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The present invention relates to a process for preparing polyisocyanates from natural raw material sources, in which a composition comprising low molecular weight aromatics which comprise at least one hydroxy group or at least one alkoxy group per molecule (oxyaromatics) is produced from a biomass m

The present invention relates to a process for preparing polyisocyanates from natural raw material sources, in which a composition comprising low molecular weight aromatics which comprise at least one hydroxy group or at least one alkoxy group per molecule (oxyaromatics) is produced from a biomass material, these oxyaromatics are converted into the corresponding aromatic amines and, optionally after condensation with formaldehyde, reacted further with phosgene to give compounds comprising isocyanate groups.

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1. A process for preparing a polyisocyanate, the process comprising: phosgenating a composition comprising aromatic amines having a C14 to C12 isotope ratio in the range from 0.5×10−12 to 5×10−12,wherein the composition comprising aromatic amines is prepared from a biomass starting material by decom

1. A process for preparing a polyisocyanate, the process comprising: phosgenating a composition comprising aromatic amines having a C14 to C12 isotope ratio in the range from 0.5×10−12 to 5×10−12,wherein the composition comprising aromatic amines is prepared from a biomass starting material by decomposing the biomass starting material, to obtain an oxyaromatic composition comprising an aromatic comprising at least one selected from the group consisting of a hydroxy group and an alkoxy group per molecule; andaminating the oxyaromatic composition, to obtain an amination product,wherein the composition in the phosgenating is the amination product. 2. The process of claim 1, wherein the oxyaromatic composition comprises, based on a total weight, at least 75% by weight of a monocyclic aromatic. 3. The process of claim 1, further comprising, but prior to the phosgenating: (I) decomposing the biomass starting material, to obtain an oxyaromatic composition comprising an aromatic comprising at least one selected from the group consisting of a-hydroxy group and an alkoxy group per molecule;(II) animating the oxyaromatic composition, to obtain an amination product; and(III) condensating the amination product with a formaldehyde source, to obtain a condensation product,wherein the composition in the phosgenating is the condensation product. 4. The process of claim 1, further comprising, prior to the phosgenating: a) decomposing the biomass starting material, to obtain a decomposition product;b) optionally separating the decomposition product into an aromatics-enriched fraction B1) and an aromatics-depleted fraction B2);c) optionally feeding the decomposition product or the aromatics-enriched fraction B1) into a dealkylation zone and reacting the decomposition product or the aromatics-enriched fraction B1) in the presence of at least one selected from the group consisting of hydrogen and water vapor,taking a discharge from the dealkylation zone, andoptionally separating the discharge, to obtain a stream C1) enriched in dealkylated aromatics and a stream C2) enriched in more volatile components;d) aminating the decomposition product, the aromatics-enriched fraction B1), the discharge from the dealkylation zone, or the stream C1) with an ammonia source in an amination zone, to obtain an amination product; ande) optionally condensing the amination product with a formaldehyde source, to obtain a condensation product,wherein the compound in the phosgenating is the amination product or the condensation product. 5. The process of claim 1, wherein the biomass starting material is a lignin-comprising material. 6. The process of claim 1, wherein the biomass starting material is a lignocellulose material or a digestion product of a lignocellulose material. 7. The process of claim 1, wherein the biomass starting material is a lignin-comprising stream from the digestion of a lignocellulose material for producing cellulose. 8. The process of claim 1, wherein the decomposing comprises pyrolyzing the biomass starting material. 9. The process of claim 8, wherein the pyrolyzing is not carried out with addition of a hydrogen compound. 10. The process of claim 8, wherein the pyrolyzing is carried out with addition of hydrogen. 11. The process of claim 8, wherein the biomass starting material comprises a black liquor material having a liquid content of not more than 70% by weight at 20° C., 1013 mbar, based on a total weight of the black liquor material. 12. The process of claim 1, wherein the decomposing is carried out in a liquid phase. 13. The process of claim 12, wherein the decomposing is carried out in the presence of an aqueous-alkaline, aqueous-acidic, or organic decomposition medium. 14. The process of claim 13, wherein the biomass starting material in the decomposing comprises a cellulose-depleted fraction from a pulp process. 15. The process of claim 4, wherein the separating b) is performed and is carried out by at least one selected from the group consisting of a distillation, extraction, absorption, and membrane process. 16. The process of claim 4, wherein the decomposing a) comprises pyrolyzing the biomass starting material andthe separating b) is performed and comprises an absorption. 17. The process of claim 4, wherein the decomposing a) is carried out in a liquid phase andthe separating b) is performed and comprises at least one selected from the group consisting of an extraction and a distillation. 18. The process of claim 17, wherein the separating b) is performed and comprises:b1) extracting the decomposition product, to obtain an aromatics-enriched extract and an aromatics-depleted residue;b2) optionally separating the extract into a fraction enriched in extractant and depleted in aromatics and a fraction enriched in aromatics and depleted in extractant; andb3) adding the aromatics-enriched extract of b1) or the aromatics-enriched fraction of b2) into at least one selected from the group consisting of the separating c) and the aminating d). 19. The process of claim 4, wherein a reaction in c) comprises at least one selected from the group consisting of a hydrodealkylation and a steam dealkylation. 20. The process of claim 4, wherein a temperature in the dealkylation zone is in a range from 400 to 900° C. 21. The process of claim 4, wherein an absolute pressure in the dealkylation zone is in a range from 1 to 100 bar. 22. The process of claim 4, wherein the discharge from the dealkylation zone in c) is subjected to a fractionation to obtain the following three streams:C1) a stream enriched in monocyclic oxyaromatics which are unalkylated or have a low degree of alkylation;C2) a stream enriched in aromatics which are not dealkylated or are dealkylated to only a small extent; andC3) a stream enriched in by-products which are more volatile than C1) and C2). 23. The process of claim 4, wherein the aminating is carried out with ammonia. 24. The process of claim 4, wherein the discharge from the amination zone in d) is subjected to a fractionation to obtain a stream D1) enriched in aromatic amines and an oxyaromatics-enriched stream D2). 25. The process of claim 24, wherein the fractionation comprises: d1) fractional distillation of the discharge from the amination zone, to obtain an ammonia-enriched fraction and an ammonia-depleted fraction;d2) optionally separating water from the ammonia-depleted fraction by distillation; andd3) fractional distillation, to obtain the stream D1) enriched in aromatic amines and the oxyaromatics-enriched stream D2). 26. The process of claim 24, further comprising: at least partially condensating the stream D1) with a formaldehyde source. 27. The process of claim 24, wherein the stream D1) is at least partly employed without prior condensation with a formaldehyde source in the phosgenating. 28. The process of claim 24, further comprising: further fractionation of the stream D1), to obtain a stream D1m) enriched in aromatic monoamines and a stream D1p) enriched in aromatic polyamines. 29. The process of claim 28, comprising: condensing the stream D1 m) with a formaldehyde source in e) before the phosgenating. 30. The process of claim 28, comprising condensing the stream D1p) with a formaldehyde source in e) before the phosgenating or directly phosgenating the stream D1p). 31. The process of claim 24, wherein the oxyaromatics-enriched stream D2) is recirculated to the amination zone in d). 32. The process of claim 4, further comprising: adding an amine which has not been obtained from biomass to the amination product of d) before the reaction in at least one selected from the group consisting of the condensing and the phosgenating.