Electrostatic Reduction of Misting in Roll CoatingBill Smith
Polytype Converting GmbH
AIMCAL R2R Conference USA 2018Phoenix, Arizona,
October 28-31, 2018
AIMCAL R2R Conference USA 2018, Phoenix, Arizona, October 28-31, 2018
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AIMCAL R2R Conference USA 2018, Phoenix, Arizona, October 28-31, 2018
Agenda
Electrostatic Reduction of Misting in Roll Coating
• Introduction• Experimental• Results• Conclusions
AIMCAL R2R Conference USA 2018, Phoenix, Arizona, October 28-31, 2018
Introduction
Misting from film splitting
• Liquid passing through a nip• Development of droplets upon splitting• High splitting speed• Particle size << 50 μm• Health, quality, cleanup, and cost issue.
AIMCAL R2R Conference USA 2018, Phoenix, Arizona, October 28-31, 2018
Introduction
Misting from film splitting
Extended ribs break up
Michel S. Owens 2004
Ribbing lines in forward roll coating
Dontula 1996
AIMCAL R2R Conference USA 2018, Phoenix, Arizona, October 28-31, 2018
W3
W2
W1
W0W00
Introduction
Current options for handling the misting (example: silicone coater)• Chemical anti-misting additives• Mist particle evacuation
5-roll coater: F. Krebs and P. M. Schweizer, Coating 2005 6 , p214-217 and Coating 2005 7, p268-270
5 roll coater
AIMCAL R2R Conference USA 2018, Phoenix, Arizona, October 28-31, 2018
Introduction
Novel electrostatic approach from Eltex: Misting Tacker
F. Knopf, Eltex Elektrostatik GmbH, WO2014030077(A2), DE102012207148A1
AIMCAL R2R Conference USA 2018, Phoenix, Arizona, October 28-31, 2018
Introduction: Misting Tacker
Low Energy DC–Plasma Electrode
DC-Plasma Deposition Unitview into a cross-section
Electrode Tip
Counter Electrode
Plasma Cone
ca.10 mm
AIMCAL R2R Conference USA 2018, Phoenix, Arizona, October 28-31, 2018
Introduction
Misting Tacker: Low Energy DC–Plasma Electrode
deflection instead of suppression
airstreamplasma cone(ionization)
AIMCAL R2R Conference USA 2018, Phoenix, Arizona, October 28-31, 2018
Experimental
Raw MaterialsSilicones from Bluestar:• Thermal curing 100% system
– Curing at 180°C• UV curing 100% system
– No initiators added, cured using e-beam
Substrates:• Craft Paper 35 µm, Cobb 30 g/m2
• BOPP 50 µm• PET 12 µm
AIMCAL R2R Conference USA 2018, Phoenix, Arizona, October 28-31, 2018
Experimental
5 roll silicon coater and electrode placement
AIMCAL R2R Conference USA 2018, Phoenix, Arizona, October 28-31, 2018
Experimental
Techma coater – web upstream view (backside)
W3
W2
W1
AIMCAL R2R Conference USA 2018, Phoenix, Arizona, October 28-31, 2018
Experimental – Data Collection
Measurement around Application Unit – Electrodes off(600m/min)
0
20
40
60
80
100
120
140
160
11:08:30 11:09:00 11:09:30 11:10:00 11:10:30 11:11:00 11:11:30
Part
icle
Conc
entra
tion [
mg/
m3]
Total Concentration of Particles PM1, PM2.5, and PM10
Nip W2/3 Nip W1/2 side AS
(max. >150 mg/m3)
AIMCAL R2R Conference USA 2018, Phoenix, Arizona, October 28-31, 2018
Experimental – Data Collection
Measurement around Application Unit – Electrodes on(600m/min)
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
11:40:00 11:40:30 11:41:00 11:41:30 11:42:00 11:42:30 11:43:00
Part
icle
Con
cent
ratio
n [m
g/m
3]
Total Concentration of Particles PM1, PM2.5, and PM10
(max scale of graph: 1.8 mg/m3)
AIMCAL R2R Conference USA 2018, Phoenix, Arizona, October 28-31, 2018
Experimental – Data Collection
Aerosol sensor placed at fixed point between roll W2 and W3
AIMCAL R2R Conference USA 2018, Phoenix, Arizona, October 28-31, 2018
Results – Data Collection
Measurement of Aerosols at fixed pointstep by step increase of web speed up to 1000 m/min
0
5
10
15
20
25
30
35
13:19:00 13:20:00 13:21:00 13:22:00 13:23:00 13:24:00 13:25:00 13:26:00 13:27:00
Tota
l con
c of p
artic
les (
mg/
m3)
POLY368-XL325-CATA11091M-MG KRAFT-STARKRAFT--300-600-800-900-1000 m/min
Masking Nip W0/W1Nip below aerosol sensor covered
100 m/min
300 m/min600 m/min
800 m/min
1000 m/min
0
5
10
15
20
25
30
35
00:00:00 00:01:00 00:02:00 00:03:00 00:04:00 00:05:00 00:06:00 00:07:00 00:08:00 00:09:00 00:10:00
Silic
one
part
icle
s (m
g/m
3)
Total Particle Concentration -- 100-300-600-800-1000 m/min(max scale of graphs: 35 mg/m3)
AIMCAL R2R Conference USA 2018, Phoenix, Arizona, October 28-31, 2018
Results – Data Collection
UV: Effect of misting from second nip (W0 / W1)- Run8: nip unmasked- Run9: nip masked
0.0
0.2
0.4
0.6
0.8
1.0
1.2
0 100 200 300 400 500 600
Silic
one m
ist (
mg/
m3)
Machine speed (m/min)
Impact W0-W1 masking (PET-EB)
Run8-no masking Run9-with masking
Web speed W1 speed
300 m/min 210 m/min
400 m/min 280 m/min
500 m/min 350 m/min
AIMCAL R2R Conference USA 2018, Phoenix, Arizona, October 28-31, 2018
Results – Thermic Silicone
Comparison of electrostatic to chemical method- Run2: no measure- Run6: chemical additive- Run5: electrostatic DC-Plasma
0
20
40
60
80
100
120
140
160
0 200 400 600 800 1000 1200
Silic
one m
ist (
mg/
m3)
Machine speed (m/min)
Method Influence Overview (Thermic)
Run2-none Run6-Additive Run5-DC-Plasma
AIMCAL R2R Conference USA 2018, Phoenix, Arizona, October 28-31, 2018
Results – Thermic Silicone
Comparison of electrostatic to chemical method- Run5: electrostatic DC-Plasma- Run6: chemical additive
0
5
10
15
20
25
0 200 400 600 800 1000 1200
Silic
one m
ist (
mg/
m3)
Machine speed (m/min)
Electrostatic vs Chemical Method (Thermic)
Run5-DC-Plasma Run6-Additive
AIMCAL R2R Conference USA 2018, Phoenix, Arizona, October 28-31, 2018
Results – Thermic Silicone
Comparison of effect by different substrates- Run5: 35 µm Paper- Run7: 12 µm PET
0
5
10
15
20
25
0 200 400 600 800 1000 1200
Silic
one m
ist (
mg/
m3)
Machine speed (m/min)
Comparison of Substrates (Thermic)
Run5-MGKraft Run7-PET
AIMCAL R2R Conference USA 2018, Phoenix, Arizona, October 28-31, 2018
Results – UV Silicone
Comparison of electrostatic to chemical method- Run12: electrostatic DC-Plasma- Run13: chemical additive- Run10: no measures taken
0
5
10
15
20
25
30
35
40
0 100 200 300 400 500 600
Silic
one m
ist (
mg/
m3)
Machine speed (m/min)
Method Influence Overview (UV)
Run12-DC Plasma Run13-Additive Run 10-none
AIMCAL R2R Conference USA 2018, Phoenix, Arizona, October 28-31, 2018
Results – UV Silicone
Comparison of electrostatic to chemical method- Run12: electrostatic DC-Plasma- Run13: chemical additive
0.0
0.5
1.0
1.5
2.0
2.5
3.0
0 100 200 300 400 500 600
Silic
one m
ist (
mg/
m3)
Machine speed (m/min)
Electrostatic vs Chemical Method (UV)
Run12-DC Plasma Run13-Additive
AIMCAL R2R Conference USA 2018, Phoenix, Arizona, October 28-31, 2018
Results – UV Silicone
Comparison of effect by different substrates- Run9: 12 µm PET- Run12: 35 µm Paper- Run11: 50 µm BOPP
0.000.050.100.150.200.250.300.350.400.45
0 100 200 300 400 500 600
Silic
one m
ist (
mg/
m3)
Machine speed (m/min)
Comparison of Substrates (UV)
Run9-PET Run12-MGKraft Run11-BOPP
AIMCAL R2R Conference USA 2018, Phoenix, Arizona, October 28-31, 2018
Conclusions
• The electrostatic DC-plasma system by Eltex worked very efficiently :– On all tested substrates – With both tested silicon types– It can be used instead of any chemical antimisting additive
• Worked as efficient in Thermic silicones• Worked better for the UV silicones
• all three nips in 5 roll coater need an antimisting device, especially if high web speeds are targeted.
• the deflection of misting by the DC-plasma system might be used where no chemical means are available
• Two industrial implementations already in progress– Silicon coating and coating of a thin wax layer
• Studies to explore the deeper understanding of all the variables would be welcome
AIMCAL R2R Conference USA 2018, Phoenix, Arizona, October 28-31, 2018
Acknowledgements
go to all participants of the tests:– Gilbert Gugler (iPrint, Fribourg, Switzerland; previously at Polytype), – Franz Knopf (Transferzentrum, Offenburg, Germany)– Eltex-Elektrostatik-GmbH (Weil am Rhein, Germany)– Bluestar Silicones (Saint Fons, France)– Techma Team at Polytype Converting AG
AIMCAL R2R Conference USA 2018, Phoenix, Arizona, October 28-31, 2018
Electrostatic misting reduction
Questions?