Agenda 1. BASICS: FREQUENT PROBLEMS IN CONVERTING

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2 Agenda 1. BASICS: FREQUENT PROBLEMS IN CONVERTING PROCESS 2. DESCRIPTION OF THE BACKGROUND 3. LIMITS OF STANDARD TESTING DEVICES 4. SUPPORT IN SOLVING THESE PROBLEMS 5. APPLICATION EXAMPLES 6. DIFFERENTIATION BETWEEN AVAILABLE MEASURING DEVICES 7. CONCLUSION 2

3 1 Basics (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. Problem But sometimes there are problems in converting although the agreed specifications are the same. Nobody knows why! 3

4 2 Reasons for Problems in the Converting Process Rough principle of the three typical converting processes: Gluing process Coating process Printing process 4

5 Reasons for Problems in the Converting Process Gluing 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 5

6 Reasons for Problems in the Converting Process Similar to the gluing process: Coating 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 6

7 Reasons for Problems in the Converting Process Similar to the gluing and coating process: Printing 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 7

8 3 Limits of Standard Porosimeter to solve the problems Comparison of a sample with different pore structure from top side (TS) and wire side (BS) Measurement Results Bendtsen Porosimeter Air flow through the paper in z-direction is determined by the sum of the pore area. But: Paper two-sided und inhomogeneous. Bendtsen BS = Bendtsen TS Pore Structure BS = Pore Structure TS = wrong! No information about the surface pore structure, not enough resp. wrong information for prediction of converting problems EST12 PDA.C 02 Contact from BS Contact from TS Parameter: t95 Test liquid: Water-IPA- Mixture t95 BS t95 TS = right! Provides information about the actual pore structure of paper / board surface 8

9 Limits of Cobb Tester to solve the problems Comparison of two samples concerning the distribution of the sizing in z-direction Sample 1 Sample 2 high low high low high low Surface sizing Internal sizing Surface sizing Cobb Measurement Penetration depth of water = Volume over time Results Cobb 1 Cobb 2 = wrong! Cobb Test Reason: Only indication of an average value of surface sizing plus internal sizing No information concerning surface pore structure / sizing Not enough resp. wrong information for the prediction of converting problems 9

10 Limits of Cobb Tester to solve the problems Comparison of two samples concerning the distribution of the sizing in z-direction Sample 1 Sample 2 high low high low high low Surface sizing Internal sizing Surface sizing PDA/EST Measurement Results EST12 PDA.C 02 Time point MAX represents the surface hydrophoby / sizing. MAX 1 >> MAX 2 = right! 10

11 4 Why can the EST/PDA help to solve converting problems? 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: Surface porosity Surface hydrophoby/sizing Parameter t95 MAX 11

12 Why can the EST/PDA help to solve converting problems? (3) Mixture of water + acetic acid: Surface quality of CaCO 3 coated paper I (%) Parameter t t95 (1) t95 (2) 3s t Automatic calculation of the relevant quality parameters 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 MAX = surface hydrophoby / sizing by the time point of curve maximum 12

13 5 Application Examples of EST12 / PDA.C02 QA, Process control Product/Process optimization, R&D Trouble shooting, Complaint management Also possible: simulation of real converting processes like coating, gluing or printing by 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]. 13

14 1. Application example: Gluability problem of uncoated board (1/4) Gluability problem of uncoated liner board 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 14

15 1. Application example: Gluability problem of uncoated board (2/4) Characterization of surface porosity of uncoated board Test liquid: water-ipa mixture, Parameter: t95/99 t99 1 t99 2 t99 3 Good gluability, test liquid water+ipa Medium to good gluability, test liquid water+ipa Bad gluability, test liquid water+ipa Sample with bad gluability: t99 at later time point Smaller pores / closed pore structure Evaluation of the first ms! Perfect correlation to the gluability Probably the problem is caused by surface pore structure. 15

16 1. Application example: Gluability problem of uncoated board (3/4) Characterization of surface sizing/hydrophoby of uncoated board Test liquid: water, Parameter: MAX MAX 2 MAX 3 MAX 1 Good gluability, test liquid water Medium to good gluability, test liquid water Bad gluability, test liquid water No correlation to the gluability The problem is not caused by surface sizing. 16

17 1. Application example: Gluability problem of uncoated board (4/4) Conclusion of Example 1 The problem of the poor gluability is in this case caused by surface porosity and not by surface sizing 17

18 2. Application example: Printability/runnability problem of board (1/8) Printability/runnability problem of one-side coated board Two different qualities from two different producers Problem 1: Runnability in sheet offset Different fountain solution absorption of the uncoated side Problem 2: Good and bad printability in sheet offset of the coated side Different oil absorption from the transferred ink In particular: Printing speed for the bad example cannot be set up as high as required. Good product: 10,000 sheets per hour Bad product: 6,000 sheets per hour The customer who produces the bad product could lose further orders. 18

19 2. Application example: Printability/runnability problem of board (2/8) Investigation of reasons for problem 1 Characterization of surface hydrophoby of liner board [uncoated side] Test liquid: water Sample with good runnability: First slow, then faster water penetration high surface sizing, low internal sizing I [%] one side coated board, uncoated side, water, good runnability one side coated board, uncoated side, water, bad runnability t [s] Sample with bad runnability: First fast, then slower water penetration low surface sizing, high internal sizing 19

20 2. Application example: Printability/runnability problem of board (3/8) Investigation of reasons for problem 1 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 I [%] t [s] one side coated board, uncoated side, water+ipa, good runnability one side coated board, uncoated side, water+ipa, bad runnability 20

21 2. Application example: Printability/runnability problem of board (4/8) Conclusion of Example 2 - uncoated side Runnability problem (problem 1) is due to surface sizing, not surface porosity 21

22 2. Application example: Printability/runnability problem of board (5/8) Investigation of reasons for problem Characterization of surface quality of liner board [coated side] Measurements with water and water-ipa did not show any significant differences. Therefore: measurement with test liquid: acetic acid Curves of the two samples with high differences I [%] one side coated board, coated side, acetic acid, good printing quality one side coated board, coated side, acetic acid, bad printing quality t [s] 22

23 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 concentration Possibility 2: Different pigment composition Reason cannot be identified by PDA/EST measurements 23

24 2. Application example: Printability/runnability problem of board (7/8) Characterization of pigment composition of liner board [coated side] with ACA Ash Content Analyzer Questionable: Differences due to suboptimal binder concentration or different pigment mixtures? Measurement with ACA can provide the relevant information ACA shows different pigment composition of the two samples: Good sample: 50 % CaCO 3, 50 % Kaolin Bad sample: 100 % CaCO 3 Leading to different printability! 24

25 2. Application example: Printability/runnability problem of board (8/8) Final conclusion of Example 2 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 25

26 3. Application example: Comparison with Bentsen/Gurley (1/1) Assessment of porosity on the surface of base board 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 ~100ms ~1300ms I [%] 100 t Jumbo roll 2 Bendtsen: 504 ml/min Gurley: 21.4 s t (95 %) [s] FIRST = t [s] Jumbo roll 1 Bendtsen: 500 ml/min Gurley: 22.4 s t (95 %) [s] FIRST =

27 4. Application example: Comparison with Cobb (1/1) Assessment of hydrophoby / sizing on the surface of corrugated cardboard testliner Corrugated cardboard Testliner 1 & 2 Test liquid water Cobb60 shows same values! MAX shows 700 % difference ~1s ~5s 100 I [%] Cobb60 = 86 MAX = Testliner 1 Testliner 2 Cobb60 = 91 MAX = t [s] 27

28 5. Application example: Frequent mistakes at investigations (1/2) Characterization of the surface hydrophoby / sizing of copy paper Copy Paper from different suppliers Test liquid water same Cobb60 - Value Assumption when only looking at surface sizing: Paper 1 = Paper 2 28

29 5. Application example: Frequent mistakes at investigations (2/2) Characterization of the surface porosity of copy paper Copy Paper from different suppliers Test liquid water-ipa mixture ~106ms ~1000ms t95 t(95%) : finer pores But big differences in surface porosity! 29

30 6 Differentiation between available Measuring Devices Phase 1: Basic application devices in contact with test liquids Main applications: Prediction of Gluability, Printability, Coatability and Dusting Tendency of Paper and Board for: QA R&D/Product Development Process Optimization Trouble Shooting Modular System PDA.C02 Module Standard EST12 Surface & Sizing Tester Additional benefits: Determination of melamine resin absorption of decorative paper Cuvette possible for quick change between H 2 O and IPA First measuring results after 6 ms when contacted with liquid Higher resolution (1 cm diameter) Additional benefits: Easy portable device Well suitable for application engineers 30

31 Differentiation between available Measuring Devices Phase 2: Special application devices in contact with real process liquids Modular System PDA.C02 Module HVL High Viscous Liquid Modular System PDA.C02 Module Standard Coating with CMA Coating Measurement Accessory Main application: Characterization of the interaction between highly viscous and contaminating liquids (e.g. adhesives, printing ink, oil, gypsum paste) and paper / board surfaces Main application: Characterization of the interaction between coating color and base paper surfaces by simulation of the applicator of a coating machine 31

32 7 Conclusion 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 optimization Quality Assurance/ Process Control Troubleshooting/ Complaint management [ Initiate necessary actions, control ] 32

33 Conclusion Advantages: 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. 33

34 Thank you for your attention! emtec Electronic GmbH Gorkistr Leipzig Germany Tel.: