PORON® 4790-92 Extra Soft Slow Rebound (Supported)
PORON® 4790-92 is an extra soft, slow rebound cellular polyurethane foam cast directly onto a 0.05 mm (2 mil) clear polyester (PET) film, available in three density grades — 240 (15), 320 (20), and 400 (25) kg/m³ (lb/ft³) — with typical compression force deflection values of 12 (1.7), 22 (3.2), and 37 (5.3) kPa (psi) at 25% deflection. The material exhibits a vertical rebound of 5% (240 kg/m³ grade) and compression set of 2–4% maximum at 23°C (73°F) for the 240 and 320 kg/m³ grades. Recommended constant use temperature is 90°C (194°F), with intermittent use to 121°C (250°F).
Key Properties
- Compression Force Deflection — Typical, kPa (psi): 12 (1.7) / 22 (3.2) / 37 (5.3) at 240 / 320 / 400 kg/m³; ASTM D3574-95; 0.51 cm/min, 25% deflection
- Resilience by Vertical Rebound, %: 5 (240 kg/m³); ASTM D2632-96
- Compression Set, % max @ 23°C (73°F): 2 / 4 at 240 / 320 kg/m³; ASTM D1667-90 Test D
- Density: 240 kg/m³ (15 lb/ft³), 320 kg/m³ (20 lb/ft³), 400 kg/m³ (25 lb/ft³); ASTM D3574-95, Test A (± 10% all grades)
- Supporting Film: 0.05 mm (2 mil) clear polyester (PET), permanently bonded
- Recommended Constant Use Temperature (Max.): 90°C (194°F)
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- Specifications
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Physical Properties — Polyurethane Foam
| Property | Value | Test Method |
| Color (Code) | Black (04) | — |
| Density Tolerance | ± 10% (all grades) | ASTM D3574-95, Test A |
| Thickness, mm (inches) — 240 kg/m³ | 0.53–1.04 (0.021–0.041) | — |
| Thickness, mm (inches) — 320 kg/m³ | 1.00–3.05 (0.039–0.120) | — |
| Thickness, mm (inches) — 400 kg/m³ | 2.06 (0.081) | — |
| Thickness Tolerance — 240 kg/m³ | ± 15% | — |
| Thickness Tolerance — 320 and 400 kg/m³ | ± 10% | — |
| Compression Force Deflection — Typical, kPa (psi) | 12 (1.7) / 22 (3.2) / 37 (5.3) at 240 / 320 / 400 kg/m³ | ASTM D3574-95; 0.51 cm/min, 25% deflection |
| Compression Force Deflection — Range, kPa (psi) | 2–24 (0.3–3.5) / 7–35 (1–5) / 8–58 (1.25–8.5) at 240 / 320 / 400 kg/m³ | ASTM D3574-95; 0.51 cm/min, 25% deflection |
| Hardness, Durometer Shore O — 240 kg/m³ | 2 | ASTM D2240-97 |
| Compression Set, % max @ 23°C (73°F) | 2 / 4 at 240 / 320 kg/m³ | ASTM D1667-90 Test D |
| Resilience by Vertical Rebound, % — 240 kg/m³ | 5 | ASTM D2632-96 |
Electrical Properties
| Property | Value | Test Method |
| Dielectric Strength, V/mil | 50 | ASTM D149-97a |
| Dielectric Constant K’ (“DK”) @ 22°C, 50% RH | 1.48 | ASTM D150 |
| Dissipation Factor tan D (“DF”) | 0.04 | ASTM D150-98 |
| Volume Resistivity, ohm·cm | 8 × 10¹¹ | ASTM D257-99 |
| Surface Resistivity, ohm/sq | 10 × 10¹¹ | ASTM D257-99 |
Thermal Properties
| Property | Value | Test Method |
| Thermal Conductivity, W/m·°C (BTU·in/hr·ft²·°F) | 0.083 (0.53) | ASTM C518-98 |
| Coefficient of Thermal Expansion | 2.3–3.1 × 10⁻⁴ in/in/°C (1.3–1.7 × 10⁻⁴ in/in/°F) | — |
| Recommended Constant Use Temperature (Max.) | 90°C (194°F) | — |
| Recommended Intermittent Use Temperature (Max.) | 121°C (250°F) | — |
| Embrittlement Temperature | -18°C (0°F) | ASTM D746-98 |
| Cold Flexibility @ -40°C (-40°F) | Pass | MIL-P-12420D 1991 |
Flame & Fire Performance
| Property | Value | Test Method |
| UL 94 HBF — Min. Thickness Passed, mm (in) | 2.06 (0.081) at 240 and 320 kg/m³ | UL 94 HBF (File E20305) |
| FMVSS 302 — Min. Thickness Passed, mm (in) | 2.06 (0.081) at 240 kg/m³ | SAE J-2236 |
| CSA Comp HBR — Min. Thickness Passed, mm (in) | 2.06 (0.081) at 240 kg/m³ | CSA (File 188149) |
| Fogging | Pass (240 and 320 kg/m³) | SAE J-1756, 3 hrs @ 100°C |
Outgassing
| Property | Value | Test Method |
| Outgassing TML, % | 1.73 / 1.63 at 240 / 320 kg/m³ | ASTM E595-93, 24 hrs @ 125°C, <7×10³ kPa |
| Outgassing CVCM, % | 0.14 / 0.29 / 0.27 at 240 / 320 / 400 kg/m³ | ASTM E595-93 |
| Outgassing WVR, % | 0.71 / 0.49 / 0.44 at 240 / 320 / 400 kg/m³ | ASTM E595-93 |
Environmental Performance
| Property | Value | Test Method |
| Moisture Absorption — High Humidity, % Weight Gain — 240 kg/m³ | 2 | AMS 3568-95 |
| Water Absorption — Immersion, % Weight Gain | 23 / 25 / 14 at 240 / 320 / 400 kg/m³ | ASTM D570-95 |
| UV Resistance | Good | ASTM G53-96 |
| Staining | No Stain | ASTM D925 |
Supporting Material — Clear Polyester Film (PET)
| Property | Value | Test Method |
| Density, kg/m³ (lb/ft³) | 1395 (87.1) | ASTM D1505 |
| Tensile Strength — MD, kPa (psi) | 3.5 × 10⁶ (500,000) | ASTM D882 |
| Modulus — MD, kPa (psi) | 2.1 × 10⁵ (30,000) | ASTM D882 |
| Yield Strength (F5) — MD, kPa (psi) | 1.0 × 10⁵ (15,000) | ASTM D882 |
| Ultimate Elongation, % | 150 | ASTM D882 |
| Coefficient of Friction A/B (Kinetic) | 0.40 | ASTM D1894 |
| Shrinkage — MD, % (TD) | 1.2 (0.0) | 39 min @ 150°C (302°F) |
Compliance
- UL 94 HBF — Compliant (File E20305)
- FMVSS 302 — Compliant (SAE J-2236)
- CSA Comp HBR — Compliant (File 188149)
- Extra soft seals and gaskets for delicate electronics and automotive assembly components
- Slow rebound cushioning where controlled energy return is required after impact or compression
- EMI and environmental sealing in thin-section electronics assemblies
- Vibration dampening in compact automotive and consumer electronics applications
- Die-cut gasket components requiring PET film support for easy handling and precise placement
Common industries: automotive, electronics, consumer electronics.
PORON® 4790-92 is an extra soft, supported grade within the PORON® cellular polyurethane foam family. The foam is cast directly onto a 0.05 mm (2 mil) clear polyester (PET) film in a permanent bond, providing dimensional support and ease of handling during converting and assembly. Three density grades — 240 (15), 320 (20), and 400 (25) kg/m³ (lb/ft³) — offer compression force deflection ranges from 2 to 58 kPa (0.3 to 8.5 psi) at 25% deflection.
The slow rebound characteristic (5% vertical rebound, 240 kg/m³ grade) makes it suited for applications where controlled, gradual energy return is needed.
Electrical properties include a dielectric strength of 50 V/mil, a dielectric constant of 1.48 at 22°C and 50% RH, and volume resistivity of 8 × 10¹¹ ohm·cm. Thermal conductivity is 0.083 W/m·°C (0.53 BTU·in/hr·ft²·°F). UV resistance is rated Good per ASTM G53-96, and staining is absent per ASTM D925. The supporting PET film has a tensile strength of 3.5 × 10⁶ kPa (500,000 psi) MD, ultimate elongation of 150%, and a kinetic coefficient of friction of 0.40.
Compliant with UL 94 HBF (File E20305), FMVSS 302 (SAE J-2236), and CSA Comp HBR (File 188149).
What differentiates PORON® 4790-92 from firmer PORON® grades?
PORON® 4790-92 delivers the lowest compression force deflection in its series — 12 to 37 kPa (1.7 to 5.3 psi) typical at 25% deflection — combined with a slow rebound characteristic (5% vertical rebound for the 240 kg/m³ grade), making it suited for applications requiring very gentle sealing loads and controlled energy dissipation rather than rapid spring-back.
Why is compression set critical for this material?
Compression set indicates whether the foam will maintain contact pressure after prolonged compression. PORON® 4790-92 achieves a maximum compression set of 2–4% at 23°C (73°F) for the 240 and 320 kg/m³ grades, ensuring the foam retains its original thickness and continues to seal effectively over the life of the assembly despite its very low stiffness.
What is the service temperature range for PORON® 4790-92?
The recommended constant use temperature is 90°C (194°F) maximum, with intermittent use to 121°C (250°F). Cold flexibility passes at -40°C (-40°F) per MIL-P-12420D 1991, and embrittlement temperature is -18°C (0°F) per ASTM D746-98.
Is PORON® 4790-92 suitable for flame-rated environments?
Yes, for the 240 kg/m³ density grade. It is compliant with UL 94 HBF (File E20305) at a minimum thickness of 2.06 mm (0.081 in), FMVSS 302 (SAE J-2236) at 2.06 mm (0.081 in), and CSA Comp HBR (File 188149) at 2.06 mm (0.081 in). Compliance for the 320 kg/m³ grade is limited to UL 94 HBF only; the 400 kg/m³ grade has no flame compliance listed on the TDS.
How should PORON® 4790-92 be specified?
Specify grade (PORON® 4790-92), density (240, 320, or 400 kg/m³), thickness, compliance requirements, dimensional tolerances, and finished format.
