Phenyl isocyanate conversion process

Patent metadata

Field	Value
Publication number	US-12030836-B2
Application number	US-202017426227-A
Country	US
Kind code	B2
Filing date	Jan 23, 2020
Priority date	Feb 7, 2019
Publication date	Jul 9, 2024
Grant date	Jul 9, 2024

Abstract

Phenyl isocyanates are removed from a solvent stream obtained from an MDI and/or PMDI manufacturing process by reaction in the presence of a carbodiimidization catalyst to form the corresponding N,N-diphenylcarbodiimides. The N,N-diphenylcarbodiimides can be recycled into the MDI and/or PMDI manufacturing process where they can react with MDI and/or PMDI to form uretonimines. The uretonimines have at most minimal effect on the properties and usefulness of the MDI and/or PMDI product and so can be left in the MDI and/or PMDI product.

First claim

What is claimed is:

1. An MDI and/or polymeric MDI manufacturing process, comprising the steps of:
a) reacting aniline with formaldehyde to produce a mixture of methylene dianiline (MDA), one or more polymethylene polyanilines having at least three aniline groups (PMDA) and unreacted aniline;
b) removing aniline from the mixture produced in step a) to produce a process stream containing the MDA, PMDA and residual aniline;
c) phosgenating the process stream from step b) in a non-polar solvent to form an isocyanate process stream containing the non-polar solvent, MDI, one or more polymethylene polyphenylisocyanates that have at least three phenyl isocyanate groups (PMDI) and at least one phenyl isocyanate;
d) separating the MDI and PMDI from the isocyanate process stream obtained in step c) by distillation to produce a solvent stream containing the non-polar solvent, greater than zero up to 10 weight percent of the at least one phenyl isocyanate based on the weight of the solvent stream and 0 to 5 weight percent, based on the weight of the solvent stream, of the MDI and/or PMDI;
e) reacting the solvent stream obtained in step d) in the presence of a catalytically effective amount of a carbodiimidization catalyst, to convert at least a portion of the at least one phenyl isocyanate to an N,N′-diphenylcarbodiimide;
f) optionally removing and/or deactivating the carbodiimidization catalyst; and
g) recycling the N, N′-diphenylcarbodiimide formed in step e), optionally the nonpolar solvent and optionally the carbodiimidization catalyst and/or residues from the deactivation of the carbodiimidization catalyst, directly or indirectly into step d).

2. The manufacturing process of claim 1 wherein the carbodiimization catalyst is one or more of a phospholene compound; a phospholidine compound; a phosphate ester; a phosphine oxide; a diazaphospholane; an oxaza-phospholane; a diazaphosphorinane; an oxazaphosphorinane; a triaryl arsine; an arsine oxide; a metallic derivative of acetylacetone; a metal complex derived from a d-group transition element and a T-bonding ligand; a urea compound; a biuret compound; an amide compound; an imide compound; and an anilide compound.

3. The manufacturing process of claim 2 wherein the carbodiimization catalyst is a phospholidine.

4. The manufacturing process of claim 2 wherein the carbodiimization catalyst is a phospholidine oxide.

5. The manufacturing process of claim 2 wherein the carbodiimization catalyst is a phospholene oxide.

6. The manufacturing process of claim 2 wherein step f) is performed and is performed by adding a chemical deactivator.

7. The manufacturing process of claim 6 wherein the chemical deactivator includes a Lewis acid.

8. The manufacturing process of claim 7 wherein the Lewis acid includes tin(II) chloride.

9. The manufacturing process of claim 1 wherein the N, N′-diphenylcarbodiimide recycled in step d) reacts with the MDI and/or the PMDI to form one or more uretonimine compounds.

Assignees

• Dow Global Technologies Llc
• Dow Portugal Produtos Quimicos Soc Unipessoal Lda

Inventors

• Hefner Jr Robert E
• Braun Helge
• Costa Armenio
• Cramm Brian

Classifications

• C08G18/797 Primary

  containing carbodiimide and/or uretone-imine groups · CPC title

• C08G18/7671

  containing only one alkylene bisphenyl group · CPC title

• C07C263/10

  by reaction of amines with carbonyl halides, e.g. with phosgene · CPC title

• C08G18/025

  the polymeric products containing carbodiimide groups · CPC title

• C07C267/00 Primary

  Carbodiimides · CPC title