There have different series of polyurethane prepolymers, and there are great differences between different series. Although the MDI and TDI series appear to be in the same category, they are also fundamentally different.
In the synthesis of polyurethane prepolymers, traditional methods generally use TDI as the raw material for diisocyanate, while there are relatively few methods that use MDI as the raw material. MDI is not just pure MDI, crude MDI, liquefied MDI, and mixtures of MDI isomers (such as MDI-50 and Huntsman 3051). Different fields have different target MDI products. Compared with TDI, MDI has its own advantages. For example, MDI is less toxic than TDI and is relatively cheap. Using MDI to replace the prepolymer synthesized by TDI can effectively reduce the content of free TDI, which can not only protect the health of production operators and construction personnel, but also protect the environment. At the same time, using MDI instead of TDI to synthesize polyurethane prepolymer is less harmful to the human body and is more conducive to environmental protection.
The molecular structure of MDI is symmetrical, and coatings made of MDI have better impact resistance and flexibility. In addition, MDI has cost advantages. TDI is generally more expensive than MDI. The use of MDI to synthesize polyurethane prepolymer has the advantages of low cost, easy availability of raw materials, and high economic benefits.
If polyurethane prepolymer is used without considering other uses, it should be used correctly in the future so that it can be used more effectively and achieve better results.