neo chemical seminar 2007 toine dinnissen / march 28th 2007page 1 voc-free waterborne epoxy...

NEO Chemical Seminar 2007

Toine Dinnissen / March 28th 2007

VOC-free Waterborne

Epoxy Emulsions and Dispersions

for Ambient Cure Coatings



Waterborne Epoxy dispersions?

– Stricter legislation is limiting the use of solvents-Volatile Organic Compounds (VOC) in paints e.g.

• European directive 1999/13/EC and amendment 2004/42/EC– first stage implemented in 2007– second stage implemented in 2010

• U.S.: 3 major organizations driving the reduction of VOC– Environmental Protection Agency (EPA, through Clean Air Act)– South Coast Air Quality Management District (SCAQMD)– Ozone Transportation Commission (OTC)

– “Green Image” – environmental friendly coatings– Low odor, low flammability– Easy cleaning of equipment with water

Making use of the excellent properties of Epoxy resins (e.g. corrosionresistance, chemical resistance, adhesion,…) with minimal amounts of solvent to fulfill legal and environmental requirements



Drivers and alternative approaches

• Typical solvent borne formulations for Marine and Protective coatings are based on epoxy resin grades with an Epoxy Equivalent Weight of ~500 gr/eq containing solvents like Xylene

• Typical solvent content of these solid epoxy resin solutions is 25%• Major contributor to the overall VOC content of a solvent borne

formulation• Several approaches exist to minimize or eliminate the VOC content

– High solids coatings– Powder coatings– Radiation cured coatings– Waterborne coatings



Dow’s Technology Approach

• Dow technology– Non ionic surfactant was especially developed for WB epoxy

resins– Surfactant is epoxy functional so that it will be part of the cured

matrix– Unique dispersion process which allows mono modular and

submicron particle size distributions– Submicron particle size distributions allow a good storage

stability and film formation– Formulator can use solvent of choice – No additional solvent, so low VOC formulations can be

prepared

• Grades– Emulsion of a Liquid Epoxy Resin – commercial grade– Dispersion of an Epoxy Novolac Resin – commercial grade– Dispersion of a Solid Epoxy Resin – commercial grade

Chemistry

Process

Properties

+

Ambient cured coatings



VOC free WB epoxy dispersions

Aqueous dispersion based on

Liquid

Epoxy

Resin

SolidEpoxyResin

Epoxy

Novolac

Resin

Grade XZ 92598.00 XZ 92533.00 XZ 92546.00

Epoxy Equivalent Weight (gr/eq)

194 – 204 475 – 500 184 – 204

Solid content 60 - 75 % 46 - 48 % 56 - 59 %

Viscosity @ 23 °CBrookfield, mPa•s

3000 - 30.000 3000 - 9000 5000 - 10.000

Typical average Particle size D[4.3]

0.5 µm 0.5 µm 0.5 µm



Typical Particle Size distributions

Particle Size Distribution

0.01 0.1 1 10 100 1000 10000

Particle Size (µm)

0

2

4

6

8

10

12

14

Vol

ume

(%)

XZ 92533.00 T60B, Friday, November 12, 2004 3:15:26 PM

Particle size distributionof an aqueous dispersionof a solid epoxy resin

Particle Size Distribution

0.01 0.1 1 10 100 1000 10000

Particle Size (µm)

0

2

4

6

8

10

12

14

16

Vol

ume

(%)

XZ9254600 pure, Tuesday, June 14, 2005 11:12:10 AM

Particle size distributionof an aqueous dispersionof an epoxy novolac resin



Storage Stability

Weeks ofstorage

Averageparticle size

D[4.3]

EpoxyEquivalent

Weight

Brookfieldviscosity at 23°C

0 0.385 µm 190 g/eq 4660 mPa•s

27 0.385 µm 191 g/eq 4200 mPa•s

56 0.390 µm 191 g/eq 4200 mPa•s

Submicron particle size distributions lead to excellent storage stabilitiesdemonstrated with the example of a WB epoxy novolac dispersion XZ 92546.00

Only very light sediment after one year of storage at 23°C which can be easily stirred in



Viscosity profile of epoxy dispersion

Solid contents up to 54% without solvents can be achieved if high viscosities can be tolerated

XZ 92533.00 Good shear thinning properties allowing good flow and spray properties

0

1

2

3

4

5

6

7

8

9

10

0.1 1 10 100 1000

s-1

Pa*

s

XZ 92533.00 up

XZ 92533.00 down



Mechanical dispersion Process

Process patented by Dow:

Continuous feed of resin and water to the mixing unit under high shear High viscous resins can be dispersed without the addition of solvents Excellent transfer of process parameters from lab to pilot to manufacturing scale Submicron and mono modular particle size distributions



Influence of process parameters

Particle size can be influencedby the total flow rate

Influence of flow rates on average particle size of WB Epoxy Novolac Dispersion

R2 = 0.9262

0.30

0.35

0.40

0.45

0.50

0.55

0.60

0.65

0.70

0.75

0.80

0 500 1000 1500 2000 2500

Flow rate, g/min

Vm

ean p

articl

e si

ze

(mic

rons)



Viscosity versus particle size for WB Epoxy Novolac dispersion samplesViscosity measured by Brookfield DV-1 with Spindle #3 at 5 rpm, 23 ° C

R2 = 0.9884

0

2000

4000

6000

8000

10000

12000

14000

16000

0.250 0.300 0.350 0.400 0.450 0.500 0.550

V Mean particle size (microns)

Vis

cosi

ty (m

Pa*s

)

Significant increasein viscosity with decreasingparticle size distribution

Influence of process parameters



Solid Epoxy Resin Dispersion



Cure Rate

Persoz Hardness

050

100150200250300350

1 2 3 4 5 6 7

days of cure at 23°C

s

Curing agent 1

Curing agent 2

Both Curing agentsare based on water soluble epoxy amine adducts

Drying times based on drying time recorder

Curing agent 1

Curing agent 2

End of gel tear

2.9 h 2.4 h

End of scratch

7 h 9.4 h



Pot life

As 2K WB epoxy systems don’t have necessarily a visible end of pot lifelike their solvent borne counterparts other properties are tested

Some 2K WB epoxy systems based on Dow’s dispersion technology show excellent gloss retention over time

Gloss measurement over potlife XZ 92441.01

0

20

40

60

80

100

120

0 0.5 1 2 3 4

h

20°

60°

85°



Anti-corrosive Primer White

Component A Weight-%1 Curing Agent 2 13,4

2 Demineralised water 29,13 TEGO Dispers 750W Tego-Chemie 1,64 BYK 019 / 024 (3:2) BYK Chemie 0,55 Omya BLR 3 Omya 17,56 Micro-Talc AT Extra Omya 9,07 Micro-Talc AT 1 Omya 8,08 Heucophos ZPA Heubach 10,09 Kronos 2059 Kronos 10,010 Aerosil R 972 Degussa 0.9Total Component A: 100,0

Component B

1-Type Dispersion 87,0



Barrier properties

• Good barrier properties against solvents, water and basic materials

• The clear coated systems show some minor deficiencies against some acids

• Fully formulated systems based on commercial available anticorrosion pigments achieve 1000 hours of salt spray resistance on pretreated steel panels

• Corrosion/salt spray resistance on cold rolled steel of 1000 hours could be achieved with the help of adhesion promoters e.g. based on epoxy silane chemistry



Salt-Spray Test DIN 50021

• Exposure 1000 hours– Blistering: none (m0g0)– Under rusting: <1 mm– Adhesion: < GT1– Scratch-Test: o.k. (K0)

• Substrate– Cold Rolled Steel,

Type R-46 (Q-panel)



Institutional Coating Part A PBW Solid epoxy resin dispersion 668 668 Part B Curing Agent 3 64.3 Demi-water 62.2 Surfynol DF-62 Defoamer 4 Acetic Acid 0.9 Ti-Pure R-706 Titanium Dioxide 230 Grind to Hegmann 6 Demi-water 47.4 Curing Agent 3 26.4 Surfynol 420 2.8 Demi-water 15.4 Rheolate 310 4.6 Total: 458 458 1126 Typical Coating Constants Total Weight Solids 53.4 Total Volume Solids 41.8 Pigment Volume Concentration 15.3 VOC [gr/l] 7.59



Pot-life and Drying

Dry Times (1.5 mil dry films)Set-To-Touch 0.4 hrs.Surface Dry 0.6 hrs.Dry Through 5.0 hrs.

20 Degree GlossNo Induction 10130 Min. 1011 Hr. 1012 Hr. 923.5 Hrs. 784.5 Hrs. 65



Resistance

Cure: 14 days @ R.T. conditions of 72 0F and 50-55 % R.H.Test Method: ASTM D-1308 ( covered spot test, 18 hr. exposure time, no recovery)

Solvents Mineral Spirits No Effect 50 % Ethanol Softens to 5B Stains Grape Juice No Effect Red Wine Slight Stain Coffee Very Slight Stain Mustard Severe Stain Shoe Polish Moderate Stain Lipstick No Effect Ketchup No Effect Chemical and Fluid Resistance 5 % Glacial Acetic Acid Very Slight Swelling 10 % Hydrochloric Acid CLOA 10 % Sulfuric Acid CLOA 10 % Nitric Acid CLOA 10 % Sodium Hydroxide No Effect 10 % Ammonium Hydroxide No Effect De-Ionized Water No Effect 5 % Sodium Chloride No Effect Anti-Freeze No Effect Unleaded Gasoline No Effect Brake Fluid Softens to >6B Skydrol LD Softens to >6B



Combination Epoxy / PU Dispersion

• Combinations are possible but appropriate hardener selection is required (clarity)

• Gloss of cured mixtures is in the same high range as for the PUD alone

• Flexibility is improved when PUD is added to Epoxy Dispersions

• Coating hardness follows the ratio of Epoxy to PUD for 90% stoichiometric hardener ratio.

• Especially solvent resistance is improved when epoxy dispersion is added to the PUD



Conclusions

epoxy functional surfactant

+ Continuous process

VOC free WB epoxy dispersions

Excellent storage stability, film formation, mechanical properties, barrier properties

Good fit for ambient cured coatings

also in combination with DOW PUD`s

neo chemical seminar 2007 toine dinnissen / march 28th 2007page 1 voc-free waterborne epoxy...

Documents

epoxy resin grades

epoxy novolac resin

solid epoxy resin solutions

waterborne epoxy dispersions

neo chemical seminar

toine dinnissen

epoxy equivalent weight

coatings waterborne