PU foam board is made of polyurethane using plastic chemicals, in fact, pu foam board is a plastic board, but the chemical substance is polyurethane, to produce polyurethane, there are two types of substances that require at least two kinds of functions as a reactant: contains isocyanate functional group Compounds, and compounds containing active hydrogen atoms. The physicochemical properties, structure, and molecular size of these compounds will lead to polymerization, ease of processing, and isocyanate, and the main process for producing isocyanates is the reaction of amines with phosgene. The raw material amines are hydrogenated from the corresponding nitrites. For example, toluene diamine (TDA) is produced from dinitrotoluene and then converted to toluene diisocyanate (TDI). Diaminodiphenylmethane or phenylmethane is derived from The benzylbenzene forms aniline, which is then converted to diphenylmethane (MDI). The two most important aromatic isocyanates are: toluene diisocyanate (TDI) and diphenylmethane diisocyanate (MDI). TDI includes 2,4-toluene. Two isomers of diisocyanate and 2,6 toluene diisocyanate, the most important species being TDI-80 (TD-80), containing 80% of 2,4-isomer and 20% of 2,6-isomer This mixture is widely used in the manufacture of polyurethane flexible slabstock foam and molded foam, TDI, especially crude TDI and TDI/MDI blends can be used in rigid foam products, but slowly polymerized MDI Instead, TDI-polyether and TDI-polyester prepolymers are used in high-performance coatings and elastomers. In the use of prepolymers, vacuum is used to remove TDI monomers. There are three types of diphenylmethane diisocyanate (MDI). Isomers, 4,4'-MDI, 2,4'-MDI, and 2,2'-MDI, can also be implemented or even enhanced by polymerization The functional properties of the functional esters of the three isomers have an effect.