Table 1. Waterborne Resin Attributes
Properties
Units
Bayhydrol A 2542
Bayhydrol A 2546
Type
Hydroxy functional
polyacrylic dispersion
Hydroxy functional
polyacrylic dispersion
Solids Content
Equivalent Weight
pH Content
Viscosity at 23° C cps.
Weight/gal. 25° C lbs.
Use and Attributes
%
50
630
7. 5
2000
9. 5
High gloss resin
41
1000
7. 5
120
9.2
Matte resin
Table 2. 2K Waterborne Guide Formulas
Component 1
Bayhydrol A 2542
Bayhydrol A 2546
Deaerating additive
Defoaming agent
Flow and leveling additive
Rheology additive
Water
Component 2
Bayhydrol XP 2547
Bayer Gloss Formula
45.75
--
0.31
0.12
0.49
--
14.2
39.1
by weight
Bayer Matte Formula
15. 26
35.60
0.32
0.14
--
2.28
9.61
36.79
nificant reductions in VOC and solvent levels. These second generation waterborne
polyurethane coatings have achieved the
property goals and are “truly waterborne” –
having 0-20g/L VOC levels. Due to the increased demand for higher durability concrete sealers, this waterborne polyurethane
technology has been looked at as a replacement for the traditional acrylic stainguard
products currently being used. Essentially, a
“stainguard on steroids.”
Two-component waterborne
polyurethane coatings
Experimental
Several waterborne resins were considered
within the scope of this paper for use in
the decorative concrete floor environment
due to their desirable physical traits (Table
1). These traits include:
- Near zero-VOC formulas with excel-
lent abrasion and chemical resistance
- No odor when applied in the field
with other trades or building occupants
present
- Adjustable gloss levels from high
gloss to matte
- Ability to be used as a higher solids
sealer for more porous decorative con-
crete or as a lower solids sealer for pol-
ished concrete and/or densified concrete.
Guide formulas were prepared using
two Bayer waterborne resins along with the
necessary additives (Table 2). The gloss levels were varied via the resins employed in
the formula rather than the use of flattening
aids. Bayhydur® XP 2547, a hydrophilic
HDI trimer, was used as the hardener with
a NCO:OH ratio of 3:1. This over-index-ing can be accomplished with aliphatic isocyanates without detrimental bubble
formation2. The guide formula coatings
were applied at approximately 2-3 wet mils
with a dry mil thickness of approximately
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