Covestro Deutschland Ag

Jan Busch

Friedhelm Steffens

Frank Richter

Andreas Hecking

Reinhard Halpaap

Josef Sanders

Oswald Wilmes

Tim Loddenkemper

Stefan Groth

Christian Steffens

Jürgen Arras

Dietmar Wastian

Manfred Keller-Killewald

Holger Conzelmann

Klaus Tidow

Markus Hollaus

The invention relates to an improved process for making available the coproduct hydrogen chloride obtained in the preparation of an isocyanate by phosgenation of the corresponding amine for a desired subsequent use (i.e. a chemical reaction), in which part of the total hydrogen chloride obtained is isolated in gaseous form at a pressure which is higher than the pressure desired for the subsequent use of the hydrogen chloride by lowering the pressure of the crude product from the phosgenation and the remaining part of the total hydrogen chloride obtained is separated off at a pressure lower than that desired for the subsequent use from the liquid crude product from the phosgenation remaining after lowering of the pressure and is subsequently compressed to a pressure which is higher than that desired for the subsequent use, and in which the two hydrogen chloride streams obtained in this way are, preferably together after having been combined, purified so as to give a purified hydrogen chloride at a pressure which is higher than the pressure desired for the subsequent use.

Process for providing hydrogen chloride for chemical reactions

The invention relates to a novel method for producing polyisocyanurates comprising isocyanate groups, based on 2,4- and 2,6-toluylene diisocyanate (TDI) and to the use thereof in coating compositions.

Method for producing TDI-trimerisates with high purity

The invention relates to polyisocyanates comprising urethane groups, based on toluylene diisocyanate, to a method for their production, and to their use as the polyisocyanate component in one- and two-component polyurethane coatings.

Method for producing light-coloured TDI-polyisocyanates

The present invention relates to a continuous process for preparing a polyisocyanate, in which a polyamine and phosgene are first converted predominantly to carbamoyl chloride and amine hydrochloride and only in minor proportions to polyisocyanate, and a portion of the carbamoyl chloride- and amine hydrochloride-containing reaction mixture thus obtained is recycled into the reaction with phosgene, wherein polyamine, phosgene and the carbamoyl chloride- and amine hydrochloride-containing reaction mixture are mixed intimately in a mixing unit. The portion of the carbamoyl chloride- and amine hydrochloride-containing reaction mixture which is not recycled into the phosgenation is worked up to give the polyisocyanate.

Process for preparing polyisocyanates

The present invention relates to a process for obtaining organic isocyanate from a phosgenation product comprising the isocyanate, comprising the following steps: a) workup to the phosgenation product, the workup comprising at least one distillation step in which a first portion of the organic isocyanate is removed as distillate and a distillation residue comprising a second portion of the organic isocyanate is obtained, b) workup of the distillation residue obtained in a), the workup comprising at least one distillation step which is conducted at a temperature of up to 110&#xb0; C. at a pressure of not more than 1 mbar, wherein at least 50% by weight of the second portion of the organic isocyanate is removed from the distillation residue.

Process for obtaining organic isocyanates from distillation residues from isocyanate preparation

The invention relates to a method for producing an isocyanate by reacting the corresponding primary amine with phosgene in a reactor () which comprises at least one reaction zone () and a quenching zone () arranged below said reaction zone, having the following steps: (i) introducing a gaseous amine flow () and a gaseous phosgene flow () into the reactor () and reacting the flows in the reaction zone () into a product gas flow () comprising isocyanate and hydrogen chloride and optionally excess phosegene; (ii) introducing the product gas flow () into the quenching zone (), in which the product gas flow is cooled by injecting a quenching liquid () via at least one quenching nozzle () such that a liquid flow () comprising the quenching liquid () and isocyanate and a gaseous flow () comprising hydrogen chloride and optionally phosgene are obtained; and (iii) separating the isocyanate from the liquid flow () obtained in step (ii); wherein the temperature T*, of the wall of the reaction zone () directly above the quenching zone () is kept at a value which lies maximally 4.0%, preferably maximally 2.0%, below the maximum temperature, T, of the wall of the reaction zone, said maximum temperature being specified in Kelvin.

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Dusseldorf, Germany

Jan Busch