Rhoplex ™ 4400 Acrylic Polymer
Enabling Chemistry for Plasticizer-Free and
Reduced-Plasticizer Caulk and Sealant Formulations
Proper application of caulks and sealants is generally regarded as one
of the marks of a quality paint job. But the time and effort invested
to fill gaps and create a smooth, paintable surface can be wasted
when caulk and sealant materials contain plasticizer. That’s because
plasticizer migrates over time, causing a host of problems, including:
• Paint discoloration
Dirt and Mildew Pickup
Dirt and mildew pickup related to plasticizer
migration are additional concerns that plague
professional and DIY painters.
Exterior Interior
• Glossing
• Dirt and mildew pickup
• Earlier fungal growth
Paint Discoloration
Discoloration occurs when the plasticizer in the sealant leaches into
the paint and reacts with the colorant. Discoloration is especially rapid
in flat paints.
Earlier Fungal Growth
Plasticizers have been shown to contribute to earlier
fungal growth. One reason is that some microorganisms
use the plasticizer as a carbon source.
In this example, sealants were cured for one week at room temperature, then
coated with flat paint containing 15-2 e-phthalo blue pigment. After just one
year stored in ambient conditions, note the discoloration in paint applied over
sealant containing plasticizer.
Glossing
Plasticizer migration can also trigger glossing in paint. Rather than
helping to enhance architectural details like crown molding and
baseboards, glossing detracts from the aesthetics of the paint job.
Aureobasidium, a common fungus found in wood, textiles,
soil, plant debris and indoor air
Plasticized sealant
Plasticizer-free sealant
TECHNICAL BULLETIN I 1
Eliminate Plasticizer for High-Performance Painters Caulk and Other Sealant Formulations
RHOPLEX™ 4400 acrylic polymer is a novel chemistry developed to provide wide formulation latitude and comply with ASTM C920 and
ASTM C834 specifications, enabling high-performance formulations at the same pigment to binder (P/B) levels, but without plasticizer.
It can also be used to develop lightly plasticized formulations.
By eliminating plasticizer migration, RHOPLEX 4400 enables enhanced:
•
Aesthetics – significantly reduced dirt pickup, glossing, mildew growth and
paint discoloration
•
Long-term performance – excellent adhesion and weatherability properties
•
Compatibility with construction components – eliminating degradation
of EPS or PVC caused by plasticizer attack
EPS and PVC Degradation
Plasticizer is incompatible with some common building materials, such as EPS
foam and PVC. As shown here, plasticizer migration can dissolve the plastic
foam. It can also cause sealant debonding and blistering.
Where Does Plasticizer-Free Make Sense?
Often added to caulks and sealants to increase
flexibility and elasticity, plasticizers have been shown
to negatively impact caulk and sealant performance.
Plasticizer-free formulations are especially
appropriate for:
• Painters caulks
• Kitchen and bath products
• Applications where plasticizer migration may
present a potential health concern (e.g., schools
and nurseries)
• Elastomeric patches and sealants (smooth,
textured, knife and trowel grades)
• Air and weather barriers (both roll-on and
trowel-on)
• HVAC duct mastics/firestops
• Low-rise industrial sealants
Plasticizer with EPS foam insulation
• Sealants used in combination with elastomeric
wall and roof coatings
• CARB-compliant or low-VOC formulations
Dirt Pickup and Discoloration
Typical Physical Properties
of RHOPLEX™ 4400
•
•
•
•
•
Plasticizer-containing sealants are especially prone to attracting dirt and grime
in exterior applications. The joints of this commercial building were sealed with
a plasticized polyurethane sealant, then covered with an acrylic elastomeric wall
coating. Plasticizer migration through the coating has enhanced dirt pickup and
discoloration along the building’s seams.
2 I TECHNICAL BULLETIN
-43°C Tg
63% solids
180 cPs viscosity
8.6 lbs/gal
4.5 pH
Scan this QR code for
more information
about RHOPLEX™ 4400
acrylic polymer.
Additional Advantages of RHOPLEX™ 4400 Acrylic Polymer
Excellent Long-Term Performance and Weatherability
RHOPLEX™ 4400 acrylic polymer allows you to develop plasticizer-free products with excellent flexibility, adhesion and joint movement
capability for long-term performance. Without the concerns associated with plasticizer migration, your formulations will deliver improved
weatherability, with reduced dirt pickup and discoloration in exterior applications. See Figures 1a and 1b.
Sustainable Attributes
While plasticizer content in sealants is currently
not regulated in the United States, negative
press and concerns about phthalates are
causing some manufacturers to reduce or
eliminate plasticizers in their products.
Figure 1a
Figure 1b
After 4700 hours
of Xenon Arc
weathering, the
surfaces of these
ASTM C920 sealant
samples based on
RHOPLEX™ 4400
acrylic polymer
remain smooth and
exhibit no cracking,
crazing or other
degradation.
Including RHOPLEX™ 4400 in your caulk and
sealant formulations allows you to meet or
exceed current and future standards for “green”
building materials.
Sustainable attributes include:
P/B vs Plasticizer Formulation Space for ASTM C920 Waterborne Sealants
Weathering – ASTM C290, Class 12.5
• APEO-free, St-free, AN-free
• Ultra-low formaldehyde
Weathering – ASTM C920, Class 25
3
Class
2.5
12.5
Commercial
Class 12.5 – 35
Sealants
P/B
• Can be formulated into CARB-compliant and low-VOC formulations with a reduced 2need for biocide
5
2
Class
35
s
s
Cla
1.5
Wide Formulation Latitude Helps Reduce Formulation Costs
Lightly Plasticized
By eliminating plasticizer or adjusting P/B ratios, RHOPLEX™ 4400 acrylic polymer allows
1 manufacturersTMto tailor formulations to their specific
RHOPLEX 4400 Sealants
performance and cost requirements.
0.5
0
Figure 2: Lightly Plasticized ASTM C920 Waterborne Sealants
0
10
30
Figure 3: Plasticizer
Increases20Formulating
Space
% Plasticizer
120
2.5
lass 1
25
Class
35
s
Clas
1.5
Stress at 25% Elongation (psi)
2
P/B
Commercial
Class 12.5 – 35
Sealants
C
Lightly Plasticized
RHOPLEXTM 4400 Sealants
1
0.5
0
0
10
20
30
40
% Plasticizer
Stress at 25% Elongation (psi)
ASTM C920 Class 12.5 Sealants
100
80
60
1.9
40
2.7
2.5
2.2
20
50
0
0
Effect of Plasticizer on S25 as f(P/B)
120
50
Effect of Plasticizer on S25 as f(P/B)
P/B vs Plasticizer Formulation Space for ASTM C920 Waterborne Sealants
3
2.5
40
5
10
15
20
25
Plasticizer (% on Polymer Solids)
ASTM C920 Class 12.5 Sealants
100
80
60
40
20
1.9
2.2
2.5
2.7
TECHNICAL BULLETIN I 3
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Employing construction chemical application and manufacturing expertise to offer solutions based on customer needs, Dow
Construction Chemicals can help you take performance to the next level. We look forward to working with you to develop innovative
solutions for your products. And we’ll be here to respond quickly with technical service and support.
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Published May 2012
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TECHNICAL BULLETIN I 1