TDI is toluene diisocyanate, and there are two isomers, 2,4-TDI and 2,6-TDI.
The most common TDI product in TDI industrial products is TDI-80 or TDI-80/20, commonly known as T80, which is a mixture of 2,4-TDI and 2,6-TDI with a mass ratio of 80:20. Similarly, TDI-65 (TDI-65/35, T65) is a mixture of 2,4-TDI and 2,6-TDI with a mass ratio of 65:35, while TDI-100 (T100) is all composed of 2,4-TDI.
The molecular formula of TDI is: C9H6N2O2, and the molecular weight is 174.15, so no matter what type of TDI product, the NCO content is fixed at 48.2%.
The freezing points of TDI-100/TDI-80/TDI-65 vary depending on the number of isomers present, which are：19.5~22;11.5~14;3.5~7.At the same time, because of the presence of isomers, the activities of the three are also very different. The higher the content of 2,4-TDI, the higher the product activity. Therefore, although TDI-80 is the most widely used, TDI-100 is more popular in systems with longer operating time requirements.
TDI-65 is mainly used for high load-bearing and high rebound polyurethane soft foams, polyester polyurethane foams, etc.
TDI-80 is mainly used for polyurethane soft foams, polyurethane elastomers, coatings, adhesives, etc.
TDI-100 has a regular structure and is mainly used for the synthesis of special prepromers, mainly for cast polyurethane elastomers and polyurethane coatings.