Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Letter
  • Published:

Air entrapment in coatings by way of a tip-streaming meniscus

Nature volume 403, pages 641–643 (2000)Cite this article

Abstract

Entrapment of small air bubbles is a problem for continuous liquid-film coatings processes. The coating of any surface requires that the surrounding air in contact with it be displaced by an advancing liquid interface. Studies of dynamic wetting suggest that if the interface motion is too rapid, the air is not completely removed and it becomes entrained in the coating material1. This process, which can lead to undesirable flaws in the form of bubbles, blemishes or voids, limits the speed at which the substrate can be moved in the production of uniform precision coatings. However, the entrapment process is not understood in detail. Here we report an experimental investigation of air entrapment in high-speed coating operations. Tip streaming—a phenomenon well known in emulsification technology2, involving the ejection of a fine filament from the cusped interface between two immiscible fluids—is shown to be the precursor of air entrainment. We demonstrate that tip-streaming air filaments emanating from the contact zone of a dynamic liquid interface give rise to minute (∼10 µm) bubbles.

This is a preview of subscription content, access via your institution

Access options

Buy this article

  • Purchase on Springer Link
  • Instant access to full article PDF
Buy now

Prices may be subject to local taxes which are calculated during checkout

Figure 1: The air–liquid interface near the contact line on a 240-µm fibre.
Figure 2: Close-up of the contact region.
Figure 3: Representative bubble distribution from a tip-streaming meniscus.
Figure 4: A tip-streaming filament (A) with an elongated bubble (B) on a fibre moving at 0.3 m s-1; Ca = 5.0, Red = 0.04.

Similar content being viewed by others

References

  1. Benjamin, D. F. et al. Coating flows: form and function. Indust. Coating Res. 1, 1–37 (1991).

    Google Scholar 

  2. Grace, H. P. Dispersion phenomena in high viscosity immiscible fluid systems and the application of static mixers as dispersion devices in such systems. Chem. Eng. Commun. 14, 225–277 (1982).

    Article  CAS  Google Scholar 

  3. Kistler, S. F. in Wettability (ed. Berg, J. C.) 311–429 (Marcel Dekker, New York, 1993).

    Google Scholar 

  4. Blake, T. D. & Ruschak, K. J. A maximum speed of wetting. Nature 282, 489–491 (1979).

    Article  ADS  Google Scholar 

  5. Bolton, B. & Middleman, S. Air entrainment in a roll coating system. Chem. Eng. Sci. 35, 597–601 (1980).

    Article  CAS  Google Scholar 

  6. Ghannam, M. T. & Esmail, M. N. Effect of substrate entry angle on air entrainment in liquid coating. Am. Inst. Chem. Engrs J. 36, 1283–86 (1990).

    Article  CAS  Google Scholar 

  7. Jeong, J. -T. & Moffatt, H. K. Free-surface cusps associated with flow at low Reynolds numbers. J. Fluid Mech. 241, 1–22 (1992).

    Article  ADS  MathSciNet  CAS  Google Scholar 

  8. Joseph, D. D., Nelson, J., Renardy, M. & Renardy, Y. Two-dimensional cusped interfaces. J. Fluid Mech. 223, 383–409 (1991).

    Article  ADS  CAS  Google Scholar 

  9. Taylor, G. I. The formation of emulsions in definable fields of flow. Proc. R. Soc. Lond. A 146, 501–523 (1934).

    Article  ADS  CAS  Google Scholar 

  10. Dussan, V. E. B. & Davis, S. H. On the motion of a fluid–fluid interface along a solid surface. J. Fluid Mech. 65, 71–95 (1974).

    Article  ADS  Google Scholar 

  11. Pozrikidis, C. Numerical studies of cusp formation at fluid interfaces in Stokes flow. J. Fluid Mech. 357, 29–57 (1998).

    Article  ADS  MathSciNet  CAS  Google Scholar 

  12. Shiikhmurzaev, Y. D. On cusped interfaces. J. Fluid Mech 359, 313–328 (1998).

    Article  ADS  MathSciNet  Google Scholar 

  13. Sherwood, J. D. Tip streaming from slender drops in a nonlinear extensional flow. J. Fluid Mech. 144, 281–295 (1984).

    Article  ADS  Google Scholar 

  14. Smith, P. G. & Van de Ven, T. G. M. Shear induced deformation and rupture of suspended solid/liquid clusters. Colloids Surf. 15, 191–210 (1985).

    Article  CAS  Google Scholar 

  15. Stone, H. A. Dynamics of drop deformation and breakup in viscous fluids. Annu. Rev. Fluid Mech. 26, 65–102 (1994).

    Article  ADS  MathSciNet  Google Scholar 

  16. Eggers, J. Nonlinear dynamics and breakup of free-surface flows. Rev. Mod. Phys. 69, 865–929 (1997).

    Article  ADS  CAS  Google Scholar 

  17. de Bruijn, R. A. Tip streaming of drops in simple shear flows. Chem. Eng. Sci. 48, 277–284 (1993).

    Article  Google Scholar 

  18. Siegal, M. Influence of surfactant on rounded and pointed bubbles in 2-D Stokes flow. SIAM J. Appl. Math. 59, 1998–2007 (1999).

    Article  MathSciNet  Google Scholar 

Download references

Acknowledgements

We thank R. Slagle (Oxford Lasers, Inc.) for help in obtaining the high-speed images displayed in Figs 2 and 4, and C. Pozrikidis for helpful comments on an earlier version of the manuscript.

Author information

Authors and Affiliations

  1. Bell Laboratories, Lucent Technologies, Murray Hill, 07974, New Jersey, USA

    P. G. Simpkins & V. J. Kuck

Authors
  1. P. G. Simpkins
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. V. J. Kuck
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding author

Correspondence to P. G. Simpkins.

Rights and permissions

Reprints and permissions

About this article

Cite this article

Simpkins, P., Kuck, V. Air entrapment in coatings by way of a tip-streaming meniscus. Nature 403, 641–643 (2000). https://doi.org/10.1038/35001043

Download citation

  • Received:

  • Accepted:

  • Issue Date:

  • DOI: https://doi.org/10.1038/35001043

This article is cited by

Comments

By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.

Search

Advanced search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing