Microsoft PowerPoint - Pira - clay presentation

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Starch as a DriverStarch as a DriverIn Papermaking DevelopmentIn Papermaking Development

A. Ragauskas*, Y. Deng*, P. Jones**, D. White*A. Ragauskas*, Y. Deng*, P. Jones**, D. White**Institute of Paper Science and Technology*Institute of Paper Science and Technology

Georgia Institute of TechnologyGeorgia Institute of Technology****ImerysImerys

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Advantages of Using Filler in PaperAdvantages of Using Filler in Paper

• Increased filler content in paper will improve paper optical properties – Brightness– Opacity– Print quality

• Increased filler content in paper will reduce papermaking materials costs– Pulp price: $250-400/ton– Filler cost (clay or PCC): $100-130/ton

• Increase water drainage, drying rate

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Potential Problems Potential Problems of Using Filler in Paperof Using Filler in Paper

• Effects on wet and dry end operations – Retention– Water clarification– Dusting

• Effects on sheet properties– Sheet two-sidedness– Reduced paper strength– Reduced bulk– Linting

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Past Research in Filler ModificationPast Research in Filler Modification

•• New filler developmentNew filler development–– Fibril fillersFibril fillers–– Pretreatment of fillersPretreatment of fillers

•• Coating polymer on filler surfaceCoating polymer on filler surface–– Polymers used in the literature are relatively Polymers used in the literature are relatively

expensiveexpensive–– Some polymers can cause environmental problemsSome polymers can cause environmental problems–– Effect on paper properties, such as causing Effect on paper properties, such as causing

unnecessary sizing, increasing recycling difficultyunnecessary sizing, increasing recycling difficulty

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ObjectiveObjective

Develop new bonding fillers to improve Develop new bonding fillers to improve existing sheet properties while existing sheet properties while decreasing fiber costsdecreasing fiber costs

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Conceptual diagram showing impact of filler/ aggregate size on strength

Small fiber-fiber contact area: low paper strength

Large fiber-fiber contact area: high paper strength

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Our Approach: Filler Treatment Using Starch

Filler

Starch adsorbed on filler Starch coated on filler

StarchIn traditional papermaking

Our approachfiber

fiber

Coated Filler

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Approach Using Starch Coating

Filler aggregates coated with starch and with suitable

particle size

Larger particle size: decreased contact area between fiber and filler

Increased mechanical retention

Improved bonding (increased bonded

area vs. untreated clay)

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Filler Treatment with Starch

Filler + starch + water

Starch cooked with or without clay

Filler + dissolved starch + water

Dried (feed range of 20-50% solids)

Starch-coated filler

FillerFiller

2.5 or 5% starch based on clayDuring drying, starch forms network Clay is encapsulated with starch molecules 20-40 µm; starch coated

Coated starch relatively water-insoluble

Starch

Clay

Starch-coated Clay

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Clay Modification

Clay Clay with 5% coated cationic starch

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Clay Modification

Clay with 5% coatedraw potato starch

Clay with 25% coated raw potato starch

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Starch Dissolving Profile of 2.5% Starch Modified Clay (stirring speed 1200 rpm, clay consistency 10g/L)

0

5

10

15

20

25

0 20 40 60 80 100 120 140 160 180 200

Stir time, min.

Star

ch d

isso

lvin

g, %

( on

star

ch c

oate

don

cla

y)

25℃, Cornstarchmodif ied clay

25℃, potatostarchmodif ied clay

55℃, cornstarchmodif ied clay55℃, potatostarchmodif ied clay

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Starch Swelling Power vs. Time and Temperature

0

2

4

6

8

10

12

14

0 20 40 60 80

Time, min.

Swel

ling

pow

er,g

wet

film

/g d

ryst

arch

corn starch,25℃

corn starch,55℃

potato starch,25℃

potato,55℃

Dried starch absorbs water, swells, deforms – indication of behavior on clay

which would enhance bonding

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Lab Results

• Starch coated and dried on clay surface can increase paper strength significantly (10-15%) vs. use of unmodified clay– Ring crush– Similar optical properties

• Different starches (corn, potato, cationic starch) gave similar effects

• Starch amount as little as 2.5% of the filler to give significant positive effect

Ring crush vs. filler content

50

55

60

65

70

75

80

85

0 10 20 30

Filler content,%

Ring

cru

sh,lb

f

pure clay

corn starch modif iedclaypotato starch modifiedclaypotato starch+clay

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Lab Results (Continued)

•• Confirmed Confirmed sprayspray--drieddried starch coated clay has increased starch coated clay has increased paper strength vs. unmodified clay (handsheets)paper strength vs. unmodified clay (handsheets)–– Also bulk and stiffness improvement Also bulk and stiffness improvement –– Modified clay does not reduce clayModified clay does not reduce clay’’s ability to increase s ability to increase

paper brightnesspaper brightness• Potential to use low cost clay and low grade starch to

produce high strength paper/board with high filler content

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Laboratory ResultsLaboratory Results

30

50

70

90

0 10 20 30

Filler content (%)

Tens

ile in

dex

(Nm

/g)

Control2.5Corn5Corn2.5Potato5Potato

30

50

70

90

0 10 20 30

Filler content (%)Te

nsile

inde

x (N

m/g

)


Before Before CalenderingCalendering CalenderedCalendered

Handsheet Tensile StrengthHandsheet Tensile Strength

Control: 5% starch based on unmodified clay;i.e., at 10% clay in sheet: 0.5% starch in sheet (10 lb/t)

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Ring Crush, Ring Crush, CalenderedCalendered Handsheets Handsheets

Can add at least 10-15% modified clay and get same ring crush

10

15

20

25

30

0 10 20 30

Filler content (%)

Rin

g C

rush

(lbf

), G

M


18

32126.2

53238.25

14106919.5

31241622351

52463343562

84827088885

969791959810

Percentage less than given particle sizeParticle size (micron)

8.38.27.07.910.7Surface area (m2/g)

7.5%Potato

2.5%Potato

5%Corn

2.5%Corn

Clay

Clay CharacterizationClay CharacterizationClay surface area and particle size

Modified clays: lower surface area, larger particle size

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Pilot ResultsPilot Results

• Modified clay filler produced using pilot spray dryer at IPST, at IMERYS

• Pilot mill trial at Herty Foundation with spray dried clay from Imerys spray dryer

•• Confirmed scaleConfirmed scale--up up –– Sheet propertiesSheet properties–– Dewatering improvement with clay Dewatering improvement with clay

additionaddition

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Spray Dryer EvaluationSpray Dryer EvaluationClay ViscosityClay Viscosity

• Shear viscosity measured for control clay and modified clay – To assess

potential for spray drying

– Control: 50% solids unmodified clay

– Modified clay: 20-50% solids range investigated

0102030405060708090

100

0 200 400 600Shear Rate

Visc

osity

(cP)

50% clay40-2.5corn40-2.5potato40-5corn40-5potato30-2.5corn30-2.5potato30-5corn30-5potato20-2.5corn20-2.5potato20-5corn20-5potato

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Spray Dryer EvaluationSpray Dryer Evaluation

• Results: modified clay can be spray dried up to 40-45% clay

Gas Temp (oC) Sample Feed rate (ml/min) Inlet Outlet

Mass yield (%)

20% Clay 24.5 210 120 72.0 20-2.5Corn 22.3 210 120 99.0 20-5Corn 25.3 210 120 88.1 20-2.5Potato 35.6 210 120 74.0 20-5Potato 24.6 210 120 82.1 50% Clay 27.5 210 120 79.7 30-2.5Corn 25.3 210 120 96.9 35-2.5Corn 17.3 210 120 95.1 40-2.5Corn 20.8 210 120 97.8 45-2.5Corn 7.5 210 120 92.6

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• Modified Clay – IMERYS (Atlanta, GA)– Modified clay coated with

precooked 2.5% corn starch via spray drying of 40% clay slurry

– Particle size (light scattering, in suspension) increased with modified clay vs.conventional clay

• Furnish– SW kraft pulp, kappa 105, Inland– Pulp was beaten to C.S.F. 350 ml

• Handsheets– TAPPI method, 180 g/m2 , CPAM

retention aid.

Spray – Dried Starch-Coated Clay – Handsheet TrialsTensile Index vs. Filler Content

30

35

40

45

50

55

0 5 10 15 20Filler Content (%)

Tens

ile In

dex

(Nm

/g)

Orig. Clay

2.5Corn

Ring Crush Index vs. Filler Content at Different CPAM Levels

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12

13

14

15

16

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0 2 4 6 8 10 12 14

Filler Content (%)

RIn

g C

rush

Inde

x (N

m/g

)

Orig. C lay (0-2 ppm C P A M )

Spray-D ried M o d. C lay, 2.5C o rn (0-2 ppm C P A M )

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Spray-Dried Starch-Coated Clay-Herty Pilot Trial

Single ply; BW 170 g/m2 ; 75 fpmPM

Reslushed liner furnish (IP), mixed SW/HW, CSF 500-550 ml Furnish

RA: CPAM

Mod. Clay (1.8% starch; spray dried@20% solids )• 10 %• 20 %

STARCH COATED CLAY

Corn starch (2.5%)RA: CPAM (Percol175) 1 ppm

Corn starch Chemicals(pH 6-7)

Stnd clay(High AR)• 10 %• 20 %

NoneFiller

ORIGINAL CLAYCONTROL (No clay)

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Spray-Dried Starch-Coated Clay- Herty Pilot Trial

Over 10% increase in tensile and ring crush with modified vs. cOver 10% increase in tensile and ring crush with modified vs. conventional clayonventional clayDecrease in strength vs. unfilled control (starch content less tDecrease in strength vs. unfilled control (starch content less than targethan target)

20

25

30

35

40

45

0 5 10 15 20 25

Clay content (%)

Tens

ile In

dex

(Nm

/g),

GM Modified clay

Original clay

GM Ring Crush Index vs. Clay Content

7

8

9

10

11

12

13

0 5 10 15 20 25

Clay Content in Sheet (%)

GM

Rin

g C

rush

inde

x (N

m/g

)

Original ClayModified Clay

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Herty Pilot Trial : Bulk, StiffnessHerty Pilot Trial : Bulk, Stiffness

Bulk maintained at 10% modified clay contentStiffness reduced only slightly at 10% modified clay content; stiffness increases with bonding, but is more sensitive to sheetthickness (Moberg)

1.5

2.0

2.5

3.0

3.5

0 5 10 15 20 25

Clay content (%)St

iffne

ss (m

Nm

), G

M

Modified clayOriginal clay

1.2

1.3

1.4

1.5

1.6

0 5 10 15 20 25

Clay content (%)

Bul

k (c

m3 /g

)


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BrightnessBrightness

10

15

20

25

30

35

0 5 10 15 20 25

Clay content (%)

Brig

htne

ss (I

SO)


Similar brightness increase with modified and conventional clay

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Effect of Dispersion TimeEffect of Dispersion Time

Long dispersion time had no effect on tensile, but possible effect on ring crush

20

25

30

35

40

45

0 5 10 15 20 25

Clay content (%)

Tens

ile In

dex

(Nm

/g),

GM

Modified clayOriginal clay20 hrs Mod. Clay

GM Ring Crush Index vs. Clay Content - Effect of Dispersion Time

7

8

9

10

11

12

13

0 5 10 15 20 25

Clay Content in Sheet (%)G

M R

ing

Cru

sh In

dex

(Nm

/g)

Original ClayModified Clay20 hrs. Mod. Clay

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10% original clay10% modified clay

Consistent with particle size measurements: IPST (laser- orig. clay: 9.5 µm, modified clay: 38.2 µm); Imerys (Sedigaph: mod. clay slightly coarser)

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20% unmodified clay 20% modified clay

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Effect of Clay on Dewatering

Significant effect of clay or modified clay on dewatering.

Effect of Clay on Sheet Dewatering

0

10

20

30

40

50

60

0 10 20 30 40 50 60Sheet Ash Content (%)

Con

sist

ency

(%)

Clay, Couch CMod. Clay, Couch CClay, Press CMod. Clay, Press C

Dryness off Couch

Dryness out of Press

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Source:P Ince, 2001 USDA FPL

Linerboard Capacities

Linerboard capacities in USA are close toKaolin deposits in SE

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Kaolin Belt

Augusta

Macon

Logistics Unique to SE USA PaperIndustry

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SummarySummary

• Modified filler platform developed• Potential to use low cost clay and low grade starch to

produce high strength paper/board with high filler content–– Decreased fiber and processing costsDecreased fiber and processing costs

•• Evaluating options for modified clay productionEvaluating options for modified clay production–– Lower cost clay sources and processingLower cost clay sources and processing–– Process development and scale up of modified fillerProcess development and scale up of modified filler–– Support of further pilot filler production and applications Support of further pilot filler production and applications

testingtesting

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Acknowledgement

• Georgia TIP3 Program for financial support • Imerys

Documents

Microsoft PowerPoint - Pira - clay presentation