From Nano to Paper Machine Scale
Joakim Carlén & Michael Persson2008 International Conference on NanotechnologyJune 25-27 2008 St Louis
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2
Silica Nanoparticles
• Binding• Flocculation• Polishing• Frictionizing• Abrasion resistance• Adhesion Improvement• Anti-soiling• Dispersing• Strength and stability• Gelling• Sealing• …and straighter cucumbers
4th Generation of Nano-particlesfor Retention and Dewatering
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Nano-particle retention aid system
Shearforces
Cationicpolymer
Dispersedflocs
Nano-particle
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Benefits of a nano-particle retention aid system
Retention Drainage
Prod
uctiv
ity/C
ost E
ffici
ency
Qua
lity
Cleaner system
Improvedrunability
Decreased addition of filler, size and dye
Improved wire life
Improved filler and dye distribution
Less two-sidednessBetter strength
Decreased vacuum
Increased press solids
Increased speed Lower steam consumption
Reduced headboxconsistency
Improved strength/formation
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050
100150200250300350400450
No.
Pap
er &
Boa
rd
Mac
hine
s
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
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1980 81
1982 83
1984 85
1986 87
1988 89
1990 91
1992 93
1994 95
1996 97
1998 99
2000
2001
2002
2003
2004
Total
Volume development of Eka Nano-particles
First generation
Secondgeneration
Third generation
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Average dosage of nano-particleper ton of paper and board
0
200
400
600
800
1000
1200
1980 1985 1990 1995 2000YEAR
NP(
ppm
)
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Important properties of silica nano-particles
Primary particle size
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Surface area – charge density
5 nm
550 m2/g
3 nm
900 m2/g
Reducing particle diameter from 5 to 3 nmincreases the charge added per gram of silicaby more than 60%
From Sears (1956), Andersson et al (1996)
Silica nano-particle [mg/g of fibre]
Fine
s re
tent
ion
[%]
0 0,1 0,2 0,3 0,4 0,5
30
40
50
60
70
80
90
8 mg cationic starch added per g of fibre
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A mixture of C60 and C70 fullerenes werefully hydroxylated giving the C60/70 fullerol.
Hypothesis
Smaller particle size Larger specific surface area
More charge added Higher performance
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Fullerols
0
5
10
15
20
0 0,2 0,4 0,6 0,8 1
Dra
inag
e tim
e [s
]
Nano-particle [mg/g]
3.5 meq/g
0.86 meq/g
Fullerol
Silica
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0
5
10
15
20
0 0,2 0,4 0,6 0,8 1
Dra
inag
e tim
e [s
]
Nano-particle [mg/g]
Fullerol
Silica
Linked Fullerol
3.5 meq/g
0.86 meq/g
Fullerols
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Conclusion: Particles can be too small
There is a need for linking particles together
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Important properties of silica nano-particles
Primary particle size
Size of aggregate
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S-value
5 nm 5.6 nm
Monolayer of water gives 40 % higher volume fraction
S-value about 80
From: Mooney (1951), Alexander (1956) Iler (1979)
S-value is the percent by weight of silica in the dispersed phase
Normal range of S-valuesfor silica nano-particles is10 to 50.
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468
10121416
0 250 500 750 1000
The importance of S-value
Dra
inag
e tim
e [s
]
Nano-particle area added [m2/g]
41292216
Lower S-value
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Aggregate size
Added surface area [m2/g]
Dra
inag
e tim
e [s
]
0 200 400 600 800 1000 1200 1400 16005
6
7
8
9
10
11
12
13
14
High specific surface area
Low specific surface area 26 nm
24 nm
Aggregate size as determined by SR-SAXS© Eka Chemicals 2008
Conclusion: size of aggregate and primary particle size not enough to explain performance differences
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Important properties of silica nano-particles
Primary particle size
Size of aggregate
Morphology
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Axial ratio – a way to describe the shape• Combine radius of gyration from scattering
experiments with measurements of intrinsic viscosity.• Assume that the aggregates have a shape of an
ellipsoid.• Calculate what dimensions the ellipsoid whould have
to satisfy the size and viscosity• The ratio R between the two axis is a measure of
how extended the aggregate is.
From Walldahl, Wall and Biddle (1996), Liveland (1999)
2r1
2r2
Axial ratio R=r1/r2
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Structure
0
2000
00
4000
00
6000
00
8000
00
1000
000
1200
000
1400
000
1600
000
1800
000
2000
000
2200
000
2400
0005
6
7
8
9
10
11
12
Surface area added per kg of paper
Dra
inag
e tim
e [s
] Aggregate size from light scattering: 19.6nmMore globular morphology
Aggregate size from light scattering: 20.6nmMore extended morphology
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Extended or elongated aggregates perform better than more globular aggregates
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Summary• Primary particle size, aggregate size and aggregate
morphology are important parameters when optimizing the silica nano-particles
• Aggregates can be too small• Elongated particle morphology perform better
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6
8
10
12
14
16
0 0,1 0,2 0,3 0,4 0,5
• Paper Machine Trial results• Coated finepaper - Equal performance at 30-50%
lower dosage• Bleached box board – 7-10% increased production
Dew
ater
ing
time
[s]
Dosage [mg/g]
4th Generation silica nanoparticles
3d Generation4th Generation
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Nanoparticles as emulsifiers for ASA.
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Conventionally starch or other polymer is used as emulsion stabilizer
Silica nanoparticles are used as stabilizers
What is nano-stabilized ASA?
+ Simpler equipment for emulsification+ Easy to retain of fibers+ Less dependence on starch quality
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Blue spot problem
020406080
100120140160180
0 10 20 30
Standard ASA
Standard ASA +DyesNano ASA
Nano ASA +Dyes
Par
ticle
size
, 90%
bel
ow[µ
m]
Time [min]•Cleaning frequency every 5 days due to blue spots. •Now running for 6 months without blue spot problems
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Conclusions
• By controlling the nano-scale structure both papermachine performance and paper properties can be greatly improved.
• Nano-technology is and will be an important tool in ”ournew toolbox”• It makes it possible to influence material properties at
the length scales where a lot of the material propertiesare determined.
• Silica based nano-particles is the ”affordable” nano-particle for large scale application.
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Acknowledgements
• Michael Persson• The Mithra and Louis development teams• Caterina Camerani, Ann Terry and Maxlab for synchrotron
beamtime• Jonas Liesén & Marie Turunen• Samantha Jenkins & Stephen Kirk – West Sweden
University for molecular modelling work
Thank you for your attention
© Eka Chemicals 2008