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CHEM 550 – Formulation of Modern Coatings Spring 2006
Polymers and Coatings ProgramCalifornia Polytechnic State University 1
ppt00 1 1
AntisettlingAntisettling agentsagents Catalysts and driersCatalysts and driers
Corrosion inhibitorsCorrosion inhibitors Coalescing agentsCoalescing agents
Coupling agentsCoupling agents CrosslinkingCrosslinking agentsagents
DefoamersDefoamers DispersantsDispersants
Flatting agentsFlatting agents Flow control agentsFlow control agents
Lubricants, waxLubricants, wax PlasticizersPlasticizers
StabilizersStabilizers SurfactantsSurfactants
ThickenersThickeners UV absorbers & stabilizersUV absorbers & stabilizers
Coating AdditivesCoating Additives
ppt00 2 2
Stabilizers for Improved Weathering
Improve exterior durability – Color, gloss, mechanical property retention– Various types available– Usually used in combination
UV absorbers– Preferentially absorb UV– Prevent free radical formation
Hindered amine light stabilizers (HALS)– Quickly remove free radicals
Antioxidants– Reduce oxidation of polymer binder– Also used to prevent skinning in can
CHEM 550 – Formulation of Modern Coatings Spring 2006
Polymers and Coatings ProgramCalifornia Polytechnic State University 2
ppt00 3 3
Other Additives
Flash rust inhibitors: Prevent rust during application and drying of waterborne coatings
Freeze – thaw stabilizers: Prevent freezing of paint and / or coagulation of coating at low temperatures
Water scavengers: React with or adsorb water to make it unavailable in the coating– Moisture cure urethanes– Zinc – rich coatings
Lubricants: Improve feel, slip, mar resistance
Biocides; Anti-microbials: Prevention of mildew growth in can
ppt00 4 4
Recommendations for Additives Usage
Keep it simple
Know all the components of the coating
Try to solve the performance problem without additives first
Use additives only when necessary
A simple formulation is easier to prepare and troubleshoot
Additives solve and create problems
Consult with the additive supplier
CHEM 550 – Formulation of Modern Coatings Spring 2006
Polymers and Coatings ProgramCalifornia Polytechnic State University 3
ppt00 5 5
Dispersant ChemistryDispersant Chemistry
(-CH2-C-)x (CH2)y-CH3
CH3
C=OO- Na+
(-CH2-C-)x
CH3
C=OO- Na+
Tamol 731 Tamol 850
O=P__O__P=OO
_
Na+O
_
Na+
Na+
O_ Na+
O_
TSPP
ppt00 6 6
Types of Surfactants: NonionicTypes of Surfactants: NonionicAlkylphenol Ethoxylates(APE)– Igapel, Triton
Acetylenic Diols– Surfynol
EO/PO Block Copolymers– Pluronics
Provide steric stabilization in waterborne coatingsOften used with anionics
HO CH
CH3
CH2 O CH2CH2 O CH
CH3
CH2 O Ha b a
C
OH
CH3 CH3CH3
OH
C CCH3 CH CH2
CH3
CH2 CH CH3C
R O(CH2CH2O)XH
CHEM 550 – Formulation of Modern Coatings Spring 2006
Polymers and Coatings ProgramCalifornia Polytechnic State University 4
ppt00 7 7
Types of Surfactants: AnionicTypes of Surfactants: AnionicAlkyl Benzene Sulfonates
Fatty Alcohol Sulfates– Sodium Dodecyl Sulfate
Alkylphenol Ether Sulfates
Provide electrostatic stabilization in waterborne coatings
ppt00 8 8
Types of Surfactants: Cationic and Types of Surfactants: Cationic and ZwitterionicsZwitterionics
Cationic Example: CTAB (Cetyl trimethyl ammonium bromide
Pigment Dispersion
Germicidal Activity
Zwitterionic Example: N-alkyl betains
Rarely used in coatings
N+
CH3
CH3C16H33CH3
Br-
RN+(CH3)2CH2COO-
CHEM 550 – Formulation of Modern Coatings Spring 2006
Polymers and Coatings ProgramCalifornia Polytechnic State University 5
ppt00 9 9
Functions of Surfactants
Solubilization
Emulsification
Wetting
Dispersing
Foaming and Defoaming
Antistatic Activity
ppt00 10 10
CMC Values of Surfactants
1.6x10-23.6x10-30.9x10-33x10-4RNH3+ Cl-
1.8x10-23.7x10-21.4x10-34x10-4RN(CH3)3+ Cl-
Cationics
2x10-27x10-33x10-31x10-3RCOO- Na+1x10-23x10-35x10-43x10-4ROSO3
- Na+Anionics
9x10-52x10-75x10-7R(OCH2CH2)9OH8x10-51x10-59x10-63x10-7R(OCH2CH2)6OH
NonionicsC12C14C16C18
Alkyl Group (R)Surfactant
Swarup and Schoff, POC, 23, 1-22 (1993)
CHEM 550 – Formulation of Modern Coatings Spring 2006
Polymers and Coatings ProgramCalifornia Polytechnic State University 6
ppt00 11 11
Calculation of HLB: From Structural Calculation of HLB: From Structural Group ContributionsGroup Contributions
HLB = 7 + ΣH - ΣL
0.11- (CH2C(CH3)HO) -0.36- (CH2CH2O) -
0.47= CH -1.3- O -
0.47CH31.9HO -
0.47CH22.1HOOC -
0.47CH-19.0NaOOC -
L NumberGroupH NumberGroup
Lipophilic GroupsHydrophilic Groups
Patton, Paint Flow and Pigment Dispersion, Wiley (1979)
ppt00 12 12
HLB Range Application 4-6 Water-in-oil emulsifiers 7-9 Wetting Agents 8-18 Oil-in-water emulsifiers
13 - 15 Detergents 10 - 18 Solubilizaers
HLBHLBHLB (hydrophile-lipophile balance) is related to the proportion of hydrophilic (water loving) and lipophilic (oil loving) groups in the surfactant molecule
HLB system is an indicator of how nonionic surfactants behave
CHEM 550 – Formulation of Modern Coatings Spring 2006
Polymers and Coatings ProgramCalifornia Polytechnic State University 7
ppt00 13 13
OilOil--inin--water water emulsionemulsion
WaterWater--inin--oil oil emulsionemulsion
ppt00 14 14
TetramethyldecynediolSurfynol 104
C
OH
CH3 CH3CH3
OH
C CCH3 CH CH2
CH3
CH2 CH CH3C
bis(2-ethylhexyl)sulfosuccinate Aerosol OT
Wetting AgentsWetting AgentsSpreading Coefficient must be positive for spontaneous wetting
Sw/s = γsa – (γsw + γwa) solidwater
air
CHEM 550 – Formulation of Modern Coatings Spring 2006
Polymers and Coatings ProgramCalifornia Polytechnic State University 8
ppt00 15 15
Rheology ModifiersRheology ModifiersAqueous– Cellulosics– Other Carbohydrates– Associative Thickeners– Inorganics
Non-Aqueous– Organo-clays– Hydrophobic Fumed Silica– Castor Oil Derivatives
ppt00 16 16
Inorganic Rheology Inorganic Rheology ModifiersModifiers
Inorganic
Ultra-Fine Clays(Laponites)
Other Inorganics(Smectite Clays,
Attapulgite)
++
_ _ _ _ Positive Edges & NegativePositive Edges & NegativeFacesFaces
Weak Structure, HighlyWeak Structure, HighlyShear ThinningShear Thinning
CHEM 550 – Formulation of Modern Coatings Spring 2006
Polymers and Coatings ProgramCalifornia Polytechnic State University 9
ppt00 17 17
CellulosicCellulosic ThickenersThickeners
R = -CH2CH2OH = HydroxyethylR = -CH2COONa = CarboxymethylR = - C2H5, -CH2CH2OH,= Ethyl, HydroxyethylR = - CH3, -CH2CH2OH,= Methyl, Hydroxyethyl
OCH2
OR
OHO
H
ORH
H
H
( )n
ppt00 18 18
Effect of Molecular Weight on Effect of Molecular Weight on ThickeningThickening
HMW Shear-thinning
LMW Newtonian
CHEM 550 – Formulation of Modern Coatings Spring 2006
Polymers and Coatings ProgramCalifornia Polytechnic State University 10
ppt00 19 19
1 0 -2 1 0 - 1 1 0 0 1 0 1 1 0 21 0 3
1 0 -2
1 0 - 1
1 0 0
1 0 1
1 0 2
1 0 3
1 0 4
R a te [s -1 ]
Eta
(A)
[
P]
A i r f le x 8 0 9 / N a t r o s o l 2 5 0 H R
Aq. HEC 1.0Wt.%
Control FormulationNo Thickener
Semi-gloss Formulation44 Wt.%; 25 PVC withHEC 0.66Wt.%
Effect of HEC on Coating ViscosityEffect of HEC on Coating Viscosity
ppt00 20 20
CellulosicsCellulosics --Thickening MechanismsThickening Mechanisms
A.A. Contribution to Hydrodynamic Volume
B.B. Chain Entanglements
Visc
osity
Molecular Weight
LSV
HSV
CHEM 550 – Formulation of Modern Coatings Spring 2006
Polymers and Coatings ProgramCalifornia Polytechnic State University 11
ppt00 21 21
CellulosicsCellulosics -- Thickening MechanismsThickening MechanismsC.C. Depletion Flocculation
G = H - T S
Lower Total Entropy Higher Total EntropyNonNon--Adsorbing Polymer Causes Depletion Flocculation & Aggregation Adsorbing Polymer Causes Depletion Flocculation & Aggregation Leading toLeading to
1) Viscosity Changes1) Viscosity Changes2) Phase Separation (2) Phase Separation (SyneresisSyneresis))
ppt00 22 22
Effect of Particle Flocculation / Effect of Particle Flocculation / Aggregation on ViscosityAggregation on Viscosity
“Vis
cosi
ty”
% Volume Solids 64
Non-aggregated
Aggregated
CHEM 550 – Formulation of Modern Coatings Spring 2006
Polymers and Coatings ProgramCalifornia Polytechnic State University 12
ppt00 23 23
CellulosicCellulosic ThickenersThickenersV
isco
sity
Thickener Wt.%
HMW HECMMW HEC
LMW HEC
HMW HECMMW HEC
LMW HEC
LSV - LowShear Viscosity
HSV - HighShear ViscosityV
isco
sity
Thickener Wt.%
ppt00 24 24
CellulosicsCellulosics -- Advantages & DisadvantagesAdvantages & DisadvantagesAdvantages - Cellulosics are Low Cost Universal ThickenersBased on Natural ResourcesDisadvantages:
Poor Leveling (High LSV; Yield Stress)
Reduction of Gloss (Depletion Flocculation; Poor Leveling)
Roller Spatter (Extensional Viscosity)
Water Sensitivity (WSP Hydrophilicity)
Bio-degradation (Enzyme Attack on beta 1-4 Linkage)
Syneresis (Depletion Flocculation)
CHEM 550 – Formulation of Modern Coatings Spring 2006
Polymers and Coatings ProgramCalifornia Polytechnic State University 13
ppt00 25 25
SyneresisSyneresis
ppt00 26 26
Associative ThickenersAssociative Thickeners
HEUR (Hydrophobically-Modified EthoxylatedUrethanes)
HASE (Hydrophobically-Modified Alkali-SwellableEmulsions)
HMHEC (Hydrophobically-Modified HEC)
HMPE (Hydrophobically-Modified Polyether)
HEAT (Hydrophobically-Modified Aminoplast Ether)
First Introduced to Coating Industry in Late 1970s
Several Different Types Currently in the Market
CHEM 550 – Formulation of Modern Coatings Spring 2006
Polymers and Coatings ProgramCalifornia Polytechnic State University 14
ppt00 27 27
R, RR, R’’ = C= C1212--CC1818; R; R”” = C= C77--CC3636; x = 90 ; x = 90 -- 455; n = 1455; n = 1--4 4
Associative Thickeners Associative Thickeners -- HEUR TypeHEUR Type
Acrysol QR-708 Acrysol RM-8 Acrysol RM-825(C12H25 Terminal Hydrophobes; 40,000 Approx. M.W.)
Acrysol RM-2020UCAR SCT-275 Acrysol SCT-275
(Comb-type; 100,000 Approx.. M.W.)
RR--NN--CC--(O(O--CHCH22--CHCH22))xx--[[OO--CC--NN--RR””--NN--CC--(O(O--CHCH22--CHCH22))xx]]nn--OO--CC--NN--RR’’=
O= O
= O= O
= O= O = O= O
--
HH
--
HH
--
HH
--
HH
ppt00 28 28
Associative Thickeners Associative Thickeners -- HASE TypeHASE Type
Acrysol TT-615Alkali-Swellable,
AssociativeThickener Dispersion at
“High” Concentration (30%)
(-CH2-C-) (-CH2-CH-) (-CH2-C-)CH3
CH3
C=O C=O C=OOH OC2H5 O
CH2CH2O(
(
20C18H37
As pH increases
CHEM 550 – Formulation of Modern Coatings Spring 2006
Polymers and Coatings ProgramCalifornia Polytechnic State University 15
ppt00 29 29
Viscosities of Viscosities of AqAq. Thickener Solutions. Thickener Solutions
1 0 -2 1 0 - 1 1 0 0 1 0 1 1 0 21 0 3
1 0 -1
1 0 0
1 0 1
1 0 2
R a te [s -1 ]
Eta
(A)
[
P]
A q u e o u s T h ic k e n e r S o lu t io n s
Natrosol 250HR 1.0%
HASE TT-935 1.0%
HEUR SCT-275 1.0%
HEUR RM2020 4.0%
ppt00 30 30
Effect of HEUR 275) Coating ViscosityEffect of HEUR 275) Coating Viscosity
1 0 -2 10 -1 10 0 10 1 10 21 0 3
1 0 -1
10 0
10 1
10 2
1 0 3
R ate [s -1 ]
Eta
(A)
[
P]
S C T -275 S o lu tion / 0 .5% S C T -275 in 809 S em i-G loss P a in t
Semi-gloss Formulation44 Wt.%; 25 PVC withAcrysol SCT275 0.5Wt.%
Acrysol SCT275 1.0Wt.%
CHEM 550 – Formulation of Modern Coatings Spring 2006
Polymers and Coatings ProgramCalifornia Polytechnic State University 16
ppt00 31 31
Comparison of HEC and Assoc. Thickeners
HEC
Glass, Fernando, Jongewaard, and Brown, J. Oil Colour Chem. Assoc., 67, 256 (1984)
ppt00 32 32
Thickening Efficiency Thickening Efficiency -- HSVHSV
Glass, Fernando, Jongewaard, and Brown, J. Oil Colour Chem. Assoc., 67, 256 (1984)
HEC
CHEM 550 – Formulation of Modern Coatings Spring 2006
Polymers and Coatings ProgramCalifornia Polytechnic State University 17
ppt00 33 33
Associative Thickeners Associative Thickeners -- HEUR HEUR Association ModesAssociation Modes
Many Association Modes PossibleDepending on Molecular Architecture
Adsorption– Hydrophobic– Ion-Dipole
Self Association– Intra-Molecular– Inter-Molecular
Mix Micelle Formation
ppt00 34 34
Associative Thickeners Associative Thickeners -- HEUR HEUR Association ModesAssociation Modes
Many Association Modes PossibleDepending on Molecular Architecture
Adsorption– Hydrophobic– Ion-Dipole
Self Association– Intra-Molecular– Inter-Molecular
Mix Micelle Formation
CHEM 550 – Formulation of Modern Coatings Spring 2006
Polymers and Coatings ProgramCalifornia Polytechnic State University 18
ppt00 35 35
Associative Thickeners Associative Thickeners -- HEUR HEUR Association ModesAssociation Modes
Many Association Modes PossibleDepending on Molecular Architecture
Adsorption– Hydrophobic– Ion-Dipole
Self Association– Intra-Molecular– Inter-Molecular
Mix Micelle Formation
ppt00 36 36
Associative Thickening Associative Thickening Mechanisms Mechanisms –– Effect of AdsorptionEffect of Adsorption
“Vis
cosi
ty”
% Volume Solids 64
No Adsorption
5nm LayerAdsorption
50nm LayerAdsorption
05nm50nm
CHEM 550 – Formulation of Modern Coatings Spring 2006
Polymers and Coatings ProgramCalifornia Polytechnic State University 19
ppt00 37 37
Sensitivity of Associative ThickenersSensitivity of Associative Thickeners
Latex Particle Characteristics
Surfactants
Dispersants
Cosolvents
Performance Sensitivity to Formulation Variables Performance Sensitivity to Formulation Variables --Major Drawback of Associative ThickenersMajor Drawback of Associative Thickeners
ppt00 38 38
Surface Stabilization
Latex Polymer Composition
Particle Size(nm)
Protective Colloid
Non-Ionic Surfactants
Anionic Surfactants
Acid Monomer
VAE155 Vinyl Acetate (87)Ethylene (13)
155 Yes Yes No No
VAEVCl Vinyl Acetate (36)Ethylene (24)Vinyl Chloride (39)
154 No Yes Yes Yes
VAE145 Vinyl Acetate (85)Ethylene (15)
145 No Yes No Yes
EVCl Ethylene (15)Vinyl Chloride (85)
131 No No Yes Yes
UrAcr Urethane-Acrylic 85 No No No Yes
Acr All-Acrylic 130 -- -- -- --
VAcr Vinyl-Acrylic 149 -- -- -- --
Assoc. Thickener Sensitivity to Latex Assoc. Thickener Sensitivity to Latex
Fernando, Wickmann, Louie, and Chelius, ICE Proceedings, 2000
CHEM 550 – Formulation of Modern Coatings Spring 2006
Polymers and Coatings ProgramCalifornia Polytechnic State University 20
ppt00 39 39
1.E+00
1.E+01
1.E+02
1.E+03
1.E+04
1.E- 02 1.E- 01 1.E+00 1.E+01 1.E+02 1.E+03 1.E+04
Shear Rate (s-1)
Visc
osity
(mPa
s)
∗ - VAE155; - VAEVCl+ - VAE145; - EVCl× - UrAcr; - Acr
- VAcr
HEURHEUR--2020 (1.0wt.%)/Latex (30wt.%) 2020 (1.0wt.%)/Latex (30wt.%) Aqueous BlendsAqueous Blends
Fernando, Wickmann, Louie, and Chelius,ICE Proceedings, 2000
ppt00 40 40
Thickener Sensitivity to DispersantThickener Sensitivity to DispersantTamol 731 Addition to 0.75% Natrosol Solution
1.00E+00
1.00E+01
1.00E+02
1.00E+03
1.00E+04
1.0E-2 1.0E-1 1.0E+0 1.0E+1 1.0E+2 1.0E+3
Shear Rate, s-1
Visc
osity
, cen
tipoi
se
0%0.025%0.05%0.075%0.1%0.2%0.5%
CHEM 550 – Formulation of Modern Coatings Spring 2006
Polymers and Coatings ProgramCalifornia Polytechnic State University 21
ppt00 41 41
Thickener Sensitivity to SurfactantThickener Sensitivity to SurfactantTergitol 15S7 Addition to 0.75% Natrosol Solution
1
10
100
1000
10000
100000
1000000
1.0E-2 1.0E-1 1.0E+0 1.0E+1 1.0E+2 1.0E+3
Shear Rate, s-1
Visc
osity
, cen
tipoi
se
0.00%0.10%2.00%
ppt00 42 42
Associative Thickener Sensitivity to Surfactant - Example
Flat (57PVC) formulations with small-particle (100nm), all-acrylic latex
Surfactant type varied; amount constant (4.28x10-4
moles/100g)– Tergitol NP-40– Tergitol NP-4
Thickeners added to adjust Stormer Viscosity at Target Kus– 90– 105
C9H9
(OCH2CH2)40OH
C9H9
(OCH2CH2)4OH
CHEM 550 – Formulation of Modern Coatings Spring 2006
Polymers and Coatings ProgramCalifornia Polytechnic State University 22
ppt00 43 43
Assoc. Thickener Sensitivity to Surfactant in “90 KU” & “105 KU” Formulations
800.32860.40890.56NP-4
860.38900.61861.16NP-40
KUWt.%KUWt.%KUWt.%Surfactant
HECHEUR 708HEUR 200
1000.431000.571040.77NP-4
1050.471020.771021.50NP-40
ppt00 44 44
Thickener Sensitivity to SurfactantThickener Sensitivity to Surfactant
Tergitol 15S7 Addition to Acrysol 0.5% Solution
1
10
100
1000
10000
100000
1000000
1.0E-2 1.0E-1 1.0E+0 1.0E+1 1.0E+2 1.0E+3
Shear Rate, s-1
Visc
osity
, cen
tipoi
se
0.00%0.10%2.00%
CHEM 550 – Formulation of Modern Coatings Spring 2006
Polymers and Coatings ProgramCalifornia Polytechnic State University 23
ppt00 45 45
Thickener Sensitivity to SurfactantThickener Sensitivity to Surfactant
Tergitol 15S7 Addition to 0.5% HASE 935 Solution
0
50000
100000
150000
200000
0.0% 1.0% 2.0% 3.0% 4.0% 5.0%
Tergitol Concentration
Visc
osity
, cen
tipoi
se
01000200030004000500060007000
0.088.00
Shear Rate,s-1
ppt00 46 46
Thickener Sensitivity to SurfactantThickener Sensitivity to SurfactantPolymer / surfactantcomplex formation
CHEM 550 – Formulation of Modern Coatings Spring 2006
Polymers and Coatings ProgramCalifornia Polytechnic State University 24
ppt00 47 47
Tint Base Viscosity Tint Base Viscosity -- DiscussionDiscussionViscosity of a Tint-Base containing associative thickeners is highly sensitive to colorants– Light colors vs deep tones
This is related to assoc. thickeners sensitivity to surfactants
Approaches to address the problem– Over-thicken tint base– Use thickener blends– New class of assoc. thickeners [Steinmetz, FSCT
Symposium on Waterborne Coatings: Meeting the Challenges, May, 2002]
ppt00 48 48
Thickener Sensitivity to DispersantThickener Sensitivity to Dispersant
Tamol 731 Addition to 0.5% Acrysol Solution
1.00E+00
1.00E+01
1.00E+02
1.00E+03
1.00E+04
1.00E+05
1.00E-02 1.00E-01 1.00E+00 1.00E+01 1.00E+02 1.00E+03
Shear Rate, s-1
Visc
osity
, cen
tipoi
se
0%0.025%0.05%0.075%0.1%0.2%0.5%
CHEM 550 – Formulation of Modern Coatings Spring 2006
Polymers and Coatings ProgramCalifornia Polytechnic State University 25
ppt00 49 49
Associative Thickeners Associative Thickeners -- HASE TypeHASE Type
Acrysol TT-615Alkali-Swellable,
AssociativeThickener Dispersion at
“High” Concentration (30%)
(-CH2-C-) (-CH2-CH-) (-CH2-C-)CH3
CH3
C=O C=O C=OOH OC2H5 O
CH2CH2O(
(
20C18H37
As pH increases
ppt00 50 50
Acrysol TT-615Alkali-Swellable, Associative
increase pH
poly (sodium methacrylate)
Thickener Sensitivity to DispersantThickener Sensitivity to Dispersant
add dispersant