Transcript Waterborne Epoxy Products

NEO Chemical Seminar 2007
VOC-free Waterborne
Epoxy Emulsions and Dispersions
for Ambient Cure Coatings
Toine Dinnissen / March 28th 2007
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NEO Chemical Seminar 2007
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. corrosion
resistance, chemical resistance, adhesion,…) with minimal amounts
of solvent to fulfill legal and environmental requirements
Toine Dinnissen / March 28th 2007
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NEO Chemical Seminar 2007
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
Toine Dinnissen / March 28th 2007
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NEO Chemical Seminar 2007
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
Toine Dinnissen / March 28th 2007
Chemistry
+
Process
Properties
Ambient
cured
coatings
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NEO Chemical Seminar 2007
VOC free WB epoxy dispersions
Aqueous dispersion
based on
Liquid
Epoxy
Resin
Solid
Epoxy
Resin
Epoxy
Novolac
Resin
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 °C
Brookfield, 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
Grade
Toine Dinnissen / March 28th 2007
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NEO Chemical Seminar 2007
Typical Particle Size distributions
Particle Size Distribution
Particle size distribution
of an aqueous
dispersion
of an epoxy novolac
resin
16
Volume (%)
14
12
10
8
6
4
2
0
0.01
0.1
1
10
100
1000
10000
Particle Size (µm)
Particle Size Distribution
14
12
Volume (%)
Particle size
distribution
of an aqueous
dispersion
of a solid epoxy resin
10
8
6
4
2
0
0.01
0.1
1
10
100
1000
10000
Particle Size (µm)
Toine Dinnissen / March 28th 2007
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NEO Chemical Seminar 2007
Storage Stability
Submicron particle size distributions lead to excellent storage stabilities
demonstrated with the example of a WB epoxy novolac dispersion XZ 92546.00
Weeks of
storage
Average
particle size
D[4.3]
Epoxy
Equivalent
Weight
Brookfield
viscosity
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
Only very light sediment after one year of storage at 23°C which can be easily
stirred in
Toine Dinnissen / March 28th 2007
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NEO Chemical Seminar 2007
Viscosity profile of epoxy dispersion
10
9
8
XZ 92533.00 Good shear
thinning properties allowing
good flow and spray properties
7
XZ 92533.00 up
6
Pa*s
XZ 92533.00 down
5
4
3
2
1
0
0.1
1
10
100
1000
s-1
Solid contents up to 54% without
solvents can be achieved
if high viscosities can be tolerated
Toine Dinnissen / March 28th 2007
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NEO Chemical Seminar 2007
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
Toine Dinnissen / March 28th 2007
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NEO Chemical Seminar 2007
Influence of process parameters
Influence of flow rates on average particle size of
WB Epoxy Novolac Dispersion
Vmean particle size
(microns)
0.80
2
R = 0.9262
0.75
0.70
Particle size
can be
influenced
by the total
flow rate
0.65
0.60
0.55
0.50
0.45
0.40
0.35
0.30
0
500
1000
1500
2000
2500
Flow rate, g/min
Toine Dinnissen / March 28th 2007
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NEO Chemical Seminar 2007
Influence of process parameters
Viscosity versus particle size for WB Epoxy Novolac dispersion samples
Viscosity measured by Brookfield DV-1 with Spindle #3 at 5 rpm, 23 ° C
16000
14000
Significant
increase
in viscosity with
decreasing
particle size
distribution
Viscosity (mPa*s)
12000
10000
8000
6000
R2 = 0.9884
4000
2000
0
0.250
0.300
0.350
0.400
0.450
0.500
0.550
V Mean particle size (microns)
Toine Dinnissen / March 28th 2007
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NEO Chemical Seminar 2007
Solid Epoxy Resin Dispersion
Toine Dinnissen / March 28th 2007
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NEO Chemical Seminar 2007
Cure Rate
s
Persoz Hardness
350
300
250
200
150
100
50
0
Curing agent 1
Curing agent 2
1
2
3
4
5
6
Both Curing agents
are based on water
soluble epoxy amine
adducts
7
days of cure at 23°C
Drying times based on drying time recorder
End of gel
tear
End of
scratch
Toine Dinnissen / March 28th 2007
Curing
agent 1
Curing
agent 2
2.9 h
2.4 h
7h
9.4 h
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NEO Chemical Seminar 2007
Pot life
As 2K WB epoxy systems don’t have necessarily a visible end of pot life
like their solvent borne counterparts other properties are tested
Gloss measurement over potlife XZ 92441.01
120
100
80
20°
60
60°
40
85°
20
0
0
0.5
1
2
3
4
h
Some 2K WB epoxy systems based on Dow’s dispersion technology show
excellent gloss retention over time
Toine Dinnissen / March 28th 2007
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NEO Chemical Seminar 2007
Anti-corrosive Primer White
Component A
1 Curing Agent 2
2 Demineralised water
3 TEGO Dispers 750W
4 BYK 019 / 024 (3:2)
5 Omya BLR 3
6 Micro-Talc AT Extra
7 Micro-Talc AT 1
8 Heucophos ZPA
9 Kronos 2059
10 Aerosil R 972
Total Component A:
Component B
1-Type Dispersion
Toine Dinnissen / March 28th 2007
Tego-Chemie
BYK Chemie
Omya
Omya
Omya
Heubach
Kronos
Degussa
Weight-%
13,4
29,1
1,6
0,5
17,5
9,0
8,0
10,0
10,0
0.9
100,0
87,0
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NEO Chemical Seminar 2007
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
Toine Dinnissen / March 28th 2007
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NEO Chemical Seminar 2007
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)
Toine Dinnissen / March 28th 2007
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NEO Chemical Seminar 2007
Institutional Coating
Part A
Solid epoxy resin dispersion
Part B
Curing Agent 3
Demi-water
Surfynol DF-62 Defoamer
Acetic Acid
Ti-Pure R-706 Titanium Dioxide
Demi-water
Curing Agent 3
Surfynol 420
Demi-water
Rheolate 310
Total:
Typical Coating Constants
Total Weight Solids
Total Volume Solids
Pigment Volume Concentration
VOC [gr/l]
Toine Dinnissen / March 28th 2007
PBW
668
64.3
62.2
4
0.9
230
Grind to Hegmann 6
47.4
26.4
2.8
15.4
4.6
458
668
458
1126
53.4
41.8
15.3
7.59
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NEO Chemical Seminar 2007
Pot-life and Drying
Dry Times (1.5 mil dry films)
Set-To-Touch
Surface Dry
Dry Through
0.4 hrs.
0.6 hrs.
5.0 hrs.
20 Degree Gloss
No Induction
101
30 Min.
101
1 Hr.
101
2 Hr.
92
3.5 Hrs.
78
4.5 Hrs.
65
Toine Dinnissen / March 28th 2007
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NEO Chemical Seminar 2007
Resistance
Solvents
Mineral Spirits
50 % Ethanol
Stains
Grape Juice
Red Wine
Coffee
Mustard
Shoe Polish
Lipstick
Ketchup
Chemical and Fluid Resistance
5 % Glacial Acetic Acid
10 % Hydrochloric Acid
10 % Sulfuric Acid
10 % Nitric Acid
10 % Sodium Hydroxide
10 % Ammonium Hydroxide
De-Ionized Water
5 % Sodium Chloride
Anti-Freeze
Unleaded Gasoline
Brake Fluid
Skydrol LD
No Effect
Softens to 5B
No Effect
Slight Stain
Very Slight Stain
Severe Stain
Moderate Stain
No Effect
No Effect
Very Slight Swelling
CLOA
CLOA
CLOA
No Effect
No Effect
No Effect
No Effect
No Effect
No Effect
Softens to >6B
Softens to >6B
Cure: 14 days @ R.T. conditions of 72 0F and 50-55 % R.H.
Toine Dinnissen / March 28th 2007 Test Method: ASTM D-1308 ( covered spot test, 18 hr. exposure time, no recovery)
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NEO Chemical Seminar 2007
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
Toine Dinnissen / March 28th 2007
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NEO Chemical Seminar 2007
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
Toine Dinnissen / March 28th 2007
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