Novel epoxy toughening technology for coatings and ... · PDF fileSeptember 26, 2008 Page 1...
Transcript of Novel epoxy toughening technology for coatings and ... · PDF fileSeptember 26, 2008 Page 1...
September 26, 2008 Page 1
Rajesh Turakhia, George Jacob, Marv Dettloff and Ha Pham The Dow Chemical Company, Freeport, Texas, U.S.A.
Novel epoxy toughening technology for coatings and composites applications
AcknowledgementsSteve Hoyles, Fabio Aguirre, Nikhil Verghese, Bill Dellinger, Carol Wright
September 26, 2008 Page 2
Presentation Contents
• Background • Flexibility vs. Toughening• Novel Toughening Technology• Fundamental Properties• Applications
» Marine & Protective Coatings» Composites» Powder Coatings
• Conclusions
September 26, 2008 Page 3
Develop novel toughening technology for epoxy thermosets to increase ductility without negatively impacting other properties like viscosity, impact resistance, and Tg
Developmental Need
September 26, 2008 Page 4
Epoxy resins in Coatings and Composites
Epoxy coatings are mostly cross-linked glassy thermosets
• Positive Attributes:― excellent adhesion― thermal resistance― chemical resistance― corrosion resistance
• Limitation:• ductility/fracture toughness or “flexibility”
Can & Coil Marine & Protective
Automotive
Powder
UV Cure
Can & Coil Marine & Protective
Automotive
Powder
UV Cure
Can & Coil Marine & Protective
Automotive
Powder
UV Cure
Can & Coil Marine & Protective
Automotive
Powder
UV Cure
Composites
9/26/2008 DOW CONFIDENTIAL - Do not share without permission Page 5
Definitions
• Toughness – energy, a sample can absorb before it breaks• Amphiphilic Block Co-polymer
“epoxyphilic”(epoxy miscible)
“epoxyphobic”(epoxy immiscible)
•
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Two approaches to increase ductility of epoxy thermosets…
• Use of Plasticizers and diluents • Lower Crosslink Density• Decrease in overall functionality
• Introduction of second phase (rubber)• Interfacial strength• Particle size• Polydispersity
Flexibilization
Toughening
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Epoxy Flexiblization/Toughening Technologies
Aliphaticbackbone
Plastisizer
CTBN
Core ShellRubbers
Tg
Chem Resist
Viscosity
Corrosion
Modulus
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Flexibility versus Toughening
0.00
0.10
0.20
0.30
0.40
0.50
0.60
100 110 120 130 140 150 160 170
Tg via DMTA Tan delta
Frac
ture
Tou
ghne
ss, K
1c
Bisphenol- A SeriesBisphenol-F SeriesToughening
Flexbilization
Toughening
September 26, 2008 Page 9
Epoxy Curing Agent Polymer
Cure
Cure
Macrophase Separation (example CTBN technology)
Novel Self Assembly Nanophase technology
Novel vs. Conventional Toughening Technology
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EpoxyCuring agent
curing
CopolymerCured epoxy
Self Assembled Block Copolymers
September 26, 2008 Page 11
Self-assembled morphology development
Uncured Cured
9/26/2008 DOW CONFIDENTIAL - Do not share without permission Page 12
+ Epoxy
Epoxy Miscible BlockEpoxy Immiscible Block
Vesicle+ Epoxy Matrix
Amphiphilic block copolymer toughening phase
Spherical micelle
Wormlike micelle
Amphiphilic block co-polymer self-assembly
Self-assembled morphology development summary
September 26, 2008 Page 13
Effect on Tg and Modulus
Results from a plaque
Trademark of The Dow Chemical Company
1.E+05
1.E+06
1.E+07
1.E+08
1.E+09
1.E+10
0 50 100 150 200 250 300
Temperature (°C)
Stor
age
Shea
r Mod
ulus
, G' (
Pa)
DER 383 epoxy resin cured with Phenolic Hardener (CONTROL)
Modified with 5wt.% Toughening Agent
September 26, 2008 Page 14
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
0 5
Amount of Toughening Agent (wt.%)
Crit
ical
Str
ess
Inte
nsity
, K1c
(MPa
.m1/
2 )
104
106
108
110
112
114
116
118
120
122
124
Yiel
d St
reng
th (M
Pa)
ToughnessYield strength
Effect on Material Properties
Epoxy Resin Cured with Phenolic Hardener
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Self-Assembly vs. Macro-phase Separation
• Low concentrations (5-10 vol%)• low viscosity• self -assemble into dispersed morphologies• nanophase possible (< 100 nm)
• Controlled structure size• discrete particle size• can retain optical clarity
• Minimum detrimental effects on• glass transition temperature, Tg • modulus, E
• High concentrations (10-30 vol%)• high viscosity• macro phase separation• micro sizes (> 100 nm)
• Hard to control structure size • agglomeration • loss of optical clarity
• Detrimental effects on • glass transition temperature, Tg • modulus, E
Self-Assembly
Macro-phase (e.g. CTBN)
9/26/2008 DOW CONFIDENTIAL - Do not share without permission Page 16
Overview of FORTEGRA™ Epoxy Toughening productsLoading Level EEW Viscosity
@ 25C (cP)Form
FORTEGRA 100 100% toughening agent
3,600 Liquid
FORTEGRA 383-5 5 wt% in D.E.R.™ 383
185-194 8,000-10,000
Liquid
FORTEGRA 383-50 50 wt% in D.E.R. 383
365-395 5,000-8,000
Liquid
FORTEGRA 664-12 12 wt% in D.E.R. 664UE
960-1060 Flake
Typical viscosity range for D.E.R. 383 = 9,000 – 10,500
Fortegra is a trademark of The Dow Chemical Co.
Commercial Products
www.dowepoxy.com
September 26, 2008 Page 17
Marine & Protective Coatings
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Clear Coat Testing
• Ancamine 1618*
• modified IPDA adduct• cut in benzyl alcohol
• Ancamide 2353*
• TETA polyamide• cut in benzyl alcohol
• NC541LV **• phenalkamine
* Air Products** Cardolite
Curing of D.E.R.* 331 epoxy resin with:
September 26, 2008 Page 19
Formulation D.E.R.* 331 Ancamine 1618
Ancamide 2353
NC 541LV Toughening agent
Formulation 1 56.4% 33.6% 10% Formulation 2 62.7% 37.3% 0 Formulation 3 56.3% 33.8% 10% Formulation 4 62.5% 37.5% 0 Formulation 5 53.9% 36.2% 10% Formulation 6 59.9% 40.1% 0
• Prepared by Draw Down• B1000 panels and free films from tin plate• Cured at 60°C• DFT = 110 +/- 5 microns
Clear Film Formulations
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Typical Impact Testing Result
panels shown cured with Ancamine 1618110 +/- 5 microns
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Typical Tensile behavior
0.0E+00
5.0E+06
1.0E+07
1.5E+07
2.0E+07
2.5E+07
3.0E+07
3.5E+07
4.0E+07
4.5E+07
5.0E+07
0 5 10 15 20 25 30Strain (%)
Stre
ss (P
a)
Modified
Unmodified
Reduction ofyield stress
September 26, 2008 Page 22
Free Film Tensile Results
0%
5%
10%
15%
20%
25%
30%
35%
Ancamine 1618 Ancamide 2353 NC541LV
Elon
gatio
n at
bre
ak
Unmodified
Modified
Free films evaluations
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• Based on D.E.R. 331 cured with Ancamide 2353• Pigmented with red iron oxide, extender and an anticorrosive
pigment• Toughening agent added at both 6.8% and 13.3% by volume
dry paint• Coatings spray applied on bare cold rolled steel panels• Cured for 14 days at room temperature. • DFT = 3.5 mils
Pigmented system
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STANDARD High Solids Epoxy Formulation Based on D.E.R. -331 Epoxy Resin and
Air Products' Ancamide 2353 Polyamide Curing Agent Material NV NV Lbs. - Part A - Pounds Gallons Pounds Gallons VOM D.E.R.-331 Epoxy Resin 233.7 24.09 233.7 24.09 -------- MPA-1078 4.0 0.54 1.6 0.21 2.4 BYK Anti-Terra U 7.5 0.96 5.4 0.64 2.1 10ES Wollastokup 395.0 16.32 395.0 16.32 -------- ** High Speed Disperse to a Texture of 5-6 NS, then add: ** Xylene 45.0 6.21 ---------- ----------- 45.0
685.2 48.12 635.7 41.26 49.5 - Part B - Ancamide 2353 Curing Agent 125.6 15.21 125.6 15.21 -------- MPA-1078 4.0 0.54 1.6 0.21 2.4 Beetle 216-8 15.0 1.72 9.0 0.84 6.0 Red Iron Oxide 60.0 1.44 60.0 1.44 -------- Beaverwhite 325 96.7 4.20 96.7 4.20 -------- Phosplus J-0866 141.4 5.07 141.4 5.07 -------- ** High Speed Disperse to a Texture of 4.5-5.5 NS, then add: ** Diacetone Alcohol 31.3 4.00 ---------- ---------- 31.3 Aromatic 150 106.8 14.69 ---------- ---------- 106.8 580.8 46.87 434.3 26.97 146.5
Pigmented standard formulation
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Test Standard 6.8 Vol% 13.3 Vol%PVC 37.5% 38.6% 38.6%VOC 330.2 g/l 312.0 g/l 300.4 g/lViscosity, 25°C 110 K.U. 98 K.U. 93 K.U.Sprayable vol. solids 62.2% 64.3% 65.7%Hardness 6H 3H 3HDry Adhesion 2B 4B 4BDirect Impact 15 20 22
Pigmented system Test Results
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Effect on Gel and cure times
• Minimal effect on gel time • Effect is that of a non-functional
diluent• decreases the concentration of
reactive groups 0
10
20
30
40
50
60
Gel Time (min) Dust Free (hours) Through Dry(hours)
Standard
XU19108.00
0102030405060708090
Gel Time (min) Dust Free (hours) Through Dry(hours)
Standard
XU19108.00
Ancamine 1618
Ancamide 2353
0102030405060708090
Gel Time (min) Dust Free (hours) Through Dry(hours)
Standard
XU19108.00
NC541LV
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Significant Adhesion Improvement
5.5% modificationAncamide* 2353 cured
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Salt Spray Results
ASTM B117, 1000 hours on cold rolled steel Ancamide 2050 cured
There is no apparentdifference in corrosionresistance between the standard and the
modified system
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Composites
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Epoxy Thermoset Systems (Tg’s < 120 oC)
Control Formulation (phr) Toughened Formulation (phr) Epoxy mixture 100 100 Amine mixture 31 31 Fortegra 100* 0 6.9 *Toughening agent is 5 wt% of the formulation
Cure schedule: 70 oC for 7 hours
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Viscosity Profile
0.01
0.1
1
10
100
1000
10000
0 20 40 60 80 100 120 140 160 180 200
Time (minutes)
Visc
osity
Eta
* (Pa
-s)
0
10
20
30
40
50
60
70
80
Tem
pera
ture
(OC
)
Toughened System
Control
Temperature Profile
Ares Rheometer; constant frequency of 1 Hz; temperature ramp rate 0.25 oC/min.
9/26/2008 DOW CONFIDENTIAL - Do not share without permission Page 32
Control Toughened Tg1 (oC) [DSC] 78 75 Tensile Yield Strength, MPa 67 59 Tensile Modulus, GPa 3 2.8 Tensile Elongation @ Yield, % 4.6 4.4 Tensile Elongation @ Break, % 9.7 13.9 Fracture Toughnes (MPa m0.5) 1.05 to 1.15 2.82 to 2.92
Cured Properties
9/26/2008 DOW CONFIDENTIAL - Do not share without permission Page 33
Toughening of Glass Fiber Composites Block copolymer• FORTEGRA 100 (5 wt%)Epoxy Composite• Epoxy resin: DER383
• Hardener: Hexahydrophthalic Anhydride
• Catalyst: 2-Ethyl-4-Methylimidazole
• Glass Fiber: 50% Vf
Main Tool
Resin Inlet Resin OutletFiber Preform
Vacuum Bag
Release Film
Distribution Medium
Vacuum Assisted Resin Transfer Molding
Type Lay-upUnidirectional [0]8s
Lower η toughened system – Can be infused at lower Temp – Longer pot life
9/26/2008 DOW CONFIDENTIAL - Do not share without permission Page 34
Tg ~ 145 oC
Thermocouple Locations
Cure Profile
Torsion Rectangular
No Post Cure needed because of the Exotherm
Glass Composite
9/26/2008 DOW CONFIDENTIAL - Do not share without permission Page 35
No Filtration of the FORTEGRA 100
Formation of the Second Phase in the Presence of Fibers
9/26/2008 DOW CONFIDENTIAL - Do not share without permission Page 36
Fracture Toughness Modes
GIc
GIIc
GIIIc
Mode I
Mode II
Mode III
End Notch Flexure (ENF)
Opening Mode
Shear Mode
Tearing Mode
Bending Loads
More Prevalent in Laminated Composites due to Layered Construction
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Mode II - End Notch Flexure (ENF)
ENF Test in Progress
)32(29
33
22
αα+
=Lb
PCGII
PC δ=
Compliance Method Based on Beam Theory
P = Critical load at crack initiationα = Initial Crack Lengthb = Width of the specimenL = Span length of the specimenC = Complianceδ = Crosshead displacement
9/26/2008 DOW CONFIDENTIAL - Do not share without permission Page 38
0
1000
2000
3000
4000
5000
6000
7000
8000
9000
0 0.02 0.04 0.06 0.08 0.1 0.12 0.14
Crack Length (m)
GII
(J/m
^2)
F1-4F1-2F1-6F2-6F2-7F2-4F1 averageF2 average
~24%
ENF Testing – Mode II Results
F1-ControlF2-Toughened
September 26, 2008 Page 39
First Installation - 1960
Picture courtesy of 3M Co.
Powder Coatings Damage Tolerant Coatings
September 26, 2008 Page 40
Pipe Coating Formulation (phr)
Ingredients Control Toughened4 type epoxy resin 100 100
Dicyandiamide (DICY) curing agent 1.5 1.5Imidazole accelerator 1.2 1.2
WollastoniteTM # 325 filler 45.8 45.8ModaflowTM Powder III flow modifier 1.5 1.5
Toughening agent - 8
D.E.R. 664UE – 4-Type Epoxy Resin
September 26, 2008 Page 41
Pipe Coating Testing
• Formulations were dip applied • 8”x1”x3/8” sand blasted bars• 4 point bend at sub-ambient temperatures (-38 to -45oC)
• InstronTM test frame• number of hard cracks recorded
• Glass transition temperatures measured from free films
September 26, 2008 Page 42
Sub-ambient (- 38 to – 45 oC) Flexibility Test Results
Test Control ToughenedTg (°C) 110 °C 107
Flexibility @ - -38°C /~400 mic. 10 cracks No cracks
Flexibility @ - -38°C /~500 mic. 17 cracks No cracks
Flexibility @ - -45°C /~375 mic. 12 cracks No cracks
°C
September 26, 2008 Page 43
Sub-ambient Temperature 4 point bend performance
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Conclusions
Dow’s novel self-assembled block copolymer toughening agents• Easy to add to formulations
» Non-reactive and low in viscosity• Changes in conventional Viscosity – Tg - Toughness paradigm• Coatings Application
» improved impact resistance on coatings » improved adhesion» improved toughness/flexibility of FBE at low concentrations (5-10%)
• Composites» no filtration of toughening agent» formation of second phase in presence of fibers
September 26, 2008 Page 45
5% by weight block copolymer in Phenolic Cured Epoxy Plaques
0 10 20 30 40 500
200
400
600
800
1000
1200
Stra
in E
nerg
y Re
leas
e Ra
te, G
1cJ/
m2
Wt % DERTM 560 in DERTM 383 epoxy
wormlike micelles
spherical micelles
vesiclesunmodified
Polycarbonate:
G1c ≅ 1,600 J/m2
September 26, 2008 Page 46
Box-Behnken Design of Experiment (DoE)• Toughening Agent (wt %)
• 2.5 – 5.0 – 7.5 Weight percentage of total formulation.• It reduces the negative impact of higher filler content on coating
flexibility.• Filler Volume Concentration (FVC %)
• 10 – 20 – 30 Volume percentage of total formulation.• It improves coating hardness
• DICY Stoichiometric Ratio (%)• 45 – 60 – 75 • Control polymer crosslinking density
• 15 Formulations• To generate a quadratic model for each response
• Responses• Coating Glass Transition Temperature (°C)• Pill Flow (mm)• Impact Test• Total Average Number of Hard Cracks at -30°C, -35°C, -40°C, -
45°C, -50°C and -55°C
0+--0-0++000000+0+--00-++0-0000---+0-0++-0++0
Pattern5
2.5555
7.52.5
57.5
55
2.52.57.57.5
Toughening Agent (w t %)302030202020101020201030201030
FVC (%)454575606075607545604560756060
DICY SR (%)
September 26, 2008 Page 47
DoE results on powder Tg and Pill flow
100
150
200
250Pi
llFl
ow (m
m)
199.
3333
±11.
4415
8
3 4 5 6 7
5Toughening
Agent (wt %)
10 15 20 25 30
20FVC (%)
45 50 55 60 65 70 75
60DICY SR (%)
Prediction Profiler
( )
109
110
111
112
113
DM
TA T
g11
2.09
±0.3
7231
5
3 4 5 6 7
5Toughening
Agent (wt %)
10 15 20 25 30
20FVC (%)
45 50 55 60 65 70 75
60DICY SR (%)
Prediction Profiler