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|Section2= |Section7= |Section8= }} Methylene diphenyl diisocyanate, most often abbreviated as MDI, is an aromatic diisocyanate. It exists in three isomers, 2,2'-MDI, 2,4'-MDI, and 4,4'-MDI, however, the 4,4' isomer is most widely used. This isomer is also known as Pure MDI. MDI reacts with polyols in the manufacture of polyurethane. It is the most produced diisocyanate, accounting for 61.3% of the global market in the year 2000. ==Production== Total world production of MDI and polymeric MDI is over 5 million tonnes per year (Mt/a in 2011). The largest producer is Bayer followed closely by Yantai Wanhua. Other major producers are BASF, BorsodChem, Dow, Huntsman, Nippon Polyurethane Industry, OCI. All major producers of MDI are members of the International Isocyanate Institute, whose aim is the promotion of the safe handling of MDI and TDI in the workplace, community and environment. The first step of the production of MDI is the reaction of aniline and formaldehyde, using hydrochloric acid as a catalyst to produce a diamine precursor under the chemical formulation: 2 C6H5NH2 + CH2O → CH2(C6H4NH2)2 + H2O Then, these diamines are treated with phosgene to form an MDI. The isomer ratio is determined by the isomeric composition of the diamine. Distillation of the MDI mixture gives polymeric MDI (a mixture of oligomeric polyisocyanates) and an MDI isomer mixture which has a low 2,4' isomer content. Further purification entails fractionation of the MDI isomer mixture. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Methylene diphenyl diisocyanate」の詳細全文を読む スポンサード リンク
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