Process for the production of methylene diphenyl diisocyanate isomer mixtures with high 2,4'- methylene diphenyl diisocyanate purity

Process for the production of methylene diphenyl diisocyanate isomer mixtures with high 2,4'- methylene diphenyl diisocyanate purity

  • CN 104,039,757 A
  • Filed: 11/19/2012
  • Published: 09/10/2014
  • Est. Priority Date: 11/30/2011
  • Status: Active Grant
First Claim
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1. the method for the mixture of production methylenediphenyl diisocyanates (MDI) isomer, comprising:

  • By making the reaction under acid catalyst exists of aniline and formaldehyde form methylenediphenyl diamines and the polyamines of diphenylmethane series;

    Make the methylenediphenyl diamines of diphenylmethane series and polyamines phosgenation with the mixture of preparation MDI isomer and polymeric MDI;

    From the mixture separation of MDI isomer and polymeric MDI, go out the first fraction, the described first step is divided the described MDI isomer that comprises at least 98 % by weight, and described MDI isomer comprises 2 of at least 56 % by weight, 4 '"'"'-MDI and 2,2 '"'"'-MDI, the gross weight based on described the first fraction;

    WithFrom described the first fraction, isolate the second fraction, the described MDI isomer that comprises at least 99 % by weight is divided in the described second stage, and described MDI isomer comprises 2 of at least 95 % by weight, 4 '"'"'-MDI, the gross weight based on described the second fraction.

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