coating plasma innovation - aimcal...5 corona high voltage ambient air filamentary discharge •...
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1
Coating Plasma Innovation
Atmospheric Plasma treatment, effect on the plasma chemistry on adhesion
Nicolas Vandencasteele
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Plasma
Applications
Adhesion improvement
Conclusion
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Plasma4th state of matter: ionized gas
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Cold atmospheric plasma
Energetic electrons chemistry
Cold:Tgas < 100 °CTions,neutrals < 100 °C Telectrons ≈ 10 000 °C
Atmospheric:Plasma gas is at atmospheric pressure Open reactor, high density of particles
Hot:Tgas ≈ Tions,neutrals ≈ Telectrons
104<T<108 °C
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Corona
High Voltage
Ambient airFilamentary discharge
• Used for activation or cleaning• Flat substrate• Most of the time need to be used
inline with other process• Gas used: none (ambient air)
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Plasma DBD
High Voltage
Controlled atmosphereHomogeneous discharge
• Used for activation or cleaning and deposition
• Flat substrate• Used online or offline• Gas used:N2, (Ar, He)
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Plasma vs Corona
Controlled chemistry Stable treatment
Surface energy measurements on BOPP film
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Plasma vs CoronaMicroscopy (AFM) image of BOPP film1 µm x 1 µm images (Tapping)
Identical discharge power
Es = 38 mN/mEs ≤ 30 mN/m Es = 60 mN/m
Untreated Plasma
DBD Corona
Controlled chemistry, homogenous discharge no surface damage
Process
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Plasma gas + dopant
Dopant:ppm of reactive gases mixed with plasma gas (only safe gas green top bottles)
APPLICATIONS
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Applications: Cleaning
Cleaned sample
CO2↗, H2O ↗ …
Contaminated surface
Plasma
Surface contamination
Removal of surface contamination without substrate degradation
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Applications: Grafting
C
O
C
O
C
O
C
O
H
CC
O
C
OO
C
O
C
O
H
C CC CC C
O
Amine Amide Imide
N
C
H H
C2O
C
NH
C
O
C
ON
C
H
C
Gas: N2 + dopants
Surface functionalization
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Applications: Grafting
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
Amine Amide Imide
Qua
ntity
(a.u
.)
Grafting of nitrogen containing groups
Standard
Advanced 1
Advanced 2
Atom
ic %
(XP
S)
Dopant 2
Tunable surface functionalization
Dopant 1
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Applications:CoatingSpecific molecules (precursor ) are added to the plasma gas. Those molecules are activated ( ) by the plasma and react with the sample surface to form a thin film.
SiOx film (hydrophilic)HMDSO precursor
Coating nature dependend on precursor AND plasma chemistry
SiCyOx film (hydrophobic)
ADHESION IMPROVEMENT
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ECTFE – Surface energy increase
Very limited ageing after 3 weeks
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ECTFE – Adhesion increase
Different plasma chemistries
0
10
20
30
40
50
60
70
0
50
100
150
200
250
Untreated Corona Plasma 1 Plasma 2 Plasma 3
Surf
ace
ener
gy [m
N/m
]
Peel
For
ce [N
/m]
ECTFE laminate (Araldite 2028)
Peel Force Surface Energy
Surface energy is not the main factor improving adhesion
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ECTFE – Adhesion increase
Chemistry, not SE, is the main factor improving adhesion
0
2
4
6
8
10
12
0
50
100
150
200
250
Untreated Corona Plasma 1 Plasma 2 Plasma 3
at. %
N
Peel
For
ce [N
/m]
ECTFE laminate (Araldite 2028)
Peel Force %N grafted
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PET – Adhesion increase
Adhesion not always directly related to surface energy
0
10
20
30
40
50
60
0
100
200
300
400
500
600
700
800
900
1000
Untreated Corona Plasma a Plasma b Plasma c
Surf
ace
Enrg
y [m
N/m
]
Peel
For
ce [N
/m]
PET thermoset adhesive
Peel force Surface Energy
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PET – Adhesion increase
Chemistry, not SE, is the main factor improving adhesion
00.511.522.533.54
0
100
200
300
400
500
600
700
800
900
1000
Untreated Corona Plasma a Plasma b Plasma c
At. %
Nitr
ogen
Peel
For
ce [N
/m]
PET thermoset adhesive
Peel force Surface Composition
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Adhesion increase
Acrylic PETUntreated vs Corona 15%Untreated vs Plasma Up to 85%
Corona vs Plasma 35%
Thermoset PETUntreated vs Corona 200%Untreated vs Plasma Up to 2300%
Corona vs Plasma 800%
Araldite 2028 ECTFEUntreated vs Corona 1000%Untreated vs Plasma Up to 4870%
Corona vs Plasma 350%
Results depend on adhesive and plasma chemistries
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Conclusion
• Plasma treatment enables stable modification of surface energy
• Plasma allows to tailor the surface modifications to specific adhesive and substrate combination
• Level of adhesion can be controlled over a large range
• Plasma treatment can be applied to almost any materials (PEEK, Fluorinated polymers, PI, metals, paper…)
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