8380 MF SCB Thickener Brochure

8/6/2019 8380 MF SCB Thickener Brochure

1/8

Thickeners/Rheology Guide


2/8

Rheology

Rheology is dened as the study o the deormation and fow o materials. When a orce is applied to a liquid, the

liquid will fow to relieve the strain rom this orce. Dierent systems will resist this fow more than others and the

measurement o this resistance is a measure o the viscosity o the system. Newton rst introduced a basic model or

the fow measurement o a liquid between two parallel plates and this is represented in gure 1.

Area A

Upper moveable plate

y

x

Lower fixed plate

Force F

Speed v

gure 1

Newtonian Fluid

Shear Rate

Viscosity

Newtonian Fluid

Shear Rate

SheerStress

02 Scott Bader Thickeners/Rheology

Newtonian Fluids examples include water, certain oils

and dilute resin solutions. The viscosity o a Newtonian

fuid is independent o shear rate or put another way the

rate o deormation is directly proportional to the applied

orce. This is shown in the two dierent plot types below:

Using this model a number o common rheology terms

can be dened as ollows:

Shear Stress the orce experienced by the liquid is

proportional to the area o the upper plate and is dened

as the shear stress, = F/A (Units = Nm-2 or Pascals [Pa])

Shear Rate the velocity gradient or the rate o change

o velocity at which one layer passes over an adjacent

layer is the shear rate, = dv/dx (Units = s-1)

Viscosity this is expressed mathematically as, = shear stress/shear rate and is the measurement o

the resistance to fow o a fuid. Pascal.second (Pa.s) is

the basic unit o viscosity, but Poise or centpoise (cp =

one hundredth o a Poise) is oten used and one cp is

equivalent to a millpascal-second, mPa.s. When quoting

viscosities the shear rate (or measurement method/

equipment used) should be stated together with the

temperature at which the measurement was taken.


3/8

Dilatant Fluid

Shear Rate

Viscosity

4) Rheopexy rheopectic fuids show the oppositebehavior to thixotropic fuids i.e. they increase in

viscosity over time or a given shear orce until a

maximum is reached ollowed by a viscosity reduction

over time when the shear is stopped. This type o

behavior is extremely rare.

Pseudoplastic Fluid

Shear Rate

Viscosity

Pseudoplastic Fluid

Shear Rate

ShearStress

Thixotropy

Shear Rate

Viscosity

hysteresisarea

>

>

Scott Bader Thickeners/Rheology 03

2) Dilatancy dilatant fuids show the opposite type o

behavior to pseudoplastic systems i.e. they show an

increase in viscosity as the shear rate increases (shear

thickening). It is seen in highly concentrated

suspensions or slurries. This type o behavior is

relatively uncommon, but is represented in theplot below:

1) Pseudoplasticity a large number o liquids show alarge decrease in viscosity when the shear rate is

increased and this type o fow is dened as

pseudoplastic or shear thinning behavior. Emulsions,

suspensions and dispersions are typically

pseudoplastic as are many paint, ink and adhesive

systems. At higher shear rates the fow behavior

becomes more linear (Newtonian). A related type o

fow behavior is that o plastic materials, which

initially resist deormation until a certain yield stress

is reached. Beyond this point the fow is then that o a

pseudoplastic fuid. Pseudoplastic behavior is

portrayed below in two dierent plot types:

Non-Newtonian Systems many systems show

behavior that deviates rom that o simple Newtonian

fow and examples o this are dened below:

3) Thixotropy or thixotropic liquids the viscosity

decreases over time or a given shear rate until a

minimum is reached. Once the shearing orce is

stopped the viscosity recovers over time. The degree

o thixotropy can be represented by what is termed a

hysteresis area This is typical o the behavior observed

in gelled paints applied to a vertical surace, where the

viscosity reduces under the shear o the brush or roller

and then recovers to prevent sagging. This is

represented in the plot below:


4/8

Brookfeld Viscometer Low to medium shear

Stormer Medium shear

ICI Cone and Plate High shear

Rheometer Low to high shear


Practical Rheology or Surace Coatings and

Adhesives ormulators use a number o viscometer

types and methods to measure and understand the

behavior o their systems. Some common viscometer

types are listed below together with the shear ranges

they typically represent:

The Brookeld viscometer is a very common type that is

simple to operate and is oten used as a QC tool to check

a single viscosity measurement at a specied

temperature, and they can also be used to get a basic

rheology prole under lower shear conditions. For a more

complete understanding o the rheology prole o yoursystem it may be necessary to use a rheometer that can

make multiple measurements over a wide shear range. It

is also worth mentioning that various dierent fow cup

types exist and are used as QC tools and to check

viscosities in production. They measure the time taken or

a set volume o fuid to fow through a given size o orice

in the bottom o the cup and are not truly viscometers.

However, the fow time is related to the viscosity o the

liquid and higher viscosity liquids take longer to fow

through the hole.

Many paints and adhesives show either pseudoplastic or

thixotropic behavior and thus show a viscosity reductionwhen sheared. A knowledge o the rheology o a system

can be very useul in understanding its stability and fow

behavior under dierent shear conditions. Settling,

sagging and levelling occur under very low shear

conditions whereas application o the coating or adhesive

generally happens under relatively high shear conditions

e.g. brushing, spraying and rolling. Pumping and general

mixing o ingredients are carried out at low to medium

shear rates. Paints oten require a degree o levelling

ater application, so it may not be desirable to have ast

recovery o viscosity. However, too slow a recovery can

lead to sagging and dripping. Other systems may require

more instantaneous recovery o viscosity. In such cases a

knowledge o the fow behavior imparted by dierent

thickener systems will aid selection o the best product

or the job.


5/8

Stabilizers

Stabilizers


Scott Bader

Inverse Emulsion Thickeners

Conventional emulsions, in technical terms, are oil-in-

water emulsions i.e the continuous phase is water.

Inverse emulsions are simply the opposite i.e water in oil

emulsions with the continuous phase being an oil. Texipol

inverse emulsions are manuactured directly rom the

pre-neutralized liquid monomers that are intimately

dispersed in the oil phase ollowed by a controlled

polymerization process to yield the liquid thickener. The

diagram below shows the essential dierences between

conventional and inverse emulsions.

Mechanism and Benefts o Texipol

Inverse Emulsion Thickeners

When Texipols are added to water or a waterborne

system, the Texipol inverts with the help o the watersoluble emulsiers and water becomes the continuous

phase. The hydrophilic polymer particles swell rapidly

and the resulting highly swollen structure leads to a rapid

increase in viscosity.

Texipol thickeners are supplied in a pre-neutralized orm

which means there is no requirement or additional alkali

or suractant to achieve thickening. In most applications,

Texipol thickeners can be added at any stage o

ormulating, including post-thickening o systems, thus

allowing greater fexibility when ormulating.

In general terms a thickener has 3 unctions to ull

in a typical ormulation:

a. To increase viscosity

b. To stabilize the dispersion o insoluble components

such as pigments

c. To modiy the fow.

Formulation Guidelines or Texipols:

Product selection: The rheology, fow and viscosity

eciency is dependent on other ingredients in a

ormulation. Dissolved salts and suractants are known to

eect both the fow and eciency o a Texipol thickened

solution.

To determine the concentration level o Texipol

required in a ormulation: The exact amount o

thickener required can only be determined by

experimentation and depends on the required viscosity

and the nature o the other ingredients in the ormulation.

For typical applications o Texipols where paste-like

viscosities are required, start with a 2%

(by weight) addition level o Texipol and increase the

amount until the desired viscosity is achieved. For lower

ormulation viscosities, 1% or less o the Texipol may be

needed. Since the polymer is preneutralised the

thickening eect is almost instantaneous under high

shear stirring and can be added to thicken a ormulation atany stage o the manuacturing process. Additional

Texipol can be added at the end o a batch to conveniently

adjust the viscosity up to the target level.

How to add: The batch to be thickened should

be thoroughly and uniormly mixed to achieve a

homogenous product and to avoid local thickening. High

shear mixing is recommended or the best results.

Problems can arise i the stirrer is too slow or too small

and does not move the total batch (i.e. a localized

thickening eect is noticed around the blade, and the mix

is not homogenous.) Texipol is shear stable, but it does

shear thin.

What to avoid: High concentrations o dissolved salts

and some suractants will dramatically reduce the

viscosity eciency o Texipol. The presence o polyvinyl

alcohol emulsions can cause sharp viscosity increases in

some inverse emulsion thickened compounds.


6/8

1) 63-201: 1% in DI water Brookeld RVT, Spindle 3, 50 rpm, @ 25C. 2) 63-202: 4% in DI water Brookeld RVT, Spindle 6, 5 rpm, @ 25C.3) 63-253: 2% in DI water Brookeld RVT, Spindle 6, 5 rpm, @ 25C. 4) 63-237: 2% in DI water Brookeld RVT, Spindle 6, 5 rpm, @ 25C.5) 63-258: 2.5% in DI water Brookeld RVT, Spindle 6, 5 rpm, @ 25C. 6) 63-510: 4% in DI water Brookeld RVT, Spindle 6, 5 rpm, @ 25C.

Viscosity of water when Mixed with 2% Texipol

Shear rate (s-1)

Viscosity of water when Mixed with 2% Texipol

Shear rate (s-1)

0.01

0.1

1

10

100

1000

0.1 1 10 100 1000

Viscosity(Pa.s=

1,0

00cP)

Texipol 63-201

Texipol 63-202Texipol 63-237

Texipol 63-253

Texipol 63-258

Texipol 63-510


Texipol Flow Typical thickenedviscosity mPa.s Typical pHusage range

63-201 Long stringy 700 1) 5.0 - 12.0

63-202 Short 35,000 2) 5.5 - 11.0

63-237 Extremely short 30,000 3) 6.0 - 12.0

63-253 Extremely short 45,000 4) 6.0 - 11.0

63-258 Extremely short 100,000 5) 6.5 - 10.0

63-510 Short 100,000 6) 2.0 - 12.0

Rheology Curves :

Texipol selection chart

This chart is intended as a guideline to use when selecting a grade o Texipol or certain applications.


7/8

Effect of pH on the Viscosities of Water and Texipol Solutions

[2.0% Texipol in Water and @50 s-1]

pH of the Solution

Effect of pH on the Viscosities of Water and Texipol Solutions

[2.0% Texipol in Water and @50 s-

pH of the Solution

100

1000

10000

0 1 2 3 4 5 6 7 8 9 10 11 12

Viscosity(Pa.s=

1,0

00cP)

Texipol 63-201

Texipol 63-202Texipol 63-237

Texipol 63-253

Texipol 63-258

Texipol 63-510


NOTICE: The inormation and recommendations in this publication are, to the best o ouractual knowledge, reliable. Suggestions made concerning uses or applications are only

the opinion o Scott Bader, Inc. and users o these products should make their own tests

to determine the suitability o these products or their own particular purposes. Because

o the numerous actors beyond our control aecting the results o the use o these

products, SCOTT BADER, INC. MAKES NO WARRENTY OF ANY KIND, EXPRESSED OR

IMPLIED, INCLUDING THOSE OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR

PURPOSE, OTHER THAN THAT THE PRODUCT CONFORMS TO ITS APPLICABLE CURRENT

STANDARD SPECIFICATION.

Suggestions or uses o our products should not be understood as recommending

the use o our products in violation o any patent.


8/8

Speciality Polymers

Scott Bader Group of Companies

USAScott Bader Inc

4280 Hudson Drive,

Stow, OH 44224

Tel: +1 330 920 - 4410 Fax: +1 330 920 - 4415

email: [email protected]

United Kingdom

Scott Bader Company LimitedTel: +44 1933 663100 Fax: +44 1933 666529


FranceScott Bader SA

Tel: +33 3 22 66 27 66 Fax: +33 3 22 66 27 80


SwedenScott Bader Scandinavia AB

Tel: +46 346 10100 Fax: +46 346 59226


Republic o South Arica

Scott Bader (Pty) LtdTel: +27 31 736 8500 Fax: +27 31 736 8511


UAEScott Bader Middle East Ltd

Tel +971 48835025 Fax: +971 48835319


Czech RepublicScott Bader Eastern Europe

Tel: +420 48 5228 344 Fax: 420 48 5228


Croatia

Scott Bader d.o.oTel: +385 1 240 6440 Fax: +385 1 240 45


SpainScott Bader Ibrica S.L.

Tel: +34 93 553 1162 Fax: +34 93 805 1


Bedord Specialty Sales, Inc.

Shirley, MA

(800) 815 - 7429

www.bedfordsales.com

Dempsey Corporation

Toronto, Ontario

(416) 461 - 0844

www.dempseycorporation.com

EM Sullivan Associates, Inc.

Paoli, PA

(610) 725 - 8717

www.emsullivan.com

Kohl Marketing

Roswell, GA

(800) 333 - 5645

www.kohlmarketing.com

www.scottbader.com

Speciality Polymer North America

Distributors

Paciic Coast Chemicals

Berkeley, CA(510) 549 - 3535

www.pcchem.com

Palmer Holland Inc.

North Olmsted, OH

(440) 686 - 2300

www.palmerholland.com

Points West Distributors LLC

Surrey, British Columbia

(604) [email protected]

Specialty Chemical Sales, Inc.

Kansas City, KS

(913) 915 - 5315

www.specialtychemicalsales.com

The NP Group, LLC.

Houston, TX

(713) 690 - 6202

www.npgroupinc.com

8380 MF SCB Thickener Brochure

Documents

Transcript of 8380 MF SCB Thickener Brochure