Chem550 Spring 06 5 - calpoly.edurhfernan/chem550/pdf/Chem... · sw + γ wa) solid water air ......

CHEM 550 – Formulation of Modern Coatings Spring 2006

Polymers and Coatings ProgramCalifornia Polytechnic State University 1

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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

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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



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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

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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



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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

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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



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Types of Surfactants: AnionicTypes of Surfactants: AnionicAlkyl Benzene Sulfonates

Fatty Alcohol Sulfates– Sodium Dodecyl Sulfate

Alkylphenol Ether Sulfates

Provide electrostatic stabilization in waterborne coatings

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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-



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Functions of Surfactants

Solubilization

Emulsification

Wetting

Dispersing

Foaming and Defoaming

Antistatic Activity

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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)



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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)

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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



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OilOil--inin--water water emulsionemulsion

WaterWater--inin--oil oil emulsionemulsion

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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



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Rheology ModifiersRheology ModifiersAqueous– Cellulosics– Other Carbohydrates– Associative Thickeners– Inorganics

Non-Aqueous– Organo-clays– Hydrophobic Fumed Silica– Castor Oil Derivatives

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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



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CellulosicCellulosic ThickenersThickeners

R = -CH2CH2OH = HydroxyethylR = -CH2COONa = CarboxymethylR = - C2H5, -CH2CH2OH,= Ethyl, HydroxyethylR = - CH3, -CH2CH2OH,= Methyl, Hydroxyethyl

OCH2

OR

OHO

H

ORH

H

H

( )n

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Effect of Molecular Weight on Effect of Molecular Weight on ThickeningThickening

HMW Shear-thinning

LMW Newtonian



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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

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CellulosicsCellulosics --Thickening MechanismsThickening Mechanisms

A.A. Contribution to Hydrodynamic Volume

B.B. Chain Entanglements

Visc

osity

Molecular Weight

LSV

HSV



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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))

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Effect of Particle Flocculation / Effect of Particle Flocculation / Aggregation on ViscosityAggregation on Viscosity

“Vis

cosi

ty”

% Volume Solids 64

Non-aggregated

Aggregated



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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.%

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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)



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SyneresisSyneresis

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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



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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

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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



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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%

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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.%



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Comparison of HEC and Assoc. Thickeners

HEC

Glass, Fernando, Jongewaard, and Brown, J. Oil Colour Chem. Assoc., 67, 256 (1984)

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Thickening Efficiency Thickening Efficiency -- HSVHSV

Glass, Fernando, Jongewaard, and Brown, J. Oil Colour Chem. Assoc., 67, 256 (1984)

HEC



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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

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Associative Thickening Associative Thickening Mechanisms Mechanisms –– Effect of AdsorptionEffect of Adsorption

“Vis

cosi

ty”

% Volume Solids 64

No Adsorption

5nm LayerAdsorption

50nm LayerAdsorption

05nm50nm



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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

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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



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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

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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%



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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%

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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



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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

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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%



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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

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Thickener Sensitivity to SurfactantThickener Sensitivity to SurfactantPolymer / surfactantcomplex formation



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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]

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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%



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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

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Acrysol TT-615Alkali-Swellable, Associative

increase pH

poly (sodium methacrylate)

Thickener Sensitivity to DispersantThickener Sensitivity to Dispersant

add dispersant

Chem550 Spring 06 5 - calpoly.edurhfernan/chem550/pdf/Chem... · sw + γ wa) solid water air ......

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Transcript of Chem550 Spring 06 5 - calpoly.edurhfernan/chem550/pdf/Chem... · sw + γ wa) solid water air ......