Halve The Curing Time of Powder-on-Powder with Infrared Emitters

Posted by Andreas Winkler on February 3rd, 2020

Metal pillars, containers or housing parts are protected from corrosion with a base coating and then finished with a decorative coating. However, until now, the complete curing of both coatings comes at a cost, both in money and time. Infrared (IR) ovens from Heraeus can significantly help with this, as metal coatings can be cured in half the usual time. Heraeus Noblelight is showing application-targeted infrared and ultra-violet systems for efficient coating curing at the PaintExpo exhibition, which takes place in Karlsruhe in April. In conventional powder curing, metal components usually pass through a multi-stage coating process. First of all, the component is coated with the base powder, then conveyed to a drying oven where the base coating is cured. After this, the finish powder coating is applied and the component again passes through the drying oven for curing. This process is very reliable and often used. However, many coaters would prefer not to have to use the time-consuming double pass through the drying oven. Fortunately, this two-part coating process can now be optimized by a "Powder-on-Powder" process, at the heart of which is an infrared booster, located immediately after the first coating. The Powder-on-Powder Process Unlike conventional powder coating, with the Powder-on-Powder process the base coating is applied and then immediately gelled by infrared heat. The finish coating is then applied while the base coating is still in the gel state. The component, with the base coating gelled and the finish coating still powder, is then passed into the existing drying oven for complete curing. The process requires an additional infrared oven, the booster. The existing drying oven can still be used. Infrared systems transfer large amounts of energy very quickly so that, as a rule, infrared boosters are very compact and can be integrated into an existing line with minimum effort. Efficiently Interconnected UV and IR for Optimum Energy Application Generally, powders absorb infrared radiation very efficiently. The powder is heated rapidly and is gelled significantly faster than in a convection oven. Without air-circulation, there are no dust inclusions in the oven environment and the powder is not agitated or disturbed. Moreover, fast gelling improves the coating quality and allows line speed through the oven to be increased. Some coatings require UV curing, involving polymerization, where photo-initiators are activated by intense UV light to cross-link in fractions of a second. As a result, the material is quickly cured, the surface is dry, abrasion-resistant and suitable for further processing. Lacquers and coatings remain scratch-resistant and in mint condition when they are optimally cured. This means that wavelengths, UV light intensity and dosage must be matched to suit the photo-initiators of the coating formulation. Increasingly, there are coating processes which benefit from a combination of UV and IR. Heat improves the mobility of the molecules and thus the final result of the curing reaction. By pre-heating the substrate with infrared, better sticking and cross-linking of the UV lacquer is achieved and it has been shown that targeted heating of materials before UV cross-linking can be very advantageous. By the innovative combination of infrared heating and UV technologies, the energy efficiency of the IR curing is improved while the cross-linking of UV lacquers is optimized. The Application Centre at Heraeus Noblelight Heraeus Noblelight has been developing and manufacturing infrared and UV system for applications in industry and science for many years. Its in-house Applications Centre offers the facility to carry out practical tests and investigations under competent, technical supervision. Such tests are evaluated and discussed together with customers, with the aim of determining the best type of emitter and the best emitter configuration for each application, in order to fine tune the drying or curing process to match requirements precisely and efficiently

A globally leading technology group, Heraeus is headquartered in Hanau, Germany. Founded in 1851, it is a family-owned portfolio company which traces its roots back to a pharmacy opened by the family in 1660. Today, Heraeus combines businesses in the environmental, energy, electronics, health, mobility and industrial applications sectors. In the 2018 financial year, Heraeus generated revenues of €20.3 billion with approximately 15.000 employees in 40 countries. Heraeus is one of the top 10 family-owned companies in Germany and holds a leading position in its global markets. With technical expertise, a commitment to excellence, a focus on innovation and entrepreneurial leadership, we are constantly striving to improve our performance. We create high-quality solutions for our clients and strengthen their long-term competitiveness by combining unique material expertise with leadership in technology. Heraeus Noblelight with its headquarters in Hanau and with subsidiaries in the USA, Great Britain, France and China is one of the technology- and market-leaders in the production of specialty light sources and systems. The organization develops, manufactures and markets infrared and ultraviolet emitters, systems and solutions for applications in industrial manufacture, environmental protection, medicine and cosmetics, research, development and analytical measurement techniques.

Contact Heraeus Noblelight GmbH Marie-Luise Bopp Reinhard-Heraeus-Ring 7 63801 Kleinostheim Phone: +49 6181/35-8547 Fax: +49 6181/35-16 8547 E-Mail: marie-luise.bopp@heraeus.com Url: https://www.heraeus.com/en/hng/press/press_overview_hng.aspx