Isosyanaatit

Isosyanaatit, or isosyanates, are a class of organic compounds that contain the isocyanate functional group −N=C=O. They are typically di- or polyfunctional and are widely used as reactive intermediates in polymer chemistry. The most important subgroups are aromatic diisocyanates, such as toluene diisocyanate (TDI) and methylene diphenyl diisocyanate (MDI); and aliphatic diisocyanates, such as hexamethylene diisocyanate (HDI) and isophorone diisocyanate (IPDI).

Isocyanates are usually colorless liquids or solids at room temperature and react readily with nucleophiles such as water, alcohols and amines. They are especially valued for their ability to form polyurethane linkages when reacted with polyols. In polymerization, diisocyanates and polyols combine to produce polyurethane foams, coatings, adhesives and elastomers. In moisture-containing environments, isocyanates hydrolyze to amines and carbon dioxide, a reaction that can contribute to foam formation and exothermic processes in polyurethane production.

Safety and handling are central considerations with isosyanates. They are potent respiratory and skin irritants and can cause sensitization, including occupational asthma, in exposed workers. Handling requires adequate ventilation, containment, and personal protective equipment, along with substitution with less hazardous materials where feasible.

Industrial production of diisocyanates typically involves phosgenation of the corresponding diamines or related synthesis routes to yield common isosyanates such as TDI, MDI, HDI and IPDI. They are stored under controlled conditions to minimize moisture uptake and unintended reactions.

Major applications include polyurethane foams for furniture and bedding, rigid foams for insulation, coatings, adhesives, sealants and elastomeric materials used across construction, automotive and consumer products.