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PAINT & PINTURA
Jan/Fev 2012
67
Table 1. White Primer Cure Rate & Film Hardness Development Comparison*
Cure Properties
Solvent-borne Primer
NewGen™ White Primer
Set to Touch
0.5
0.25
Cotton Free
7.5
2.0
Thru Dry
10.5
3.5
1 Day Pencil Hardness
<6B
F
1 Week Pen. Hardness
2B
F
Cross Hatch Adhesion*
5A
5A
MEK Double Rubs*
>200
132
Salt Fog Resistance (888 hrs)
Undercutting/Rust, mm
Blisters @ Scribe (field)
3 / 2
6F
0 / 0.5
None
* 2.5 – 2.7 mils DFT after 7 Days cure at 25°C and 55% Relative Humidity on cold rolled steel
Table 2. Gloss White Enamel Property Comparison*
White Enamel Property
Solvent-borne
NewGen
Through Dry; Hours
8.5
6.0
Pencil Hardness ( 1 day / 1 week)
4B / H
5B / F
Gloss per cent ( 60° / 20°)
95 / 87
102 / 90
Impact Resistance ( dir / rev inch-lb.)
160 / 160
160 / 160
MEK double rubs*
337
308
25°C Water Immersion; days
Blister Rating, field*
>250
10 (none)
>250
10 (none)
Salt spray resistance; hours
Blister rating, field*
1152
6F – 6M
1152
10 (none)
* 2.5 – 2.7 mils DFT after 14 Days cure at 25°C and 55% Relative Humidity on cold rolled steel
Conclusions
Over the last thirty years, Momentive
Specialty Chemicals has developed
several generations of waterborne ep-
oxy systems (resin plus curing agent).
Additional information about the
formulation of these systems is avail-
able elsewhere.
Waterborne epoxy formulations based
on a new generation, 2K waterborne
epoxy system
4
deliver:
Improved compatibility and coales-
cence;
Reduced tendency to form amine blush;
Improved performance with faster
dry, faster hardness with superior
corrosion- and chemical-resistance
properties at VOC levels less than 100
g/L.
References
Elmore, J, et al, Waterborne Protec-
tive Coatings for Metal; Journal of
Coatings Technology, Vol. 74, No. 932,
August 2002; pp 63-72.
Weinmann, D. J., et. al. (2001) “For-
mulating Water-borne Epoxy Coat-
ings”, 44
th
Annual Technical Sympo-
sium; Water-borne Coatings: Sink or
Swim, May 17-18, 2001, Cleveland,
Ohio. Sponsored jointly by the Cleve-
land Society for Coatings Tech. and
the Pittsburgh Society for Coatings
Tech.
Please see “Starting Formulations
from Momentive Specialty Chemicals”
products web site
.
Momentive’s NewGen waterborne
system is EPI-REZ Resin 6520-WH-53
combined with
EPIKURE Curing Agent 6870-W-53.