From Nano to Paper Machine Scale. Joakim Carlén & Michael Persson 2008 International Conference on Nanotechnology June St Louis

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1 From Nano to Paper Machine Scale Joakim Carlén & Michael Persson 2008 International Conference on Nanotechnology June St Louis

2 Silica Nanoparticles Binding Flocculation Polishing Frictionizing Abrasion resistance Adhesion Improvement Anti-soiling Dispersing Strength and stability Gelling Sealing and straighter cucumbers 2

3 4th Generation of Nano-particles for Retention and Dewatering

4 Nano-particle retention aid system Cationic polymer Shear forces Nano-particle Dispersed flocs

5 Productivity/Cost Efficiency Benefits of a nano-particle retention aid system Improved runability Cleaner system Retention Improved wire life Decreased addition of filler, size and dye Increased speed Decreased vacuum Drainage Lower steam consumption Increased press solids Quality Improved filler and dye distribution Reduced headbox consistency Better strength Less two-sidedness Improved strength/formation

6 No. Paper & Board Machines

7 Volume development of Eka Nano-particles Total First generation Third generation Second generation

8 Average dosage of nano-particle per ton of paper and board NP(ppm) YEAR

9 Important properties of silica nanoparticles Primary particle size

Surface area charge density 90 Fines retention [%] 80 70

more than 60% 0 0,1 0,2 0,3 0,4 0,5 Silica nano-particle

10 Surface area charge density 90 Fines retention [%] nm 3 nm 550 m2/g 900 m2/g Reducing particle 8 diameter mg cationic from starch 5 to 3 nm added per g of fibre increases the charge added per gram of silica by more than 60% 0 0,1 0,2 0,3 0,4 0,5 Silica nano-particle [mg/g of fibre] From Sears (1956), Andersson et al (1996)

11 Hypothesis Smaller particle size Larger specific surface area More charge added Higher performance A mixture of C 60 and C 70 fullerenes were fully hydroxylated giving the C 60/70 fullerol.

12 20 Fullerols Drainage time [s] ,2 0,4 0,6 0,8 1 Nano-particle [mg/g] Fullerol 3.5 meq/g Silica 0.86 meq/g

13 20 Fullerols Drainage time [s] ,2 0,4 0,6 0,8 1 Nano-particle [mg/g] Fullerol 3.5 meq/g Linked Fullerol Silica 0.86 meq/g

14 Conclusion: Particles can be too small There is a need for linking particles together

15 Important properties of silica nanoparticles Primary particle size Size of aggregate

16 S-value Monolayer of water gives 40 % higher volume fraction 5 nm 5.6 nm S-value about 80 S-value is the percent by weight of silica in the dispersed phase Normal range of S-values for silica nano-particles is 10 to 50. From: Mooney (1951), Alexander (1956) Iler (1979)

17 The importance of S-value Drainage time [s] Lower S-value Nano-particle area added [m 2 /g]

Drainage time [s] Aggregate size 14 13 12 Low specific

0 200 400 600 800 1000 1200 1400 1600 26 nm 24 nm Added

18 Drainage time [s] Aggregate size Low specific surface area High specific surface area nm 24 nm Added surface area [m 2 /g] Aggregate size as determined by SR-SAXS

19 Conclusion: size of aggregate and primary particle size not enough to explain performance differences

20 Important properties of silica nanoparticles Primary particle size 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.

21 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. 2r 1 2r 2 Axial ratio R=r 1 /r 2 From Walldahl, Wall and Biddle (1996), Liveland (1999)

22 Structure 12 Drainage time [s] Aggregate size from light scattering: 19.6nm More globular morphology Aggregate size from light scattering: 20.6nm More extended morphology Surface area added per kg of paper

23 Extended or elongated aggregates perform better than more globular aggregates

24 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

26 4th Generation silica nanoparticles Dewatering time [s] ,1 0,2 0,3 0,4 0,5 Dosage [mg/g] Paper Machine Trial results Coated finepaper - Equal performance at 30-50% lower dosage Bleached box board 7-10% increased production 3d Generation 4th Generation

27 Nanoparticles as emulsifiers for ASA.

28 What is nano-stabilized ASA? Conventionally starch or other polymer is used as emulsion stabilizer Silica nanoparticles are used as stabilizers + Simpler equipment for emulsification + Easy to retain of fibers + Less dependence on starch quality

29 Particle size, 90% below [µm] Blue spot problem Standard ASA Standard ASA + Dyes Nano ASA Nano ASA + Dyes Time [min] Cleaning frequency every 5 days due to blue spots. Now running for 6 months without blue spot problems

30 Conclusions By controlling the nano-scale structure both paper machine performance and paper properties can be greatly improved. Nano-technology is and will be an important tool in our new toolbox It makes it possible to influence material properties at the length scales where a lot of the material properties are determined. Silica based nano-particles is the affordable nanoparticle for large scale application.

31 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

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