Toluene Diisocyanate (TDI) is an important organic compound primarily used in the production of polyurethane foams. It is a type of diisocyanate, meaning it contains two reactive isocyanate (-NCO) groups. TDI is typically a mixture of two isomers: 2,4-TDI (a major isomer) and 2,6-TDI (a minor isomer), with the most common commercial mixture containing about 80% 2,4-TDI and 20% 2,6-TDI.
TDI is a colorless to pale yellow liquid at room temperature, known for its strong odor and highly reactive nature, particularly with water, alcohols, and amines, making it an essential ingredient in various polyurethane products.
Properties of Toluene Diisocyanate (TDI):
- Appearance: Colorless to pale yellow liquid at room temperature.
- Odor: Strong, pungent odor, characteristic of isocyanates.
- Density: 1.22–1.24 g/cm³ at 20°C.
- Boiling Point: 250–255°C (482–491°F).
- Melting Point: -28°C (-18.4°F).
- Viscosity: 1.2–1.5 cP at 25°C (low viscosity).
- Solubility: Insoluble in water but soluble in organic solvents like acetone, benzene, toluene, and ether.
- Vapor Pressure: Low vapor pressure at room temperature (about 0.1 mm Hg at 25°C), but can form potentially hazardous vapors at higher temperatures.
Key Uses of Toluene Diisocyanate (TDI):
- Polyurethane Production: Used in the manufacture of flexible polyurethane foams, commonly used in furniture, automotive seating, and insulation.
- Coatings: Used in coatings, adhesives, and sealants.
- Rubber: Used in the production of synthetic rubber.