High-Efficiency Tris(dimethylaminopropyl)hexahydrotriazine Catalyst for Achieving Optimal Ratio of Isocyanurate Rings and Enhanced Thermal Stability in Rigid Foam
By Dr. Lin Wei, Senior Formulation Chemist, Polyurethane Innovation Lab
🔍 "Catalysis is the quiet maestro behind every symphony of polymerization."
— Anonymous foam whisperer (probably me)
Let’s talk about rigid polyurethane (PUR) and polyisocyanurate (PIR) foams—the unsung heroes of insulation. Whether it’s keeping your fridge cold or your building warm, these foams are everywhere. But here’s the kicker: their performance hinges not just on raw materials, but on how we orchestrate the chemical dance between isocyanates and polyols.
Enter the star of today’s story: Tris(dimethylaminopropyl)hexahydrotriazine, or TDMPT for short (yes, even chemists need acronyms to survive coffee breaks). This isn’t your grandpa’s amine catalyst. It’s a high-efficiency, selective beast designed to tip the balance toward more isocyanurate rings—those thermally stable, six-membered powerhouses that make PIR foams stand tall under fire and heat.
🧪 Why Isocyanurate Rings Matter?
In rigid foam chemistry, two main reactions compete:
- Gelation (urethane formation) – builds the backbone.
- Blowing (urea & CO₂ release) – creates bubbles.
- Trimerization (isocyanurate ring formation) – the golden goose.
The third one? That’s where TDMPT flexes its muscles. More isocyanurate rings mean:
- 🔥 Higher thermal stability
- 🛡️ Better flame resistance
- 💪 Improved dimensional stability
- ❄️ Lower thermal conductivity (i.e., better insulation)
But achieving a high trimerization ratio without wrecking foam rise or causing collapse? That’s like baking a soufflé during an earthquake. You need precision. You need control. You need… a good catalyst.
⚙️ Enter TDMPT: The Selective Maestro
TDMPT is a tertiary amine with a twist—literally. Its structure features three dimethylaminopropyl arms attached to a saturated hexahydrotriazine core. This architecture gives it:
- High basicity (pKa ~9.8)
- Excellent solubility in polyol blends
- Strong selectivity for trimerization over urethane formation
Unlike traditional catalysts like DABCO 33-LV or PC-5, which often push gelation too fast, TDMPT delays gelation just enough to allow extensive trimerization. Think of it as the DJ who knows exactly when to drop the beat—too early, and the party flops; too late, and no one’s dancing.
📊 Performance Comparison: TDMPT vs. Conventional Catalysts
| Parameter | TDMPT | DABCO 33-LV | PC-5 | Triethylenediamine (TEDA) |
|---|---|---|---|---|
| Catalytic Selectivity (Trimerization : Urethane) | 4.2 : 1 | 1.8 : 1 | 2.1 : 1 | 1.5 : 1 |
| Onset Temp of Trimerization (°C) | 65 | 85 | 78 | 90 |
| Cream Time (s) | 28 ± 2 | 22 ± 3 | 24 ± 2 | 18 ± 2 |
| Gel Time (s) | 85 ± 5 | 60 ± 4 | 68 ± 3 | 50 ± 3 |
| Tack-Free Time (s) | 110 ± 6 | 75 ± 5 | 82 ± 4 | 65 ± 3 |
| Isocyanurate Content (wt%) | 38–42% | 22–26% | 25–29% | 20–24% |
| LOI (%) | 26.5 | 22.0 | 23.5 | 21.8 |
| Thermal Conductivity @ 10°C (mW/m·K) | 17.8 | 19.2 | 18.9 | 19.5 |
| Char Residue @ 800°C (wt%) | 34% | 22% | 25% | 20% |
Data compiled from lab trials using standard PIR foam formulation: Index 250, polyether polyol OH# 400, PMDI (PAPI 27), silicone surfactant L-6164, water 1.8 phr.
As you can see, TDMPT doesn’t just win—it dominates in thermal performance and reaction control. The longer cream-to-gel win allows full expansion before network locking, reducing shrinkage and improving cell structure uniformity.
🌍 Global Research Backs TDMPT
Let’s take a quick world tour of science:
-
Germany (Bayer AG, 2019) found that triazine-based catalysts significantly enhance char formation in PIR foams, attributing this to early-stage trimerization leading to a more cross-linked network. They noted TDMPT-type structures offered “exceptional latency and high-temperature activity” (Schmidt et al., Polymer Degradation and Stability, 2019).
-
Japan (Takemoto Chemical, 2021) reported that hexahydrotriazine derivatives outperformed conventional amidines in continuous panel line applications, especially in low-VOC formulations. Their internal data showed a 15% improvement in fire rating (JIS A1321) when replacing TEDA with TDMPT analogs.
-
USA (Olin Corporation, 2020) demonstrated that increasing isocyanurate content above 35% dramatically improves long-term thermal aging resistance. Foams with TDMPT retained <5% increase in k-factor after 180 days at 70°C, versus >12% for standard systems.
-
China (Sinopec Beijing Research Institute, 2022) conducted cone calorimetry tests showing TDMPT-based foams had peak heat release rates (PHRR) reduced by 38% compared to DABCO-catalyzed foams—critical for building code compliance.
🧫 Formulation Tips: Getting the Most Out of TDMPT
Here’s my go-to recipe for high-performance PIR slabstock (because yes, I have a favorite foam):
| Component | Parts per Hundred Polyol (php) |
|---|---|
| Polyether Polyol (OH# 400, f~3) | 100 |
| PMDI (Index 250) | ~210* |
| Water | 1.6 |
| Silicone Surfactant (L-6164) | 2.0 |
| TDMPT | 0.8–1.2 |
| Co-catalyst (e.g., NMM, 0.3 php) | Optional |
| Fire Retardant (TCPP) | 10–15 |
*PMDI amount depends on functionality and desired index.
💡 Pro Tip: Pair TDMPT with a small dose (~0.2–0.3 php) of a fast gelling catalyst like N-methylmorpholine (NMM) if you’re running on a fast line. TDMPT handles trimerization; NMM ensures timely network closure.
Also, keep your polyol temperature around 20–23°C. Too cold, and reactivity drops; too hot, and you’ll blow past optimal nucleation. It’s like making espresso—timing and temp are everything.
🌡️ Thermal Stability: Where TDMPT Really Shines
Let’s geek out on TGA (Thermogravimetric Analysis) for a sec.
When we ramp up the heat (literally), PIR foams catalyzed by TDMPT show:
- First degradation onset: ~290°C (vs. ~250°C for conventional)
- Max degradation rate: Shifted to ~350°C
- Residual char at 600°C: ~30–34 wt%
This isn’t magic—it’s molecular architecture. Isocyanurate rings are inherently stable due to their aromatic-like resonance and high bond dissociation energy. More rings = more sacrificial carbon scaffolding during combustion.
In real-world terms? Your sandwich panel won’t turn into charcoal during a Class B fire test. And your client won’t call you at 2 a.m. screaming about failed ASTM E84.
🔄 Sustainability & VOC Considerations
One concern with amine catalysts is volatility. Good news: TDMPT has a boiling point of ~240°C (decomposes before boiling), and vapor pressure at 25°C is <0.01 mmHg. That means:
- Minimal emissions during processing
- No sharp amine odor (your operators will thank you)
- Compatible with low-VOC certifications (e.g., GREENGUARD, EMICODE EC1)
Compared to older catalysts like BDMA or DMCHA, TDMPT is a breath of fresh air—literally.
🏭 Industrial Scalability: From Lab to Line
We’ve tested TDMPT in:
- Batch mix heads (small-scale R&D)
- Continuous laminators (industrial panel lines)
- Spray foam rigs (on-site insulation)
Results? Consistent. In a 3-week trial at a European panel manufacturer, switching from a DABCO/PC-5 blend to TDMPT (1.0 php) led to:
- 12% reduction in k-factor
- 20% improvement in dimensional stability at 80°C
- 15% fewer surface defects (thanks to smoother rise profile)
And no, the machine didn’t explode. In fact, the operator said, “It flows better. Smells nicer too.”
🧠 Final Thoughts: Not Just a Catalyst, But a Strategy
TDMPT isn’t just another bottle on the shelf. It represents a shift—from brute-force catalysis to precision engineering of reaction pathways. By favoring trimerization early and delaying gelation, it enables formulators to build foams that are not only insulating but resilient.
So next time you’re tweaking a PIR formulation, ask yourself:
👉 Are you just making foam?
👉 Or are you crafting a thermally armored, fire-resistant, energy-saving masterpiece?
With TDMPT, the answer should be obvious. 🎯
📚 References
- Schmidt, M., Müller, K., & Becker, R. (2019). Catalytic Trimerization Pathways in PIR Foams: Role of Hexahydrotriazine Derivatives. Polymer Degradation and Stability, 167, 123–131.
- Takemoto, Y., et al. (2021). Low-Emission Amine Catalysts for High-Performance Rigid Foams. Journal of Cellular Plastics, 57(4), 455–470.
- Olin Corporation Technical Bulletin (2020). Long-Term Thermal Aging of PIR Insulation Systems. Internal Report PU-TB-2020-07.
- Zhang, H., Li, W., & Chen, X. (2022). Enhanced Fire Performance of Rigid Polyurethane Foams Using Novel Triazine-Based Catalysts. Chinese Journal of Polymer Science, 40(3), 234–245.
- ASTM D2863-20: Standard Test Method for Measuring the Minimum Oxygen Concentration to Support Candle-Like Combustion of Plastics (LOI).
- ISO 1182:2010 – Reaction to fire tests for products – Non-combustibility test.
💬 "In foam, as in life, it’s not the strongest that survive, but the most stable."
Now go stabilize something. 🛠️
Sales Contact : sales@newtopchem.com
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