Today we will introduce the liquefied MDI with the largest volume in the modified MDI. It is based on pure MDI as raw material, and the appropriate catalyst (such as cyclic phosphine oxide compound) is selected. After heating together, the MDI self-polymerizes and releases carbon dioxide to form a liquid mixture containing part of the carbonized diimide group (-N=C=N-).Of course, due to the different modification methods, the modified MDI can be mainly divided into MDI modified by carbamate, MDI modified by carbonized diimide, MDI modified by diazocyclobutanone imine and MDI modified by carbamate and diazocyclobutanone imine.Since pure MDI is solid at room temperature, it is inconvenient to use, and 4,4-MDI has poor stability during storage. Pure MDI needs to be heated and melted into a liquid before use, and repeated heating affects the quality of MDI, so modified MDI is generally used.
Which industries are modified MDI generally used in?
So what industries are modified MDI generally used in?According to Xiaobian's understanding, modified MDI has the advantages of good stability and delicate pores, so it has a high popularity and utilization rate in the automotive industry and the furniture industry.Not only that, because modified MDI is more convenient to use than pure MDI, it is also used in various occasions such as soles, solid tires, car bumpers, and armrests, which can be described as having great development potential.
Modified MDI, the popular title in the market after MDI is modified, currently there is no unified and clear definition in the market.In layman's terms, the mainstream modified MDI on the market is divided into three types, namely：
(1) Carbonized diimide modified MDI, that is, liquefied MDI, also known as monomer modified MDI, is pure MDI through its own condensation reaction, in which carbonized diimide groups (-N=C=N-) are introduced, the purpose is to make it easier to store, transport, and process.It is mainly used in the fields of molding, self-skinning, shoe materials, etc.
(2) MDI-50, 4-4MDI (pure MDI) and 2-4MDI are mixed in a ratio of about 50% each. It is actually a special blended modified MDI, which is mainly used in runway adhesives, adhesives, coatings and other fields.
(3) MDI prepromers, reactive semi-finished products containing active hydroxyl groups, mercapto groups, amino groups, etc. or polyethers thereof react with excess MDI to form carbamate bonds and are terminated by NCO groups.According to the different modified raw materials required, they are used downstream of the target, mainly in automotive molding, furniture bedding, adhesives, elastomers and other fields.