Nanoparticle Deposition on Packaging Materials by the Liquid Flame
Spray
Hannu Teisalaa, Mikko Tuominena, Mikko Aromaab, Jyrki M. Mäkeläb, Milena Stepienc, Jarkko J. Saarinenc,
Martti Toivakkac and Jurkka Kuusipaloa
a
Paper Converting and Packaging Technology, Tampere University of Technology,P.O.Box 541, FI-33101
Tampere, Finland
b
Aerosol Physics Laboratory, Tampere University of Technology,PO.Box 692, FI-33101 Tampere, Finland
c
Laboratory of Paper Coating and Converting, Center for Functional Mateials, Åbo Akademi University, FI20500 Turku, Finland
Email: [email protected]
Metal oxide nanoparticles were successfully deposited on-line at atmospheric conditions on
packaging materials using a thermal liquid flame spray (LFS) method. LFS is a novel method for
producing nanoparticle coatings on paper, paperboard and low density polyethylene (LDPE)
laminates. Most of the present surface treatment/deposition methods are batch processes and
require special conditions, e.g. low pressure atmosphere, which increase the operation costs and
set limits for industrial applications.
The LFS coating process is demonstrated in Figure 1a and the influences of process
parameters on coating quality are presented. Physical and chemical properties of nanocoatings
were investigated using scanning electron microscopy (SEM), water contact angle measurement,
X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry
(ToF-SIMS). Droplet behaviour on the nanocoated surfaces was illustrated by high speed video
system images.
a)
b)
Figure 1. a) The LFS coating process (on-line) and b) SEM images of the pigment coated paperboard surface before
(above) and after (below) TiO2 nanocoating.
Titanium dioxide (TiO2), silicon dioxide (SiO2), aluminium oxide (Al2O3) and zirconium
oxide (ZrO2) nanoparticle coatings were generated on packaging material surfaces. Such coatings
possess high surface roughness in both micro- and nanoscale, and hence the hydrophobicity or
hydrophilicity of the surfaces is increased. Figure 1b shows the specific hierarchical roughness of
the TiO2 coating that increases the hydrophobicity of the surface. Falling water droplets were
able to bounce off from the nanocoated surface (Fig. 2a), on which the highest measured water
contact angle was over 160°. Regardless of the high hydrophobicity, the coating showed sticky
nature, creating a high adhesion to water droplets immediately as the motion of the droplets
stopped. Because of the adhesive forces, water droplets are able to remain on the surface even
though it is flipped upside down (Fig. 2b). Opposite to TiO2 coating, on SiO2 nanocoating the
surface roughness benefits the wetting of the surface, and therefore the water contact angles even
below 10° were obtained.
Figure 2. a) Dynamics of the falling water droplet on
the paperboard (rows a and c) and on the nanocoated
paperboard (rows b and d). The droplet is able to
bounce off the nanocoated surface. b) A set of images
from the CA measurement illustrates the high
adhesion between the water droplet and the
nanocoating surface (left). 5 µl droplet is able to
remain on the flipped surface (right).
The composition and thickness of the nanocoating, and thus surface properties can be tailored
with the coating parameters, i.e., with the concentration and the feed rate of the precursor
solution, the burner distance and the line speed. Depending on the type of the substrate, different
kinds of coating parameters are also needed in order to obtain superhydrophobicity or
superhydrophilicity. The LFS coating process is a relatively simple, inexpensive and continuous
method for the production of surfaces with nanoparticles of variable sizes from various materials.
The method can be up-scaled straightforwardly for the industrial applications.
1
2010 INTERNATIONAL CONFERENCE ON NANOTECHNOLOGY
FOR THE FOREST PRODUCTS INDUSTRY
Nanoparticle Deposition on Packaging
Materials by the Liquid Flame Spray
HANNU TEISALA, M. TUOMINEN, J. KUUSIPALO (1
M. AROMAA, J. M. MÄKELÄ (2
M. STEPIEN, J. J. SAARINEN, M. TOIVAKKA (3
1) Paper
Converting and Packaging Technology, Tampere University of Technology, P.O. Box 541, FIN-33101, Tampere, FINLAND
of Physics, Tampere University of Technology, P.O. Box 692, FIN-33101, Tampere, FINLAND
3) Laboratory of Paper Coating and Converting, Åbo Akademi University, Turku, FINLAND
2) Department
2
3
4
Content
• Background
• Liquid Flame Spray (LFS) process
• Results
• Superhydrophobicity and superhydrophilicity
• Superhydrophobicity vs. adhesion
• The amount of coating and the line speed
• Conclusions
Nanoparticle Deposition on Packaging Materials by the Liquid Flame Spray/Hannu Teisala
5
Background
• Generate nanoparticles with flame
process, i.e. liquid flame spray
• Particle material: TiO2, SiO2, ZrO2, Al2O3,
Ag, Pd, Pt, Au, oxides of Na, Mg, Sr, Si, Ti, Al, V, Cr, Mn,
Fe, Co, Ni, Cu, Zn, Y, Zr, Mo, Ag, W, Pl, Nd, Pr, Yb, Se
… and mixtures/composites
• Nanomaterial feed rate: 0.001-2.0 g/min
• Particle size range: 2-200 nm
• Develop thin layer -coatings
on fiber based packaging materials:
• Pigment coated paperboard Î Paperboard
• Uncoated paper Î Paper
• Low density polyethylene coated paper Î LDPE
Nanoparticle Deposition on Packaging Materials by the Liquid Flame Spray/Hannu Teisala
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Liquid Flame Spray (LFS) process
LFS BURNER
LFS PROCESS
PRECURSOR
SOLUTION
HYDROGEN
OXYGEN
DROPLETS
LFS COATING
PARAMETERS
LEVELS
LINE SPEED
30–150 m/min
BURNER
DISTANCE
4–25 cm
FEED RATE
4–32 ml/min
CONCENTRATION
10 – 50 mg (atomic
metal)/ml
VAPOUR
NANOPARTICLE
COATING
NANOPARTICLES
MOVING SUBSTRATE
ROLL 1
ROLL 2
Nanoparticle Deposition on Packaging Materials by the Liquid Flame Spray/Hannu Teisala
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Superhydrophobicity and superhydrophilicity
Paperboard, (ref.), CA=77°
SiO2 coated, CA=12°
TiO2 coated, CA=161°
Coated, TiO2
• Coating parameters of SiO2 and TiO2:
• Fixed parameters: line speed 50 m/min, concentration 50 mg (atomic metal)/ml
• Variable parameters: 1) feed rate 32 ml/min, distance 15 cm
Nanoparticle Deposition on Packaging Materials by the Liquid Flame Spray/Hannu Teisala
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Superhydrophobicity and superhydrophilicity
Uncoated
1 µm paper, (ref.), CA=120°
1 µm
SiO2 coated, CA=7°
TiO2 coated, CA=164°
200 nm
• Coating parameters of SiO2: 2) feed rate 12 ml/min, distance 15 cm
• Coating parameters of TiO2: 3) feed rate 12 ml/min, distance 6 cm
Nanoparticle Deposition on Packaging Materials by the Liquid Flame Spray/Hannu Teisala
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Superhydrophobicity and superhydrophilicity
TiO2 coated LDPE, CA=151°
∼ 30
mg/m2
LDPE, (ref.), CA=98°
SiO2 coated LDPE, CA=33°
∼ 10 mg/m2
• Coating parameters of TiO2: 1) feed rate 32 ml/min, distance 15 cm
• Coating parameters of SiO2: 2) feed rate 12 ml/min, distance 15 cm
Nanoparticle Deposition on Packaging Materials by the Liquid Flame Spray/Hannu Teisala
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Superhydrophobicity vs. adhesion
• Paper substrate (Bendtsen roughness: ~ 180 ml/min)
< 10°
> 10°
Î non-adhesive surface
• Paperboard substrate (Bendtsen roughness: ~ 20 ml/min)
90°
90°
Î highly adhesive surface
Nanoparticle Deposition on Packaging Materials by the Liquid Flame Spray/Hannu Teisala
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1
The amount of coating and the line speed
•Total amount of titania on paperboard Î
• ICP-MS – Inductively Coupled Plasma Mass Spectrometry
• Flame temperature at 10–15 cm: 450–2000°C
• Paperboard temperature: 70–115°C
• LDPE, (1parameters = 40 mg/m2
• Paper, (3parameters = 30 mg/m2
• Paperboard, (3parameters = 45 mg/m2
Nanoparticle Deposition on Packaging Materials by the Liquid Flame Spray/Hannu Teisala
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The amount of coating and the line speed
Paperboard (ref. 77°)
Paper (ref. 120°)
LDPE coating (ref. 98°)
• Coating parameters 1-3) were
constant at different line speeds
TiO2
The amount of TiO2 coating on
paperboard, (1parameters:
• 50 m/min = 47 mg/m2
• 100 m/min = 43 mg/m2
• 150 m/min = 38 mg/m2
SiO2
Nanoparticle Deposition on Packaging Materials by the Liquid Flame Spray/Hannu Teisala
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Surface characteristics
• XPS, X-ray photoelectron spectroscopy, (ESCA)
• SiO2 and TiO2 coatings on paperboard, coating parameters1)
Nanoparticle Deposition on Packaging Materials by the Liquid Flame Spray/Hannu Teisala
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Conclusions
• Liquid Flame Spray (LFS) can be used to generate superhydrophobic and
superhydrophilic surfaces onto paperboard and paper
• LFS has great potential for industrial scale method because of its continuous
nature, low coating amounts and high line speeds
• The micro- and nanoroughness of surfaces enable the superhydrophobicity and
superhydrophilicity
• The adhesive forces of superhydrophobic surfaces depend on the contact area
between the liquid and the solid
Î larger contact area leads to higher adhesive forces
• The different amount of carbonaceous material on the TiO2 and SiO2 coatings is
the main reason for the opposite wetting behaviour of the surfaces
Nanoparticle Deposition on Packaging Materials by the Liquid Flame Spray/Hannu Teisala
15
2010 INTERNATIONAL CONFERENCE ON NANOTECHNOLOGY
FOR THE FOREST PRODUCTS INDUSTRY
• Thank you!
Acknowledgements
• Tekes (Finnish Funding Agency for Technology and Innovation)
• Industrial partners: Stora Enso, UPM, Kemira and Beneq
Nanoparticle Deposition on Packaging Materials by the Liquid Flame Spray/Hannu Teisala