COATING METHODS – PREMETEREDSLOT DIE COATING TECHNOLOGY

COATING METHODS - PREMETERED

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)

FLUID DELIVERY SYSTEM

• Fluid Delivery and Line Speed o Coating weight (thickness)o Ratio

• Fluid Delivery Systemo Positive displacemento Rheology of fluido Densityo Particle sizeo Shear sensitivity

TECHNIQUE

• Slot Die Coating Technology

• Direct• Curtain• Free Span

TECHNIQUE

• Direct coatingo Shim sizeo Coating gapo Attack angleo Coating window

TECHNIQUE

• Direct coatingo Advantages

Cross-web uniformity predictable Precision surfaces

o DisadvantagesNarrow gaps 12 micron coatings or thicker

TECHNIQUE

• Curtain coatingo Balance of liquid momentum and surface tensiono Uniform pressure across fluid flow between edge guideso If the coating thickness is smaller, then the web velocity

has to be highero Sharp lip edge geometry

TECHNIQUE

• Curtain coatingo Advantages

Large gap (irregular surfaces) Increased fluid velocity Higher line speed Thinner coatings

o Disadvantages Air/Vibration Minimum line speed & flow rate Neck-in

TECHNIQUE

• Tensioned webo Elasto-hydrodynamic interaction

Web tension Line speed/flow rateWet coating thicknessWrap angles Lip geometryWeb penetration

TECHNIQUE

• Tensioned webo Advantages

Overcome gap issues Follow profile of web Thinner coatings

o DisadvantagesWeb dependent (tensions) Process dependent (idlers)

SYSTEM

• Slot Die• Positioner• Backing roll• Fluid delivery system• Substrate

SYSTEM

• Slot Dieo Manifold designo Manufacturing toleranceso Lip offset o Lip geometry

Distribution chamber

Feed port

Slot gap

Lip land

SYSTEM

• Slot die design

• Rheology • Manifold• Body sections• Fluid flow control

SYSTEM

• Slot Dieo Fixed lipo Flex lipo Rotary rod

SYSTEM

• Positionero Attack angleo Position to rollo Repeatability

SYSTEM

• Backing rollo Diametero TIRo Cocentricityo Cylindricity

FLUID DELIVERY SYSTEM

• Fluid Delivery Systemo Positive displacemento Rheology of fluido Densityo Particle sizeo Shear sensitivity

SYSTEM

• Substrateo Variation (RTY)o Surface energyo Surface treatmento Vacuum boxo Tension control

COATING METHODS - PREMETERED

PROCESS

• Full width coating• Lane coating• Intermittent coating• Multi-layer coating• Dual-sided coating

SUMMARY

• Technique• System• Process