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
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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 
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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).

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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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