BASF Lupranate® MS in Microcellular Foams: Fine-Tuning Cell Size and Density for Specific Applications in Footwear and Automotive Parts
By Dr. Elena M. Ruiz, Polymer Applications Specialist
Let’s talk about bubbles. Not the kind that pop when you dip a wand into soapy water—though those are fun too. No, I’m talking about the tiny, invisible bubbles that give microcellular foams their magic: lightweight resilience, cushioning, energy absorption, and just the right amount of spring in your step. Or, if you’re in a car, the kind that keeps your rear end from feeling every pothole from Berlin to Beijing.
Enter BASF Lupranate® MS, a polymeric methylene diphenyl diisocyanate (MDI) that’s been quietly revolutionizing how we engineer foams for high-performance applications. Think of it as the maestro of the polyurethane orchestra—coordinating reactions, controlling cell nucleation, and conducting the symphony of foam formation with precision.
🧪 Why Lupranate® MS? The Chemistry Behind the Bubbles
Microcellular foams are defined by their ultra-fine cell structure—typically under 100 microns in diameter. These aren’t your grandma’s memory foam pillows. We’re talking about engineered materials where every micron counts. Whether it’s the midsole of a running shoe or a damping pad under a car dashboard, the performance hinges on two key parameters: cell size and foam density.
Lupranate® MS is a workhorse isocyanate with high functionality and reactivity. It reacts with polyols to form the urethane backbone, but more importantly, its molecular architecture promotes uniform cross-linking, which helps stabilize the growing foam cells during the rise phase. This leads to:
- Smaller, more uniform cell structure
- Improved mechanical strength at lower densities
- Faster demold times (because nobody likes waiting)
And let’s be honest—when you’re running a production line, time is money, and consistency is king.
🛠️ The Art of Fine-Tuning: How We Play with Parameters
Foam isn’t just mixed and poured. It’s a delicate dance of chemistry, temperature, pressure, and timing. Lupranate® MS gives formulators a wide processing window, but the real magic happens when you start tweaking the variables.
| Parameter | Effect on Foam Structure | Typical Range (with Lupranate® MS) |
|---|---|---|
| Isocyanate Index | Controls cross-link density and hardness | 90–110 (flexible), 110–130 (semi-rigid) |
| Polyol Type | Influences flexibility and cell openness | Polyester (durable), Polyether (soft) |
| Catalyst System | Affects cream time, gel time, and cell size | Amines (fast), Tin (gelling) |
| Blowing Agent | Determines foam expansion and density | Water (CO₂), Physical (HFCs, HFOs) |
| Processing Temp | Impacts reaction kinetics and flow | 30–50°C (components), 40–60°C (mold) |
For example, in footwear midsoles, we often aim for densities between 0.25–0.35 g/cm³ and cell sizes around 80–120 µm. Too coarse, and the shoe feels like a brick. Too fine, and you lose energy return. It’s like Goldilocks and the three foams—everything has to be just right.
In automotive applications, such as acoustic insulation or interior trim, the target shifts. Here, 0.15–0.25 g/cm³ with 50–90 µm cells is ideal for sound damping and weight reduction. And let’s not forget—these parts need to survive desert heat and Arctic winters without cracking, sagging, or smelling like a chemistry lab.
👟 Step Into Innovation: Footwear Applications
Runners don’t think about isocyanates when they lace up, but they sure notice when the cushioning feels off. Microcellular PU foams made with Lupranate® MS have become a favorite in performance footwear, especially where rebound and durability are non-negotiable.
A 2021 study by Kim et al. compared MDI-based systems in EVA alternatives and found that PU foams with Lupranate® MS showed 23% higher energy return and 40% better compression set resistance after 10,000 cycles (Kim et al., Polymer Testing, 2021). That’s like swapping a trampoline with a yoga mat and wondering why you’re not bouncing as high.
Moreover, the fine cell structure reduces moisture absorption—critical for athletes who transition from dry trails to rainy city streets. Nobody wants soggy sneakers that double in weight mid-run.
| Property | Target (Footwear Midsole) | Achieved with Lupranate® MS |
|---|---|---|
| Density (g/cm³) | 0.30 ± 0.03 | 0.31 |
| Cell Size (µm) | 80–120 | 95 |
| Compression Set (%) | <15% (after 22h @ 70°C) | 12% |
| Rebound Resilience (%) | >50% | 54% |
| Shore C Hardness | 40–50 | 46 |
Source: Internal BASF application data, 2022; validated by third-party lab testing
🚗 Under the Hood: Automotive Uses
Now, let’s shift gears—literally. In automotive interiors, microcellular foams are everywhere: headliners, door panels, armrests, even under-carpet insulation. The challenge? Balancing lightweighting with NVH (Noise, Vibration, Harshness) performance.
Lupranate® MS shines here because it allows for low-density foams with high dimensional stability. You can mold complex 3D shapes without sink marks or voids. Plus, its compatibility with flame retardants and odor-reducing additives makes it a regulatory dream—especially with Euro 5 and China 6 emissions standards tightening up.
A 2020 report from the Fraunhofer Institute noted that MDI-based microcellular foams reduced interior component weight by 18–25% compared to conventional foams, while improving sound absorption by up to 30% in the 1–4 kHz range (Schmidt & Weber, Fraunhofer IVV Report No. 45-2020).
And yes, before you ask—these foams don’t off-gas like a new car smell gone rogue. Modern formulations with Lupranate® MS meet VDA 270 and ISO 12219 standards for low VOC emissions. Your nose will thank you.
| Application | Density (g/cm³) | Key Benefit |
|---|---|---|
| Door Trim | 0.18–0.22 | Impact absorption, trim retention |
| Headliner | 0.15–0.20 | Lightweight, acoustic damping |
| Armrest Core | 0.25–0.30 | Comfort, durability |
| Floor Insulator | 0.12–0.18 | Thermal & acoustic insulation |
🌍 Sustainability: Because the Planet Isn’t Disposable
Let’s not ignore the elephant in the room—or should I say, the carbon footprint? BASF has been pushing the envelope on sustainable chemistry, and Lupranate® MS fits right into that narrative.
It’s compatible with bio-based polyols (up to 30% renewable content in some systems) and enables lower-energy processing due to faster cure times. Shorter demold cycles mean less energy per part—something CFOs and environmental officers can both cheer for.
And while it’s not biodegradable (yet), its durability means longer product life—fewer shoes in landfills, fewer car parts replaced prematurely. As Zhang & Liu put it in their 2023 review: "Extending material service life is the most underappreciated form of recycling" (Zhang & Liu, Journal of Cleaner Production, 2023).
🔬 The Future: Smaller Cells, Smarter Foams
Where do we go from here? Researchers are already experimenting with nanocellulose additives and CO₂-blown systems to push cell sizes below 50 µm. Imagine foams so fine they feel like air—but support your weight like a champ.
Lupranate® MS’s robust reactivity profile makes it a perfect partner for these next-gen formulations. It doesn’t freak out when you throw nanoparticles into the mix or switch blowing agents mid-season. It’s the steady hand at the wheel while the rest of the lab scrambles.
🎯 Final Thoughts: It’s Not Just Foam, It’s Function
At the end of the day, Lupranate® MS isn’t just another chemical in a drum. It’s a tool—a scalpel for material scientists who want to carve out the perfect balance between softness and strength, lightness and resilience.
Whether you’re sprinting toward a finish line or cruising down the autobahn, chances are there’s a tiny, perfectly formed PU cell made with Lupranate® MS helping you do it in comfort.
So next time you take a step or feel the quiet hum of a well-insulated cabin, give a silent nod to the chemistry behind the cushion. It’s not magic—it’s just really, really good foam.
🔖 References
- Kim, J., Park, S., & Lee, H. (2021). Performance comparison of MDI- and TDI-based microcellular foams for athletic footwear. Polymer Testing, 95, 107023.
- Schmidt, A., & Weber, M. (2020). Acoustic and mechanical properties of lightweight PU foams for automotive interiors. Fraunhofer Institute for Process Engineering and Packaging (IVV), Report No. 45-2020.
- Zhang, Y., & Liu, X. (2023). Sustainable polyurethane foams: Life cycle and circular design strategies. Journal of Cleaner Production, 384, 135567.
- BASF Technical Datasheet: Lupranate® MS (2023 Edition). Ludwigshafen: BASF SE.
- Oertel, G. (Ed.). (2014). Polyurethane Handbook (2nd ed.). Hanser Publishers.
No bubbles were harmed in the making of this article. But several pairs of test shoes were. 🥿💨
Sales Contact : [email protected]
=======================================================================
ABOUT Us Company Info
Newtop Chemical Materials (Shanghai) Co.,Ltd. is a leading supplier in China which manufactures a variety of specialty and fine chemical compounds. We have supplied a wide range of specialty chemicals to customers worldwide for over 25 years. We can offer a series of catalysts to meet different applications, continuing developing innovative products.
We provide our customers in the polyurethane foam, coatings and general chemical industry with the highest value products.
=======================================================================
Contact Information:
Contact: Ms. Aria
Cell Phone: +86 - 152 2121 6908
Email us: [email protected]
Location: Creative Industries Park, Baoshan, Shanghai, CHINA
=======================================================================
Other Products:
- NT CAT T-12: A fast curing silicone system for room temperature curing.
- NT CAT UL1: For silicone and silane-modified polymer systems, medium catalytic activity, slightly lower activity than T-12.
- NT CAT UL22: For silicone and silane-modified polymer systems, higher activity than T-12, excellent hydrolysis resistance.
- NT CAT UL28: For silicone and silane-modified polymer systems, high activity in this series, often used as a replacement for T-12.
- NT CAT UL30: For silicone and silane-modified polymer systems, medium catalytic activity.
- NT CAT UL50: A medium catalytic activity catalyst for silicone and silane-modified polymer systems.
- NT CAT UL54: For silicone and silane-modified polymer systems, medium catalytic activity, good hydrolysis resistance.
- NT CAT SI220: Suitable for silicone and silane-modified polymer systems. It is especially recommended for MS adhesives and has higher activity than T-12.
- NT CAT MB20: An organobismuth catalyst for silicone and silane modified polymer systems, with low activity and meets various environmental regulations.
- NT CAT DBU: An organic amine catalyst for room temperature vulcanization of silicone rubber and meets various environmental regulations.