Ribbing instability in rigid and deformable forward roll coating flows

Je Hoon Lee, Sang Kwon Han, Joo Sung Lee, Hyun Wook Jung, Jae Chun Hyun

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

Dynamics and ribbing instability for Newtonian and viscoelastic liquids have been investigated in both rigid and deformable forward roll coating flows. Especially, the role of viscoelasticity of coating liquids and roll deformability or hardness on the coating flow has been scrutinized. Coating thickness at steady uniform states and wavelength and severity at unstable ribbing states have been measured, incorporating thickness measurement device and two-roll coating equipment. Relationship between wavelength and severity in ribbing instability strongly depends on the viscoelasticity as well as other operating conditions such as capillary number, coating gap, and roll deformability. Coating windows demarcating uniform and ribbing instability are considerably reduced by increasing viscoelasticity and decreasing roll deformability. In other words, ribbing is aggravated as the viscoelasticity of coating liquids that can generate the extensional property in film splitting region rises or roll deformability decreases, leading to higher severity and narrower wavelength.

Original languageEnglish
Pages (from-to)75-80
Number of pages6
JournalKorea Australia Rheology Journal
Volume22
Issue number1
Publication statusPublished - 2010

Keywords

  • Coating window
  • Forward roll coating
  • Ribbing
  • Roll deformability
  • Severity
  • Viscoelasticity
  • Wavelength

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics

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