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Methylenediphenyl Diisocyanate - MDI

Метилендифенилдиизоцианат - MDI , Methylene diphenyl diisocyanate, is most often abbreviated as 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. 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.

Polyurethanes are some of the most versatile polymers in existence and can be found in numerous forms ranging from lightweight, rigid foams to dense, solid compositions and from soft, flexible foams to tough, elastomeric moldings.

The major application of 4,4'-MDI is the production of rigid polyurethane. Typically, one metric ton of polyurethane foam needs 616 kg of MDI and 386 kg of polyol, with 54 kg of pentane as a blowing agent. These rigid polyurethane foams are good thermal insulators and used in nearly all freezers and refrigerators worldwide, as well as buildings. Typical polyols used are polyethylene adipate (a polyester) and poly (tetramethylene ether) glycol (a polyether).

4,4'-MDI is also used as an industrial strength adhesive, which is available to end consumers as various high-strength bottled glue preparations.

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