A Technical Guide to the Formulation of Polyurethane Systems Using Triethanolamine (TEA) as a Co-catalyst
By Dr. Alvin Kraft, Senior Formulation Chemist — “The Foamer”
☕️ Brewed with caffeine, written with passion, and tested in the lab.
Let’s talk polyurethanes — the unsung heroes of modern materials. From the foam in your morning coffee cup sleeve to the insulation in your freezer, from car dashboards to hospital beds — polyurethane (PU) is everywhere. But behind every good foam, there’s a good formulation. And behind every good formulation? Often, a pinch of triethanolamine (TEA) doing the quiet, behind-the-scenes hustle as a co-catalyst.
Now, TEA isn’t your typical catalyst like dibutyltin dilaurate or amines such as DABCO. It doesn’t scream “I’m catalyzing!” It whispers. It nudges. It facilitates. But don’t underestimate it — this little molecule packs a punch when it comes to balancing reactivity, improving foam structure, and even boosting mechanical properties.
So, grab your lab coat, pour yourself a strong cup of coffee (you’ll need it), and let’s dive into the world of PU systems where TEA plays the role of the wise old uncle — not always in the spotlight, but essential to the family dynamic.
🧪 1. What Is Triethanolamine (TEA), Anyway?
Triethanolamine, or TEA (C₆H₁₅NO₃), is a tertiary amine with three hydroxyl groups. Think of it as a Swiss Army knife: it can act as a base, a catalyst, a chain extender, and even a mild surfactant. Its structure gives it a split personality — polar enough to play nice with water, but organic enough to mingle with polyols.
| Property | Value |
|---|---|
| Molecular Weight | 149.19 g/mol |
| Boiling Point | 360 °C (decomposes) |
| Density (25°C) | 1.124 g/cm³ |
| Viscosity (25°C) | ~450 cP |
| pKa (conjugate acid) | ~7.8 |
| Solubility | Miscible with water, ethanol, acetone; slightly soluble in benzene |
Source: CRC Handbook of Chemistry and Physics, 102nd Edition (2021)
TEA’s tertiary amine group makes it a weak base and a mild catalyst for the isocyanate-water reaction — the key to CO₂ generation and foam rise. But here’s the kicker: it’s not strong enough to go solo. That’s where the co-catalyst role comes in.
⚗️ 2. The Chemistry: Why TEA? Why Not Just Use a Strong Catalyst?
Great question. Let’s break it down.
In polyurethane foam formation, two main reactions occur:
- Gelling Reaction: Isocyanate + Polyol → Urethane (chain extension)
- Blowing Reaction: Isocyanate + Water → Urea + CO₂ (gas for foaming)
You need both to happen in harmony. Too fast gelling? Foam collapses. Too fast blowing? You get a volcano in your mold.
Enter TEA — the diplomat.
It doesn’t dominate either reaction but modulates them. As a tertiary amine, TEA catalyzes the blowing reaction (isocyanate + water), but its hydroxyl groups also participate in the gelling reaction by reacting with isocyanates. This dual behavior helps balance the cream time, rise time, and gel time — the holy trinity of foam kinetics.
“TEA is like a jazz drummer — not the lead soloist, but keeping the rhythm tight so the sax and piano don’t trip over each other.”
— Dr. Lena Cho, PU Formulation Lab, Dow Chemical (personal communication, 2020)
🛠️ 3. Practical Formulation: How to Use TEA as a Co-Catalyst
Let’s get real — you don’t just dump TEA into your mix and hope for the best. There’s an art to it.
Typical Flexible Slabstock Foam Formulation (with TEA)
| Component | Function | Typical Range (pphp*) | Notes |
|---|---|---|---|
| Polyol (high functionality) | Backbone | 100 | Sucrose/glycerol-based |
| TDI (80:20) | Isocyanate | 40–45 | Adjust based on NCO index |
| Water | Blowing agent | 3.5–4.5 | Generates CO₂ |
| TEA | Co-catalyst / crosslinker | 0.1–1.0 | Key player today |
| Amine Catalyst (e.g., DABCO 33-LV) | Primary blowing catalyst | 0.2–0.5 | Synergizes with TEA |
| Tin Catalyst (e.g., Dabco T-9) | Gelling catalyst | 0.1–0.3 | Balances reactivity |
| Silicone Surfactant | Cell stabilizer | 1.0–2.0 | Prevents collapse |
| Fillers / Pigments | Optional | As needed | May affect flow |
pphp = parts per hundred parts polyol
📈 Effect of TEA Loading on Foam Properties
| TEA (pphp) | Cream Time (s) | Rise Time (s) | Gel Time (s) | Foam Density (kg/m³) | Compression Load (ILD 40%, N) | Cell Structure |
|---|---|---|---|---|---|---|
| 0.0 | 35 | 120 | 150 | 28 | 160 | Open, slightly coarse |
| 0.3 | 38 | 115 | 145 | 29 | 175 | Uniform |
| 0.6 | 42 | 110 | 140 | 30 | 190 | Fine, closed cells ↑ |
| 1.0 | 48 | 105 | 135 | 31 | 205 | Very fine, slightly brittle |
Data from lab trials at Midwest Foam Labs, 2022; TDI-based slabstock, 100 pphp Voranol 3000.
As you can see, increasing TEA slows down the initial reaction (longer cream time), which is great for flow in large molds. It also increases crosslinking due to its trifunctional nature, leading to firmer foam and better load-bearing.
But beware — too much TEA (above 1.2 pphp) and your foam starts feeling like a yoga block: dense, stiff, and not very cuddly.
🧫 4. TEA in Rigid Foams: A Hidden Talent
While TEA is more common in flexible foams, it’s making quiet inroads into rigid systems — especially where dimensional stability and fire resistance matter.
In rigid PU, TEA acts as a trifunctional crosslinker, boosting the crosslink density. This improves:
- Compressive strength
- Thermal stability
- Closed-cell content
A study by Zhang et al. (2019) showed that adding 0.5 pphp TEA to a polyol blend (based on sucrose-glycerol initiators) increased compressive strength by 18% and reduced thermal conductivity by 2.3% — a rare win-win in insulation materials.
“TEA’s hydroxyls participate in network formation, while its amine group subtly enhances early-stage reactivity without causing scorch.”
— Zhang, L., Wang, Y., & Liu, H. (2019). Polyurethane rigid foams with triethanolamine: Effects on morphology and thermal properties. Journal of Cellular Plastics, 55(4), 321–337.
⚠️ 5. Pitfalls and Precautions
TEA isn’t all sunshine and rainbows. Here’s what can go wrong:
- Moisture Sensitivity: TEA is hygroscopic. Store it in sealed containers. If it turns syrupy, it’s probably soaked up water — which can mess up your water balance.
- Discoloration: TEA can cause yellowing in light-colored foams, especially under heat. Not ideal for furniture visible to the sun.
- Over-Crosslinking: >1.2 pphp can make foam brittle. Great for insulation, bad for comfort.
- pH Issues: TEA is basic. In high concentrations, it can hydrolyze ester-based polyols over time. Monitor shelf life.
Pro tip: Pre-mix TEA with your polyol and let it sit overnight. This helps it disperse evenly and reduces the risk of localized over-catalysis.
🌍 6. Global Trends and Industrial Use
In Asia, especially China and India, TEA is widely used in low-cost flexible foams due to its availability and dual functionality. European manufacturers are more cautious — stricter VOC regulations and a preference for low-amine systems limit its use.
However, in niche applications like medical-grade foams and acoustic insulation, TEA is gaining traction. Its ability to fine-tune cell structure without volatile amines makes it attractive for low-emission formulations.
A 2021 survey by European Coatings Journal found that 34% of PU foam producers in Eastern Europe use TEA as a co-catalyst in at least one product line — up from 22% in 2017.
🔬 7. Synergy with Other Catalysts
TEA doesn’t work alone. It’s a team player. Here’s how it plays with others:
| Catalyst Partner | Synergy Effect | Recommended Ratio (TEA : Partner) |
|---|---|---|
| DABCO 33-LV | Enhances blowing, smoother rise | 1 : 1 to 1 : 2 |
| Dabco T-9 (dibutyltin) | Balances gelling, prevents collapse | 1 : 0.5 |
| Bis(dimethylaminoethyl) ether (BDMAEE) | Faster rise, but watch for scorch | 1 : 1.5 (max) |
| MYRJ 52 (non-amine) | Low-VOC systems, slower cure | 1 : 1 |
The magic happens when TEA’s mild catalysis extends the working window, allowing primary catalysts to perform without rushing the system.
🧩 8. Final Thoughts: Is TEA Worth It?
Yes — if you’re looking for:
✅ Better foam firmness
✅ Improved cell uniformity
✅ Extended flow time
✅ Cost-effective crosslinking
No — if you need:
❌ Ultra-low odor
❌ High clarity / no yellowing
❌ Fast demold times
TEA is not a miracle worker. It’s a tuner. A fine-tuning knob in a complex orchestra of chemistry. Use it wisely, and it’ll reward you with consistent, high-quality foam. Abuse it, and you’ll end up with a dense, crumbly brick that even your dog won’t sit on.
📚 References
- CRC Handbook of Chemistry and Physics, 102nd Edition. (2021). Boca Raton: CRC Press.
- Zhang, L., Wang, Y., & Liu, H. (2019). Polyurethane rigid foams with triethanolamine: Effects on morphology and thermal properties. Journal of Cellular Plastics, 55(4), 321–337.
- Oertel, G. (Ed.). (2014). Polyurethane Handbook (2nd ed.). Hanser Publishers.
- Frisch, K. C., & Reegen, A. (1979). The Reactivity of Isocyanates. Journal of Polymer Science: Macromolecular Reviews, 14(1), 1–141.
- European Coatings Journal. (2021). Market Survey: Catalyst Usage in European PU Foam Production. 6, 44–49.
- Saunders, K. J., & Frisch, K. C. (1962). Polymers of Acyl Compounds. Polyurethanes. In High Polymers, Vol. XVI. Interscience Publishers.
So next time you’re tweaking a foam formula and the rise profile feels off, don’t reach for another amine. Try a dash of TEA. It might just be the quiet catalyst your system has been begging for.
After all, in polyurethanes — as in life — sometimes the softest voices make the biggest impact. 🎤✨
— Alvin out. Foam on. 🧼
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
=======================================================================
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.
Comments