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Methylene diphenyl diisocyanate (MDI) is an aromatic diisocyanate. Three isomers are common, varying by the positions of the isocyanate groups around the rings: 2,2′-MDI, 2,4′-MDI, and 4,4′-MDI. The 4,4′ isomer is most widely used, and is also known as 4,4′-diphenylmethane diisocyanate. [3] This isomer is also known as Pure MDI.
The global market for diisocyanates in the year 2000 was 4.4 million tonnes, of which 61.3% was methylene diphenyl diisocyanate (MDI), 34.1% was toluene diisocyanate (TDI), 3.4% was the total for hexamethylene diisocyanate (HDI) and isophorone diisocyanate (IPDI), and 1.2% was the total for various others. [18]
More specifically, it is an aliphatic diisocyanate. It is a water white liquid at room temperature and is manufactured in relatively small quantities. It is also known as 4,4'-methylenedi(cyclohexyl isocyanate) or methylene bis(4-cyclohexylisocyanate) [2] and has the formula CH 2 [(C 6 H 10)NCO] 2.
1.1 Methylene diphenyl diisocyanate (MDI) 7 comments. 1.2 Sentient nerves. 12 comments. 1.3 Compression ratio vs displacement. 8 comments. 1.4 Flamethrowers.
In chronic toxicity tests, mice exposed to low levels of PPI developed no side effects. Only those mice exposed to the two highest concentrations developed any lung symptoms. [ 3 ] The two highest doses used in this study were 1.0 and 6.0 mg per cubic meter for 6 hours each day, 5 days each week for 2 years.
Methyl isocyanate (MIC) is an organic compound with the molecular formula CH 3 NCO. Synonyms are isocyanatomethane and methyl carbylamine.Methyl isocyanate is an intermediate chemical in the production of carbamate pesticides and Haffmann Bromamide Degradation (such as carbaryl, carbofuran, methomyl, and aldicarb).
MDA is also used extensively as a precursor to methylene diphenyl diisocyanate (MDI). Here, MDA is treated with phosgene to produce MDI. MDI, in turn, is a precursor to many polyurethane foams. [6] [7] Lower quantities are used as hardeners in epoxy resins and adhesives, as well as in the production of high-performance polymers. [3]
A significant undesired side reaction which occurs during the baking process produces aromatic polyamines. Urethane crosslinkers based on toluene diisocyanate (TDI) can be expected to produce toluene diamine as a side reaction, whereas those based on methylene diphenyl diisocyanate produce diaminodiphenylmethane and higher order aromatic ...