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Patent Searching and Data


Title:
METHOD FOR REFINING MIXTURE OF TOLUENE DIISOCYANATE
Document Type and Number:
Japanese Patent JP2004155761
Kind Code:
A
Abstract:

To provide an improved method for recovering and refining toluene diisocyanate.

This method for refining toluene diisocyanate is provided by reboiling a bottom product of a downstream side distillation column or a feed sent to the downstream side distillation column by using steam recovered from an upstream side distillation column. An unrefined distillation feed containing ≤2 wt. % phosgene is fractionated to 3 fractions of P1 to P3 and in some cases to 4th fraction P4. The P1 is a non-condensed gas stream obtained by concentrating phosgene and/or low boiling substances, P2 is a product obtained by concentrating a solvent, P3 is a bottom product obtained by concentrating high boiling substances containing toluene diisocyanate, and P4 is a stream obtained by concentrating toluene diisocyanate containing less high boiling substances and residual substances of the reaction. By the method, it is possible to reduce a total production cost by operating the recovery and refining process of toluene diisocyanate in a good energy efficiency.


Inventors:
LOKUM HEINRICH
NOMMENSEN OVE
DALLMEYER HERMANN
HAGEN WILLI
Application Number:
JP2003168866A
Publication Date:
June 03, 2004
Filing Date:
June 13, 2003
Export Citation:
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Assignee:
BAYER AG
International Classes:
B01D3/14; B01D3/10; C07C7/04; C07C15/06; C07C263/00; C07C263/10; C07C263/18; C07C263/20; C07C265/14; C10G7/00; (IPC1-7): C07C263/20; B01D3/14; C07C265/14
Attorney, Agent or Firm:
Osamu Kawamiya
Samejima Mutsumi
Genban Sanae