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DETDA: A Liquid that Delivers the Hard and Tough

published on May 17, 2019

Diethyl toluenediamine (DETDA), is also commonly known in the polyurethane industry by the brand names Ethacure 100, Lonza DETDA 80, and Nitroil ADA I80.

One of the commonly used workhorses in polyurethane industry, DETDA has low viscosity and is easy to handle. Its unmatched liquidity character enables manufacturers to perform room temperature processing and curing. DETDA also offers excellent dynamic properties comparable to 4,4'-Methylenebis(2-chloroaniline), also known as MOCA, but with less toxicity and dust concerns in the production plant. Its fast curing leaves little room for environmental factors like humidity and oxidation to affect the quality of products featuring DETDA.

DETDA is widely used in reaction injection molding (RIM) and the spray polyurea field.  In these applications, DETDA allows the flexibility of using itself as a liquid carrier and solvent for other solid curatives like MOCA, for example, and makes it possible to bring variety of needed properties into the final product. Please see below a RIM example, where we compare instances when DETDA was used as a sole amine curative alongside a DETDA/MOCA (US 4631298) solution:

  Mol Ratio Gel Time Tensile, psi Elongation, % Die C pli
DETDA 100% < 1 sec 3841 190 432
DETDA 50% 3.6 sec 4755 150 750
MOCA 50%

Another example of DETDA as a coatings co-curative is in the spray coating formulation reported in patent US8536297 B2. As we can clearly see, the processing time and physical properties can be adjusted as needed conveniently for different requirements.

DETDA as Co-Curative in Coatings

Air products PPT-80A 3.52%nco index 1.20
DOP wt%      5%
CaCO3 wt%       5% 
DETDA eq% 10 20 33 40
SBMDA eq% 90 80 67 60
Pot-life (min) ~240 176 94 69
Hardness (A) 28 40 50 52
Tensile (PSI) 269 372 429 430
Elongation (%) 1177 1019 716 649
Tear (lb/in) 49 67 89 98


Compared with DMTDA (dimethylsulfitetoluenediamine), DETDA doesn’t have the offensive sulfur odor, and the cured material is harder with better physical properties.

Along with its uses in polyurethane and polyurea curatives, we see DETDA used as a hardener and crosslinker for epoxies.  Its two amine groups react with four epoxy groups and form a crosslinking center that resists high temperatures, even with bisphenol A. By adjusting the amount used, DETDA gives the fast reaction and range of crosslinking when needed. Please see below a few examples of these structures.

detda-1

Here’s a data example of DETDA as an epoxy curing agent, compared with MDA curing:

   Epoxy Epon 828 cured w/ DETDA MDA DETDA @100C
Tensile Strength, psi 11,000 11,200 8,000
Tensile Modulus, psi 380,000 420,000 290,000
Flexural Strength, psi 18,000 17,000 13,000
Flexural Modulus, psi 390,000 420,000 280,000
Elongation, percent 4.9 4.5 5.4
Izod Impact, ft-lb/in 0.4 0.4  
Deflection Temperature, °C 169 160  
Water Boil, % weight gain 1.1 1  
Acetone Boil, % weight gain 1.6 0.5  

Made from m-TDA(m-toluene diamine), DETDA was formed by catalyzed ethylation to add two diethyl groups. The aromatic ring is activated by the two ethyl group, through their donation of electron negativity to the ring.  This change makes DETDA more reactive in the isocyanate reaction.

DETDA can also be used as a reactive catalyst in the curing process.  When the proper amount is added to polyols, DETDA accelerates the curing speed. This bigger-than-normal “catalyst” quantity avoids the sensitivity when using a small stream catalyst, and its shelf life is much longer than metal based catalysts.  

detda1We see a large volume of DETDA used spray polyurea coatings, RIM, hot/cold cast polyurethanes, composites, hardener and crosslinker in epoxies.

DETDA coloring is a reflection of its impurity level and stability: the azobenzene resulting from arylamine reacted with UV and oxygen, affected by impurity level. Azobenzene has a long-range electron resonance with aromatic region to emit a strong color absorption.  

A comparison of Gantrade’s DETDA (left) and a competitor’s sample (right) exposed in air reveals the slower color-darkening of our DETDA.

Day 1 at ambient temp Day 2 at ambient temp
detda-2 detda-3

The proton NMR and GC graphs also depict the purity of this product.

detda-puritydetda-purity-2

For those working in spray polyurea coatings, polyurethanes, composites, and epoxies, you will be hard-pressed to find a better alternative to DETDA for your processing needs. Contact Gantrade today, and our customer support team will collaborate with you to meet your DETDA supply needs.

Topics: detda