CHALLENGE

TESTED

BEYOND

DURABLE

MICRO

MATTERS

COMPOUND

KNOWLEDGE

FAMILIAR

BONDS

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The Dispersion Triangle for Carbon Black Pigments

Richard Abbott

Natalie Harris and Josh Baugh

September 8th 2021

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Table of Contents

INTRODUCTION

DISPERSION TRIANGLE CONCEPT

PIGMENT SELECTION

FORMULATION

DISPERSION PROCESS

WHY USE THE CONCEPT ?

2

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Dr. RI CHARD ABBOTT

3

• Pri nci pal Sci ent i s t ( Coat i ngs ) wi t h over 20 years of

worki ng wi t h carbon bl ack i n a vari et y of l i qui d sys t ems.

• Based at Bi rl a Carbon headquart ers & t echni cal cent er s i nce

2003.

• Respons i bl e f or devel opi ng new carbon bl acks and

l everagi ng exi s t i ng product s i nt o new and di f f erent

appl i cat i ons .

• Cont act s : Ri chard. Abbot t@adi t yabi rl a. com

• Nat al i e. Harri s@adi t yabi rl a. com

• J osh. Baugh@adi t yabi rl a. com

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Introduction

• Today we will be discussing the concept of the performance triangle.

• In turn we will cover

• Pigment selection

• Formulation

• Dispersion

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Pigment Selection

• For carbon blacks there are four fundamental properties that help determine the end performance

• Particle size distribution

• Aggregate size and shape distribution

• Pore size distribution

• Surface chemistry distribution

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Full Shade/Masstone Performance

Surface Area (Particle size) is the primary determinant of color performance.

6

200

220

240

260

280

300

320

0 50 100 150 200 250 300 350 400

Jetn

ess

My

STSA m2/g

TreatedUntreated

• Sol vat ed CAB Formul at i on.

• Di spers i on vi a chi ppi ng on 2 rol l mi l l

• The chi p approach ensures a hi gh l evel of

di spers i on

15 g CAB chi p ( 15- 40% CB)

60 g N- but yl acet at e

75 g 3/32 s t eel shot

1 hour shake t i me

• Hi gher surf ace area gi ves hi gher J et ness .

• Sol vent borne f ormul at i on, so t he ef f ect of

t reatment becomes very apparent at hi gh surf ace

area.

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Tinting Product Selection Involves Trading Off Strength and Tone

-5.00

-4.00

-3.00

-2.00

-1.00

0.00

0.0 40.0 80.0 120.0 160.0 200.0

Hu

nte

r U

nd

erto

ne

(b)

STSA (m²/g)

-5.00

-4.50

-4.00

-3.50

-3.00

-2.50

-2.00

-1.50

-1.00

-0.50

0.00

0 20 40 60 80 100 120

Hu

nte

r U

nd

erto

ne

(b)

Tinting Strength (%)

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Pigment Selection Additional Criteria

• Aggregate size and shape distribution

Higher structure carbon blacks will create a higher viscosity, as well as providing an easier dispersion. This will usually come at a minor cost in color performance.

• Pore size distribution

Outside of conductive coatings, this is not normally an important parameter

• Surface chemistry distribution

Post-treated carbon blacks have an acidic surface. This is important in how the pigment interacts with other formulation ingredients

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Formulation

• The formulation chosen has a major effect on the performance of the carbon black

• Some general comments

• Ensure adequate levels of dispersant (in terms of %SOP)

• Check dispersant/resin compatibility

• In solventborne applications, post-treated/acidic products tend to perform better than untreated products

• Good color/dispersion in a concentrate/grind doesn’t necessarily mean good color in a final coating.

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High Color Carbon Blacks: Waterborne Ladder study shows expected high dispersant demand for optimum performance

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2.50

2.70

2.90

3.10

3.30

3.50

3.70

3.90

60 70 80 90 100 110 120 130

Jet

nes

s H

un

ter

L

Dispersant Amount Wt %

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Solventborne Automotive:Fall off in performance at different loadings reflects different surface characteristics

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275

280

285

290

295

300

305

0% 20% 40% 60% 80% 100% 120%

Jet

nes

s M

y

Dispersant Amount

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Effect of Dispersant Choice: WB Automotive Large swings in both jetness and bluetone

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3.49

3.02 3.042.94

2.61

3.93

3.64

2.81

-0.42

-0.05 -0.05

0.09

-0.40

-0.18 -0.19

-0.08

-0.8

-0.4

0.0

0.4

0.8

1.2

1.6

0.00

1.00

2.00

3.00

4.00

5.00

6.00

Blu

eto

ne

Hu

nte

r b

Jetn

ess

Hu

nte

r L

L b

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Effect of Dispersant Choice : Leather CoatingPredominantly a let down effect

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6.27

10.99

6.51

5.565.83

4.89

5.66

0.90

1.85

1.43

1.001.12

0.78

1.01

0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

4.50

2.00

3.00

4.00

5.00

6.00

7.00

8.00

9.00

10.00

11.00

Reference "Drop In" A B C Y Z

Blu

nes

s H

un

ter

b

Jetn

ess

Hu

nte

r L

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Dispersion

• Dispersion covers

• Pigment wetting

• Dispersion process

• Time/Energy

• Media Size and density (if applicable)

• Pre-mixing/bead breakdown (if applicable)

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Stages of Dispersion Process

Premixing Deagglomeration Depends on

- Premixing

- Deagglomeration

- Letdown

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Premix Equipment

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• Wetting is the first step in the dispersion process

• Breakdown of beads and agglomerates in to smaller fractions

• Removal of entrained air from the surface of the carbon black and replacing it with liquid vehicle

• Millbase viscosity and equipment geometry is important

• Geometry should promote rolling laminar flow (Doughnut Effect)

• High peripheral speed generates shear within liquid

• Viscosity too low = splashing, aeration and bubbles

• Viscosity too high = lack of movement, low transmission of mechanical energy

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Low & Medium Viscosity Milling Equipment

• Bead or shot mills spin pegs or disks at high speed in a cylindricalchamber partially filled with small beads or shot

• Small dense beads provide a degree of impact as well as shear

• Ball mills use larger tumbling balls to crush the pigment

• Ball mills are older, batch technology but still very effective

• Attritors fall mid way between the two techniques

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Bead MillingSelection Considerations for high color milling

• Energy density

• Usually dictated by cooling capability, a smaller chamber will allow for higher energy densities, which is a significant help to dispersing higher color pigments

• Hydraulic packing

• How is the mill preventing hydraulic packing of the media, close fitting blades, back flow pumping or other characteristics

• Screen size

• Single/multiple pass versus recirculation

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• Standard Laboratory Shaker

• Finer media gives rise to a jettercoating

• Beaded products will need to be broken down before grinding with fine media

• Finer media has higher risk of hydraulic packing

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Media Size and DensityMedia type has significant impact on color development

0 2 4 6 8 10

Jet

nes

s M

y

Milling Time

0.6 - 0.8 mm

1.0 - 1.2 mm

1.8 - 2.0 mm

1.7 - 2.4 mm

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320

325

330

335

340

345

350

355

0 2 4 6 8 10 12 14 16 18

Jetn

ess

My

Dispersion time h

• Standard Laboratory Shaker

• 0.6 - 0.8 mm Zirconia beads

• With a well matched dispersant even 16 hours of shaking has not reached the ultimate level of performance

• For production efficiency there will be a time/energy and performance balance that will be particular to any given location and product

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High Color Carbon Blacks Take a lot of time/energy to disperse fully

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Summary

• We discussed the concept of the performance triangle.

• Covering in turn

• Pigment selection

• Formulation

• Dispersion

• But why this concept, why tie them together ?

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Considering all parts of the triangleEnables proper product selection for any given application

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220 240 260 280 300 320 340 360 380 400 420

Mass Market

Premium

Best Current

Future Need

My Color Space Market

280 – 320 Mass Market Black

330 - 350 Premium Black

370 – 380 Best Current

400 + Future Need

Different High Color Products and their positioning

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What about constraints ?

• As a formulator, constraints are common. You must use pigment X, or the production time is limited so you can only disperse for Y time

• Ultimate example – Military paint

• Pigment and formulation specified

• Performance range also specified.

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Dr. RI CHARD ABBOTT

Thank you and Any Questions ?

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• Pri nci pal Sci ent i s t ( Coat i ngs ) wi t h over 20 years of

worki ng wi t h carbon bl ack i n a vari et y of l i qui d sys t ems.

• Based at Bi rl a Carbon headquart ers & t echni cal cent er s i nce

2003.

• Respons i bl e f or devel opi ng new carbon bl acks and

l everagi ng exi s t i ng product s i nt o new and di f f erent

appl i cat i ons .

• Cont act s : Ri chard. Abbot t@adi t yabi rl a. com

• Nat al i e. Harri s@adi t yabi rl a. com

• J osh. Baugh@adi t yabi rl a. com

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Thank You

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