TECHNICAL BULLETIN I 1

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

• 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.

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.

RHopLex™ 4400 Acrylic polymer Enabling Chemistry for Plasticizer-Free and Reduced-Plasticizer Caulk and Sealant Formulations

Dirt and Mildew Pickup Dirt and mildew pickup related to plasticizer migration are additional concerns that plague professional and DIY painters.

Exterior Interior

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.

Aureobasidium, a common fungus found in wood, textiles, soil, plant debris and indoor air

Plasticized sealant

Plasticizer-free sealant

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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.

Plasticizer with EPS foam insulation

Dirt Pickup and Discoloration

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.

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

• Sealants used in combination with elastomeric wall and roof coatings

• CARB-compliant or low-VOC formulations

Typical physical properties of RHopLex™ 4400

• -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.

TECHNICAL BULLETIN I 3

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.

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:

• APEO-free, St-free, AN-free

• Ultra-low formaldehyde

• Can be formulated into CARB-compliant and low-VOC formulations with a reduced need for biocide

Wide Formulation Latitude Helps Reduce Formulation Costs By eliminating plasticizer or adjusting P/B ratios, RHOPLEX™ 4400 acrylic polymer allows manufacturers to tailor formulations to their specific performance and cost requirements.

Figure 1a Figure 1b

Weathering – ASTM C290, Class 12.5 Weathering – ASTM C920, Class 25

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.

120

100

80

60

40

20

0

3

2.5

2

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Lightly Plasticized RHOPLEXTM 4400 Sealants

5

Plasticizer (% on Polymer Solids)

Stre

ss a

t 25%

Elo

ngat

ion

(psi

)

10 15 20

0 10 20 30 40 50

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ASTM C920 Class 12.5 Sealants

E�ect of Plasticizer on S25 as f(P/B)

P/B vs Plasticizer Formulation Space for ASTM C920 Waterborne Sealants

P/B

% Plasticizer

CommercialClass 12.5 – 35

Sealants

Class 12.5

Class 25

Class 35

120

100

80

60

40

20

0

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1.5

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Lightly Plasticized RHOPLEXTM 4400 Sealants

5

Plasticizer (% on Polymer Solids)

Stre

ss a

t 25%

Elo

ngat

ion

(psi

)

10 15 20

0 10 20 30 40 50

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ASTM C920 Class 12.5 Sealants

E�ect of Plasticizer on S25 as f(P/B)

P/B vs Plasticizer Formulation Space for ASTM C920 Waterborne Sealants

P/B

% Plasticizer

CommercialClass 12.5 – 35

Sealants

Class 12.5

Class 25

Class 35

Figure 3: Plasticizer Increases Formulating SpaceFigure 2: Lightly Plasticized ASTM C920 Waterborne Sealants

TECHNICAL BULLETIN I 1

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Printed in the U.S.A.Published May 2012

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