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Method for producing 4,4'-methylene (diphenyldiisocyanate)

A technology of diisocyanate and diphenylmethane, which is applied in the preparation of isocyanic acid derivatives, purification/separation of isocyanic acid derivatives, chemical instruments and methods, etc., can solve the problems of lack of application fields and high cost of solid-state transportation

Active Publication Date: 2007-05-23
COVESTRO DEUTSCHLAND AG
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] While there is a market for 2,4'-MDI distillates for specific uses, there are other markets and regions where it is practically impossible to sell these products due to lack of specific application areas
However, especially for the production of 4,4'-MDI, it is very advantageous to have a production location close to the buyer's market, since the product is solid at room temperature, but can only be stored in a liquid state due to the tendency of the product to form dimers. time, so it is expensive to ship as a solid, and must be kept cool over long distances
If there is no demand for 2,4'-MDI in such a market, the production of only the process product 4,4'-MDI and polyMDI in the proportions required by the market and in terms of the quality specified by the market will cause problems

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0027] a) Production of diamine and polyamine mixtures

[0028] Under stirring condition at 25 ℃, 2600 grams of aniline and 1000 grams of formalin (30% by weight of formaldehyde solution, based on the weight of the solution) are vigorously mixed in a stirring vessel, and in the process, the mixture is heated to 60°C. The stirrer was turned off and the aqueous phase which settled on top was removed by separation. While stirring again, 680 g of a 30% by weight aqueous hydrochloric acid solution were mixed in while cooling to maintain the temperature at 45°C. After a further 15 minutes of stirring at this temperature, instead of cooling, heating was used and the mixture was heated homogeneously to 140° C. at a pressure of 5 bar within 120 minutes and maintained at this temperature for 15 minutes.

[0029] The mixture was cooled to 100° C., the pressure was released to normal pressure, and 540 g of a 50% by weight aqueous sodium hydroxide solution was added for neutralization wh...

Embodiment 2

[0049] a) Production of diamine and polyamine mixtures

[0050] Under stirring condition at 30 DEG C, 1800 grams of aniline and 1000 grams of formalin (30% by weight of formaldehyde solution, based on the weight of the solution) are vigorously mixed in a stirring vessel, and in the process, the mixture is heated to 80°C. The stirrer was turned off and the aqueous phase which settled on top was removed by separation. While stirring again, 230 g of a 30% by weight aqueous hydrochloric acid solution were mixed in while cooling to maintain the temperature at 45°C. After a further 15 minutes of stirring at this temperature, instead of cooling, heating was used and the mixture was heated homogeneously to 140 DEG C. at a pressure of 5 bar within 150 minutes and maintained at this temperature for 20 minutes.

[0051]The mixture was cooled to 100° C., the pressure was released to normal pressure, and 180 g of a 50% by weight aqueous sodium hydroxide solution was added for neutralizat...

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PUM

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Abstract

The present invention relates to a process for the production of 4,4'-diphenylmethane diisocyanate (4,4'-MDI) by acid-catalyzed condensation of aniline with formaldehyde, reaction of the mixtures of di- and polyamines obtained with phosgene to form the corresponding mixture of MDI isomers and homologues (di- and polyisocyanates of the diphenylmethane series) and subsequent separation of the mixture by distillation to form 4,4'-MDI and polymeric MDI.

Description

technical field [0001] The present invention relates to the method for producing 4,4'-diphenylmethane diisocyanate (4,4'-MDI), described method comprises: carry out acid-catalyzed condensation of aniline and formaldehyde, obtain the mixture of diamine and polyamine and light Gas reaction to form the corresponding mixture of MDI isomers and homologues (diphenylmethane series of diisocyanates and polyisocyanates), and then separate the mixture by distillation to form 4,4'-MDI and polyMDI. In this process, any secondary stream formed when the mixture of diisocyanate and polyisocyanate is processed to form 4,4'-MDI is preferably returned to the processing step of the polyisocyanate mixture, and / or mixed into the polyMDI, so that only 4,4'-MDI in industrial purity and commercially available polyMDI are obtained as process products. Background technique [0002] Industrial-scale production of 4,4'-MDI is usually carried out by the following process steps: acid-catalyzed condensat...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C265/14C07C263/10C07C263/20
CPCC07C263/10C07C263/20C07C265/14C07C265/12
Inventor B·柯根霍夫J·S·博尔顿
Owner COVESTRO DEUTSCHLAND AG
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