Blog Archives

Part 1: Corona Treating for Coating Applications

Maintaining high quality coating on paper, film, metalized film and foil substrates at production line speeds requires a method of enhancing substrate surface energy. Corona treatment promotes bond sites and increases surface energy without sacrificing the positive properties of the substrate. In coating applications, treater system design has undergone significant changes to accommodate lighter webs, higher line speed operation and advanced substrates. The range of developments has included the requirement for handling conductive substrates, nips at the treater roll, using the treater roll as a "pull roll," and modifying the treater station design...
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Part 2: Driving and Nipping the Corona Treater Roll

In Part 1 of the Corona Treating Series we discussed the corona treating station. The requirement to nip or to drive the Corona treater roll is more often dictated by machine or substrate characteristics than by technical treatment demands. For example, treatment of substrates, especially ultra light weight substrates running under light tension, is seriously complicated by the tendency for these substrates to wrinkle under the corona discharge. The wrinkling not only causes a problem with the quality of the wound roll, but also produces backside treatment...
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Part 3: Corona Treating Power Supplies

In Part 2 of the Corona Treating Series we discussed driving and nipping the treater roll. [caption id="attachment_2962" align="alignright" width="294"]Figure 3 - Power Supply Diagram Figure 3 - Power Supply Diagram[/caption] All corona treating installations require a source of controlled electrical power. Low-voltage 60 hertz electrical power is fed into an electrical device which raises the frequency. This high-frequency electrical power is applied to a step-up transformer that increases the voltage. The high voltage, high-frequency...
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Part 4: Corona Treating Watt Density

In Part 3 of the Corona Treating Series we discussed power supply. The most significant design criterion involved in corona treatment equipment selection is sizing the system to meet the specific application requirements. Power supply size in kW is determined by the treatment power required by the most difficult-to-treat substrate to be coated. Treatment power is measured in Watt Density (Watts/Square Foot/Minute), which takes into consideration not only power level, but also the length of time the power is applied. If a given material...
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Part 5: Position of Corona Treating Station

In Part 4 of the Corona Treating Series we discussed watt density. Most roll coating and laminating is done today using water-based adhesives and coatings. The use of water-based materials requires a substrate with a higher surface energy than when solvent-based coatings are used. Therefore, pre-treated substrates should be used whenever possible and the pre-treated polymer should be treated again at the time of coating or lamination. Table 5 shows typical treatment levels for various materials. [caption id="attachment_2963" align="alignnone" width="244"]Figure 4 Read more