Surface & Panel Buyers Guide 2012
There are many attributes to consider when evaluating various finishing materials and application systems. Is the finish environmentally friendly? Is the material safe to use? How cost effective is the manufacturing and finishing process and how will it perform? These are all pertinent questions to consider. Sustainability, Innovation, Productivity, Palette and Performance are five attributes that can be used to evaluate and demonstrate the benefits and advantages of UV-cured powder coating.
Wikipedia defines Sustainability “as the capacity to endure” and includes environmental, social and economic dimensions in the definition. Since Ultra Violet (UV)-cured powder coating on medium density fiberboard (MDF) was introduced in 2001, the sustainable imperative of UV-cured powder coating chemistry and application technology has endured. Now more than ever the finishing market is demanding environmentally friendly, socially desirable and economically viable alternatives to traditional finishing materials and systems. UV-cured powder coatings are safe to handle and apply and do not pose any safety risks to employees. Environmentally mandated production constraints and permits are not required.
When evaluating finishing materials it is important to consider each material’s physical properties, liquid or powder, and their respective constituent chemistries. There are a variety of different coatings including; solventborne liquid, waterborne liquid, high solids liquid, UV-curable liquid, thermoset powder coating, low-temperature powder coating, and UV-curable powder coating. Each of these materials has a unique chemistry and set of finishing performance properties. Making things even more challenging is each of the finishing materials requires a distinct application process and equipment system.
Switching between the various materials is difficult and can be costly. The evaluation criteria and calculus to select the “right” material and finishing system is driven by a set of complex internal and external drivers; product improvement, return on investment (ROI), material costs, total applied costs, productivity, material handling, health & safety, environmental regulations, and customer expectations.
Innovation is defined by Wikipedia “as the creation of better or more effective products, processes, services, technologies or ideas that are accepted by markets, governments or societies.” The definition of Productivity “is a measure of the efficiency of production.” UV-cured powder coating is an innovative and productive finishing technology that encompasses high performance chemistries and exceptionally productive application systems. UV-cured powder coating on MDF requires only one coat of material and is completely finished in 20 minutes or less.
UV-cured powder coatings contain different chemistries than liquid and thermal powder finishing systems. UV-cured powders contain an unsaturated resin polymer, which in the presence of photo initiators are activated by UV light and instantly cured. Figure 1. is a graphic representation of the four process steps of UV-cured powder coating.
Pretreatment involves one minute of preheating, which conditions the MDF substrate, followed by an electrostatic application of UV-cured powder coating. The powder coated part is melted and flowed for one minute and then immediately cured by UV light. The total active process time to finish each part is less than 4 minutes.
The fast speed and short cycle time of the UV-cured powder coating system lends itself to short and long run flexibility, increased quality control, low energy consumption per unit of production, low labor and exceptionally fast ROI. Figure 2. is a graphic representation of the process time advantage of UV-cured powder coating compared to low temperature cure powder coating and solvent borne liquid finishing systems.
The Wikipedia definition of a Palette has a literal meaning of a board on which an artist mixes colors and a figurative meaning referring to a selection of colors. This figurative meaning is very appropriate when considering UV-cured powder coating. It is possible to select a great variety of colors, glosses and textures to finish MDF with UV powder. Color matches are formulated from the RAL, Pantone (PMS) and other color systems. Typical gloss range is 5-30 on a Gardiner 60o scale and textures range from very light to heavy.
The last definition to consider is Performance, “Testing covers a wide range of engineering or functional evaluations … emphasis is on the final measurable performance characteristics.” A great amount of work has been done to develop a comprehensive set of performance results for UV-cured powder coating on MDF. It is important to create an empirical data set of what finishing performance is required and to understand the relationship between various physical properties. For example, as hardness of the coating increases, there is a corresponding decrease in the coatings impact resistance. Figure 3. illustrates performance results for two UV-curable powder coatings.
Sustainability, Innovation, Productivity, Palette and Performance are credible and descriptive attributes that define the benefits of UV-curable power coatings. Economic, industry and consumer demands will continue to change, stimulating the continued emergence of “greener” and safer finishes applied in more efficient processes. UV-cured powder coatings are and will continue to be a viable and safer substitute for other less productive finishing systems now and in the future.
Article written by Michael Knoblauch