12017-03-23

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1. BASICS: FREQUENT PROBLEMS IN CONVERTINGPROCESS

2. DESCRIPTION OF THE BACKGROUND

3. LIMITS OF STANDARD TESTING DEVICES

4. SUPPORT IN SOLVING THESE PROBLEMS

5. APPLICATION EXAMPLES

6. DIFFERENTIATION BETWEEN AVAILABLEMEASURING DEVICES

7. CONCLUSION

Agenda

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(Almost) every paper is produced for further converting [Glueing/Printing/Coating etc.].Therefore, certain specifications between producer and customer are agreed, based on standard testing methods, and these become binding.

1 Basics

Problem But sometimes there are problems in convertingalthough the agreed specifications arethe same.

Nobody knows why!

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Gluing process Coating process

Printing process

2 Reasons for Problems in the Converting Process

Rough principle of the three typical converting processes:

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Gluing process

Reasons for Problems in the Converting Process

PHASE I: Application of a liquid film by pressure impulse into the paper / board surface in very short time (microseconds / milliseconds) Result is dependent on rheology of the liquid, pressure impulse height (machine speed/adjustments), surface porosity of the substrate

− Important for anchoring of the glue :surface pore structure= Relevant parameter to characterize with PDA/EST

PHASE II: Water absorption from the applied glue film, controlled by surface sizing / hydrophoby− Important for dewatering of the glue = increasing of

viscosity: surface sizing / hydrophoby= Relevant parameter to characterize with PDA/EST

PHASE III:Drying / hardening of the glue film

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Coating process

Reasons for Problems in the Converting Process

PHASE I: Coating color film application

Relevant parameter to characterize with PDA/EST: surface pore structure

PHASE II: Water absorption from coating film Relevant parameter to characterize with PDA/EST:

surface sizing / hydrophoby

PHASE III:Drying of coating color film

Similar to the gluing process:

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Printing process

Reasons for Problems in the Converting Process

PHASE I: Ink film application

Relevant parameter to characterize with PDA/EST: surface pore structure

PHASE II: Fountain solution / oil absorption from the ink Relevant parameter to characterize with PDA/EST:

surface sizing / hydrophoby, but also surface pore structure

PHASE III:Drying / hardening of the applied ink

Similar to the gluing and coating process:

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Contactfrom BS

Contactfrom TS

t95 BS ≠ t95 TS= right!

Comparison of a sample with different pore structurefrom top side (TS) and wire side (BS)

Air flow through the paper in z-direction is determined by the sum of the pore area. But: Paper two-sided und inhomogeneous.

Provides information about the actual pore structure of paper / board surface

No information about the surface pore structure, not enough resp. wrong information for prediction of converting problems

Bendtsen BS = Bendtsen TS

Pore Structure BS = Pore Structure TS= wrong!

3 Limits of Standard Porosimeter to solve the problems

Parameter: t95

Test liquid: Water-IPA-Mixture

Ben

dtse

nPo

rosi

met

erES

T12│

PDA

.C 0

2

Measurement Results

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Surface sizing

Internal sizing

Surface sizing

high

low

high

lowhigh

low

Sample 1 Sample 2

Cobb 1 ≈ Cobb 2= wrong!

Reason: Only indication of an average value of

surface sizing plus internal sizing No information concerning surface

pore structure / sizing

Not enough resp. wronginformation for the predictionof converting problems

Penetration depth of water = Volume over time

Comparison of two samples concerning the distribution of the sizing in z-direction

Limits of Cobb Tester to solve the problems

Cobb Measurement Results

Cob

b Te

st

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Surface sizing

Internal sizing

Surface sizing

high

low

high

lowhigh

low

Sample 1 Sample 2

PDA/EST Measurement Results

EST1

2│PD

A.C

02

Comparison of two samples concerning the distribution of the sizing in z-direction

Limits of Cobb Tester to solve the problems

MAX 1 >> MAX 2= right!

Time point MAX represents thesurface hydrophoby / sizing.

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Measurement of the interaction between test liquid and sample surface during the first milliseconds (surface porosity) resp. seconds (surface hydrophoby/sizing) after contact

Use of appropriate test liquids to gain the desired information

(1) Mixture of water+isopropyl alcohol: (2) Water:

4 Why can the EST/PDA help to solve converting problems?

Surface hydrophoby/sizing

Parameter t95 MAX

Surface porosity

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MAX = surface hydrophoby / sizing by the time point of curve maximum

t95 = surface porosity by the time point, when the curve reaches 95% (or 99%) of the ultrasound transparency after the initial contact time point 0

Why can the EST/PDA help to solve converting problems?

Automatic calculation of the relevant quality parameters

(3) Mixture of water + acetic acid:Surface quality of CaCO3 coated paper

I (%)10095

t95 (1) t95 (2) 3s t

1

2Parameter t95

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│ QA, Process control │ Product/Process optimization, R&D ││Trouble shooting, Complaint management │

Also possible: simulation of real converting processes like coating, gluing or printingby using process liquids and according specific modules of the PDA.C 02.

Measurements performed under conditions similar to the real process[liquid contact with pressure impulse, high shear impulse].

5 Application Examples of EST12 / PDA.C02

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Gluability problem of uncoated liner board1. Application example: Gluability problem of uncoated board (1/4)

Problem: Poor bonding characteristics of uncoated board

The test of the bonding, realized by splitting by hand, does not result in the desired fiber extraction.

Solution/Activities by the device system PDA / EST: 1. Measurement of samples of good/average/poor

quality with the appropriate test liquids (water+IPA mixture, water)

2. Evaluation of measurement outcomes

3. Identification of the reason of the problem: Surface pore structure or / and surface sizing

4. Determination of required steps in production / converting process

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1. Application example: Gluability problem of uncoated board (2/4)

Sample with bad gluability: t99 at later time point Smaller pores / closed pore structure

Evaluation of the first 60 – 80 ms!

Characterization of surface porosity of uncoated boardTest liquid: water-IPA mixture, Parameter: t95/99

Good gluability, test liquid water+IPAMedium to good gluability, test liquid water+IPABad gluability, test liquid water+IPA

t99 1 t99 2 t99 3

Perfect correlation to the gluability

Probably the problem is caused by surface pore

structure.

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MAX 2 MAX 3 MAX 1

1. Application example: Gluability problem of uncoated board (3/4)

No correlation to the gluability

The problem is not causedby surface sizing.

Characterization of surface sizing/hydrophoby of uncoated boardTest liquid: water, Parameter: MAX

Good gluability, test liquid waterMedium to good gluability, test liquid waterBad gluability, test liquid water

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The problem of the poor gluability is in this case

caused by surface porosity and not by surface sizing

1. Application example: Gluability problem of uncoated board (4/4)

Conclusion of Example 1

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Printability/runnability problem of one-side coated boardTwo different qualities from two different producers

2. Application example: Printability/runnability problem of board (1/8)

Problem 1: Runnability in sheet offsetDifferent fountain solution absorption of the uncoated side

Problem 2: Good and bad printability in sheet offset of the coated sideDifferent oil absorption from the transferred inkIn particular: Printing speed for the bad example cannot be set up as high as required.

Good product: 10,000 sheets per hourBad product: 6,000 sheets per hour The customer who produces the bad product could lose further orders.

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0

20

40

60

80

100

120

0 10 20 30 40 50 60

I [%

]

t [s]

Sample with goodrunnability:First slow, then faster waterpenetrationhigh surface sizing, lowinternal sizing

Sample with badrunnability:First fast, then slower waterpenetration low surface sizing, highinternal sizing

Characterization of surface hydrophoby of liner board [uncoated side]Test liquid: water

2. Application example: Printability/runnability problem of board (2/8)

one side coated board, uncoated side, water, good runnabilityone side coated board, uncoated side, water, bad runnability

Investigation of reasons for problem 1

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0

20

40

60

80

100

120

0 5 10 15 20

I [%

]

t [s]

Characterization of surface porosity of liner board [uncoated side]Test liquid: water-IPA mixture

Curves of the two samples almost identical Surface porosity

approximately identical

Investigation of reasons for problem 12. Application example: Printability/runnability problem of board (3/8)

one side coated board, uncoated side, water+IPA, good runnabilityone side coated board, uncoated side, water+IPA, bad runnability

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2. Application example: Printability/runnability problem of board (4/8)

Runnability problem (problem 1) is due to

surface sizing, not surface porosity

Conclusion of Example 2 - uncoated side

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0

20

40

60

80

100

120

0 5 10 15 20

I [%

]

t [s]

one side coated board, coated side, acetic acid, good printing qualityone side coated board, coated side, acetic acid, bad printing quality

Characterization of surface quality of liner board [coated side]

measurement with test liquid: acetic acid

Curves of the two samples with high differences

Investigation of reasons for problem 2

Measurements with water and water-IPA did not show any significant differences. Therefore:

2. Application example: Printability/runnability problem of board (5/8)

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2. Application example: Printability/runnability problem of board (6/8)

Conclusion of Example 2 - coated side

Printability problem (problem 2) is due to coating quality

Possibility 1: Binder concentrationPossibility 2: Different pigment

composition

Reason cannot be identified by PDA/EST measurements

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Characterization of pigment composition of liner board [coated side]with ACA Ash Content Analyzer

ACA shows different pigment composition of the two samples:

Good sample: 50 % CaCO3, 50 % KaolinBad sample: 100 % CaCO3

Leading to different printability !

Questionable: Differences due to suboptimal binder concentration or different pigment mixtures?

Measurement with ACA can provide the relevant information

2. Application example: Printability/runnability problem of board (7/8)

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By using of testing liquids water-IPA mixture and water, measurements with PDA show the differences in quality of the uncoated side (pore structure/ surface sizing), which result in different runnability in the printing machine

Testing liquid acetic acid can show differences in coating quality, but it is not possible to find out if it is due to binder concentration or pigment mix

Only ACA can provide this relevant information: in this case it is a problem of pigment composition

This means: PDA/EST & ACA can help to identify the reasons for problems

2. Application example: Printability/runnability problem of board (8/8)

Final conclusion of Example 2

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│ Base Board 1 & 2 │ before coating process │ same paper grade ││ same paper mill │ test liquid Water-isopropyl alcohol mixture │

Gurley and Bendtsen show the same values! t95 shows 1,500 % difference

0

20

40

60

80

100

0 0.5 1 1.5 2

I [%

]

t [s]

Jumbo roll 2Bendtsen: 504 ml/minGurley: 21.4 st (95 %) [s] FIRST = 1.283

Jumbo roll 1Bendtsen: 500 ml/minGurley: 22.4 st (95 %) [s] FIRST = 0.074

t95

3. Application example: Comparison with Bentsen/Gurley (1/1)

Assessment of porosity on the surface of base board

~100ms ~1300ms

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0

20

40

60

80

100

0 10 20 30 40 50 60

I [%

]

t [s]

Testliner 1

Testliner 2

Cobb60 = 86MAX = 5.479

Cobb60 = 91MAX = 0.807

│ Corrugated cardboard Testliner 1 & 2 │ Test liquid water │

~1s ~5s

Cobb60 shows same values! MAX shows 700 % difference

4. Application example: Comparison with Cobb (1/1)

Assessment of hydrophoby / sizing on the surfaceof corrugated cardboard testliner

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same Cobb60 - Value

│ Copy Paper from different suppliers │ Test liquid water │

Assumption when onlylooking at surface sizing:

Paper 1 = Paper 2

5. Application example: Frequent mistakes at investigations (1/2)

Characterization of the surface hydrophoby / sizing of copy paper

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t(95%) : finer pores

~1000ms~106ms

│ Copy Paper from different suppliers │ Test liquid water-IPA mixture │

But big differences in surface porosity!

t95

5. Application example: Frequent mistakes at investigations (2/2)

Characterization of the surface porosity of copy paper

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Additional benefits: Determination of melamine resin absorption

of decorative paper Cuvette possible for quick change between

H2O and IPA First measuring results after 6 ms when

contacted with liquid Higher resolution (1 cm diameter)

Modular SystemPDA.C02 Module Standard

Main applications: Prediction of Gluability, Printability, Coatability and Dusting Tendency of Paper and Board for: │ QA │ R&D/Product Development │ Process Optimization │ Trouble Shooting │

6 Differentiation between available Measuring Devices

Additional benefits: Easy portable device Well suitable for application

engineers

EST12 Surface & Sizing Tester

Phase 1: Basic application devices in contact with test liquids

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Modular SystemPDA.C02 Module HVL High Viscous

Liquid

Differentiation between available Measuring Devices

Modular SystemPDA.C02 Module Standard Coating

with CMA Coating Measurement Accessory

Phase 2: Special application devices in contact with real process liquids

Main application:Characterization of the interaction between coating color and base paper surfacesby simulation of the applicator of a coating machine

Main application:Characterization of the interaction between highly viscous and contaminating liquids (e.g. adhesives, printing ink, oil, gypsum paste) and paper / board surfaces

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Procedure: Step 1 Step 2 Step 3

Obtaining information from the converter concerning the converting properties of the paper (good, medium, bad)

Perform measurements and correlate with the information from the converter[ Identify the reason for the problem: Surface porosity and/or hydrophoby]

Product/ Process optimizationQuality Assurance/ Process ControlTroubleshooting/ Complaint management[ Initiate necessary actions, control ]

7 Conclusion

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Simulation of the real converting process(Printing/Glueing/Coating) Liquid contact with pressure impulse, high-shear

impulse Measurements in process-relevant time

(first milliseconds/seconds)Characterization of: Surface parameters Interaction paper and test (resp. process) liquid

Avoiding problems before they occur.

Stabilization of the manufacturing process.

Savings in material, man power, time, and money.

Advantages:

Conclusion

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emtec Electronic GmbHGorkistr. 31 ● 04347 Leipzig ● GermanyTel.: +49 341 2457090E-mail: info@emtec-electronic.de

Thank you for your attention!

www.emtec-electronic.de