Methylene Diphenyl Isocyanate

Methylene diphenyl isocyanate (MDI) is a chemical used to make polyurethanes, varnishes, and other materials. It's a highly reactive chemical that's harmful to human health and the environment.
Properties
MDI is a versatile chemical intermediate that's used in many industries.
It's highly reactive with water, even water vapor in the air.
MDI is soluble in octane, benzene, and kerosene.
MDI is used to make polyurethane elastomers, spandex fibers, and rubber shoe soles.
Health and environmental effects
MDI can cause respiratory problems, skin effects, and cancer.
MDI is harmful to the environment and is rapidly hydrolyzed to form 4,4'-methylenedianiline (MDA).
MDI is toxic to aquatic species, soil invertebrates, and plants.
Types of MDI
Monomeric 4,4'-MDI is a white to pale yellow solid at room temperature.
Polymeric MDI (PMDI) is a dark reddish brown liquid at room temperature.
The 4,4a isomer is most widely used, and is also known as 4,4a -diphenylmethane diisocyanate.
Safety
MDI requires strict handling and containment during its manufacture, transportation, formulation, and application.