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Tri-helical direct gravure coating

By Robert William Hewson


Tri-helical, gravure roll coating, operated in reverse mode, is investigated via a combined experimental,\ud theoretical and computational approach.\ud \ud New experiments were conducted on a pilot coating rig, designed to simulate the industrial process. Flow visualisations reveal the underlying flow structure within the roll-to-web transfer region and highlight when loss of coating stability (streaking) occurs. The latter is found to be influenced by the depth of the tri-helical grooves and the capillary number. Experiments show that as the\ud web-to-roll speed ratio is increased, so too is fluid pickout from the grooves, although the coated film thickness may decrease.\ud \ud A key feature of the present investigation is the formulation of a novel complementary mathematical\ud model. By starting with a simplified form of the coating process and progressively adding complexity a set of models are developed, first for simple zero pitch angled rectangular grooves then for grooves of arbitrary shape and groove pitch. A further extension to the model is the inclusion of a non-Newtonian model for the fluid (specifically a shear thinning power law formulation).\ud Analysis of the application of shear thinning fluids to the moving substrate is also conducted.\ud \ud The base model developed is that for rectangular grooves of zero pitch, which takes the form of an analytical solution of the flow equation (a Poisson equation) along a groove. An extension to this model is made by solving the Poisson equation for non-rectangular grooves using the finite\ud element method. Simple meniscus models were applied to make the problem tractable. Agreement between experimental data and predictions from the model is seen to be good for the range of operating conditions considered up to the onset of streaking.\ud \ud A final extension to the model considers grooves at non-zero pitch angles, representative of the industrial coating process. The limitations of this model, when compared to experimental data are examined and a physical explanation is postulated for the breakdown of the model at steep pitch\ud angles. Under conditions of breakdown, the high pressures within the groove are consistent with the idea that elastohydrodynamics is an important mechanism in the transfer of fluid within the coating bead for discrete cell gravure coating

Publisher: School of Mechanical Engineering (Leeds)
Year: 2006
OAI identifier: oai:etheses.whiterose.ac.uk:1208

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  6. (1975). A study offilm rupture in hydrodynamic lubrication.
  7. A theoretical and experimental investigation of reservoir-fed, rigid-roll coating.
  8. (1996). A theoretical investigation of reverse roll coating.
  9. A variable coefficient plate withdrawal theory for power-law fluids.
  10. (2003). Advanced Engineering Mathematics.
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  12. (1995). An experimental and theoretical investigation of gravure roll coating.
  13. (1993). An Experimental and Theoretical Study of Viscous Lifting inTribology. Phd thesis,
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  16. An investigation of the angle of contact between parafin wax and water.
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  24. (1973). Capillarity-controlled entrainment of liquid by a thin cylindrical filament moving through an interface.
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  26. Cavitation in lubrication. partl. on the boundary conditions and cavity-fluid interfaces.
  27. Coaters analyzed by form and function.
  28. Coating flow theory by finite-element and asymptotic analysis of the navier-stokes system.
  29. (1965). Coating methods.
  30. Coating rows.
  31. Coating with patterned rolls and rods.
  32. (1979). Coatings processes. In
  33. (1967). Conditions for the rupture of a lubricating film.
  34. Conditions for the rupture of a lubricating film. part 1: Theoretical model.
  35. Conditions for the rupture of a lubricating film. part 2: New boundary conditions for reynolds equation.
  36. Correlation for dynamic contact angle.
  37. (1933). Das Scwimmlager,
  38. Deposition of a viscous fluid on the wall of a tube.
  39. Developing flow of a power-law liquid film on an inclined plane.
  40. Direct forward gravure coating on unsupported web.
  41. Dragging of a liquid by a moving plate.
  42. (1987). Dynamics of Polymeric Liquids,
  43. (2004). Elastohydrodynamics of gravure: Lubrication flow between a cavity and a flexible wall.
  44. Film-splitting flows in forward roll coating.
  45. Film-splitting flows of shear-thinning liquids in forward roll coating.
  46. Films of non-Newtonian fluids adhering to flat plates.
  47. (1992). Finite element analysis : theory and practice. Harlow : Longman Scientific &
  48. (1978). Finite Element Galerkin Methods for Differential Equations,
  49. (1960). Finite-difference methods for partial differential equations.
  50. Finite-element analysis of fully-developed laminar-flow of power-law nonNewtonian fluid in a rectangular duct.
  51. (1999). Flow phenomena in fixed-gap and gravure roll coating systems.
  52. Flow structure and transfer jets in a contra-rotating rigid- roll coating system.
  53. Fluid coating on a fiber.
  54. (1999). Fluid coating.
  55. (1922). Fluidity and plasticity. Internatinal Chemical Series.
  56. Formation of ribs on rotating rollers.
  57. Gravitydriven flow of continuous thin liquid films on non- porous substrates with topography.
  58. Gravure roll coating of Newtonian liquids.
  59. Inertia effect in hydrodynamic lubrication with film rupture.
  60. Ink flow on rotating rollers.
  61. (1998). Instabilities in roll and slot coatingflows.
  62. Kinetics of liquid/liquid displacement.
  63. Knurl roll design for stable rotogravure coating.
  64. Laminar flow of non-Newtonian fluid in right triangular ducts.
  65. (1997). Liquid film coating scientific principles and their technological implications, Chapter 12b, Elastohydrodynamic Coating Systems.
  66. (1997). Liquid film coating scientific principles and their technological implications.
  67. Lubrication characteristics of involute spur gears.
  68. (2005). Lubrication flow between a cavity and a flexible wall.
  69. Marangoni effects of trace impurities on the motion of long gas-bubbles in capillaries.
  70. Mathematical-modeling of the reverse and metering roll coating flow of Newtonian fluids.
  71. Mathematical-models for coating processes.
  72. (1995). Meniscus roll coating.
  73. Modeling and analysis of meniscus roll coating.
  74. (2000). Modelling the meniscus evacuation problem in direct gravure coating.
  75. Numerical modeling of liquid withdrawal from gravure cavities in coating operations; the effect of cell pattern.
  76. (2002). Numerical Recipes in C++. Numerical Recipes.
  77. On the formulation of rheological equations of state.
  78. On the theory of lubrication and its application to mr beauchamp tower's experiment, including an experimental determination of the viscosity of olive oil.
  79. (2001). Parallel programming with matlabmpi.
  80. Perturbation method in gas-assisted power-law fluid displacement in a circular tube and a rectangular channel.
  81. (2004). Polyester films - dupont teijin shuts us plants, plans closures in europe.
  82. (2005). Private communication,
  83. (1932). Process and apparatus for applying solutions, us patent us 1847065,23/02/1932
  84. Reverse roll coating of non-Newtonian liquids.
  85. Reverse roll coating of viscous and viscoelastic liquids -response.
  86. Reverse roll coating of viscous and viscoelastic liquids.
  87. (1968). Rheological Equations for Molecular Network Theories. Phd,
  88. Rheological properties of high-viscosity solutions of long molecules.
  89. Rheology of non-Newtonian fluids -a new flow equation for pseudoplastic systems.
  90. Ribbing instability of a two roll coater- Newtonian fluids.
  91. Roll coating of purely viscous-liquids.
  92. Roll coating operations.
  93. (1992). Roll coating.
  94. (2004). Simplifications to the short bearing approximation.
  95. (2000). Solving boundary value problems for ordinary differential equations in matlab with bvp4c,
  96. Some methods for estimating the normal stress functions in viscometric flows.
  97. Some observations on the behaviour of liquids between rotating rollers.
  98. Some properties of apparent water paradox in entrainment.
  99. (2000). Spectral methods in matlab.
  100. (1999). Spectral/hp element methods for CFD.
  101. Stability of symmetrical film-splitting between counter- rotating cylinders.
  102. Stagnation-saddle points and flow patterns in stokes flow between contra-rotating cylinders.
  103. Study of advancing interface . 1. interface shape in liquid-gas systems.
  104. The distribution of pressures in the roll appliecation of Newtonian fluids.
  105. (2000). The finite element method using matlab. CRC Mechanical engineering series.
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  109. The longitudinal ridged structure in the tin coating of tinplate.
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  112. The Song of Deborah and Barak, verse 5.
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