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Rheology and Slot Die Coating Technology by Coating Tech Slot Dies

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View this presentation on Rheology and Slot Die Coating Technology given by Mark Miller. This is the presentation from AIMCAL TV's live webinar February 6, 2019.

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Rheology and Slot Die Coating Technology by Coating Tech Slot Dies

  1. 1. RHEOLOGY & SLOT DIE COATING TECHNOLOGY
  2. 2. SLOT DIE COATING TECHNOLOGY • Background • System • Technique • Process • Summary
  3. 3. BACKGROUND • Slot die basics • Closed system • Distribute fluid uniformly • Define coat width • Maintain temperature
  4. 4. BACKGROUND • Slot die applications • Viscosity versus shear rate • % Solids • Coating thickness • Particle size • Coating width • Line speed • Operating temperature
  5. 5. BACKGROUND • Slot die design • Rheology • Manifold • Body sections • Fluid flow control
  6. 6. BACKGROUND RHEOLOGY • Viscosity • Shear Rate (Stress) o 1-10,000 1/sec
  7. 7. RHEOLOGY • Test methods o ASTM D4440  Parallel plate  Cone and Plate  Cup and Bob  Capillary
  8. 8. GEOMETRIES BOB and CUP CONE and PLATE PARALLEL PLATE DMA Rotational/Oscillatory Rotational/Oscillatory Rotational/Oscillatory Oscillatory, Creep Very low to medium viscosity Low to high viscosity, constant shear rate across the sample Low viscosity to soft solids, curing studies, dispersions Solids, thermo- mechanical analysis, curing, Tg, … Relatively large volume, inertia limitations in oscillatory test Very small volume, measure of normal stresses (elasticity) Very small volume, relatively large gap Stress is force over sample cross section
  9. 9. BACKGROUND RHEOLOGY • Newtonian • Polymeric o Shear thinning o Shear thickening η γ . η γ . η γ . η γ . η γ .
  10. 10. BACKGROUND RHEOLOGY • Process Knowledge o G’ (storage) o G” (loss) o tan δ
  11. 11. SYSTEM • Slot Die • Positioner • Backing roll • Fluid delivery system • Substrate
  12. 12. SYSTEM • Slot Die o Manifold design o Manufacturing tolerances o Lip offset o Lip geometry
  13. 13. SYSTEM • Slot Die o Manifold design o Slot dimensions  Slot height  Slot length o Pressure o Velocity o Deckling Distribution chamber Feed port Slot gap Lip land
  14. 14. SYSTEM • Slot Die o Manifold design  Infinite cavity (Newtonian)  Coat hanger (Polymeric) o Goal = uniform volumetric flow rate and pressure across coat width o Range of viscosity (families)
  15. 15. SYSTEM • Slot Die o Fixed lip o Flex lip o Rotary rod
  16. 16. SYSTEM • Positioner o Attack angle o Position to roll o Repeatability
  17. 17. SYSTEM • Backing roll o Diameter o TIR o Cocentricity o Cylindricity
  18. 18. SYSTEM • Fluid Delivery System o Positive displacement o Rheology of fluid o Density o Particle size o Shear sensitivity
  19. 19. SYSTEM • Substrate o Variation (RTY) o Surface energy o Surface treatment o Vacuum box o Tension control
  20. 20. SYSTEM • Vacuum System Vacmin = (12µVLD)/dD 3 * ((dD/2)-h)) minimum vacuum required for coating thickness h (LD and dD are downstream lip length and slot die to substrate gap)
  21. 21. TECHNIQUE
  22. 22. TECHNIQUE • Direct coating
  23. 23. TECHNIQUE • Tensioned web o Elasto-hydrodynamic interaction  Web tension  Line speed/flow rate  Wet coating thickness  Wrap angles  Lip geometry  Web penetration
  24. 24. TECHNIQUE • Curtain coating o Advantages  Large gap (irregular surfaces)  Reduced lines and streaks  Increased fluid velocity (hydrodynamic assist)  Higher line speed o Disadvantages  Air  Vibration  Minimum line speed & flow rate
  25. 25. PROCESS • Full width coating
  26. 26. PROCESS • Lane coating o Deckling o Body shim o Lip shims o Spreading (experimentation)
  27. 27. PROCESS • Intermittent coating o Continuous o Discrete panel o IP o Process limitations  Head  Tail  Line speed  Start/stop phenomenon
  28. 28. PROCESS • Multi-layer coating o 2-3 layers in typical slot die design o Slide die design accommodates more layers o Separate fluid delivery system for each layer o Combined outside the slot exit σtop < σbottom (surface energy stability)
  29. 29. PROCESS • Dual-sided coating
  30. 30. SUMMARY • System • Technique • Process

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