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NEO Chemical Seminar 2007
Toine Dinnissen / March 28th 2007 Page 1
VOC-free Waterborne
Epoxy Emulsions and Dispersions
for Ambient Cure Coatings
NEO Chemical Seminar 2007
Toine Dinnissen / March 28th 2007 Page 2
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
NEO Chemical Seminar 2007
Toine Dinnissen / March 28th 2007 Page 3
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
NEO Chemical Seminar 2007
Toine Dinnissen / March 28th 2007 Page 4
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
NEO Chemical Seminar 2007
Toine Dinnissen / March 28th 2007 Page 5
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
NEO Chemical Seminar 2007
Toine Dinnissen / March 28th 2007 Page 6
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
NEO Chemical Seminar 2007
Toine Dinnissen / March 28th 2007 Page 7
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
NEO Chemical Seminar 2007
Toine Dinnissen / March 28th 2007 Page 8
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
NEO Chemical Seminar 2007
Toine Dinnissen / March 28th 2007 Page 9
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
NEO Chemical Seminar 2007
Toine Dinnissen / March 28th 2007 Page 10
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)
NEO Chemical Seminar 2007
Toine Dinnissen / March 28th 2007 Page 11
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
NEO Chemical Seminar 2007
Toine Dinnissen / March 28th 2007 Page 13
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
NEO Chemical Seminar 2007
Toine Dinnissen / March 28th 2007 Page 14
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°
NEO Chemical Seminar 2007
Toine Dinnissen / March 28th 2007 Page 15
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
NEO Chemical Seminar 2007
Toine Dinnissen / March 28th 2007 Page 16
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
NEO Chemical Seminar 2007
Toine Dinnissen / March 28th 2007 Page 17
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)
NEO Chemical Seminar 2007
Toine Dinnissen / March 28th 2007 Page 18
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
NEO Chemical Seminar 2007
Toine Dinnissen / March 28th 2007 Page 19
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
NEO Chemical Seminar 2007
Toine Dinnissen / March 28th 2007 Page 20
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
NEO Chemical Seminar 2007
Toine Dinnissen / March 28th 2007 Page 21
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
NEO Chemical Seminar 2007
Toine Dinnissen / March 28th 2007 Page 22
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
Recommended