PROCESS FOR PREPARING AT LEAST ONE POLYISOCYANATE

Abstract

The present invention relates to a process for preparing at least one polyisocyanate R(NCO)x, the process comprising preparing a mixture R1 comprising at least one polyamine R(NH.sub.2)x, with x=2 or more, in a first reaction zone Z1; passing at least a portion P1 of the mixture R1, P1 comprising R(NH.sub.2)x, into a storing device D1 and storing P1 in D1 for a period of time t1; removing, after storing for t1, at least a portion P2 of P1, P2 comprising R(NH.sub.2)x, from D1; passing P2 into a reaction zone Z2; and reacting, in Z2, R(NH.sub.2)x comprised in P2 with phosgene, obtaining a mixture R2 comprising the at least one polyisocyanate R(NCO)x; wherein t1 is in the range of from 1 minute to 7 d.

Claims

1.-15. (canceled)

16. A process for preparing at least one polyisocyanate R(NCO)x, the process comprising (i) preparing a mixture R1 comprising at least one polyamine R(NH.sub.2)x, with x=2 or more, in a first reaction zone Z1; (ii) passing at least a portion P1 of the mixture R1, P1 comprising R(NH.sub.2)x, into a storing device D1 and storing P1 in D1 for a period of time t1; (iii) removing, after storing for t1, at least a portion P2 of P1, P2 comprising R(NH.sub.2)x, from D1; passing P2 into a reaction zone Z2; and reacting, in Z2, R(NH.sub.2)x comprised in P2 with phosgene, obtaining a mixture R2 comprising the at least one polyisocyanate R(NCO)x; wherein t1 is in the range of from 1 minute to 7 days.

17. The process of claim 16, wherein the at least one polyamine R(NH.sub.2)x is selected from the group consisting of monomeric methylene diphenylene diamine (mMDA), polymethylene polyphenylene polyamine (pMDA), a mixture of monomer methylene diphenylene diamine and polymethylene polyphenylene polyamine (MDA), tolylenediamine (TDA), isomers of xylylenediamine (XDA), isomers of diaminobenzene, 2,6-xylidine, naphthylene-1,5-diamine (1,5-NDA), 1,4-diaminobutane, 1,5-diaminopentane (PDA), 1,6-diaminohexane (HDA), 1,8-diaminooctane, 1,9-diaminononane, 1,10-diaminodecane, 2,2-dimethyl-1,5-diaminopentane, 2-methyl-1,5-pentanediamine (MPDA), 2,4,4 (or 2,2,4)-trimethyl-1,6-diaminohexane (TMDA), 1,3- and 1,4-diaminocyclohexane, 1-amino-3,3,5-trimethyl-5-aminomethylcyclohexane (IPDA), 2,4- or 2,6-diamino-1-methylcyclohexane (H6-TDA), 1-amino-1-methyl-4(3)aminomethylcyclohexane (AMCA), 1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, bis(aminomethyl)norbornane (NBDA), 4,4-diaminodicyclohexylmethane, 2,4-diaminodicyclohexylmethane, triaminocyclohexane, tris(aminomethyl)cyclohexane, triaminomethylcyclohexane, 1,8-diamino-4-(aminomethyl)octane, undecane-1,6,11-triamine, 1,7-diamino-4-(3-aminopropyl)heptane, 1,6-diamino-3-(aminomethyl)hexane, and 1,3,5-tris(aminomethyl)cyclohexane.

18. The process of claim 16, wherein (i) comprises (i.1) reacting primary amines with an aldehyde compound in presence of an acid in a first reaction zone Z1, obtaining a mixture R0 comprising the primary amines and at least one polyamine R(NH.sub.2)x, with x=2 or more; (i.2) separating the primary amines from the at least one polyamine R(NH.sub.2)x comprised in the mixture R0 obtained in (i.1), obtaining a mixture R1 comprising at least one polyamine R(NH.sub.2)x.

19. The process of claim 16, wherein storing P1 in D1 according to (ii) is performed in the dark.

20. The process of claim 16, wherein storing P1 in D1 according to (ii) is performed under a gas atmosphere, the gas atmosphere being an inert gas.

21. The process of claim 16, wherein, in D1, the temperature of the liquid phase of P1, T(P1), in C., is above the melting point of the at least one polyamine R(NH.sub.2)x comprised in P1, M(P1), in C.

22. The process of claim 21, wherein M(P1) is 80 C., and, in D1, T(P1)85 C.

23. The process of claim 21, wherein, when the at least one polyamine R(NH.sub.2)x is TDA, M(P1) is 100 C., and, in D1, T(P1)105 C.

24. The process of claim 16, wherein the pressure in the storing device D1 is in the range of from 0.5 to 2 bar (abs).

25. The process of claim 16, wherein t1 is in the range of from 15 minutes to 6 days.

26. The process of claim 16, wherein reacting, in Z2, the at least one polyamine R(NH.sub.2)x comprised in P2 with phosgene according to (iii) comprises admixing a solvent to the at least one polyamine R(NH.sub.2)x comprised in P2 and stirring, obtaining a polyamine mixture; contacting the polyamine mixture with phosgene in the reaction zone Z2 and heating the obtained mixture to a temperature in the range of from 90 to 140 C., obtaining the mixture R2.

27. Polyisocyanate R(NCO)x, with x=2 or more, obtainable or obtained according to a process according to claim 16 for use in a process for preparing polyurethanes.

28. The polyisocyanate of claim 27, having a brightness value L* of at least 40.

29. Use of at least one polyisocyanate R(NCO)x, with x=2 or more, according to claim 27 for preparing polyurethanes.

30. A chemical production unit for carrying out the process for preparing at least one polyisocyanate R(NCO)x according to claim 16, comprising a reaction zone Z1 for preparing the at least one polyamines R(NH.sub.2)x, with x=2 or more, comprising a reaction means for preparing a mixture R1; a means for removing at least a portion P1 of the mixture R1 from the reaction zone Z1; a storing device D1 for storing P1 for a period of time t1, wherein t1 is in the range of from 1 minute to 7 d; a means for removing at least a portion P2 of P1, P2 comprising R(NH.sub.2)x, from D1; a reaction zone Z2 for preparing the at least one polyisocyanate R(NCO)x comprising a reaction means for reacting P2 with phosgene and obtaining a mixture R2.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0162] FIG. 1 shows the brightness value L* determined for the 4,4-MDI obtained after various storage duration namely 0, 1, 4 and 12 weeks.

[0163] FIG. 2 shows the content of EHC determined for the 4,4-MDI obtained after various storage duration namely 0, 1, 4 and 12 weeks.

CITED LITERATURE

[0164] U.S. Pat. No. 4,847,408 B [0165] US 2004/0260117 A1 [0166] EP 2 912 010 B1 [0167] U.S. Pat. No. 8,436,204 B2 [0168] WO 2013/060836 A [0169] WO 2013/079517 A