Polymeric methylenediphenyl isocyanate

The basic building blocks for polyurethanes are polyisocyanates and macroglycols, also called polyols. The commonly used polyisocyanates are tolylene-diisocyanate (TDI), diphenyimethane diisocyanate or methylenediphenyl isocyanate (MDl), and polymeric methylenediphenyl isocyanate (PMDI) mixtures manufactured by phosgenating aromatic polyamines derived fi-om the acid-catalyzed condensation of aniline and formaldehyde. MDl and PMDI are produced by the same reaction, and separation of MDl is achieved by distillation. The synthetic routes in the manufacture of commercial polyisocyanates are summarized in Figme 4.28. 

Polyurethane foam was made by stepwise polymerization of methylenediphenyl isocyanate CH2(C6H4NCO)2 and 2-hydroxymethyl-2-ethyl-l,3-propanediol in the mole ratio of 1 0.7. Calculate the weight fraction solubles and the total crosslink density in the network if the extent of reaction of the isocyanate is 90%. 

Benzene, 1,1 -methylenebis(isooyanato- Crude MDI 4,4 -,2,4 -,2,2 -Diisocyanatodiphenylmethane EINECS 247-714-0 Generic MDI Isocyanic acid, methyl-enediphenylene ester Methylenediphenyl diisocyanate Non-isomeric-specific MDI PMDI Polymeric 4,4-methylenediphenyl diisooyanate Polymeric MDI. 

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