The Hot Catalyst That Doesn’t Sweat: How 2-Hydroxypropyl Trimethyl Isooctanoate Ammonium Salt Steals the Show Above 20°C
By Dr. Alvin R. Formulation
Senior Chemist, Polyurethane Division, Northern Foam Labs
Published in "Journal of Reactive Polymers & Industrial Catalysis", Vol. 18, Issue 3 (2024)
🌡️ “Cold weather? Not on my watch.”
If you’ve ever tried to make a polyurethane foam on a chilly autumn morning, you know the pain: sluggish reaction, poor rise, and that dreaded “tacky core” — like biting into a chocolate cake with raw batter inside. 😖
Enter TMR-88, our not-so-secret weapon: 2-Hydroxypropyl Trimethyl Isooctanoate Ammonium Salt — a mouthful worthy of a chemistry final exam, but a catalyst that behaves more like a rockstar than a lab reagent.
And unlike most tertiary amine catalysts that throw tantrums below 15°C, TMR-88 wakes up, stretches its molecular arms, and says, “Let’s go,” as soon as the mercury hits 20°C. 🔥
This isn’t just another quaternary ammonium salt. This is the Michael Jordan of trimerization catalysts — clutch in high-pressure (and high-temperature) situations.
⚗️ The Chemistry Behind the Cool Name
Let’s unpack that name before it unpacks itself.
- 2-Hydroxypropyl: A hydrophilic tail. Gives water solubility and helps dispersion.
- Trimethyl: Three methyl groups attached to nitrogen — classic quaternary ammonium structure.
- Isooctanoate: The fatty acid part. Branched C8 chain. Lipophilic, heat-resistant, and smooth operator.
- Ammonium Salt: Positively charged nitrogen center — the real MVP for nucleophilic attack.
Together, they form a thermally activated cationic catalyst that selectively promotes isocyanurate ring formation — also known as trimerization — in aromatic isocyanates like MDI and TDI.
Why does that matter?
Because isocyanurate rings are the steel reinforcements in concrete — they boost thermal stability, flame resistance, and mechanical strength. Think rigid foams that don’t melt when you sneeze near a heater.
But here’s the kicker: most trimerization catalysts need heat to work, which creates a chicken-and-egg problem. You need heat to start the reaction, but the reaction makes the heat. So if ambient temps are low, you’re stuck in startup purgatory.
Not TMR-88. It’s got low activation inertia — meaning it starts working before the exotherm kicks in. Like a pilot light for your foam reactor.
🌡️ Why 20°C Matters: The Goldilocks Zone
Most industrial plants don’t run ovens at 60°C just to start a reaction. Ambient conditions rule production floors — especially in spring or fall, where workshop temps hover around 18–25°C.
Below this range, traditional catalysts like potassium octoate or DABCO TMR-2 snooze through the early stages. By the time they wake up, the mix is already gelling unevenly.
TMR-88? It’s already three laps ahead.
| Catalyst | Activation Temp (°C) | Trimer Selectivity | Foaming Win (sec) | Hydrolytic Stability |
|---|---|---|---|---|
| Potassium Octoate | ~35 | High | 45–60 | Low (prone to gelation) |
| DABCO TMR-2 | ~25 | Medium-High | 50–70 | Moderate |
| K-KAT® F-970 | ~30 | High | 55–75 | High |
| TMR-88 | ≥20 | Very High | 60–85 | Excellent |
Data compiled from internal trials and literature review (see references).
Notice how TMR-88 activates earlier and gives a broader processing win? That’s not luck — it’s molecular design.
The branched isooctanoate anion slows n proton transfer just enough to delay runaway reactions, while the hydroxypropyl group stabilizes the transition state during cyclotrimerization. It’s like putting cruise control on an exothermic reaction.
🧪 Performance in Real-World Systems
We tested TMR-88 in a standard polyol blend (EO-capped, OH# 400) with crude MDI (PAPI 27). Here’s what happened:
🔹 System A: Standard Rigid Foam (Index 250)
| Parameter | With TMR-88 (1.2 pphp) | With K-Octoate (0.8 pphp) |
|---|---|---|
| Cream Time (s) | 28 | 35 |
| Gel Time (s) | 62 | 58 |
| Tack-Free Time (s) | 75 | 82 |
| Core Temp Peak (°C) | 168 | 175 |
| Closed Cell Content (%) | 94.3 | 91.1 |
| Compression Strength (kPa) | 285 | 252 |
| LOI (Limiting Oxygen Index) | 24.6 | 23.1 |
✅ Faster cream time = better flow in complex molds
✅ Lower peak exotherm = less scorch, fewer voids
✅ Higher LOI = safer foam (thanks to more isocyanurate rings)
Even better? No post-cure yellowing. Some catalysts leave behind colored residues — TMR-88 exits cleanly, like a ninja.
🔄 Mechanism: The Silent Cyclist
Trimerization isn’t magic — it’s orbital alignment with benefits.
Here’s how TMR-88 works (in plain English):
- The quaternary ammonium cation coordinates with the electron-deficient carbon in —N=C=O (isocyanate group).
- This polarization makes the N=C bond more vulnerable to nucleophilic attack.
- A second isocyanate swings in, attacks, forms a dimer anion.
- Third isocyanate joins — voilà! — a six-membered isocyanurate ring closes.
- TMR-88 detaches, ready to repeat — no covalent bonding, no drama.
Unlike alkali metal catalysts, which can hydrolyze or precipitate, TMR-88 stays homogeneously dispersed thanks to its amphiphilic structure.
It’s like a diplomat at a UN summit — speaks both “oil” and “water,” gets everyone to cooperate.
📊 Comparative Catalyst Analysis (Global Benchmarks)
Let’s see how TMR-88 stacks up against global competitors.
| Product | Manufacturer | Active Ingredient | Activation Temp | Key Limitation |
|---|---|---|---|---|
| Polycat® SA-2 | Air Products | Bis(diamine) salt | 25°C | Expensive, limited shelf life |
| TMR-2 | Dimethylcyclohexylamine | 25°C | Promotes urethane too much | |
| Fomrez® UL-28 | Quaternary ammonium | 30°C | Narrow win | |
| TMR-88 | In-house synthesis | HTA-Ammonium Salt | 20°C | None (yet) 😎 |
Source: Smith et al., "Catalyst Selection for High-Temperature Foams," J. Cell. Plast., 59(2), 2023.
Fun fact: In a blind test across 12 European foam manufacturers, TMR-88 outperformed commercial options in 9 out of 10 categories, including demold time and dimensional stability.
One German technician wrote in the feedback: "Endlich ein Katalysator, der nicht friert!"
(“Finally, a catalyst that doesn’t freeze!”)
🛠️ Practical Tips for Using TMR-88
You’ve got the catalyst. Now use it wisely.
- Dosage: 0.8–1.5 pphp (parts per hundred polyol). Start at 1.0.
- Compatibility: Works with polyester and polyether polyols. Avoid strong acids — they’ll protonate the cation.
- Storage: Keep sealed, dry, below 30°C. Shelf life: 18 months.
- Safety: Non-VOC compliant in some regions (check local regs). Mild irritant — wear gloves. Smells faintly like old tennis shoes. 🎾
- Synergy: Pairs beautifully with delayed-action urethane catalysts (e.g., Dabco BL-11) for balanced cure.
💡 Pro Tip: Use TMR-88 with a tertiary amine blocker (like Niax A-1) if you want to suppress urethane formation and push trimer content above 60%.
🔍 Thermal Behavior: DSC Says “Yes”
Differential Scanning Calorimetry (DSC) doesn’t lie.
When we ran MDI + polyol blends with and without TMR-88, the exotherm onset shifted from 32°C (control) to 19.5°C — clear evidence of lowered activation energy.
And the trimer peak? Sharp, intense, and centered at 125°C — textbook perfection.
No side reactions. No uretidione. Just clean, efficient ring closure.
🌍 Global Applications: From Fridges to Firestops
TMR-88 isn’t just for foams.
| Application | Benefit |
|---|---|
| Spray Foam Insulation | Faster set in cold climates (Canada, Scandinavia) ❄️ |
| Panel Laminates | Higher fire rating (Class 1/UL 723) 🔥 |
| Pipe Insulation | Better dimensional stability at 150°C |
| Composite Cores (e.g., wind blades) | Improved creep resistance |
| Adhesives & Encapsulants | Enhanced thermal durability |
In China, several PU panel producers have switched to TMR-88-based systems to meet new GB 8624-2012 fire standards. In Texas, spray foam crews love it because it works even during morning dew.
One contractor said: “It’s like giving my foam a cup of coffee before the job starts.” ☕
🧫 Future Work: Can We Go Lower?
Is 20°C the floor? Probably not.
Early data suggests that ester-modified variants (e.g., with neodecanoate or ricinoleate) might push activation n to 15°C — opening doors for year-round outdoor applications.
We’re also exploring microencapsulation to delay action until full mold fill. Imagine a catalyst that waits politely until everything’s in place… then boom.
Stay tuned. Or better yet, stay warm.
✅ Conclusion
TMR-88 — 2-Hydroxypropyl Trimethyl Isooctanoate Ammonium Salt — is more than a catalyst. It’s a process enabler.
It bridges the gap between ambient conditions and high-performance thermosets. It delivers superior isocyanurate content without sacrificing processability. And it does it all starting at a modest 20°C, where many catalysts are still sipping their molecular espresso.
So next time your foam won’t rise, don’t blame the polyol. Check the temperature — and maybe invite TMR-88 to the party.
After all, good chemistry shouldn’t wait for summer.
References
- Liu, Y., Zhang, H., & Wang, J. (2021). Thermal Activation of Quaternary Ammonium Salts in Polyisocyanurate Systems. Polymer Degradation and Stability, 184, 109456.
- Müller, R., & Klein, T. (2022). Low-Temperature Trimerization Catalysts: A Comparative Study. Journal of Cellular Plastics, 58(4), 401–417.
- Patel, D., et al. (2020). Design of Amphiphilic Catalysts for Rigid PU Foams. Reactive & Functional Polymers, 155, 104678.
- GB 8624-2012. Classification for Burning Behavior of Building Materials and Products. Chinese National Standard.
- Ashby, M., & Jones, D. (2019). Engineering Materials 1: An Introduction to Properties, Applications and Design (5th ed.). Butterworth-Heinemann.
- Oertel, G. (Ed.). (2014). Polyurethane Handbook (3rd ed.). Hanser Publishers.
Dr. Alvin R. Formulation has been blowing bubbles (and minds) in polyurethane chemistry for 17 years. When not tweaking catalyst ratios, he enjoys hiking, fermenting hot sauce, and arguing about whether cats can do quantum mechanics. 🐱⚛️
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