Novel epoxy toughening technology for coatings and ... · PDF fileSeptember 26, 2008 Page 1...

September 26, 2008

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

Presentation Contents

• Background • Flexibility vs. Toughening• Novel Toughening Technology• Fundamental Properties• Applications

» Marine & Protective Coatings» Composites» Powder Coatings

• Conclusions

September 26, 2008

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

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


Automotive

Powder

UV Cure


Automotive

Powder

UV Cure


Automotive

Powder

UV Cure

Composites

9/26/2008 DOW CONFIDENTIAL - Do not share without permission

Definitions

• Toughness – energy, a sample can absorb before it breaks• Amphiphilic Block Co-polymer

“epoxyphilic”(epoxy miscible)

“epoxyphobic”(epoxy immiscible)

•

September 26, 2008

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

September 26, 2008

Epoxy Flexiblization/Toughening Technologies

Aliphaticbackbone

Plastisizer

CTBN

Core ShellRubbers

Tg

Chem Resist

Viscosity

Corrosion

Modulus

September 26, 2008

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

Epoxy Curing Agent Polymer

Cure

Cure

Macrophase Separation (example CTBN technology)

Novel Self Assembly Nanophase technology

Novel vs. Conventional Toughening Technology

September 26, 2008

EpoxyCuring agent

curing

CopolymerCured epoxy

Self Assembled Block Copolymers

September 26, 2008

Self-assembled morphology development

Uncured Cured


+ 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

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

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

September 26, 2008

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)


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

Marine & Protective Coatings

September 26, 2008

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

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

September 26, 2008

Typical Impact Testing Result

panels shown cured with Ancamine 1618110 +/- 5 microns

September 26, 2008

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

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

September 26, 2008

• 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

September 26, 2008

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

September 26, 2008

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

September 26, 2008

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


Standard

XU19108.00

Ancamine 1618

Ancamide 2353

0102030405060708090


Standard

XU19108.00

NC541LV

September 26, 2008

Significant Adhesion Improvement

5.5% modificationAncamide* 2353 cured

September 26, 2008

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

September 26, 2008

Composites


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


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.


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


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


Tg ~ 145 oC

Thermocouple Locations

Cure Profile

Torsion Rectangular

No Post Cure needed because of the Exotherm

Glass Composite


No Filtration of the FORTEGRA 100

Formation of the Second Phase in the Presence of Fibers


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


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


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

First Installation - 1960

Picture courtesy of 3M Co.

Powder Coatings Damage Tolerant Coatings

September 26, 2008

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

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

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



°C

September 26, 2008

Sub-ambient Temperature 4 point bend performance

September 26, 2008

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

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

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

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

Novel epoxy toughening technology for coatings and ... · PDF fileSeptember 26, 2008 Page 1...

Documents

Transcript of Novel epoxy toughening technology for coatings and ... · PDF fileSeptember 26, 2008 Page 1...