Diethyltoluenediamine
The chain extender that makes aromatic spray polyurea gel in seconds and build hardness and green strength.
Diethyltoluenediamine (DETDA) is an aromatic diamine: a toluene ring carrying two amine groups and two ethyl groups. Commercial DETDA is a liquid mixture of mainly 3,5-diethyltoluene-2,4-diamine and -2,6-diamine isomers, sold as Ethacure® 100 and equivalents. Its molecular weight is about 178 g/mol.
In spray polyurea B-sides, DETDA reacts very quickly with isocyanate to form hard segments between the flexible polyetheramine soft segments. It controls gel time, hardness and early strength, and is also used in reaction injection molding (RIM) and cast elastomers.
The ethyl groups next to the amines partly shield them, yet DETDA remains extremely fast with aromatic isocyanates. With two primary amine groups, its amine equivalent weight per NH₂ is about 89. Raising the DETDA level shortens gel time and increases hardness.
DETDA is harmful if swallowed or absorbed and is irritating; some aromatic amines carry long-term health warnings. Check the SDS, wear gloves and eye protection and avoid mist.
It is a highly reactive aromatic diamine that forms urea hard segments within seconds of meeting isocyanate, driving the rapid gel of spray polyurea.
DMTDA reacts more slowly, giving longer flow and better wet-out. Formulators blend them to tune gel time.
