AIMCAL 2006 Fall Technical Conference
Contribution of Plasma in Vacuum Al
Metallized Polyester Film
B. N. GUPTA
POLYPLEX CORPORATION LTD.,
B-37, SectorSector-1, Noida (U.P.) - INDIA.
E-mail: [email protected]
Web: http://www.polyplex.com
1
Outline
• Introduction
• Treatment techniques
• Plasma – A Theoretical Approach
• Experimental Work
• Evaluation / Test Conducted
• Observation
• Summary
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Introduction (Conversion)
Desired properties after metallization and
conversion process
- Bond Strength / Adhesion
- Seal Strength
- Barrier properties
To achieve these properties surface modification
of polymer films is required.
3
Surface Treatment Process
Surface modification
(Cleaning / Oxidation)
for better adhesion
Plain PET Film
Three techniques are being used for film surface treatment.
4
Flame Treatment Process
FILM WEB
GAS
AIR
5
Corona Treatment Process
OZONE EXHAUST
CORONA ELECTRODE
O3
POWER SUPPLY
FILM WEB
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Contd.
Corona treatment mechanism
ü
ü
ü
O2 + O2
O3 + O (Nascent oxygen)
O + Film Surface
Oxidation of surface
Oxidation of film surface
Increases
treatment / surface energy of film resulting as
better adhesion.
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Plasma Treatment Process
GAS
I
n Vacuum
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Plasma Mechanism
Oxygen plasma is aggressive in its reactivity and forms
numerous components. In oxygen plasma O+, O-, O2+, O2-,
O, O3, ionized ozone, metastable excited O2, and free
electrons are being observed in general. The ionization of
oxygen into the various species found in oxygen plasma can
be represented by the following reaction mechanism.
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Plasma
Gas In-let
Excited gas species
Ions
Electrons
Free Radicals
Exhaust to vacuum pump
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Plasma
11
Plasma
In plasma, the bombardment of the polymer surface by
energetic particles (free radicals, electrons, and ions).
Plasma changes only the surface of film.
Bulk properties remains unchanged.
Plasma not only does oxidation and activation of
surface but also does cleaning of film surface by
reacting with low molecular compounds (oligomers),
CO2 , water and other micro contaminants on surface.
Resulting as effective cross linking and deposition.
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Plasma
Cleaning and Activation
Activation è Replacement of low molecular weight group, CO2,
H2O by reactive species in plasma.
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Plasma
Effectiveness
Constant 2.80 Optical Density in both cases
Without Plasma Treatment
(Random / Non-effective deposition)
With Plasma Treatment
(Uniform / Effective deposition)
Gas flow rate & power to be optimized for effective plasma generation.
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Plasma
Benefits
Due to effective deposition of Al metal with
film, plasma showing:
- Better adhesion &
- Better barrier performance against
moisture and oxygen.
15
Experimental Work
In order to establish actual benefits offered by plasma
treatment experimentation done for:
o 12µ normal PET film.
o Vacuum Al metallization without plasma.
o Vacuum Al metallization with plasma at
optimized power and gas flow rate combination.
o Two set of experiments (with different power and gas
flow rate) were performed.
o Constant optical density 2.80 in both the cases.
o Other process parameters kept constant in both
the cases.
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Evaluation / Test Conducted
Metal adhesion test done by PCL method with
1mil EAA film.
Water vapor transmission rate (WVTR) test
done by MOCON Permatran by ASTM
F-1249 method.
Oxygen transmission rate (OTR) test done by
MOCON Oxtran by ASTM D-3985 method.
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Observation
Metal adhesion (Metal / Film Bond Strength)
Bond strength with and without Plasma
Bond Strength (gm/inch)
60
50
40
30
20
10
0
No
Yes
Set 1
No
Plasma Status
Yes
Set 2
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Observation
WVTR Performance
WVTR with and without Plasma
WVTR (gm/m²/day)
0.6
0.5
0.4
0.3
0.2
0.1
0
No
Yes
Set 1
No
Plasma Status
Yes
Set 2
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Observation
OTR Performance
OTR (cc/m²/day)
OTR with and without Plasma
1.3
1.2
1.1
1
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
No
Yes
Set 1
No
Plasma Status
Yes
Set 2
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Observation
Total Barrier Performance
WVTR (gm/m²/day)
0.4
0.3
0.2
0.1
0.15
0.30
0.45
0.60
0.75
0.90
OTR (cc/m²/day)
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Summary
Vacuum Al-metallization performed on 12m
normal polyester films with plasma
application gives significant improvement in
metallized film properties like metal adhesion
and barrier properties as compared with
metallized polyester film produced without
plasma application at constant process
parameters of metallizer.
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Questions (if any)
???
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POLYPLEX – Global Producer of Polyester Film
POLYPLEX – INDIA
POLYPLEX – THAILAND
Thank you.
US Contact:
Amit Kalra
POLYPLEX (America) Inc.
682.225.1503
E-mail: [email protected]
Web: http://www.polyplex.com
POLYPLEX – EUROPA
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