Hexamethylene diisocyanate

DescriptionThis diisocyanate compound is used in the manufacture of various polyurethane products: elastic and rigid foams, paints, lacquers, adhesives, bin ding agents, synthetic rubbers, and elastomeric fibers.

Uses1,6-Hexamethylenediisocyanate is a chemical intermediate used in the production of urethane products.

UsesCross-linking agent (hardener) in the production of polyurethane materials such as car paints, dental materials, and contact lenses

UsesHexamethylene diisocyanate (HDI) is one of the most common aliphatic disocyanates, It is a monomer used in the production of polyurethane foams and exceptionally high-quality coatings, and is found in some industrial paints and spray painting operations. It is a compound which reacts readily with water and alcohols (Von Burg 1993). It has a vapor pressure of 0.05 mm Hg at room temperature, but can be present in aerosol form allowing a potentially higher exposure to individuals. The HDI-BT trimer is often present for similar industrial uses. It would be expected to have a lower vapor pressure; however, the aerosol form can also be present, allowing potentially higher exposure of HDI-BT to individuals. Hexamethylene diisocyanate reacts slowly with water to form carbon dioxide (HSDB 1996). The base-catalyzed reaction of Hexamethylene diisocyanate with alcohols should be carried out in inert solvents; the reaction may occur with explosive violence in the absence of solvents (NFPA 1994).

General DescriptionA colorless crystalline solid. Toxic by ingestion and is strongly irritating to skin and eyes. 1,6-Diisocyanatohexane is used to make nylon.

PreparationHexamethylene diisocyanate (HDI) is prepared by the phosgenation of hexamethylenediamine (section lO.2.2(b)): H2N-(CH2)6-NH2--COCl2-->OCN-(CH2)6-NCOHexamethylene diisocyanate is a liquid with a volatility of the same order as that of tolylene diisocyanate. It is respiratory irritant and also has powerful effects on the skin and eyes. Hexamethylene diisocyanate was one of the first diisocyanates utilized for making polyurethanes, being used to prepare fibres and moulding compounds. These applications are no longer of importance but hexamethylene diisocyanate now finds use mainly in coatings which are more light stable than those based on aromatic isocyanates.