Process for the manufacture of aromatic di- and/or polyisocyanates
AssigneeBASF SE
InventorsFranz Merger, Friedrich Towae
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Abstract
This invention pertains to a process for the preparation of an aromatic di- and/or polyisocyanate comprising the steps of A. preparing an aromatic di- and/or polyurethane by 1. reacting a primary aromatic di- and/or polyamine with an O-alkyl carbamate at temperatures greater than 100.degree. C.; 2. separating the ammonia and other by-products from the aromatic di- and/or polyurethane; B. heating and the aromatic di- and/or polyurethane at temperatures of from 175.degree. C. to 600.degree. C.; and C. isolating the di- and/or polyisocyanate resulting from step B.
Claims14
A process for the preparation of an aromatic di- and/or polyisocyanate comprising the steps of
- A. preparing an aromatic di- and/or polyurethane by
- 1. reacting a primary aromatic di- and/or polyamine with an O-alkyl carbamate at temperatures greater than 100.degree. C.;
- 2. separating ammonia and other by-products from the aromatic di- and/or polyurethane;
- B. cleaving the aromatic di- and/or polyurethanes at temperatures from 175.degree. C. to 600.degree. C.;
- and
- C. isolating the di- and/or aromatic polyisocyanate resulting from step B.
Dependencies are inferred from the claim text.