Developments in on-line Gauging of Complex Extrusion Coating – An update

Stefan SchönebergerSession 10.4 /7629

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Presentation Overview• Introduction• Complex extrusion coating process• Optimum sensor requirements• Overview of available sensor technologies• Comparison of various sensor technologies• Best choice of optimum sensor technology: HR-FSIR• Process Control; Process Tools; Process Visualization• Conclusion: Techno-Economic Benefits

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Introduction• Rapid growth globally in complex web coating lines

• Aseptic packaging of liquid consumables– Multilayer product for barrier properties & long shelf-life– attractive packaging for consumer attention

• Highly competitive Marketplace with rising raw material costs & tightening margins

• Large capital investments in high-speed complex extrusion coating laminators

• Increasing requirements for on-line gauging

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Complex Extrusion Coating Process• Product structure

– Printed paperboard substrate or metallized film laminated substrate

– Mono layer extrusion (outside layer, tie layer)– Multilayer co-extruded barrier coatings – Lamination: Aluminum Foil or Blown Film

• Process– Extrusion Coater/Laminator– Multi coating stations (outside layer, tie-layer, inside

layers)– High speed production process

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Optimum Sensor Requirements

Ability to: • Measure true absolute thickness/basis weight of

coatings of varying densities on different substrates.

• Provide non-contacting measurement with low noise and fast response.

• Provide high performance dynamic measurement of coatings independent of substrate variations in a high-speed production environment.

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Overview of on-line sensor technologiesMajor categories of on-line sensor technologies for

complex Extrusion Coating Process are:

• Nuclear Sensors

• X-Ray Sensors

• Full Spectrum InfraRed Sensor (High Resolution FSIR) based on Absorbance Mode (SpectraBeam)

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Nuclear Sensors

• Based on Beta or Gamma Radiation; Subject to source decay: (PM-147;KR-85;SR-90:AM-241)

• Radioactive; hence requires licensing for use and disposal

• Measure Basis weight (Not thickness)• Cannot discriminate between layers in multilayer

coatings• Use subtractive measurements for coat weight• Use synchronized same-spot • Use substrate-independent calibration technique (True

Net Coat Algorithm)

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X-Ray Sensors• No licensing required.• Not subject to regulations for use at strengths below 30

keV• Measure Basis weight (Not thickness)• Cannot discriminate between layers in multilayer

coatings• Composition sensitive• Use subtractive measurements for coat weight• Use synchronized same-spot • Use substrate-independent calibration technique (True

Net Coat Algorithm)

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X-Ray & Nuclear Sensor Measurement• Both X-Ray and Beta Ray Gauges Are Total Mass Gauges

• Particles will be absorbed by all mass between source and receiver

• Must pay attention to dimensional (z) and air mass changes

Nuclear Gauge

Output Signal

Web

Pm-147 or Kr-85Source Capsule

IonizationChamber

All Mass isMeasured

Web

X-Ray Gauge

Output Signal

IsotopeOr X-Ray Tube

IonizationChamber

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High Resolution FSIR Sensors• Non-radioactive• IR measurement based on absorbance• Full spectrum analysis using Chemo-metrics effectively

eliminates or minimizes sensitivity to additives, printing etc.

• Insensitive to web or air temperature• Is an on-line spectrometer• Elliptical geometry of 6 x 25 mm design allows

measurements closer to web edge, resulting in enhanced streak-detection capability and better edge control and potential less edge trims.

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Physics Behind IR Measurement - General

Each Material Has Unique Absorption Pattern

Stronger

Weaker

Absorption is StrongerAt Certain Wavelengths

Compared to Others

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SpectraBeam FSIR Sensor

Optics

Optics

Web

MSP

Tuning Fork

Lamp

Filter Matrix

FixedDetector Array

Full Absorption Spectrum

Only Mass or Thickness of

Polymer is Measured

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SpectraBeam Sensor

Signal

Absorption

Intensity

Lamp Response

Material "Signature"

Full Spectrum Array

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Chemo-metric Analysis

Full Spectrum Array Accurate Calibration forCoatings on various substrates

(Pigmented or Printed)

Chemo-metricAnalysis

&Pattern Recognition

Software

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Chemo-metric Analysis

MeasuredStandardized

Spectrum

Composition #1

Composition #2

Effect #1(TiO2)

Effect #2(surface)

Residual

Absorption

Eliminates errors caused by Surface Finish, Colorants and other Additives

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Measurement Technology ComparisonCriteria SpectrabeamFSIR X-Ray Beta

Noise Characteristics Good Good Nuclear Statistics

Noise degradation over time

None None source decay

Tolerance to Web Flutter Best (+/- 5 mm) Good(+/- 3 mm) Fair (+/- 1 mm)

Temperature Sensitivity No Yes Yes

X,Y,Z Sensitivity No Yes Yes

Composition Sensitivity No Yes Some

Dynamic Repeatability Best Good Good

Multilayer CoatingCalibration Complexity Moderate High High

Polymer Discrimination Possible No No

Multi-Component Measurement

Yes No No

Exact same- spot Yes No No

Substrate effect Minimum Yes Some

Printing,Additive Effects

Minimum Yes Yes

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Best Choice of Optimum Sensor Technology

Based on the comparative studies of various available technologies as discussed in this presentation:

High-Resolution Full Spectrum InfraRed Sensor (on-line Spectrometer) offers the best choice for the accurate dynamic measurement of multilayer coatings in complex Extrusion Coating Applications.

Reflectance HR-FSIR configuration is ideal for measurements of outside layer on paper/board or metallized film laminated substrate and co-extruded inside layers on foil.

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Process Control

• Auto Profile Control (APC) with Accelerated Thermal Response (ATR) feature helps reduce CD Variations

• MD Control helps reduce Long Term Machine Direction variations

• Yield Optimization Control: Target Management Control (TMC) Helps in Polymer Material Savings

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Process Analytical Tool• Fast Fourier Transform (FFT)

Helps in reducing short term machine direction variations caused by extrusion/laminator equipment

• Edge Zoom based on extended data

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Process Visualization

• Contourview Display Suite- Contour View Display (3 Dimensional)- Blanket View Display (Topographical)

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Techno-Economic Benefits

• Customer Results - Multiple case studies in Complex Extrusion Coating Applications:

- Reduction in CD variations: 50 to 90%, typically 70% in 20 minutes from startup

- Faster product change-over, typical reduction by 67%

- Scrap reduction (start-ups,edge & sampling scraps): 50%

- Increased edge measurement and control: Additional 2% of width

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Conclusion

• Computer-based on-line gauging systems with optimal sensor technologies, advanced process control & process analytical tools is a powerful Process Management Tool for complex Extrusion/Laminating Processors.

Thank you for your attention.

Questions?