From Nano to Paper Machine Scale · 2008. 7. 22. · Conclusions • By controlling the nano-scale structure both paper machine performance and paper properties can be greatly improved

From Nano to Paper Machine Scale

Joakim Carlén & Michael Persson2008 International Conference on NanotechnologyJune 25-27 2008 St Louis

© Eka Chemicals 2008

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


Nano-particle retention aid system

Shearforces

Cationicpolymer

Dispersedflocs

Nano-particle


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


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


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


Average dosage of nano-particleper ton of paper and board

0

200

400

600

800

1000

1200

1980 1985 1990 1995 2000YEAR

NP(

ppm

)


Important properties of silica nano-particles

Primary particle size


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


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


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


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


Conclusion: Particles can be too small

There is a need for linking particles together




Size of aggregate


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.


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


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




Size of aggregate

Morphology


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


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


Extended or elongated aggregates perform better than more globular aggregates


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



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


Nanoparticles as emulsifiers for ASA.


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


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


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.


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


Documents

From Nano to Paper Machine Scale · 2008. 7. 22. · Conclusions • By controlling the nano-scale structure both paper machine performance and paper properties can be greatly improved