Journal of Coatings Technology and Research

, Volume 12, Issue 5, pp 819–826 | Cite as

Simultaneous multilayer coating of water-based and alcohol-based solutions

  • R. Horiuchi
  • W. J. Suszynski
  • M. S. CarvalhoEmail author


Multilayer continuous liquid coating is the most efficient way to manufacture films that require more than one layer for optimal performance. Two-layer slot coating is one of the different coating methods largely used to deposit two thin, uniform liquid layers onto a moving substrate. In recent years, the operating conditions and solution properties which are required to avoid various coating defects have been discussed in the literature. However, these past studies have not focused on the problem of top layer dewetting, which may occur at some operating conditions. It is important to include in the operating window of the process, the region of the parameter space at which the top layer dewetting is avoided. In this work, we used water-based and alcohol-based solutions to create two-layer films over a moving substrate using a two-layer slot coating die. The critical operating condition at which top layer dewetting is observed is determined experimentally for different liquid viscosities, surface tensions, and wet thicknesses. A physical mechanism that explains the reported phenomenon is proposed. The results show how dewetting can be avoided by controlling the liquid properties (surface tension and viscosity) and wet thickness of each layer and will certainly help the design of two-layer slot coating processes.


Multilayered coating Slot die Interlayer Miscible solution Dewetting 


  1. 1.
    Sartor, L, Huff, S, Kishi, CN, “Method for Multilayer Coating Using Pressure Gradient Regulations.” US Patent 5,728,430, 1998Google Scholar
  2. 2.
    Taylor, SD, Hrymak, AN, “Visualization and Flow Simulation of Two-Slot Coater.” Chem. Eng. Sci., 54 909–918 (1999)CrossRefGoogle Scholar
  3. 3.
    Nam, J, Carvalho, MS, “Mid-Gap Invasion in Two-Layer Slot Coating.” J. Fluid Mech., 631 397–417 (2009)CrossRefGoogle Scholar
  4. 4.
    Yih, CS, “Instability Due to Viscosity Stratification.” J. Fluid Mech., 27 337–352 (1967)CrossRefGoogle Scholar
  5. 5.
    Cohen, D, “Two-Layer Slot Coating Flow Visualization and Modelling.” M.Sc. Thesis, University of Minnesota, 1993Google Scholar
  6. 6.
    Musson, LC, “Two-Layer Slot Coating.” Ph.D. Thesis, University of Minnesota, 2001Google Scholar
  7. 7.
    Gutoff, EB, Cohen, ED, Coating and Drying Defects. Wiley, New York, 1995Google Scholar
  8. 8.
    Lu, SY, Lin, YP, Liu, TJ, “Coating Window for Double Layer Extrusion Slot Coating of Poly(vinyl-alcohol) Solutions.” Polym. Eng. Sci., 41 (10) 1823–1829 (2001)CrossRefGoogle Scholar
  9. 9.
    Lin, YN, Liu, TJ, Hwang, SJ, “Minimum Wet Thickness for Double-Layer Slide-Slot Coating of Poly(vinyl-alcohol) Solutions.” Polym. Eng. Sci., 45 (12) 1590–1599 (2005)CrossRefGoogle Scholar
  10. 10.
    Nam, J, Carvalho, MS, “Linear Stability Analysis of Two-Layer Rectilinear Flow in Slot.” AIChE J., 56 2503–2512 (2010)CrossRefGoogle Scholar

Copyright information

© American Coatings Association 2015

Authors and Affiliations

  • R. Horiuchi
    • 1
    • 2
  • W. J. Suszynski
    • 2
  • M. S. Carvalho
    • 3
    Email author
  1. 1.Asahi Kasei CorporationFujiJapan
  2. 2.Coating Process Fundamentals Program, Department of Chemical Engineering and Materials ScienceUniversity of MinnesotaMinneapolisUSA
  3. 3.Department of Mechanical EngineeringPontificia Universidade Catolica do Rio de JaneiroGaveaBrazil

Personalised recommendations