DuPont™ Formacel®

DEVELOPMENT PROGRAM UPDATE FOR LOW GWP

FOAM EXPANSION AGENT

W H I T E P A P E R

Gary Loh, Joseph A. Creazzo, Mark L. RobinDuPont Fluorochemicals

ABSTRACT Polyurethane foams are widely employed for thermal insulation in the appliance and construction industries. Foam expansion agents (FEAs or blowing agents) are critical for providing the insulation performance of these foams. CFC-11 and HCFC-141b were once the FEAs of choice, but their use is being phased out due to their ozone depletion potential (ODP). The current zero ODP FEAs include hydrofluorocarbons (HFCs) and hydrocarbons, but these agents face further challenges. Both HFCs and hydrocarbons are characterized by increased thermal conductivities compared to both the HCFCs and CFCs, resulting in inferior insulation performance, and HFCs such as HFC-245fa and HFC-365mfc have global warming potentials (GWPs) near 1,000. In addition, the low boiling point of HFC-245fa and the flammability of hydrocarbons and HFC-365mfc present significant challenges to processing and handling. With the increased focus on global warming potential and energy efficiency, the industry is looking for a foam expansion agent that is environmentally sustainable with superior insulation performance.

DuPont Fluoroproducts introduces a novel foam expansion agent, FEA-1100, for polyurethane foams. FEA-1100 has zero ODP and low GWP. It is also non-flammable and a stable liquid at ambient temperature. This paper discusses the properties and characteristics of FEA-1100 for PUR applications such as appliance, pour-in place, spray and PIR boardstock. We will discuss recent results in toxicity evaluation, material compatibility, and foam properties, particularly insulation performance.

INTRODUCTION In recent years concerns over climate change have intensified, and as a result the industry is seeking foam expansion agents not only characterized by zero ODP, but also by lower global warming potentials (GWPs) compared to those of the HFCs. In addition, the increased demand for energy efficiency also requires the FEAs to have low vapor thermal conductivity to produce foams with superior insulation performance. Taking these requirements into consideration, DuPont Fluoroproducts has developed a novel “Fourth-Generation” foam expansion agent FEA-1100. We report here further application studies on FEA-1100, including material compatibility and the performance of FEA-1100 with the major types of polyols employed for the manufacture of polyurethane foams. The results indicate that in addition to being characterized by improved environmental properties, FEA-1100 also provides superior insulation performance in foam applications. Data obtained to date also suggest that FEA-1100 can serve as a “drop-in” to replace other types of liquid FEAs with low conversion costs.

PROPERTIES OF FEA-1100FEA-1100 has an excellent environmental profile. It is characterized by zero ozone depletion potential and low global warming potential. Recent estimates indicate that FEA-1100 has a short atmospheric lifetime of approximately 16 days.

FEA-1100 has low vapor thermal conductivity, providing excellent insulation performance.

FEA-1100 is non-flammable in standard ASTM tests. Testing according to ASTM E 681 Standard Test Method for Concentration Limits of Flammability of Chemicals (Vapors and Gases) indicated non-flammability at temperatures of 60°C and at 100°C. The non-flammability enables the safe use of FEA-1100 in a broad range of applications.

FEA-1100 is a stable liquid at room temperature, with a boiling point > 25°C. This eliminates the handling and processing issues associated with the use of lower boiling FEAs such as HFC-245fa, allowing optimal FEA level in formulations to provide desired foam properties.

Table 1 lists the properties of FEA-1100 and other FEAs. As shown in Table 1, the previous FEA transition sacrificed some desirable characteristics (low vapor thermal conductivity, high boiling point, and nonflammability) in exchange for improved environmental properties. FEA-1100 provides improved environmental properties while maintaining the desired characteristics of low vapor thermal conductivity, non-flammability and a boiling point above 25°C.

Table 1: Properties of Foam Expansion AgentsCFC-11 HCFC-141b HFC-245fa HFC-365mfc Isopentane FE-1100

ODP 1 0.12 0 0 0 0

GWP (100 year ITH) 4750 725 1020 782 11 5

e gas 25°C mW/mK 8.4 9.7 12.7 10.5 13.3 10.7

Flash Point non none none -25.0°C -51°C none

bp °C 23.9 32.1 15.3 40.0 27.9 >25

TOXICITY ASSESSMENTToxicological testing performed to date indicates that FEA-1100 can be safely used in foam expansion applications. Table 2 summarizes these toxicity assessments. Further toxicological testing is underway to evaluate the risks of longer term exposure.

Table 2: FEA-1100 Toxicological AssessmentsTest Results

ALC and LC-50 Very low acute toxicity

Skin Irritation Non-irritating

Mutagencity-Ames Non-mutagenic

Chromosomal Aberration No genetic material damage when tested in bacterial and mammalian cell cultures

Cardiac Sensitization Favorable cardiac sensitization potential profile

28 day repeated inhalation Favorable repeated inhalation profile

COMPATIBILITY WITH METALSCompatibility tests for FEA-1100 with metals were performed in sealed tubes. Metal coupons (copper, brass, carbon steel, stainless steel and aluminum) were immersed in FEA-1100 and heated in an oven for 14 days at 100°C (212°F), and changes in weight and appearance of the metal coupons were recorded. The liquid solutions were also evaluated for ap-pearance and decomposition products such as fluoride. As shown in Table 3, FEA-1100 is compatible with metals com-monly employed in polyurethane foam processing. While these simple exposure tests help screen effects on materials of construction, the final materials selection should include testing more specific to the application.

Table 3: Metal Compatibility—2 Weeks Exposure to FEA-1100 at 100°C (212°F)Metal Coupons Metal Coupon

WeightMetal Coupon Appearance

FEA Solution Appearance

FEA Solution Analysis

Stainless Steel No weight change No sign of corrosion Clear No fluoride detected**

Carbon Steel No weight change No sign of corrosion Clear No fluoride detected**

Copper No weight change No sign of corrosion Clear No fluoride detected**

Brass No weight change No sign of corrosion Clear No fluoride detected**

Aluminum No weight change No sign of corrosion Clear No fluoride detected****Detection limit = 0.5 ppm

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COMPATIBILITY WITH PLASTICSPlastics compatibility tests were performed by exposing plastic materials to FEA-1100 at room temperature for two weeks. Weight, volume and hardness before and after the exposure were measured. Observations of changes are sum-marized in Table 4, which indicates that FEA-1100 is compatible with commonly employed plastics. As always, verifying compatibility using actually fabricated parts under end-user conditions is advised as the performance of plastics is affect-ed by polymer variations, compounding agents, fillers and molding processes.

Table 4: Plastic Compatibility—2 Weeks Exposure to FEA-1100 at Room TemperatureSymbol Material Brand % Weight

Change% Volume Change

% Hardness Change

ABS Acrylonitrile-butadiene-styrene Cycolac®EX58 -0.1% -0.6% 0.0%

HIPS High Impact Polystyrene 0.3% -0.4% -2.9%

PET Poly(ethylene terephthalate) Rynite® 0.0% 0.7% -1.2%

PS Polystyrene Styron® -0.4% 0.9% 0.0%

PVC Polyvinyl Choloride Bakelite® 0.0% 0.0% 0.0%

PTFE Fluorocarbon(PTFE) Teflon® 1.1% 0.3% -17.2%

ETFE Fluorocarbon(ETFE) Tefzel® 0.7% 0.0% 12.9%

Lonomer Suryln® 0.3% 0.0% 1.9%

POM Acetal Delrin® 0.1% -1.2% -1.3%

PC Polycarbonate Tuffak® 0.0% -0.6% 0.0%

PEEK Polyetheretherketone Victrex® 0.0% 0.2% 0.0%

Polyarylate Arylon® 0.2% -0.2% -4.4%

LCP Polyester Xydar® 0.0% -0.4% -1.5%

Nylon 6/6 Zytel® 101 0.4% -0.5% 3.1%

PEI Polyetherimide Ultem® -0.1% 0.0% 0.0%

Polyaryl sulfone Radel® -0.2% 0.3% 0.0%

PVDF Poly(vinylidene fluoride) Kynar® 0.1% -0.3% 0.0%

PP Polypropylene Tenite® 0.3% -0.5% 0.0%

LCP Zenite® -0.1% -0.9% 0.0%

HDPE High Density Polyehtylene Alathon® 0.0% 0.3% 3.3%

Phenolic Duzez® 0.0% -0.1% 1.2%

COMPATIBILITY WITH ELASTOMERSElastomeric materials were exposed to FEA-1100 at room temperature for 2 weeks, and changes in volume, weight and hardness were measured before and after the exposure. Table 5 provides a summary of results which indicate that FEA-1100 is compatible with commonly employed elastomers. While these simple exposure tests help screen effects on materials of construction, final materials selection should include testing more specific to the application.

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Table 5: Elastomer Compatibility—2 Weeks Exposure to FEA-1100 at Room TemperatureSymbol Material Brand % Weight

Change% Volume Change

% Hardness Change

NR Natural Rubber Natural Rubber 4.4% 1.9% 0.0%

CR Polychloroprene Neoprene® W 0.8% 0.1% 0.0%

NBR Acrylonitrile Butadiene BUNA N 15.3% 2.6% -13.6%

CSM Chlorosulfonated Polyethylene Hypalon 40® 0.2% 0.8% -1.3%

FFKM Fluoroelastomer Kalrez® 7.9% -3.4% -2.9%

T Polysulfide THIOKOL FA® 0.3% 6.7% -6.1%

IIR Isobutylene Isoprene Butyl Rubber 0.3% 13.1% -13.3%

EPDMHydrocarbon (Ethylene-Propylene Terpolymer) Nordel® 1.4% 5.5% -7.1%

SOLUBILITY IN POLYOLSOne of the important considerations in using a new FEA in polyurethane (PUR) and polyisocyanurate (PIR) foams is its solubility with the foam system polyols. The solubility of FEA-1100 in polyols was tested at 21°C and at 50°C using commercially available polyols from several manufacturers. FEA-1100 was added to the polyols in 5% by weight incre-ments, shaken to mix, and allowed to settle at test temperatures. The addition of FEA-1100 was repeated until the FEA-1100 weight percent reached 50% or until FEA-1100 no longer dissolved in the polyol and formed a separate layer. The maximum weight % of FEA in polyols for a single phase mixture is listed in Table 6, which demonstrates that FEA-1100 exhibits good solubility in a wide range of polyols.

Table 6: FEA-1100 Solubility in PolyolsPolyol Type OH#

(mg KOH/g)Weight % in Polyols

for Single PhaseMixture (21°C)

Weight % in Polyolsfor Single PhaseMixture (50°C)

Polyethers

Amine 391–800 5–50+ 40–50+

Sucrose/amine 400–499 50+ 50+

Sucrose/glycol 440 50+ 50+

Sucrose/glycerine 280–520 50+ 50+

Sorbitol 490 50+ 50+

Mannich-base 300–390 5–50+ 29–50+

Polyesters 240–307 5–30 23–35

VAPOR PRESSURE IN POLYOLSFEA-1100 vapor pressure tests in various polyols were performed at 50°C since FEA-1100 has very low vapor pressure at room temperature. The vapor pressure of FEA-1100 increases with its concentration in polyols and reaches a maximum as the solubility limit is approached. As shown in Figure 1, FEA-1100 vapor pressure at 50°C is well below the typical drum pressure rating of 22 psig. Good solubility and low vapor pressure allow higher FEA-1100 levels to be employed in formu-lations providing optimal foam properties.

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FEA-1100 IN MANNICH-BASE POLYETHER FOR SPRAY FOAM APPLICATIONMannich-base polyether polyols are typically employed in spray foam applications. In these tests, the effect of the FEA level was evaluated in a spray foam formulation optimized for HFC-245fa. Equimolar quantities of FEAs and water (CO2) were used for comparison. FEA-1100 was first substituted for HFC-245fa in the formulation using low levels of HFC-245fa. The FEA levels were then increased to high levels as typically employed in HCFC-141b formulations. Foams produced using high and low FEA levels were analyzed for R-value and density. The foam formulation and properties are listed in Table 7.

Figure 2 shows the effect of FEA level on R-values. FEA-1100 provided superior R-values compared to HFC-245fa at low FEA levels, however, this improvement becomes much more pronounced as the FEA level increases. Since the level of HFC-245fa in formulations is limited by its low boiling point, FEA-1100 can significantly improve foam R-values through the use of a higher level of FEA.

Table 7: Effect of FEA Level in Spray Foam Formulation

Ingredients (pbw)HFC-245fa

(low FEA level)FEA-1100

(low FEA level)HFC-245fa

(high FEA level)*FEA-1100

(high FEA level)

Mannich polyol 50 50 50 50

Polyester polyol 50 50 50 50

Surfactant 0.25 0.25 0.25 0.25

Flame retardant and additives 24.50 24.50 24.50 24.50

Catalysts 1.22 1.22 1.22 1.22

FEA (moles) 0.045 0.045 0.179 0.179

Water (moles) 0.169 0.169 0.035 0.035

Total moles (FEA + water) 0.214 0.214 0.214 0.214

Isocyanate 138 138 97 97

Reaction Profile

Cream time(s) 8 8 7 7

Rise time(s) 70 67 85 71

Tack free time(s) 70 70 90 85

Foam Initial Properties

Foam index 1.1 1.1 1.1 1.1

Sample density (pcf) 2.6 2.6 2.5 2.8

Initial R-value (ft**2-h-F/Btu-in) @ 75°F 6.1 6.2 7.2 7.7*Vapor pressure may exceed drum pressure rating

Figure 1. FEA-1100 Vapor Pressure in Polyether and Polyester Polyols

FEA-1100 Vapor Pressure at 50oC

0

10

20

30

0% 10% 20% 30% 40% 50%

FEA-1100 wt% in polyols

Vapo

r pre

ssur

e (p

sig)

Polyether Polyester Drum pressure limit

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Table 8: FEA-1100 in Sucrose-based Polyether FormulationIngredients (pbw) FEA-1100 HCFC-141b HFC-245fa HFC-365mfc

Sucrose-based polyol 100 100 100 100

Surfactant 2.00 2.00 2.00 2.00

Catalysts 4.00 4.00 4.00 4.00

Water (moles) 0.08 0.08 0.08 0.08

FEA (moles) 0.20 0.20 0.20 0.20

Isocyanate 121 121 121 121

Reaction Profile

Cream time(s) 7 6 6 7

Rise time(s) 120 120 120 130

Tack free time(s) 140 150 140 140

Foam Initial Properties

Foam index 1.1 1.1 1.1 1.1

Foam density (pcf) 1.9 2.0 2.0 1.9

Initial R-value (ft**2-h-F/Btu-in) @ 75°F 7.0 6.7 6.5 6.5

Figure 2. Effect of FEA-1100 Level on R-value

R-value Comparison (FEA-1100 vs HFC-245fa)

6.06.26.46.66.87.07.27.47.67.8

Low FEA level High FEA level (b.p >25C) HFC-245fa vs FEA-1100

R-v

alue

HFC-245 FEA-1100

FEA-1100 IN SUCROSE-BASED POLYETHER FOR APPLIANCE AND POUR-IN-PLACE APPLICATIONSSucrose-based polyols are employed to produce foams for appliance and pour-in-place applications. In these tests, FEA-1100, HFC-245fa and HFC-365mfc were “dropped-in” to a formulation optimized for HFC-141b. Equi-molar quantities of FEAs and water (CO2) were employed for comparison. Table 8 summarizes the results. FEA-1100 provided superior insulation performance compared to the HCFC and HFCs.

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FEA-1100 IN AROMATIC POLYESTER FOR PIR BOARDSTOCK APPLICATIONSAromatic polyester polyols are employed to produce polyisocyanurate (PIR) boardstocks for construction insulation. Table 9 summarizes the results of typical polyisocyanurate foams produced with FEA-1100 and HFC-245fa. Figure 3 shows the R-values of these foams measured upon aging. The foams expanded with FEA-1100 retain superior insulation performance (higher R values) compared to those expanded with HFC-245fa after 9 months of aging.

Table 9: FEA-1100 in Polyester FormulationIngredients (pbw) FEA-1100 HFC-245fa

Aromatic polyester 100 100

Surfactant 6.17 6.17

Catalysts 3.43 3.43

FEA (moles) 0.24 0.24

Isocyanate 158 158

Reaction Profile

Cream time(s) 15 14

Rise time(s) 110 110

Tack free time(s) 120 120

Foam Initial Properties

Foam index 2.5 2.5

Foam density (pcf) 2.1 2.2

Initial R-value (ft**2-h-F/Btu-in) @ 75°F 7.7 7.2

Figure 3. Aged R Value Comparisons: FEA-1100 and HFC-245fa, PIR Foam

FEA-1100 IN TDA-BASED POLYETHER FOR APPLIANCE AND POUR-IN-PLACE APPLICATIONSTDA-based polyols are employed to produce polyurethane foams for appliance and pour-in-place applications. FEA-1100, HFC-245fa, HFC-365mfc, cyclopentane and isopentane were evaluated in a generic polyurethane formulation. Equi-molar quantities of FEA and water were added to the foam formulation listed in Table 10. Foams using these FEAs all showed uniform cell size and good dimensional stability. Table 11 summarizes the results of these polyurethane foams. FEA-1100 shows superior insulation performance compared to all other zero-ODP FEAs.

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Table 10: Foam Formulation for FEA ComparisonIngredients pbw

TDA-based polyol 100

Surfactant 2.13

Catalysts 2.00

FEAs or FEA-1100 mixture (moles) 0.18

Water (moles) 0.06

Isocyanate 132

Foam index 1.2

Table 11: Foam Formulation for FEA Comparison

FEAsR-value

(ft**2-h-F/Btu-in) @ 75°FDensity

(pcf)

FEA-1100 7.2 2.1

HFC-245fa 6.9 2.2

HFC-365mfc 6.9 2.2

Cyclopentane 6.6 2.4

Isopentane 6.3 2.5

FEA-1100 AZEOTROPIC MIXTURESThe use of mixtures of physical foam expansion agents is well known, and such mixtures can be useful in optimizing foam performance and improving FEA properties. FEA-1100 forms azeotropic or azeotrope-like mixtures with HFC-245fa, HFC-365mfc, cyclopentane and isopentane.

To evaluate the effect of FEA-1100 in FEA mixtures, equi-molar quantities of mixtures of FEA-1100 with HFC-245fa, HFC-365mfc, cyclopentane and isopentane were added to the foam formulation listed in Table 11. Foams using FEA-1100 mixtures all exhibited uniform cell size good and dimensional stability. Table 12 summarizes the results and benefits of these FEA-1100 mixtures. Figure 4 shows the effect on R-value after adding FEA-1100 to other FEAs.

Table 12: FEA-1100 Azeotropic and Azeotrope-like Mixtures

FEAsR-value

(ft**2-h-F/Btu-in) @ 75°FDensity

(pcf) Benefits

HFC-245faFEA-1100-HFC-245fa mixture

6.97.1

2.22.4 Improved GWP, b.p & R-value

HFC365mfcFEA-100-HFC365mfc mixture

6.97.4

2.22.2 Improved GWP, R-value & flammability

CyclopentaneFEA-1100-cyclopentane mixture

6.67.3

2.42.3 Improved R-value & flammability

IsopentaneFEA-1100-isopentane mixture

6.36.9

2.52.4 Improved R-value & flammability

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Figure 4. Effect of FEA-1100 Mixtures with HFC-245fa, HFC-365mfc, Cyclopentane and Isopentane

Effect of FEA-1100 in Other FEAs

6.2

6.4

6.66.8

7.0

7.2

7.4

HFC-245fa & its FEA-1100 mixture

HFC-365mfc & itsFEA-1100 mixture

Cyclopentane & itsFEA-1100 mixture

Isopentane & itsFEA-1100 mixture

R-v

alue

Other FEAs FEA-1100-other FEA mixtures

CONCLUSIONSFEA-1100 is characterized by good environmental properties and can be employed in a broad range of foam applications to provide superior insulation performance compared to other current foam expansion agents. FEA-1100 based mixtures have also been shown to provide an improvement in foam insulation properties. Performance and materials compatibility test results indicate that FEA-1100 may be employed as a “drop-in” replacement for other liquid FEAs, providing superior insulation performance with low conversion costs.

BIOGRAPHIES

Gary Loh Gary Loh received his M.S. degree in Chemical Engineering from Georgia Institute of Technology and his MBA degree from James Madison University. He worked in variety of areas including manufacturing, R&D, and marketing, with ex-tensive professional experience in variety of fluorocompound products. Currently, he is a Technical Service Consultant for DuPont Formacel® Foam Expansion Agents Group, where he is responsible for new product development and technical service programs.

Joseph (Joe) A. CreazzoJoe Creazzo is a Technical Service Engineer with DuPont at its Fluorochemicals Laboratory in Wilmington, Delaware. Joe joined DuPont in 1973 after receiving his engineering degree from Stevens Institute of Technology in New Jersey. He has held a variety of technical and manufacturing assignments in a number of areas, including Manufacturing, R&D, and Marketing. In his tenure at the Fluorochemicals Lab, Joe has work on alternatives for CFCs since 1987. Over the years in Fluorochemicals, Joe has assisted customers in several market segments where CFCs and HCFCs were phased out. Cur-rently, he is primarily responsible for customer support and product development for DuPont’s Formacel® Foam Expansion Agents and Dymel® Consumer, Industrial, and Pharmaceutical Propellants.

Mark L. RobinMark L. Robin, Ph.D., is Senior Technical Services Consultant for DuPont Fluoroproducts, and has 25 years of experience in the area of fluorine chemistry, including the development of CFC and HCFC replacements for fire suppression, foam blowing, and refrigeration applications. Mark is the recipient of the 2005 U.S. EPA Stratospheric Ozone Protection Award, presented for his efforts in the development of replacements for ozone depleting substances.

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K-23366 (11/09)

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