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US 8,273,915 B2Granted
Process for preparing isocyanates
AssigneeBASF SE
InventorsBernd Rumpf, Michael Bock, Martin Fiene, Eckhard Stroefer
Life of this patent
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Abstract
The invention provides a process for preparing polyisocyanates, comprising the steps of a) reacting amines with phosgene, b) removing hydrogen chloride, excess phosgene and, if appropriate, the solvent from the reaction mixture, c) separating the liquid mixture from step b) into a liquid phase and a gaseous phase, d) working up the gaseous phase from step c) to give the polyisocyanate.
Claims20
A process, comprising
- reacting an amine with phosgene to obtain a crude isocyanate mixture comprising an isocyanate, a high-boiling component, hydrogen chloride, unreacted phosgene, and, optionally, solvent,
- removing the hydrogen chloride, unreacted phosgene and, optionally, the solvent from the crude isocyanate mixture to obtain a second mixture comprising an isocyanate and a high-boiling component,
- preheating the second mixture,
- after said preheating, separating, in a helical tube evaporator, the second mixture into a liquid phase comprising the high-boiling component and a gaseous phase comprising the isocyanate, and
- isolating the isocyanate from the gaseous phase after said separating.
2 more elements
Dependencies are inferred from the claim text.