Chapter 9: Comparative Analysis of Coating Technologies

Overview of Alternatives

Slot die vs. others:

• Knife Over Roll: Simple, low cost; less uniform for thin films due to doctoring variability.

• Gravure: Good for patterns; higher waste from engraving, limited to low viscosity.

• Roll Coating: Versatile; limited precision, shear can damage fluids.

• Dip Coating: Easy setup; uneven thickness, high waste.

• Spray Coating: Covers irregular shapes; high overspray, poor for thin uniform layers.

• Curtain Coating: High speed; sensitive to viscosity changes, air entrainment common.

• Extrusion Coating: For thick layers; less control over uniformity.

• Spin Coating: Lab-scale; not for R2R, centrifugal force limits size.

• Sputter (PVD): Vacuum-based; for metals, expensive and slow.

• Electrostatic: Powder coatings; charging issues for liquids.

Why Slot Die Stands Out

Pre-metered nature offers superior uniformity and waste reduction, especially for multi-layers and wide widths. As highlighted in University of Minnesota courses, it's ideal for viscosity-sensitive applications.​​​​​​​​​​​​​​​

Chapter 8: Applications and Industries