Method for producing xylylene diisocyanates in the gaseous phase

Patent metadata

Field	Value
Publication number	US-10294198-B2
Application number	US-201515302724-A
Country	US
Kind code	B2
Filing date	Apr 13, 2015
Priority date	Apr 11, 2014
Publication date	May 21, 2019
Grant date	May 21, 2019

Abstract

The invention relates to a method for producing the isomers 1,3- and/or 1,4-xylylene diisocyanates by reacting the corresponding 1,3- and/or 1,4-xylylene diamines with phosgene in the gaseous phase.

First claim

The invention claimed is:

1. A method for producing 1,3- and/or 1,4-xylylene diisocyanate (XDI) by phosgenation of 1,3- and/or 1,4-xylylenediamine (XDA) with phosgene in the gas phase in a reactor connected to a vaporizer circuit, the method comprising:
vaporizing xylylenediamine/xylylenediamines in a vaporizer in the vaporizer circuit, optionally with addition of stabilizers and/or an inert gas, at a pressure of <1000 mbar, with a mean residence time in the vaporizer circuit of 5 to 90 minutes and at a temperature in a pumping circuit connected to the vaporizer circuit of 40 to 190° C., wherein the temperature is maintained by cooling in a first heat exchanger in the pumping circuit,
heating XDA vapors a further 10-100° K. above the vaporization temperature of the XDA at prevailing pressure in a second heat exchanger in the pumping circuit, and
reacting the vapors from the second heat exchanger connected to the reactor with phosgene by gas-phase phosgenation in the reactor.

2. The method according to claim 1 , wherein the xylylenediamine/ xylylenediamines is vaporized at 350 to 900 mbar.

3. The method according to claim 1 , wherein the xylylenediamine/ xylylenediamines is vaporized at 500 to 800 mbar.

4. The method according to claim 1 , wherein the mean residence time in the vaporizer circuit is 10 to 60 minutes.

5. The method according to claim 1 , wherein the mean residence time in the vaporizer circuit is 10 to 45 minutes.

6. The method according to claim 1 , wherein the temperature in the pumping circuit of the vaporization is 60 to 170° C.

7. The method according to claim 1 , wherein the temperature in the pumping circuit of the vaporization is 60 to 150° C.

8. The method according to claim 1 , wherein the XDA vapors are heated by a further 20 to 50 K above the vaporization temperature of the XDA under prevailing pressure, and then reacted with phosgene via gas-phase phosgenation.

9. The method according to claim 1 , wherein the XDA is admixed prior to vaporization with one or more stabilizers in concentrations of 50-2000 ppm based on XDA.

10. The method according to claim 9 , wherein the stabilizers are sterically hindered phenols and/or alkyl-substituted benzosulfonic acids.

11. The method according to claim 1 , wherein XDA droplets are separated by a droplet separator between the steps of vaporization of the XDA in the vaporizer circuit and superheating of the XDA vapors in the pumping circuit and/or after superheating of the XDA vapors in the pumping circuit.

12. The method according to claim 11 , wherein the apparatus used for the superheating also functions as droplet separator(s).

Assignees

• Covestro Deutschland Ag

Inventors

• Halpaap Reinhard
• Weber Ralph
• Sanders Josef
• Richter Frank
• Schadlich Elsa Karoline
• Schymura Armin
• Ehrig Martin
• Hoch Sebastian
• Maleika Robert

Classifications

• C08G18/7642

  containing at least two isocyanate or isothiocyanate groups linked to the aromatic ring by means of an aliphatic group having a primary carbon atom next to the isocyanate or isothiocyanate groups, e.g. xylylene diisocyanate or homologues substituted on the aromatic ring · CPC title

• C08G18/758 Primary

  containing two or more cycloaliphatic rings · CPC title

• G02B1/041

  Lenses · CPC title

• C08K5/315

  Compounds containing carbon-to-nitrogen triple bonds · CPC title

• C08G18/3876

  containing mercapto groups · CPC title