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Premetered Coating Methods

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Learn more about premetered slot die coating methods for specialized applications. For further information visit http://www.slotdies.com/technical_content/technical_content.phtml for helpful articles

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Premetered Coating Methods

  1. 1. COATING METHODS – PREMETERED SLOT DIE COATING TECHNOLOGY
  2. 2. COATING METHODS - PREMETERED
  3. 3. COATING METHODS - PREMETERED • Pre-metered vs Self-metered • Pre-metered = amount of liquid applied to the web per unit area is predetermined by a fluid metering device upstream • Self-metered = final wet thickness of the coated film is controlled by the interactions of the fluid flow with the coating applicator • The average cross-web weight (thickness) is predetermined before the fluid is applied to the substrate (Pre-metered)
  4. 4. FLUID DELIVERY SYSTEM • Fluid Delivery and Line Speed o Coating weight (thickness) o Ratio • Fluid Delivery System o Positive displacement o Rheology of fluid o Density o Particle size o Shear sensitivity
  5. 5. TECHNIQUE • Slot Die Coating Technology • Direct • Curtain • Free Span
  6. 6. TECHNIQUE • Direct coating o Shim size o Coating gap o Attack angle o Coating window
  7. 7. TECHNIQUE • Direct coating o Advantages  Cross-web uniformity predictable  Precision surfaces o Disadvantages  Narrow gaps  12 micron coatings or thicker
  8. 8. TECHNIQUE • Curtain coating o Balance of liquid momentum and surface tension o Uniform pressure across fluid flow between edge guides o If the coating thickness is smaller, then the web velocity has to be higher o Sharp lip edge geometry
  9. 9. TECHNIQUE • Curtain coating o Advantages  Large gap (irregular surfaces)  Increased fluid velocity  Higher line speed  Thinner coatings o Disadvantages  Air/Vibration  Minimum line speed & flow rate  Neck-in
  10. 10. TECHNIQUE • Tensioned web o Elasto-hydrodynamic interaction  Web tension  Line speed/flow rate  Wet coating thickness  Wrap angles  Lip geometry  Web penetration
  11. 11. TECHNIQUE • Tensioned web o Advantages  Overcome gap issues  Follow profile of web  Thinner coatings o Disadvantages  Web dependent (tensions)  Process dependent (idlers)
  12. 12. SYSTEM • Slot Die • Positioner • Backing roll • Fluid delivery system • Substrate
  13. 13. SYSTEM • Slot Die o Manifold design o Manufacturing tolerances o Lip offset o Lip geometry Distribution chamber Feed port Slot gap Lip land
  14. 14. SYSTEM • Slot die design • Rheology • Manifold • Body sections • Fluid flow control
  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. FLUID DELIVERY 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. COATING METHODS - PREMETERED
  21. 21. PROCESS • Full width coating • Lane coating • Intermittent coating • Multi-layer coating • Dual-sided coating
  22. 22. SUMMARY • Technique • System • Process

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