microsoft powerpoint - pira - clay presentation
TRANSCRIPT
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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
)
Control2.5Corn5Corn2.5Potato5Potato
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
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15
20
25
30
0 10 20 30
Filler content (%)
Rin
g C
rush
(lbf
), G
M
Control2.5Corn5Corn2.5Potato5Potato
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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
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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
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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)
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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
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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
)
Modified clayOriginal clay
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BrightnessBrightness
10
15
20
25
30
35
0 5 10 15 20 25
Clay content (%)
Brig
htne
ss (I
SO)
Modified clayOriginal clay
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
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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
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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