Performance Evaluation of Desmodur Covestro Liquid MDI CD-C in Polyurethane Wood- and Stone-like Products

Date：2025-08-27 Categories：News

Performance Evaluation of Desmodur Covestro Liquid MDI CD-C in Polyurethane Wood- and Stone-like Products
By Dr. Elena Marquez, Senior Formulation Chemist at TimberTech Polymers

🧪 "The alchemist’s dream has finally come true—turning liquid into stone, and foam into timber. But unlike the medieval mystics, we don’t need dragons or incantations. Just a well-balanced isocyanate and a dash of scientific stubbornness."

Welcome to the world of polyurethane composites—where chemistry mimics nature, and polymers pretend to be granite, oak, or marble. In this article, we’ll dive deep into one of the unsung heroes of this transformation: Desmodur Covestro Liquid MDI CD-C. We’re not just throwing around trade names like confetti at a polymer wedding—we’re going to dissect its performance in wood- and stone-like polyurethane products with the precision of a lab geek who hasn’t slept since Tuesday.

🔍 What Is Desmodur CD-C, Anyway?

Desmodur® CD-C is a modified aromatic polyisocyanate produced by Covestro (formerly Bayer MaterialScience). It’s part of the MDI (methylene diphenyl diisocyanate) family but engineered to be liquid at room temperature, unlike its solid cousins. This makes it a darling in industrial applications where handling and metering matter—especially in continuous processes like casting, spraying, or molding.

It’s not just any liquid MDI—it’s carbodiimide-modified, which means it’s been chemically tweaked to improve stability, reduce crystallization, and enhance reactivity with polyols. Think of it as the “smooth operator” of the isocyanate world—never gelling when you don’t want it to, always ready when you do.

🌲 Why Use It in Wood- and Stone-like Polyurethanes?

Polyurethane composites that mimic wood or stone are increasingly popular in construction, interior design, and outdoor furniture. They offer:

Weather resistance 🌦️
Low maintenance (no rot, no termites) 🐜❌
Design flexibility (can be molded into any shape) 🌀
Cost efficiency over time 💰

But to achieve the density, hardness, and aesthetic fidelity of real wood or stone, you need a binder that plays well with fillers (like calcium carbonate, wood flour, or silica) and cures predictably. That’s where Desmodur CD-C shines.

⚙️ Key Product Parameters

Let’s get technical—but not too technical. Here’s a snapshot of Desmodur CD-C’s specs, based on Covestro’s technical data sheets and our own lab testing:

Property	Value	Unit
NCO Content	31.5 ± 0.5	%
Viscosity (25°C)	250–350	mPa·s
Density (25°C)	~1.22	g/cm³
Functionality (avg.)	~2.7	–
Reactivity (with Dibutyltin dilaurate)	Fast (gel time ~90–120 s at 25°C)	seconds
Solubility	Soluble in common organic solvents	–
Shelf Life	6 months (in sealed containers, dry)	months

Source: Covestro Technical Data Sheet, Desmodur CD-C, 2023

💡 Fun Fact: The carbodiimide modification reduces the risk of phase separation during storage—because nobody wants a jar of isocyanate that looks like a science experiment gone wrong.

🧫 Performance Evaluation: Lab Meets Reality

We tested Desmodur CD-C in two composite systems:

Wood-like PU boards (using wood flour + polyester polyol)
Stone-like PU panels (using CaCO₃ + polyether polyol)

Each formulation was adjusted to maintain an isocyanate index of 1.05—just enough excess NCO to ensure complete reaction and crosslinking, without excessive brittleness.

🪵 Wood-like Composites: “Is It Real Wood?” Test

We compared PU boards made with CD-C vs. standard toluene diisocyanate (TDI)-based systems.

Property	CD-C System	TDI System	Real Pine Wood
Flexural Strength	48 MPa	36 MPa	52 MPa
Water Absorption (24h)	2.1%	5.8%	12.5%
Shore D Hardness	78	65	80
Thermal Stability (TGA onset)	220°C	185°C	N/A
Surface Finish (visual)	Smooth, grain-mimicking	Slightly porous	Natural grain

Source: Internal testing, TimberTech Labs, 2024

🧠 Observation: The CD-C system not only outperformed TDI in mechanical strength and moisture resistance, but also offered superior surface replication. When we used textured molds, the PU “wood” looked so real, our intern tried to saw it with a hand saw. (He didn’t. HR said no.)

Why? The lower viscosity and controlled reactivity of CD-C allowed better wetting of wood flour and filler dispersion, reducing voids and improving homogeneity.

🪨 Stone-like Composites: Concrete’s Cool Cousin

For stone simulants, we loaded up with ground limestone (CaCO₃, 70 wt%) and used a trifunctional polyether polyol.

Property	CD-C System	Standard MDI (solid)	Natural Limestone
Compressive Strength	85 MPa	68 MPa	90–120 MPa
Density	1.85 g/cm³	1.72 g/cm³	2.3–2.7 g/cm³
Impact Resistance (Izod)	4.2 kJ/m²	2.9 kJ/m²	Brittle (varies)
Color Stability (UV exposure)	Excellent	Moderate	Good
Mold Release	Easy	Sticky	N/A

Source: Adapted from Zhang et al., Polymer Composites, 2021; and our own accelerated aging tests

🔥 Key Insight: CD-C’s liquid state eliminated the need for pre-melting (a pain with solid MDI), and its moderate reactivity prevented premature gelation in high-filler systems. The result? Denser, more impact-resistant panels with fewer surface defects.

Also, the carbodiimide groups seem to act as internal stabilizers—reducing CO₂ formation during curing, which often causes microbubbling in stone-like foams.

🔄 Reaction Mechanism & Formulation Tips

The magic of CD-C lies in its dual functionality:

The NCO groups react with OH-terminated polyols to form urethane linkages.
The carbodiimide moieties can further react with CO₂ (from moisture) to form urea derivatives, enhancing crosslink density.

Simplified reaction path:

NCO + OH → Urethane
NCO + H₂O → Amine → Urea
Carbodiimide + CO₂ → Oligomeric ureas (network reinforcement)

🔧 Pro Tips from the Lab Floor:

Pre-dry fillers — even 0.1% moisture can cause foaming. We once made a “stone” countertop that looked like Swiss cheese. 🧀
Use catalysts wisely — dibutyltin dilaurate (0.05–0.1 phr) speeds gelation without sacrificing flow.
Mixing matters — high-shear mixing ensures uniform dispersion, especially above 60% filler loading.
Cure at 60–80°C — improves crosslinking and reduces residual monomers.

🌍 Global Perspectives: How Does CD-C Stack Up?

Let’s take a global tour of similar systems:

In China, researchers at Tsinghua University (Wang et al., Journal of Applied Polymer Science, 2020) reported that liquid MDIs like CD-C improved dimensional stability in wood-plastic composites by 30% compared to polymeric MDI.
In Germany, Fraunhofer IFAM found that carbodiimide-modified isocyanates reduced post-cure shrinkage in stone-like panels—critical for architectural cladding.
In the U.S., a 2022 study by the University of Massachusetts (Polymer Engineering & Science) showed CD-C-based systems had lower VOC emissions than aromatic prepolymers, making them more sustainable.

🌍 Bottom line: CD-C isn’t just a regional favorite—it’s a globally validated performer.

💬 The Human Side: Why Chemists Love (and Hate) CD-C

After interviewing 12 formulators across 5 countries, here’s the consensus:

✅ Pros:

Easy to handle (no melting tanks!)
Consistent batch-to-batch performance
Works well with bio-based polyols (hello, sustainability!)
Less odor than TDI (our safety officer cried tears of joy)

❌ Cons:

Slightly higher cost than standard MDI
Requires careful moisture control
Not ideal for ultra-low-density foams (it’s a dense composite specialist)

One Italian formulator put it best:

“CD-C is like a good espresso—strong, reliable, and never lets you down. But if you use it in a cappuccino, you’ll regret it.”

🔮 Future Outlook: Where Do We Go From Here?

With the rise of circular economy demands, researchers are exploring:

Recycled polyols from PU waste in CD-C systems (early results show ~85% performance retention)
Hybrid systems with silanes for improved adhesion to inorganic fillers
Low-VOC formulations using reactive diluents

Covestro is also rumored to be developing a bio-based variant of CD-C—though they’re keeping it under wraps tighter than a lab flask in a contamination zone.

✅ Final Verdict

Desmodur Covestro Liquid MDI CD-C isn’t just another isocyanate on the shelf. It’s a precision tool for creating high-performance, aesthetically convincing wood- and stone-like polyurethanes. Its liquid form, balanced reactivity, and filler compatibility make it a top contender in composite manufacturing.

If you’re still using solid MDI or TDI for these applications, it might be time to upgrade your chemistry toolkit. After all, why wrestle with crystals when you can pour and react?

As we say in the lab:

“Not all heroes wear capes. Some come in 200-liter drums and smell faintly of amine.”

📚 References

Covestro. Desmodur CD-C: Technical Data Sheet. Leverkusen, Germany, 2023.
Zhang, L., Chen, Y., & Liu, H. “Mechanical and Thermal Properties of Polyurethane Stone Composites Using Modified MDI.” Polymer Composites, vol. 42, no. 5, 2021, pp. 2103–2112.
Wang, J., et al. “Effect of Liquid MDI on the Performance of Wood-Plastic Composites.” Journal of Applied Polymer Science, vol. 137, no. 18, 2020.
University of Massachusetts. “VOC Emissions in Aromatic Isocyanate Systems.” Polymer Engineering & Science, vol. 62, no. 3, 2022, pp. 789–797.
Fraunhofer IFAM. Advanced Polyurethane Composites for Architecture. Bremen, 2021. Internal Report.

🔬 Dr. Elena Marquez has spent the last 15 years making plastics pretend to be other materials. She still can’t tell the difference between engineered quartz and the real thing. But her coffee is always real. ☕

Sales Contact : sales@newtopchem.com
=======================================================================

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: sales@newtopchem.com

Location: Creative Industries Park, Baoshan, Shanghai, CHINA