Effect of upstream meniscus shape on dynamic wetting and operating limits of Newtonian coating liquids in slot coating bead flows

  • Won-Gi Ahn
  • Si Hyung Lee
  • Jaewook Nam
  • See Jo Kim
  • Kwan-Young Lee
  • Hyun Wook Jung
Article

Abstract

The coating bead flow and operability window for Newtonian coating liquids are theoretically and experimentally investigated in the slot coating process, with a focus on the shape of the upstream meniscus and contact angles. From the flow visualization in the coating bead region, the contact angles of the upstream meniscus were measured by changing the flow rate and web speed under uniform operating conditions. It was confirmed that the dynamic contact angle is closely related to the capillary number in this process, based on the Hoffman–Voinov–Tanner model. The viscocapillary and two-dimensional Navier–Stokes models using the experimentally observed contact angles accurately predicted the coating bead dynamics and operability windows for two Newtonian liquids.

Keywords

Slot coating Upstream meniscus Dynamic contact angle Static contact angle Operability window 

Notes

Acknowledgments

This work was supported by the National Research Foundation of Korean (NRF) grant funded by the Korean government (MSIP) (NRF-2016R1A5A1009592) and the Ministry of Trade, Industry & Energy (MOTIE, Korea) under the Industrial Technology Innovation Program (No.10067706).

References

  1. 1.
    Durian, DJ, Franck, C, “Wetting Phenomena of Binary Liquid Mixtures on Chemically Altered Substrates.” Phys. Rev. Lett., 59 (5) 555–558 (1987)CrossRefGoogle Scholar
  2. 2.
    Extrand, CW, Kumagai, Y, “An Experimental Study of Contact Angle Hysteresis.” J. Colloid Interface Sci., 191 (2) 378–383 (1997)CrossRefGoogle Scholar
  3. 3.
    Kistler, SF, Schweizer, PM, Liquid Film Coating. Chapman & Hall, London (1997)CrossRefGoogle Scholar
  4. 4.
    Blake, TD, Shikhmurzaev, YD, “Dynamic Wetting by Liquids of Different Viscosity.” J. Colloid Interface Sci., 253 (1) 196–202 (2002)CrossRefGoogle Scholar
  5. 5.
    Ruijter, D, Michel, J, Blake, TD, Coninck, JD, “Dynamic Wetting Studied by Molecular Modeling Simulations of Droplet Spreading.” Langmuir, 15 (22) 7836–7847 (1999)CrossRefGoogle Scholar
  6. 6.
    Tanner, LH, “The Spreading of Silicone Oil Drops on Horizontal Surfaces.” J Phys. D. Appl. Phys., 12 (9) 1473–1484 (1979)CrossRefGoogle Scholar
  7. 7.
    Huppert, HE, “The Propagation of Two-Dimensional and Axisymmetric Viscous Gravity Currents Over a Rigid Horizontal Surface.” J. Fluid Mech., 121 43–58 (1982)CrossRefGoogle Scholar
  8. 8.
    Voinov, OV, “Hydrodynamics of Wetting.” Fluid Dyn., 11 (5) 714–721 (1976)CrossRefGoogle Scholar
  9. 9.
    Bonn, D, Eggers, J, Indekeu, J, Meunier, J, Rolley, E, “Wetting and Spreading.” Rev. Mod. Phys., 81 (2) 739–805 (2009)CrossRefGoogle Scholar
  10. 10.
    Hoffman, RL, “A Study of the Advancing Interface. I. Interface Shape in Liquid—Gas Systems.” J. Colloid Interface Sci., 50 (2) 228–241 (1975)CrossRefGoogle Scholar
  11. 11.
    Higgins, BG, Scriven, LE, “Capillary-Pressure and Viscous Pressure-Drop Set Bounds on Coating Bead Operability.” Chem. Eng. Sci., 35 (3) 673–682 (1980)CrossRefGoogle Scholar
  12. 12.
    Gates, ID, “Slot Coating Flows: Feasibility, Quality.” PhD Thesis, University of Minnesota, 1999Google Scholar
  13. 13.
    Lee, SH, Koh, HJ, Ryu, BK, Kim, SJ, Jung, HW, Hyun, JC, “Operability Coating Windows and Frequency Response in Slot Coating Flows Using Viscocapillary Model.” Chem. Eng. Sci., 66 (21) 4953–4959 (2011)CrossRefGoogle Scholar
  14. 14.
    Nam, J, Carvalho, MS, “Two-Layer Tensioned-Web-Over-Slot Die Coating: Effect of Operating Conditions on Coating Window.” Chem. Eng. Sci., 65 (13) 4065–4079 (2010)CrossRefGoogle Scholar
  15. 15.
    Lee, YW, Ahn, WG, Nam, J, Jung, HW, “Operability Windows in Viscoelastic Slot Coating Flows Using a Simplified Viscoelastic-Capillary Model.” Rheol. Acta, 56 (9) 707–717 (2017)CrossRefGoogle Scholar
  16. 16.
    Huh, C, Scriven, LE, “Hydrodynamic Model of Steady Movement of a Solid/Liquid/Fluid Contact Line.” J. Colloid Interface Sci., 35 (1) 85–101 (1971)CrossRefGoogle Scholar
  17. 17.
    Kistler, SF, “Hydrodynamics of Wetting.” Wettability, 6 311–430 (1993)Google Scholar
  18. 18.
    Ding, X, Liu, J, Harris, TAL, “A Review of the Operating Limits in Slot Die Coating Processes.” AIChE J., 62 (7) 2508–2524 (2016)CrossRefGoogle Scholar
  19. 19.
    Didari, S, Ahmad, ZY, Veldhorst, JD, Harris, TAL, “Wetting Behavior of the Shear Thinning Power Law Fluids.” J. Coat. Technol. Res., 11 (1) 95–102 (2014)CrossRefGoogle Scholar
  20. 20.
    Bhamidipati, KL, Didari, S, Bedell, P, Harris, TAL, “Wetting Phenomena During Processing of High-Viscosity Shear-Thinning Fluid.” J. Non-Newtonian Fluid Mech., 166 (12) 723–733 (2011)CrossRefGoogle Scholar
  21. 21.
    Vandre, E, Carvalho, MS, Kumar, S, “Delaying the Onset of Dynamic Wetting Failure Through Meniscus Confinement.” J. Fluid Mech., 707 496–520 (2012)CrossRefGoogle Scholar
  22. 22.
    Ji, HS, Ahn, WG, Kwon, I, Nam, J, Jung, HW, “Operability Coating Window of Dual-Layer Slot Coating Process Using Viscocapillary Model.” Chem. Eng. Sci., 143 122–129 (2016)CrossRefGoogle Scholar
  23. 23.
    Ruschak, KJ, “Limiting Flow in a Pre-metered Coating Device.” Chem. Eng. Sci., 31 (11) 1057–1060 (1976)CrossRefGoogle Scholar
  24. 24.
    Koh, HJ, Kwon, I, Jung, HW, Hyun, JC, “Operability Window of Slot Coating Using Viscocapillary Model for Carreau-Type Coating Liquids.” Korea-Aust. Rheol., 24 (2) 137–141 (2012)CrossRefGoogle Scholar
  25. 25.
    Lee, SH, Kim, SJ, Nam, J, Hyun, WJ, Hyun, JC, “Effect of Sloped Die Lip Geometry on the Operability Window in Slot Coating Flows Using Viscocapillary and Two-Dimensional Models.” J. Coat. Technol. Res., 11 (1) 47–55 (2014)CrossRefGoogle Scholar
  26. 26.
    De Santos, JM, “Two-Phase Concurrent Downflow Through Constricted Passage.” PhD Thesis, University of Minnesota, 1991Google Scholar
  27. 27.
    Carvalho, MS, “Roll Coating Flows in Rigid and Deformable Gap.” PhD Thesis, University of Minnesota, 1996Google Scholar
  28. 28.
    Lee, KY, Liu, LD, Liu, TJ, “Minimum Wet Thickness in Extrusion Slot Coating.” Chem. Eng. Sci., 47 (7) 1703–1713 (1992)CrossRefGoogle Scholar
  29. 29.
    Sartor, L, “Slot Coating: Fluid Mechanics and Die Design.” PhD Thesis, University of Minnesota, 1990Google Scholar

Copyright information

© American Coatings Association 2018

Authors and Affiliations

  • Won-Gi Ahn
    • 1
  • Si Hyung Lee
    • 2
  • Jaewook Nam
    • 3
  • See Jo Kim
    • 4
  • Kwan-Young Lee
    • 1
  • Hyun Wook Jung
    • 1
  1. 1.Department of Chemical and Biological EngineeringKorea UniversitySeoulRepublic of Korea
  2. 2.Samsung Advanced Institute of Technology (SAIT)GyeonggiRepublic of Korea
  3. 3.School of Chemical and Biological EngineeringSeoul National UniversitySeoulRepublic of Korea
  4. 4.School of Mechanical EngineeringAndong National UniversityAndongRepublic of Korea

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