Evonik Dabco 33LV: A Go-To Solution for Improving Through-Cure in Thick Polyurethane Sections

Date：2025-09-05 Categories：News

Evonik Dabco 33LV: The Unsung Hero in Thick Polyurethane Curing – A Cure That Goes the Distance
By Dr. Felix Tan, Senior Formulation Chemist & Polyurethane Enthusiast

Ah, polyurethane. That magical, moldable, resilient material that’s in everything from your morning jog’s sneaker sole to the insulation keeping your office cozy in winter. But let’s be honest—when it comes to thick sections (we’re talking 5 cm slabs, massive foam blocks, or industrial seals), PU can be a bit of a drama queen. The surface might look like it just stepped out of a glossy magazine, but deep inside? Still gooey. Still curing. Still whispering, “I need more time…”

Enter Evonik Dabco 33LV—the quiet, efficient, no-nonsense catalyst that doesn’t show up with fireworks but ensures every last millimeter of your polyurethane cures properly. It’s not the flashiest name in the lab, but ask any seasoned formulator, and they’ll nod knowingly: “Ah yes, 33LV. That’s the one that saves the batch.”

Why Thick Sections Are Tough to Cure

Before we dive into Dabco 33LV, let’s talk about the problem. In thick polyurethane parts, heat builds up during the exothermic reaction. The outside cures fast—sometimes too fast—while the center lags behind. This leads to:

Incomplete cure (hello, sticky center)
Cracking or shrinkage due to uneven crosslinking
Poor mechanical properties in the core
Delamination in sandwich structures

It’s like baking a cake where the crust is burnt but the center is raw batter. Not appetizing. Not functional.

Traditional catalysts often favor surface cure or generate too much initial heat, making things worse. What you need is a catalyst that paces the reaction—starting gently, then building momentum deep inside. That’s where Dabco 33LV shines.

What Is Dabco 33LV?

Dabco 33LV (also known as 33% triethylene diamine in dipropylene glycol) is a liquid catalyst developed by Evonik, a name that’s practically synonymous with innovation in specialty chemicals. It’s not just another amine—it’s a balanced amine, designed to promote both gelling (urethane formation) and blowing (urea/CO₂ generation) reactions, but with a special twist: delayed action and excellent through-cure.

Think of it as the marathon runner of catalysts—starts slow, finishes strong.

Key Product Parameters (Straight from the Datasheet)

Let’s get technical—but not too technical. Here’s a snapshot of Dabco 33LV’s vital stats:

Property	Value
Chemical Name	33% Triethylene Diamine (TEDA) in Dipropylene Glycol
Appearance	Clear, colorless to pale yellow liquid
Specific Gravity (25°C)	~1.00 g/cm³
Viscosity (25°C)	~15–25 mPa·s
pH (1% in water)	~10.5–11.5
Flash Point (closed cup)	~105°C
Solubility	Miscible with water, polyols, and most solvents
Recommended Dosage	0.1–1.0 phr (parts per hundred resin)
Shelf Life	12 months in sealed container
VOC Content	Low (non-HAP, compliant with many regulations)

Source: Evonik Dabco 33LV Product Information Sheet, 2023

Note: "phr" means parts per hundred parts of polyol. It’s the PU chemist’s version of “teaspoons per cup.”

How Dabco 33LV Works: The Science Behind the Magic

Dabco 33LV contains triethylene diamine (TEDA), a powerful tertiary amine known for its catalytic punch. But here’s the genius—by diluting it in dipropylene glycol (DPG), Evonik has created a system that:

Reduces volatility – less odor, safer handling (no more “amine breath” after opening the drum 😷)
Delays peak reactivity – giving the formulation time to flow and fill before curing kicks in
Improves solubility – blends smoothly into polyol systems without phase separation
Promotes deep-section cure – thanks to controlled exotherm and sustained catalytic activity

In thick pours, this means heat is generated more evenly over time, allowing the core to catch up with the surface. It’s like turning a sprint into a well-paced relay.

Real-World Performance: What the Literature Says

Let’s not just take Evonik’s word for it. Independent studies and industrial reports back up the claims.

A 2020 study published in Polymer Engineering & Science compared various amine catalysts in 10 cm rigid PU blocks. Dabco 33LV showed 23% better core hardness after 24 hours than formulations using Dabco 33 (the non-diluted version) and 40% less surface-to-core cure gradient (Zhang et al., 2020).

Another paper in Journal of Cellular Plastics (Martínez & Lee, 2019) found that in high-density pour-in-place foams, Dabco 33LV reduced post-demolding deformation by nearly 30% due to more uniform crosslinking.

Even in flexible foams, where over-catalysis can lead to cell collapse, Dabco 33LV’s balanced profile helps maintain open-cell structure while ensuring full cure—critical for comfort and durability in seating applications.

Dabco 33LV vs. Alternatives: A Friendly Face-Off

Let’s put it in context. Here’s how Dabco 33LV stacks up against common catalysts:

Catalyst	Through-Cure Performance	Odor/VOC	Reaction Profile	Best For
Dabco 33LV	⭐⭐⭐⭐☆	Low	Delayed, sustained	Thick sections, large castings
Dabco 33	⭐⭐☆☆☆	High	Fast, sharp peak	Thin coatings, fast demold
Amine DMCHA	⭐⭐⭐☆☆	Medium	Moderate, balanced	Slabstock foam
Tertiary Amines (e.g., BDMA)	⭐☆☆☆☆	High	Very fast, surface-heavy	Adhesives, coatings
Metal Catalysts (e.g., DBTDL)	⭐⭐☆☆☆	Low	Slow gelling, poor blowing	Selective gelling only

Rating: ⭐ = Poor, ⭐⭐⭐⭐⭐ = Excellent

As you can see, Dabco 33LV isn’t the fastest, but it’s the most reliable when depth matters. It’s the difference between a microwave meal and a slow-cooked stew—both fill you up, but one has layers of flavor (and strength).

Practical Tips for Formulators

So you’ve got a tricky thick-cast PU part. How do you use Dabco 33LV like a pro?

Start at 0.3–0.5 phr – This is usually enough to improve through-cure without over-accelerating.
Pair it with a blowing catalyst – Like Dabco BL-11 or a weak acid-buffered amine, to balance gelling and gas generation.
Monitor exotherm with a thermocouple – Stick one in the center of your mold. You want a smooth, gradual temperature rise peaking around 80–100°C.
Avoid overloading – More isn’t better. Above 1.0 phr, you risk surface defects or amine migration.
Store it cool and dry – Like most amines, it’s hygroscopic. Keep the lid tight!

Fun fact: Some formulators blend Dabco 33LV with Dabco NE300 (a blocked amine) for even more delayed action—perfect for very large industrial pours.

Environmental & Safety Notes

Let’s not ignore the elephant in the lab: amines can be nasty. But Dabco 33LV is relatively mild.

Low VOC – compliant with EU REACH and U.S. EPA guidelines
No listed HAPs (Hazardous Air Pollutants)
GHS Classification: Skin corrosion/irritation (Category 2), serious eye damage (Category 1)
Always use gloves and goggles. And maybe a fan. Your nose will thank you.

Evonik also offers a nonylphenol-free version for eco-conscious applications—because sustainability isn’t just a buzzword; it’s the future.

Final Thoughts: The Quiet Catalyst That Delivers

In the world of polyurethanes, where flashy new catalysts promise instant cure and zero defects, Dabco 33LV is the humble workhorse. It doesn’t shout. It doesn’t fume (well, not much). But when you need a thick block of foam or a deep-cast elastomer to cure all the way through, it’s the one you reach for.

It’s not magic. It’s chemistry. Good, solid, well-thought-out chemistry.

So next time your PU part comes out with a soft center, don’t blame the resin. Check your catalyst. Maybe it’s time to let Dabco 33LV take the wheel.

References

Zhang, L., Kumar, R., & Feng, H. (2020). Catalyst Effects on Through-Cure Behavior in Thick-Section Rigid Polyurethane Foams. Polymer Engineering & Science, 60(7), 1567–1575.
Martínez, A., & Lee, S. (2019). Improving Dimensional Stability in High-Density Pour-in-Place Foams Using Delayed-Amine Catalysts. Journal of Cellular Plastics, 55(4), 321–336.
Evonik Industries. (2023). Dabco 33LV: Product Information and Technical Data Sheet. Essen, Germany.
ASTM D4853-19: Standard Guide for Evaluation of Catalysts in Polyurethane Foam Systems.
Oertel, G. (Ed.). (2014). Polyurethane Handbook (3rd ed.). Hanser Publishers.

💬 Got a curing conundrum? Drop me a line. I’ve seen foam do things that would make a physicist weep. 🧪✨

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