Q: Can one coating method be used for all required coating steps in a process? Part 2 of 4

By Dr. Edward D. Cohen

Coating applicator fundamentals

Since the first roll coater was developed in 1850, there have been 40 major coating methods that have been demonstrated with about 800 to 1,000 specific configurations that have been developed and are in routine use. These methods have resulted in an increased range of coater operating capability, improved coating quality, and economic efficiency. This, in turn, has lead to a wide range of new products being commercialized with an equally wide range of coating requirements. Systems are being used to coat a variety of current and new products as the market for these materials continues to expand. It’s not just pressure-sensitive tapes and coated paperboards anymore. Thin-film batteries, organic photovoltaic cells and wearable medical devices are just a few of the breakthrough new developments made possible by web coating.

The coating-method operating range is characterized by the following parameters under which the coater will give good quality:

       Wet thickness range
       Viscosity range
       Line speed range
       Coatweight uniformity
       Number of layers that can be coated simultaneously
       Patch coating capability

Parts 3-4 of this column will cover in detail the coating-application step objectives of initial product concept development, R&D product development, scale-up, and manufacturing.

References

Cohen, E.D., “How The Coating Process Operating Window Helps Achieve Defect-free Products,” Converting Quarterly, 2013 Quarter 1, page 60.
Wagner, J.R., Multilayer Flexible Packaging, Elsevier, 2nd ed., 2016.
J. Greener, G. Pearson, M. Cakmak, Roll-to-Roll Manufacturing: Process Elements and Recent Advances, John Wiley & Sons, 2018.
Cohen, E.D., Lightfoot, E.J., Coating, Coating Process, Kirk Othmer, Encyclopedia of Chemical Technology, John Wiley & Sons, 2011.
AIMCAL SourceBook, www.aimcal.org