By Karin Hofer, Technical University of Graz. This was presented during the New Ideas for the Paper Industry: Young Researchers' Presentations session, organised as part of European Paper Week 2015. More at http://www.cepi.org/epw

1. u www.tugraz.at
Determination of Latex and Starch
Penetration via Serial Sectioning in
Combination with Fluorescence
Microscopy
Karin Hofer1, Bernhard Seidl2, Martin Kozich2, Wolfgang Bauer1
17.11.2015
EFPRO European Paper Week 2015
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1 Institute of Paper, Pulp and Fiber Technology, Graz University of Technology, AUSTRIA
2 Agrana Research and Innovation Center, Tulln, AUSTRIA

2. Presentation Overview
 Binder Penetration/Migration
 Establishment of a New Method to Analyze Binder
Penetration
 Serial Sectioning in combination with Fluorescence Microscopy
(SSFM)
 Results
 The Influence of Base Paper Properties on Latex Penetration
 The Influence of Solids Content on Starch Penetration
 Double-staining to localize Starch and Latex
 Evaluation of SSFM via CLSM
 Conclusion and Outlook
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3. Binder Penetration/Migration
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Binder migration
 Binder follows the evaporated
water phase to the surface
Binder penetration
 Binder follows the water into the
paper substrate
Binder
2
1
Whalen-Shaw, 1993
Localization of Binder
after the Coating Process

4. Establishment of a New Method to analyze
Binder Penetration
 Starch
 Reactive staining with 5-([4,6-Dichlorotriazin-2-
yl]amino)fluorescein
 Latex
 Staining by adsorption into the latex particle
with Rhodamine B
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Staining the
binder
Coating
Embedding
Image
Processing
3D Data
Calculations
Serial
Sectioning
Staining the
binder
Fluorescein
Dichlorotriazin
Reactive group
Covalent bond
8mm
25mm

5. Establishment of a New Method to analyze
Binder Penetration
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Staining the
binder
Coating
Embedding
Serial
Sectioning
Image
Processing
3D Data
Calculations
Paper sampleMicroscope view
Cutting process
Filter cubes
Lenses
10/20/50x
Diamond knife
Microscope unit Microtome unit
Rotary microtome
Sample holder
Serial
Sectioning

6. Establishment of a New Method to analyze
Binder Penetration
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Staining the
binder
Coating
Embedding
Image
Processing
3D Data
Calculations
Serial
Sectioning
Output SSFM
VIS
UV
Coating layer
thickness
Fluorescent layer
thickness
Binder
Penetration Depth

7. Establishment of a New Method to analyze
Binder Penetration
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Staining the
binder
Coating
Embedding
Serial
Sectioning
Image
Processing
3D Data
Calculations
Serial
Sectioning
Segmentation
3D data evaluation
Image
Processing
3D Data
Calculations
CD
ZD
MD
12µm
5,4mm
100 cuts
in MD

8. u www.tugraz.at
RESULTS
8

9. The Influence of Base Paper Properties on
Latex Penetration
Recipe [%] I II III
CaCO3 100 100 100
Latex stained 8 16 6
Starch 4
NaOH set pH to 8,5 set pH to 8,5 set pH to 8,5
Target solids
content
65 65 65
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Base paper type Pulp Refining Additive
A Eucalyptus bleached 2000 PFI -
B Eucalyptus bleached 6000 PFI -
C Eucalyptus bleached 2000 PFI 20% filler (CaCO3) + Retention agent
(Percol 8383)
D Eucalyptus bleached 2000 PFI Pre-Calendering – once each side per
sheet (2000daN, room temperature)
Coating Formulation
Base Paper Type

10. The Influence of Base Paper Properties on
Latex Penetration
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0,0
5,0
10,0
15,0
20,0
25,0
30,0
35,0
40,0
0,0 5,0 10,0 15,0 20,0
Penetrationdepth[µm]
Coat weight [g/m²]
Base Paper A Base Paper B Base Paper C Base Paper D
0
5
10
15
20
25
30
35
0,010,1110
incrementalspecificintrusion[µl/g]
pore diameter [µm]
2000rpm PFI 6000rpm PFI 2000rpm PFI
+ filler
2000rpm PFI
calendered
Results of SSFM
Mercury Porosimetry base paper

11. The Influence of Solids Content on Starch
Penetration
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Recipe [%] ST 70 ST 60
CaCO3 100 100
Latex 6 6
Starch 4 4
Thickener 0,1 0,1
NaOH set pH to 8,5 set pH to 8,5
Target solids content 70 60
Coating Formulation
0
200
400
600
800
1000
1200
1400
1600
1800
0 5 10 15 20 25 30 35
lowshearviscosityBF100[mPas]
Penetration depth [µm]
Blade Sumet
ST 70
ST 60
ST 60
Depletion
of starch
at the
coating
surface

12. Double staining to localize Latex and Starch
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Latex Latex + Starch Starch

13. Evaluation of SSFM via CLSM
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R² = 0,8755
0
5
10
15
20
25
30
35
40
45
50
0 5 10 15 20 25 30 35 40 45
CLSMPenetrationdepth[µm]
SSFM Penetration depth [µm]

14. Conclusion and Outlook
 SSFM is an appropriate method to localize the binder after
the coating process
 3D-data evaluation can be performed and a mean
penetration depth into the base paper can be calculated
 Staining procedure for starch and latex (most common
coating binders) was developed
 Good correlation with CLSM
 Further influences on binder penetration can be tested
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Thank you for your attention!
Contact:
Karin Hofer
University assistant
Institute of Paper Pulp and Fibre Technology
Graz University of Technology
Inffeldgasse 23
8010 Graz/ Austria
Tel: +43 316 873 30756
Mail: karin.hofer@tugraz.at
Web: www.ipz.tugraz.at
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