Journal of Coatings Technology and Research

, Volume 15, Issue 5, pp 899–911 | Cite as

Slot die stripe coating of low viscous fluids

  • Sebastian M. RauppEmail author
  • Marcel Schmitt
  • Anna-Lena Walz
  • Ralf Diehm
  • Helga Hummel
  • Philip Scharfer
  • Wilhelm Schabel


Slot die coating is applied to deposit thin and homogenous films in roll-to-roll and sheet-to-sheet applications. The critical step in operation is to choose suitable process parameters within the process window. In this work, we investigate an upper limit for stripe coatings. This maximum film thickness is characterized by stripe merging which needs to be avoided in a stable process. It is shown that the upper limit reduces the process window for stripe coatings to a major extent. As a result, stripe coatings at large coating gaps and low viscosities are only possible for relatively thick films. Explaining the upper limit, a theory of balancing the side pressure in the gap region in the cross-web direction has been developed.


Slot die coating Stripe coating Process window Minimum film thickness Upper limit Low viscous liquids Model for film spreading 



Correction factor




Height (z-axis) (µm)


Length (x-axis) (mm)


Power law exponent


Pressure (mbar)




Specific volume flow (m2/min)


Time (s)


Speed (m/min)


Width (y-axis) (mm)


x-axis in web direction


y-axis in cross-web direction

Greek letters

\(\dot{\gamma }\)

Shear rate (1/s)


Newtonian viscosity (Pa s)


Static contact angle (°)


Dynamic contact angle (°)


Consistency factor (Pa sε)


Surface tension (mN/m)







Capillary number


































Position 1


Position 2


Position 3



The authors acknowledge financial support via the projects KOBALT and POESIE of the German Federal Ministry of Education and Research (Contract Nos. 13N0883 and 13N13692) and Philips Technologie GmbH Innovative Technologies, Aachen. We would like to thank all involved mechanics, assistants, and students for contributing to this work as well as TSE Troller AG, Murgenthal, Switzerland, for technical support.

Supplementary material

11998_2017_39_MOESM1_ESM.pdf (2.4 mb)
Supplementary material 1 (PDF 2459 kb)


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Copyright information

© American Coatings Association 2018

Authors and Affiliations

  • Sebastian M. Raupp
    • 1
    • 3
    Email author
  • Marcel Schmitt
    • 1
  • Anna-Lena Walz
    • 1
  • Ralf Diehm
    • 1
    • 3
  • Helga Hummel
    • 2
  • Philip Scharfer
    • 1
    • 3
  • Wilhelm Schabel
    • 1
  1. 1.Institute of Thermal Process Engineering, Thin Film Technology, Karlsruhe Institute of TechnologyKarlsruheGermany
  2. 2.Chemistry and Biotechnology, University of Applied Sciences, FH AachenJülichGermany
  3. 3.InnovationLabHeidelbergGermany

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