Novel packaging materials using functional thin films and coatings

Novel packaging materials using functional
thin films and coatings
European Coatings Conference
“Packaging and can coatings”
on 11 and 12 June, 2013 in Düsseldorf, Germany
Juha Nikkola*, Jari Vartiainen, Mika Vähä-Nissi and Kalle Nättinen
VTT Technical Research Centre of Finland
*Speaker information: Juha Nikkola, PO. Box 1300; 33101 Tampere,
Finland; +358 20 722 3672; juha.nikkola@vtt.fi
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Outline
 Introduction
 Novel packaging materials
 Coatings and surface modification
 Sol-gel coatings
 Atomic layer deposition
 Conclusion
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Innovative materials
and surfaces
Safe and sustainable
value chain
Printing and
communication
Protection and
quality maintenance
of packed products
VTT
PACKAGING
Consumer
convenience
Agile processes
Testing services
Value network
development
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Eco-efficient materials
Biobased plastics
Reduce
Biobased latex
Light weight materials
Biobarriers and hybrid materials
High performance hybrid
materials and barriers
Thin film barriers
Bioreplacement oil-based
materials
Biofoam materials
Replacement of aluminum
Biobased glues and adhesives
Resource efficient fiber based
materials
Recycle
Renew
Mouldable fiber web
Bio-inks
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100% bio based packaging
 Recyclable fiber based and biopolymer materials.
 Efficiently processable biopolymer solutions
for packaging applications.
 Flexible working models to interact and co-operate
with the industry and packaging value chain.
Light
Mouldable
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Limitations of bio based packaging
 The current trend in packaging materials heads towards green
chemistry using sustainable and renewable materials
 However, they have minor challenges, such as sensitivity to
moisture
 The thin coatings (e.g. sol-gel or ALD) could solve the problem,
by improving the moisture, gas and grease barrier performance.
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Barrier properties of typical coatings
(normalized to 100μm thickness)
PO+Cell
blend
TOFA
Cellulose
Grafted
Hemicel.
Pectin
hybride
Solgel
ALD
Source: SustainPack and Pira International Ltd
Nanocel.
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Routes for Surface Functionalization
Further surface
processing
Functionalized
surfaces
Activation
Unmodified
surfaces
Deposition
ALD/MLD
Sol-gel Technology
Atmospheric Plasma
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Important Base Material Parameters
Roughness
and pore
structure
Surface chemistry
Diffusion &
solubility
Surface morphology
Polymer surface
Paper/board/
bulk polymer
Thermal stability
Moisture content
 Based on our hypothesis surface chemistry affects nucleation, initial
layer growth rate and bonding potential making biopolymer surfaces
very interesting substrates
 Factors related to surface interactions and having effect on layer
performance include choice of precursors and surface pretreatments
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Key Tools and Facilities
Pilot coating environments at VTT in
addition to versatile laboratory tools
Plasma online
system by VITO/AFS
ALD reactor in
semi-clean room
Sol-gel coatings
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Sol-gel synthesis and crosslinking
X = reactive groups for cross-linking;
~ = cross-linked polymer chain;
R = functional organic groups or components;
M = metals such as Zr, Ti, Al.
R
OH
R
OH
O
O
Si
M
OR
R
RO M OR + RO Si OR
OR
OR
X
O
+H2O
+ RO Si OR
OR
O
Si
O
R
O
HO
HO
Si
O
-ROH
O
Si
Si
O
Si
O
R
O
Si
O
X
X
Si
O
Si
R
HO
O
O
OH
R
Si
O
Si
Si
Si
O
O
O
O
O
R
Si
M
O
Si
O
Si
O
R
O
Si
O
HO
O
Si
O
O
O
Si
Si
OH
O
OH
X
HO
OH
OH
O
T, h•
Si
Si
R
Si
O
O
X
O
OH
M
O
O
O
O
Si
Si
O
Si
O
X
R
X
X
Si
X
Si
O
M
O
O
R
R
X
O
O
Si
O
OH
OH
O
O
Si
Si
Si
O
Si
O
O
O
Si
O
X
O
O
X
R
Si
O
O
Si
OH
O
OH
O
HO
R
-H2O
Source: Dr. Klaus Rose, Fraunhofer ISC
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Sol-gel coating application methods
Brabec, C., Dyakonov, V. & Scherf, U. . Organic Photovoltaics - Materials, Device Physics, and Manufacturing
Technologies. John Wiley & Sons. ISBN 978-3-527-31675-5.
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Roll-to-roll coated sol-gel coating on PLA-Cardboard
Sol-gel hybrid coating on PLA laminated paperboard.
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Grease barrier performances
Uncoated Paper, Paper + LDPE and Paper + PLA (T0 + 1h and 6h):
Sol-gel coated paper + PLA (T0 + 14d):
Fluorinated
Non-fluorinated
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Atomic layer deposition (ALD)
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Principle of Atomic Layer Deposition (ALD)
www.beneq.com
Above: single cycle with trimethylaluminium and water vapor as precursors




Thin film grows layer-by-layer based on self-limiting gas-solid reactions
Pressure from 10 Pa to atmospheric and temperature 50-500 C
Typical applications range from catalysts, microelectronics and beyond
Purging the slowest process step
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Effect of Oxidant & Pretreatment on PLA-coated Board
 Pre-treatments prior to the ALD can improve barrier properties,
 Most likely surface chemistry affects nucleation and initial growth rate
 Choice of oxidant affects barrier properties – denser Al2O3 films with O3
 Eveness of polymer-coating is of high importance for the ALD
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Coating of Fibres and Nanocoral Structures
ALD-Al2O3 on NFC fibres
ALD-Al2O3 on PVA fibres
Hollow ALD-Al2O3 fibres
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Flexibility Through Structural Tailoring
 Metal oxide layers are brittle
 Mechanical stresses and thick
layers lead to impaired barrier
 There are indications that
chemical bonding with base
substrate is beneficial
Inorgnic barrier
”Organic spacer”
Inorgnic barrier
Inorgnic barrier
”Organic spacer”
Surface of streched
PLA film with Al2O3
 Flexibility & elasticity improved
by dividing thick barrier layer
into thinner stacks and
separating these with flexible
”organic spacer” layer
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Effect of 5-layer Al2O3/Alucone Nanolaminates on BoPLA
Water vapor transmission rate (WVTR):
350
80
300
70
WVTR, g/m2/d
OTR, cm3/m2/d/105 Pa
Oxygen transmission rate (OTR):
250
200
150
100
60
50
40
30
20
50
10
0
0
0
1
2
Strain, %
3
0
1
2
3
Strain, %
10 nm of Al2O3
Al2O3/alucone (150/50/150/50/150)
25 nm of Al2O3
Al2O3/alucone (50/50/50/50/50)
Al2O3/alucone (50/100/50/100/50)
OTR sensitive to defects, WVTR more to overall thin film properties
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ALD-Al2O3 layer (25 nm) does not impair disintegration
100
positive control
negative control
board
board+ PLA
board+PLA+ALD
Non-degraded sample (%)
Non-degraded sample (%)
0 + board with
PLA
& without
ALD:
0
BOPLA
BOPLA+ALD
BOPLA metallized
2 x BOPLA+ALD
2 x BOPLA metallized
100
PLA with &
without ALD
after 5 weeks:
0
5
Weeks
10
15
0
5
10
15
Weeks
20
Role and distribution of base substrate dominates!
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Towards R2R Processing
Kodak
Applied Materials
Lotus Applied Tech.
Beneq
General Electric
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Conclusions & Summary
 Bio-based packaging materials have many advantages over their nonbiodegradable competitors.
 However, they have minor challenges, such as sensitivity to moisture,
restricting their use in some application, which requires high barrier
properties.
 Therefore, application of additional thin coating layer (e.g. sol-gel or
ALD) could be one way to overcome these problems and to improve
the barrier properties of such materials.
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Acknowledgements
 Funding:
 EU-FP7-NMP (PLASMANICE project)
 Tekes – Finnish Funding Agency for Technology and Innovation
 VTT Technical Research Centre of Finland
 Collaboration:
 Fraunhofer ISC, Germany (Dr. Klaus Rose)
 Tampere University of Technology, Finland (Dr. Johanna Lahti)
 Josef Stefan Institute, Slovenia (Dr. Janez Kovac)
14/06/2013
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