To get additional information, you can use the following link: goo.gl/dxR59V In this presentation, the technical expert explains how Rheology influences in-can properties, paint texture, application properties & film properties. You will find some product recommendations: the right dispersants and thickeners (Acrylic, HEUR) to be used in various formulation types to improve coating properties. If you would like to get more detailed information on Rheology, click on the following link: goo.gl/dxR59V

1. Technical document
Introduction to Waterborne
Paints & Coatings Rheology
Presentationfrom Coatex at Chinacoat2014

2. Add a drop of rheology to your paints and coatings
Introduction to Waterborne
Paints & Coatings Rheology

3. 3
Rheology is part of our daily life!
We look at honey flowing out of the jar, we eat yoghurt with pieces of fruit
suspended in it
We squeeze toothpaste tube and wait for shower gel coming out of the bottle
Rheology is simply one way of describing those sensations!
What is…Rheology?

4. 4
World leading designer and producer of waterborne
Rheology Additives
Entirely dedicated to water based processes and
formulations with minerals
More than 40 years of experience in Rheology
Coatex and Rheology

5. 5
Summary
From Paint to Rheology
• In-can properties
• Paint texture
• Application properties
• Film properties
From Rheology to Paint
• Mechanisms
• Viscosity - Definition
• Rheology profiles
• Shear rates and Paint Properties
• Shear rates and Viscosimeters
• Conclusion

6. 6
From Paint to Rheology
In-can properties

7. 7
From Paint to Rheology: In-can properties
No re-agglomeration of particles
Optimized dispersion of pigments and
fillers
Use a suitable and effective dispersant
Coadis™ and Ecodis™
 good dispersion of fillers and
pigments
 facilitation of the dispersibility
 prevention of re-agglomeration
throughout storage
 good stability and shelf life of the
paint
 good optical properties of the film
2- Dispersing
agent
3- Fillers
Stirring
1- Water
Dispersion of Ca CO3 into water
100
200
300
400
500
20 30 40 50 60 70 80 90
Without
dispersing agent
Solids content of the slurry
With dispersing
agent
Viscosityoftheslurry

8. 8
From Paint to Rheology: In-can properties
The right dispersing agent with
the right dosage
Solids content increase
While maintaining viscosities low
Significant improvement in stability
during storage at high temperature
with Ecodis™ P 90
0 0.3
% dispersing Agent (dry/dry)
Viscosity(mPa.s)
Ecodis™P 90
70% CaCO3
0.5 0.7 0.9
With
Polyphosphates
With
Ecodis™ P 90

9. 9
From Paint to Rheology: In-can properties
Paint stability
No sedimentation of particles
Low shear viscosity control
Gravity on mineral particles  sedimentation
Thickeners generating high viscosities at low
shear  prevention of dense mineral particles
sinking
Acrylic thickeners Viscoatex™ 46 and 730
with a pseudoplastic type rheology  prevent
sedimentation

10. 10
From Paint to Rheology: In-can properties
No liquid phase floating
Control of syneresis
Hydrophobically modified,
associative thickeners
Associative interaction  network/bridging
between
•particles of binder
•thickeners hydrophobic end groups
•aqueous phase
•pigments
Hydrophobically modified thickeners,
HASE or HEUR
Rheotech™ 2000/2800
Coapur ™ XS 71

11. 11
From Paint to Rheology
Paint texture

12. 12
From Paint to Rheology: Paint texture
Feel of consistency & smoothness
Mid-shear viscosity (about 100 s-1)
Rheotech™ 2800 for semi-gloss or
one coat matt paints
Rheotech™ 3800 for matt or semi-
matt paints
Rheotech™ 4800 for matt paints or
fillers
Paint texture
Medium shear viscosity
KU or Stormer viscosity
Rheological Behaviour of Acrylic Thickeners Rheotech™ X800 series

13. 13
From Paint to Rheology: Paint texture
Optimized behaviour after tinting
 stability after color addition
No viscosity drop upon tinting & no
color float
 associative acrylic rheology
modifiers: Rheotech™ range
Tinting system
Color acceptance

14. 14
From Paint to Rheology
Application properties

15. 15
From Paint to Rheology: Application properties
Ease of application
Easy to load paint (brush
or roller)
Viscosity control at low
to medium shear
With standard
thickeners
With
Coapur™ 975 W

16. 16
From Paint to Rheology: Application properties
Ease of application
Low spatter ability
Viscosity control at
medium to high shear With cellulosic
thickeners
With
Rheotech™ 2800

17. 17
From Paint to Rheology: Application properties
Good covering power
Good film build &
brushability
Viscosity control at high
shear
With cellulosic
thickeners
With
Coapur™ 3025

18. 18
From Paint to Rheology
Film properties

19. 19
From Paint to Rheology: Film properties
Good film build, brushability &
flow/leveling
Fine tuned viscosity at high &
low shear
With cellulosic
thickeners
With accurate
control of viscosity
Newtonian to balanced polyurethane
thickeners offer optimized flow and leveling:
Coapur™ 830 W for medium PVC
Coapur™ 2025 for low PVC

20. 20
From Paint to Rheology: Film properties
Water & Weather
resistance
Wet scrub resistance
Hydrophobic thickeners
In medium and high PVC paints,
hydrophobic characteristics of
polyurethane thickeners (HEUR) improve
water resistance
Coapur™ 830 W (for medium/high PVC)
Coapur™ 975 W (for high/medium PVC)

21. 21
From Paint to Rheology: Film properties
Water & Weather resistance
Wet scrub resistance
Dispersant showing a strong
hydrophobic character
Very high PVC Paints
binder not sufficient to encircle mineral
particles
 hydrophobic dispersant increase the
water resistance
2 000 cycles 10 000 cycles
Matt paint PVC = 77%
with Coadis™ 123K

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From Rheology to Paint
Mechanisms

23. 23
From Rheology to Paint: Mechanisms - Dispersion
Repulsive energy between particles prevents agglomeration and
sedimentation
d
E
dc
In can long term pigment
stabilization
Prevents flocculation and
acceleration of settling
Stabilization by
adsorption of a
polyelectrolyte dispersant

24. 24
From Rheology to Paint: Mechanisms - Thickening
ASE (Alkali Swellable Emulsion)  acrylic polymers in water emulsion
Neutralization of the acid groups using an alkali to get the polymer soluble in water
Resulting anionic groups trap water molecules in hydrodynamic volumes of entangled
polymers by hydrogen bonds, generating a gel
Low shear viscosity get increased
Carboxylate groups
Acrylic chain
C
O-
O
O
H
H
Hydrogen
bonds

25. 25
From Rheology to Paint: Mechanisms - Thickening
HASE (Hydrophobically modified Alkali Swellable Emulsion)  acrylic
polymers with hydrophobic monomers in water emulsion
Interaction with the binder + gelling effect : both increase viscosities
Add increased response at medium and high shear rates
Carboxylate groups
Acrylic chain
O
H
H
C
O-
O
Hydrogen
bonds
Hydrophobic
monomer
Binder
Associative
interaction

26. 26
From Rheology to Paint: Mechanisms - Thickening
HEUR (Hydrophobic Ethoxylated URethane)  polymers with a
hydrophilic core grafted at both ends with hydrophobic groups of well
selected size/shape by a urethane bond
Thickening is obtained at:
• high shear rates through the associative mechanism
• low shear rates through the association mechanism
Hydrophilic
backbone
PEG
Urethane
link
Linear hydrophobic
end group
Branched hydrophobic
end group

27. 27
From Rheology to Paint: Mechanisms - Thickening
ASSOCIATIVE  HASE or HEUR
 viscosity at high shear rate.
Hydrophobic chains react with binder’s particles by adsorption at their surface or by
ion-dipole interaction
The created bonds generate a given resistance against higher shear stress
Hydrophobic
chains
Binder
Associative
interaction

28. 28
From Rheology to Paint: Mechanisms - Thickening
ASSOCIATION  HASE or HEUR
 viscosity at low shear rate
Well selected hydrophobic end groups contribute to form a hydrophobic network
structuring the aqueous system and boost viscosities at low shear rate
This network is intended to break up temporarily under prolonged shear and to form
again after a given rest time, generating a real thixotropic effect
Association
mechanism

29. 29
From Rheology to Paint
Viscosity - Definition

30. 30
From Rheology to Paint: Viscosity - Definition
Pure substance based liquids show a Newtonian rheological behavior. Formulations are made
of a blend of liquids, organic and mineral solids and do not follow a single or simple
rheological model. The viscosity of formulations depends on the applied shear stress or the
resulting shear rate
Viscosity is the measurement of a resistance to flow
η = shear stress / shear rate = (F/A) / (V/d)
The measurement of viscosity for a given paint is therefore determined by setting either a
shear stress value or a shear rate value
The minimum stress needed to initiate flow is called yield point
Film
Thickness
A : Area [m2]
Liquid Layer d
Shear stress = F / A [N.m-2]
F : Force
[N]
Liquid Layer d
Shear rate = V / d [s-1]
V : Velocity
[m.s-1]

31. 31
From Rheology to Paint
Rheology profiles

32. 32
From Rheology to Paint: Rheology profiles
Newtonian profile:
Viscosity independent of shear rate
Typically pure substances such as water
Varnishes, lacquers and gloss paints should ideally exhibit a Newtonian-like
rheology profile to enhance application properties such as brushability at
application and flow & leveling

33. 33
From Rheology to Paint: Rheology profiles
Dilatant or shear thickening profile:
Viscosity increases as the shear rate increases
This behavior should be avoided as it will give problems either at the paint
manufacturing or at the paint use

34. 34
From Rheology to Paint: Rheology profiles
Pseudoplastic or shear thinning profile:
Viscosity decreases as the shear rate increases
Waterborne formulations naturally tend to exhibit a pseudoplastic type rheology
profile that should be properly tuned with the use of appropriate thickeners

35. 35
From Rheology to Paint: Rheology profiles
Thixotropic behavior:
This behavior depends on shear duration, which induces a temporary decrease in
viscosity
Viscosity recovers its initial value once shear has stopped after a period of time
that depends on the intensity and duration of shear

36. 36
From Rheology to Paint
Shear rates and Paint Properties

37. 37
From Rheology to Paint: Shear rates and Paint
Properties
Many properties are correlated with viscosity measurements at the various
shear rates applicable to paint
Good storage stability and good sag resistance  viscosity at very low shear
rate
Rate of loading of application tools - brush or spatula  viscosity at low shear
rate
Feeling at hand stirring at can opening  viscosity at medium shear rate
Dynamic properties during application - brush, roller, spray gun – spread
ability, film build, spatter resistance  viscosity at high shear rate

38. 38
From Rheology to Paint
Shear rates and Viscosimeters

39. 39
From Rheology to Paint: Shear rates and
Viscosimeters
Viscosity is measured the most simply using a viscosimeter
Rheological properties measurements depend on time, temperature and stress
Taking into account these factors can require a rheometer rather than a
viscosimeter
Depending on the shear conditions, different types of viscosimeters and
different methods will be chosen to measure and interpret the behavior of the
system under consideration
Description of the most widely used viscosimeters in the paint and coating
industry are below, as well as the shear ranges to which they are best suited

40. 40
From Rheology to Paint: Shear rates and
Viscosimeters
Brookfield viscosimeter:
Typically used in Quality Control
Rheology at low shear rates
Rotation viscosimeter
Measurement is obtained from the rotation of a spindle immersed in a liquid at a
given and adjustable speed (“shear rate” controlled)
The spindle is connected by its shaft to a calibrated spring whose torsion rate is
proportional to the measured shear stress
The shear potential will vary on the basis of the size of the spindle and the
rotation speed UnitsUnits:
mPa.s
12000
10rpm

41. 41
From Rheology to Paint: Shear rates and
Viscosimeters
Stormer or Krebs viscosimeter:
Rotational viscosimeter widely used in the paint industry
Viscosity at medium shear rate
The viscosity is determined by measuring the torque needed to achieve a
rotation speed of 200 rotations per minute.
Viscosity value expressed in Krebs Unit (KU).
This measurement is used extensively to evaluate paint applied with a brush or a
roller.
105105
Stormer
Viscosimeter
Units
:
Kreb
s
(KU)
Stormer
Viscosimeter
Units
:
Kreb
s
(KU)

42. 42
From Rheology to Paint: Shear rates and
Viscosimeters
Cone & Plate or ICI viscosimeter:
Viscosity at high shear rate
Easiest method to evaluate film build and spatter resistance
Cone with a 0.5° angle in direct contact with the lower plate
Evaluation of the torque needed to obtain the rotation speed generating a shear
rate of 10000 s-1 and covering viscosities ranging from 0 to 0.5 Pa.s
High ICI viscosity values  film build
 spatter resistance
 ease of application
 surface covered between two tool loadings
Cone and
plate

43. 43
From Rheology to Paint
Conclusion

44. 44
From Rheology to Paint: Key points

45. 45
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