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Analytical determination of process windows for bilayer slot die coating

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Abstract

Slot die coating is a film casting process with a highly diverse variety of everyday applications. As a pre-metered process it not only guarantees excellent film uniformity, but is also suitable for simultaneously applied multilayer coatings. Characteristic singularities like the behavior of the liquid–liquid interface and the impact of the additional mid-lip on film uniformity were already investigated before. However, the effect of an altered gap pressure regime on commonly used coating windows has not yet been discussed. In this work, we therefore extended available single-layer coating windows for Newtonian and power-law liquids to the bilayer case. Here, the emphasis was laid on the air entrainment limit. Subsequently, the theoretical results were compared to experimental data. It was found that the onset of air entrainment strongly depends on the top to bottom film thickness ratio for bilayer coatings. A critical film thickness ratio which delivers similar coating limits as those for single-layer coatings was derived and confirmed by experimentally gained results.

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Abbreviations

h :

Height (z-axis) (µm)

l :

Length (x-axis) (mm)

p :

Pressure (mbar)

u :

Speed (m/min)

\(\dot{\gamma }\) :

Shear rate (1/s)

\(\varepsilon\) :

Power law exponent

\(\kappa\) :

Consistency factor (Pa sn)

\(\eta\) :

Newtonian viscosity (Pa s)

crit :

Critical

D :

Downstream

G :

Gap

M :

Mid-lip

U :

Upstream

W :

Web

References

  1. Kistler, SF, Schweizer, PM, Liquid Film Coating: Scientific Principles and Their Technological Implications. Chapman & Hall, London (1997)

    Book  Google Scholar 

  2. Cohen, ED, Gutoff, EB, Modern Coating and Drying Technology. Wiley, New York (1992)

    Google Scholar 

  3. Nam, J, Carvalho, MS, “Mid-Gap Invasion in Two-Layer Slot Coating.” J. Fluid Mech., 631 397 (2009)

    Article  Google Scholar 

  4. Gutoff, EB, Cohen, ED, Kheboian, GI, Coating and Drying Defects: Troubleshooting Operating Problems. Wiley-Interscience, New York (2006)

    Book  Google Scholar 

  5. Schmitt, M., et al. “Wet Film Characterization of Slot Die Coated Multilayer Electrodes (Talk)”. 16th International Coating Science and Technology Symposium. International Society of Coating Science and Technology, Atlanta, GA (2012)

  6. Schmitt, M., et al. “Break-Up Phenomena in Multilayer Slot Die Coating of Lithium-Ion Batteries (Poster)”. European Coating Symposium 2013, Mons, Belgium, 2013

  7. Taylor, D, Two-Layer Slot Coating: Study of Die Geometry and Interfacial Region, in Chemical Engineering. McMaster University, Hamilton, ON (1997)

    Google Scholar 

  8. Hrymak, AN, Taylor, D, “Visualization and Flow Simulation of a Two-Layer Slot Coater.” Chem. Eng. Sci., 54 909–918 (1999)

    Article  Google Scholar 

  9. Durst, FD, Dongari, N, Sambasivam, R, “Slot Coaters Operating in Their Bead Mode.” Coating, 11 1–6 (2007)

    Google Scholar 

  10. Higgins, BG, Scriven, LE, “Capillary Pressure and Viscous Pressure Drop Set Bounds on Coating Bead Operability.” Chem. Eng. Sci., 35 (3) 673–682 (1980)

    Article  Google Scholar 

  11. Ruschak, KJ, “Limiting Flow in Pre-metered Coating Device.” Chem. Eng. Sci., 31 1057–1060 (1976)

    Article  Google Scholar 

  12. Carvalho, MS, Kheshgi, HS, “Low-Flow Limit in Slot Coating: Theory and Experiments.” AIChE J., 46 (10) 1907–1917 (2000)

    Article  Google Scholar 

  13. Weinstein, SJ, Ruschak, KJ, “Coating Flows.” Annu. Rev. Fluid Mech., 36 (1) 29–53 (2004)

    Article  Google Scholar 

  14. Romero, OJ, et al., “Low-Flow Limit in Slot Coating of Dilute Solutions of High Molecular Weight Polymer.” J. Nonnewton. Fluid Mech., 118 (2–3) 137–156 (2004)

    Article  Google Scholar 

  15. Schmitt, M, et al., “Slot-Die Processing of Lithium-Ion Battery Electrodes—Coating Window Characterization.” Chem. Eng. Process., 68 32–37 (2013)

    Article  Google Scholar 

  16. Schmitt, M, Scharfer, P, Schabel, W, “Slot Die Coating of Lithium-Ion Battery Electrodes: Investigations on Edge Effect Issues for Stripe and Pattern Coatings.” J. Coat. Technol. Res., 11 57–63 (2013)

    Article  Google Scholar 

  17. Schmitt, M, et al., “An Experimental and Analytical Study on Intermittent Slot Die Coating of Viscoelastic Battery Slurries.” J. Coat. Technol. Res., (2015). doi:10.1007/s11998-015-9717-9

    Google Scholar 

  18. Tsuda, T, “Coating Flows of Power-Law Non-Newtonian Fluids in Slot Coating.” Nihon Reoroji Gakkaishi, 38 (4–5) 223–230 (2010)

    Article  Google Scholar 

  19. Lee, SH, et al., “Operability Coating Windows and Frequency Response in Slot Coating Flows from a Viscocapillary Model.” Chem. Eng. Sci., 66 (21) 4953–4959 (2011)

    Article  Google Scholar 

  20. Kamişli, F, Ryan, ME, “Perturbation Method in Gas-Assisted Power-Law Fluid Displacement in a Circular Tube and a Rectangular Channel.” Chem. Eng. J., 75 (3) 167–176 (1999)

    Article  Google Scholar 

Download references

Acknowledgments

Part of this work has been supported in the frame of the project Competence E (KIT) by the German Federal Ministry of Economics and Technology on the basis of a decision by the German Bundestag (Funding Nr. 03ET6016). The authors would like to thank all involved mechanics, assistants and the students Robert Schneider, Susanne Unger, Caroline Schober and Michael Wittek for their supporting work and building of the experimental set-up. We specially thank Valentin Wenzel and Steffen Schmelzle (KIT-MVM-VM) for mixing support, Boris Bitsch (KIT-MVM-AM) for rheological measurements, Kevin Stella and Matthias Loeble (KIT-COMPETENCE E) and Anke Scherf (KIT-IAM-WK-PM) for REM measurements. We also want to thank our cooperation partners TSE Troller AG, Switzerland for the technical support.

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Authors and Affiliations

  1. Institute of Thermal Process Engineering, Thin Film Technology, Karlsruhe Institute of Technology, Karlsruhe, Germany

    Marcel Schmitt, Sebastian Raupp, Dennis Wagner, Philip Scharfer & Wilhelm Schabel

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  1. Marcel Schmitt
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  2. Sebastian Raupp
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  3. Dennis Wagner
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  4. Philip Scharfer
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  5. Wilhelm Schabel
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Correspondence to Marcel Schmitt.

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Schmitt, M., Raupp, S., Wagner, D. et al. Analytical determination of process windows for bilayer slot die coating. J Coat Technol Res 12, 877–887 (2015). https://doi.org/10.1007/s11998-015-9701-4

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