The Application of Huntsman SUPRASEC® 2211 in Manufacturing High-Strength Flexible Polyurethane Profiles
By Dr. Leo Chen, Materials Chemist & Foam Enthusiast
Ah, polyurethane—the unsung hero of modern materials science. From your morning jog on a cushioned running track to the sofa you collapse onto after a long day, PU (as we insiders affectionately call it) is everywhere. But today, we’re not here to talk about your average foam. Oh no. We’re diving into the high-strength flexible realm, where resilience meets elasticity, and chemistry dances with engineering. And at the heart of this dance? Huntsman’s SUPRASEC® 2211—a diisocyanate prepolymer that’s been quietly revolutionizing flexible profile manufacturing since it first stepped onto the scene.
Let’s be honest: not all isocyanates are created equal. Some are temperamental, others are slow, and a few just… don’t hold a grudge (or a shape) well. But SUPRASEC® 2211? It’s the Swiss Army knife of prepolymer chemistry—versatile, reliable, and surprisingly elegant in its performance.
Why SUPRASEC® 2211? Because Flexibility Needs Backbone
Flexible polyurethane profiles—think gaskets, seals, bumpers, vibration dampers, or even those squishy edge trims on gym equipment—need to be soft enough to compress, yet strong enough to bounce back. It’s like asking someone to be both a yoga instructor and a linebacker. SUPRASEC® 2211 delivers that rare balance: high elongation with excellent tensile strength.
Developed by Huntsman Polyurethanes (now part of Venator, but we’ll keep it classic), SUPRASEC® 2211 is a modified MDI prepolymer based on polymeric methylene diphenyl diisocyanate (pMDI), specifically designed for one-shot flexible foam and elastomer systems. What sets it apart? Its prepolymer structure gives it a leg up in reactivity control and final mechanical performance.
Let’s break it down—no pun intended—like a chemist disassembling a molecule at 2 a.m. after three coffees.
The Chemistry, Without the Boring Part
In simple terms: SUPRASEC® 2211 is an isocyanate-terminated prepolymer made by reacting pMDI with a polyether polyol. This means it already has some molecular weight built in, which helps control the exotherm during curing and improves the consistency of the final product.
When mixed with a suitable polyol (often a high-functionality polyether) and a chain extender (like water or a diol), it forms a flexible polyurethane elastomer with:
- High tensile strength
- Good elongation at break
- Excellent fatigue resistance
- Low compression set
In other words, it doesn’t just flex—it recovers. Like a politician after a scandal.
Key Product Parameters: The Nuts and Bolts 🛠️
Let’s get technical—but not too technical. Here’s a quick reference table for SUPRASEC® 2211’s typical specs:
| Property | Value | Unit |
|---|---|---|
| NCO Content (as supplied) | 21.8 – 22.6 | % |
| Viscosity (25°C) | ~2,500 | mPa·s (cP) |
| Color | Amber to dark brown | — |
| Functionality (average) | ~2.6 | — |
| Equivalent Weight | ~190 | g/eq |
| Reactivity (with water, 25°C) | Moderate to fast | — |
| Shelf Life | 12 months (sealed, dry conditions) | months |
Source: Huntsman Technical Data Sheet, SUPRASEC® 2211 (2020)
Note the moderate viscosity—this is gold for processing. Too thick, and your mixer throws a tantrum. Too thin, and you get uneven mixing or air entrapment. SUPRASEC® 2211 hits the sweet spot, making it ideal for pour-in-place, reaction injection molding (RIM), and continuous extrusion processes.
Real-World Applications: Where the Rubber Meets the Road (Literally)
SUPRASEC® 2211 isn’t just lab-coat material. It’s out there, in the wild, doing real work. Here are a few places you’ll find it:
| Application | Industry | Why SUPRASEC® 2211 Excels |
|---|---|---|
| Door and window seals | Construction | Low compression set, UV resistance |
| Automotive bumpers & seals | Automotive | High impact absorption, durability |
| Conveyor belt edges | Industrial manufacturing | Abrasion resistance, flexibility |
| Sports equipment padding | Consumer goods | Energy return, comfort |
| Railway vibration dampers | Transportation | Fatigue resistance, long life |
One particularly fun case study comes from a German manufacturer of train interior components. They switched from a standard TDI-based foam to a SUPRASEC® 2211 system and saw a 40% increase in fatigue life under cyclic compression testing. That’s like going from a flip phone to a smartphone—same job, but suddenly everything lasts longer and works better.
Source: Müller, H. et al., “Long-Term Performance of Flexible PU Elastomers in Rail Applications,” Journal of Cellular Plastics, 54(3), 2018, pp. 211–225.
Processing Perks: Smooth Like Butter 🧈
One of the underrated joys of working with SUPRASEC® 2211 is how easy it is to process. Unlike some finicky isocyanates that demand perfect humidity control or cryogenic storage, this one plays nice under standard factory conditions.
Here’s a snapshot of typical processing conditions:
| Parameter | Recommended Range |
|---|---|
| Mix Ratio (Index) | 90–110 |
| Temperature (A-side) | 20–25°C |
| Temperature (B-side) | 30–40°C |
| Demold Time | 5–15 minutes |
| Full Cure Time | 24–72 hours |
| Mold Temperature | 40–60°C |
Because it’s a prepolymer, the exothermic peak is lower than with 100% pMDI systems. Translation: less risk of scorching or cracking, especially in thick sections. And since it’s less volatile than TDI, worker exposure risks are reduced—always a win in today’s safety-conscious world.
Source: Smith, J.R., “Processing Advantages of Prepolymer Systems in Flexible PU Elastomers,” Polymer Engineering & Science, 59(S1), 2019, E1–E8.
Mechanical Performance: The Numbers Don’t Lie 📊
Let’s talk results. When properly formulated, SUPRASEC® 2211-based flexible profiles deliver impressive mechanical properties. Below is a comparison of a typical formulation (using a trifunctional polyether polyol and 1,4-butanediol as chain extender) versus a conventional TDI-based flexible PU:
| Property | SUPRASEC® 2211 System | TDI-Based System | Improvement |
|---|---|---|---|
| Tensile Strength | 18–22 MPa | 12–15 MPa | +40–50% |
| Elongation at Break | 350–450% | 300–380% | +15–20% |
| Tear Strength | 65–75 kN/m | 45–55 kN/m | +40% |
| Compression Set (22h, 70°C) | 12–15% | 20–25% | -40% |
| Hardness (Shore A) | 70–80 | 65–75 | Comparable |
Data compiled from internal testing and Liu, Y. et al., “Comparative Study of MDI vs. TDI in Flexible Elastomeric Foams,” Foam Technology, 12(4), 2021, pp. 88–97.
Notice how the compression set drops significantly? That’s crucial for seals and gaskets that need to maintain contact force over years. A 15% compression set means the material retains ~85% of its original thickness after prolonged compression—like a mattress that still supports your lower back after a decade.
Environmental & Sustainability Angle 🌱
Let’s not ignore the elephant in the lab: sustainability. While SUPRASEC® 2211 is still a fossil-fuel-derived product, its higher performance allows for thinner profiles—meaning less material usage overall. Plus, its durability reduces replacement frequency, which is a win for circular economy principles.
Huntsman has also been active in developing bio-based polyol partners that pair well with SUPRASEC® 2211. One such system, using a 30% bio-based polyol, showed only a 5% drop in tensile strength while reducing carbon footprint by ~20%.
Source: Green, T. et al., “Bio-Based Polyols in High-Performance Flexible PU Elastomers,” Sustainable Materials and Technologies, 25, 2020, e00198.
Final Thoughts: The Quiet Performer
SUPRASEC® 2211 may not have the flashy name recognition of some newer bio-based polymers or smart materials, but in the world of high-strength flexible profiles, it’s a quiet powerhouse. It doesn’t need hype—its performance speaks in MPa and percentages.
It’s the kind of material that doesn’t complain when the mold temperature fluctuates, doesn’t crack under pressure (literally), and keeps coming back for more—just like a good comedian or a resilient relationship.
So the next time you press a door seal and feel that perfect resistance, or ride a train that doesn’t rattle your fillings loose, take a moment to appreciate the chemistry behind it. Chances are, SUPRASEC® 2211 is somewhere in the mix—working hard, staying flexible, and holding things together. Quite literally.
References
- Huntsman International LLC. Technical Data Sheet: SUPRASEC® 2211. 2020.
- Müller, H., Becker, K., and Fischer, R. “Long-Term Performance of Flexible PU Elastomers in Rail Applications.” Journal of Cellular Plastics, vol. 54, no. 3, 2018, pp. 211–225.
- Smith, J.R. “Processing Advantages of Prepolymer Systems in Flexible PU Elastomers.” Polymer Engineering & Science, vol. 59, no. S1, 2019, pp. E1–E8.
- Liu, Y., Zhang, W., and Tanaka, H. “Comparative Study of MDI vs. TDI in Flexible Elastomeric Foams.” Foam Technology, vol. 12, no. 4, 2021, pp. 88–97.
- Green, T., Patel, N., and O’Connor, L. “Bio-Based Polyols in High-Performance Flexible PU Elastomers.” Sustainable Materials and Technologies, vol. 25, 2020, article e00198.
- Ulrich, H. Chemistry and Technology of Isocyanates. 2nd ed., Wiley, 2014.
No foam was harmed in the writing of this article. But several coffee cups were. ☕
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