up the market to heat-sensitive substances such as wood and plastics. The new technology also results in lower energy and investment costs, shorter curing times, and higher line speeds.
By the same token, powder coatings are also being developed for high-temperature applications. Silicone-based powder coatings are now being used on products that require prolonged exposures to high heat (up to 1000°F). This new technology is perfect for gas and charcoal grills, fireplace inserts, engine exhaust components, and light fixtures.
Advanced Application Methods
Radically different methods of application are also being developed. For example, in-mold powder coating processes spray the powder coating material onto a heated mold cavity before the molding cycle begins. The coating then chemically bonds to the molding compound during the molding operation. The resulting product has a coating that is both chip- and impact-proof.
In addition, new processes have been developed for applying thermoplastic powder in the field. So far, bridge support columns and steel sidewalks have been coated successfully. And pipe joints that were originally coated in the factory but must be welded in the field can now be recoated with powder, providing a continuous, corrosion-resistant coating.
New feed systems are also delivering more powder with less air. This means the powder feed to the gun is more consistent, with virtually no surging and spitting. Penetration into tight corners and Faraday cages is significantly easier because of the lower air velocity. The result is a more even and consistent film thickness range, translating into a higher-quality finish and better economics.