Search

EP-4735495-A1 - METHOD FOR PREPARING ISOCYANURATE-GROUP-CONTAINING POLYISOCYANATES

EP4735495A1EP 4735495 A1EP4735495 A1EP 4735495A1EP-4735495-A1

Abstract

The invention relates to a method for preparing isocyanurate-group-containing polyisocyanates P by trimerising • A) at least one organic di- or polyisocyanate with isocyanate groups bound aliphatically, cycloaliphatically and/or araliphatically independently of one another in the presence of • B) at least one trimerisation catalyst selected from the group consisting of quaternary tetraalkylammonium hydroxides, quaternary trialkylarylammonium hydroxides and hydroxyalkyl-substituted quaternary ammonium hydroxides of the choline type and • C) at least one alcohol as solvent.

Inventors

  • Kaese, Esther
  • Munera Parra, Alejandro
  • KIECHERER, Johannes
  • Golka, Leonie
  • BEHRENDT, FRANK
  • Heilmann, Alicia

Assignees

  • Covestro Deutschland AG

Dates

Publication Date
20260506
Application Date
20240610

Claims (14)

  1. 1. Process for the preparation of polyisocyanates P containing isocyanurate groups by trimerization A) at least one organic di- or polyisocyanate having independently aliphatically, cycloaliphatically and/or araliphatically bound isocyanate groups, in the presence of B) at least one trimerization catalyst selected from the group consisting of quaternary tetraalkylammonium hydroxides, quaternary trialkylarylammonium hydroxides and hydroxyalkyl-substituted quaternary ammonium hydroxides of the choline type and C) at least one alcohol as solvent, comprising or consisting of the following steps I) placing component A in a reactor, II) adding the total amount of catalyst component B, as well as a first portion of component C (CTI), and trimerizing component A until a degree of trimerization T g in the range from > 0.5 to < 25%, preferably from > 0.5 to < 20%, is obtained, where T g = (NCOo - NCOt) / NCOo, where NCOo corresponds to the amount of free NCO groups originally present in the submitted component A and NCOt corresponds to the amount of free NCO groups in the reaction solution at time t, determined by NCO titration according to M105-ISO 11909, III) Adding a second portion of component C (CT2) while continuing the trimerization of component A.
  2. 2. Process for the preparation of polyisocyanates P‘ containing isocyanurate groups by trimerization A') at least one organic di- or polyisocyanate having independently aliphatically, cycloaliphatically and/or araliphatically bound isocyanate groups, in the presence B') at least one trimerization catalyst selected from the group consisting of quaternary tetraalkylammonium hydroxides, quaternary trialkylarylammonium hydroxides and hydroxyalkyl-substituted quaternary ammonium hydroxides of the choline type and C‘) at least one alcohol as solvent, comprising or consisting of the following steps T) placing component A’ in a reactor, IT) supplying a first partial amount of the catalyst component B'(B'TI), as well as a first partial amount of the component C'(C'TI), wherein the catalyst component B'TI is used in amounts of > 0.6 to < 8 wt.%, preferably > 0.8 to < 5 wt.%, particularly preferably > 0.8 to < 2 wt.%, based on the first partial amount of the component C'(C'TI) used in step IT, and trimerizing the component A' until a degree of trimerization T g ' is obtained in the range of > 0.5 to < 25%, preferably of > 0.5 to < 20%, wherein T g ' = (NCOo - NCOt) / NCOo, where NCOo corresponds to the amount of free NCO groups originally present in the submitted component A’ and NCOt corresponds to the amount of free NCO groups in the reaction solution at time t, determined by NCO titration according to M105-ISO 11909, IIT) Adding a second portion of the catalyst component B'(B' T 2), as well as a second portion of the component C'(C'T2), wherein the catalyst component B' T 2 is used in amounts of > 0 to < 0.5 wt. %, preferably > 0 to < 0.1 wt. %, based on the second portion of the component C'(C' TO) used in step IIT, while continuing the trimerization of the component A'.
  3. 3. Process according to claim 1, wherein the at least one organic di- or polyisocyanate (A) is selected from the group consisting of PDI, HDI, MPDI, 1,3- and 1,4-HeXDI, 1,3- and 1,4-XDI and NBDI, or Process according to claim 2, wherein the at least one organic di- or polyisocyanate (A') is selected from the group consisting of PDI, HDI, MPDI, 1,3- and 1,4-H 6 XDI, 1,3- and 1,4-XDI and NBDI.
  4. 4. Process according to claim 1 or 3, wherein at least one benzyltrialkylammonium hydroxide and/or at least one hydroxyalkyl-substituted quaternary ammonium hydroxide of the choline type is used as component B, or process according to claim 2 or 3, wherein at least one benzyltrialkylammonium hydroxide and/or at least one hydroxyalkyl-substituted quaternary ammonium hydroxide of the choline type is used as component B'.
  5. 5. The process according to claim 4, wherein benzyltrimethylammonium hydroxide (Triton-B) and/or 2-hydroxyethyltrimethylammonium acetate (choline acetate) is used.
  6. 6. Process according to one of claims 1 or 3 to 5, wherein aliphatic and/or cycloaliphatic mono- or diols are used as component C, preferably those having at least one primary alcohol group, or Process according to one of claims 2 to 5, wherein aliphatic and/or cycloaliphatic mono- or diols are used as component C', preferably those having at least one primary alcohol group.
  7. 7. Process according to one of claims 1 or 3 to 6, wherein catalyst component B is used in amounts of > 0.001 to < 2 wt. %, preferably from > 0.001 to < 1 wt. %, and particularly preferably from > 0.001 to < 0.2 wt. %, in each case based on the amount of isocyanate component A used, or process according to one of claims 2 to 6, wherein catalyst component B' is used in amounts of > 0.001 to < 2 wt. %, preferably from > 0.001 to < 1 wt. %, and particularly preferably from > 0.001 to < 0.2 wt. %, in each case based on the amount of isocyanate component A' used.
  8. 8. Process according to one of claims 1 or 3 to 7, wherein the catalyst component B is used in amounts of > 0.3 to < 8 wt. %, preferably > 0.5 to < 5 wt. %, particularly preferably > 0.8 to < 2 wt. %, based on the first partial amount of component C (CTI) used in step II.
  9. 9. Process according to one of claims 1 or 3 to 8, wherein the trimerization in step II is carried out at reaction temperatures of > 50 to < 120 °C, preferably > 55 to < 90 °C, or process according to one of claims 2 to 7, wherein the trimerization in step IT is carried out at reaction temperatures of > 50 to < 120 °C, preferably > 55 to < 90 °C.
  10. 10. Process according to one of claims 1 or 3 to 9, wherein the total amount of solvent component C (CTI + C 2) supplied in steps II and III is > 0.3 to < 5 wt. %, preferably > 1 to < 2 wt. %, in each case based on the amount of isocyanate component A used, or Process according to one of claims 2 to 7 or 9, wherein the total amount of solvent component C' (C'TI + CV2) supplied in steps II' and IIT is > 0.3 to < 5 wt. %, preferably > 1 to < 2 wt. %, in each case based on the amount of isocyanate component A' used.
  11. 11. Process according to one of claims 1 or 3 to 10, wherein the trimerization in step III is carried out at reaction temperatures of > 50 to < 120 °C, preferably > 55 to < 90 °C, or process according to one of claims 2 to 7 or 9 or 10, wherein the trimerization in step IIT is carried out at reaction temperatures of > 50 to < 120 °C, preferably > 55 to < 90 °C.
  12. 12. Process according to one of claims 1 to 11, wherein the process is carried out as a batch process, semi-batch process or continuously, in one or more stirred tanks.
  13. 13. Process according to one of claims 1 or 3 to 12, wherein the trimerization of component A is stopped chemically or thermally, preferably thermally, when a desired degree of trimerization is reached, or process according to one of claims 2 to 7 or 9 to 12, wherein the trimerization of component A' is stopped chemically or thermally, preferably thermally, when a desired degree of trimerization is reached.
  14. 14. Process according to one of claims 1 or 3 to 13, characterized in that in a subsequent step any monomeric di- and/or polyisocyanate of component A still present is separated from the reaction product by distillation, or process according to one of claims 2 to 7 or 9 to 13, characterized in that in a subsequent step any monomeric di- and/or polyisocyanate of component A' still present is separated from the reaction product by distillation.

Description

Process for the preparation of polyisocyanates containing isocyanurate groups The production of polyisocyanates containing isocyanurate groups by trimerization of monomeric di- and/or polyisocyanates has long been known. Typically, trimerization catalysts are used, such as quaternary tetraalkyl or trialkylarylammonium hydroxides, such as Triton-B, and hydroxyalkyl-substituted quaternary ammonium hydroxides of the choline type, e.g. choline acetate. The known processes of the prior art (e.g. EP 2 700 665 A1) are carried out in such a way that an alcoholic solution of the catalyst is first added to the isocyanate component to be trimerized. The resulting start of the exothermic reaction causes the temperature of the reaction mixture to rise. The exothermicity is controlled during the further course of the process by adding appropriate amounts of the catalyst solution. It has now surprisingly been found that the reaction behavior can be improved if, after the start of the reaction, only alcohol is added, but no further catalyst is added by initially adding an alcoholic catalyst solution. This dosing behavior means that less catalyst is used for a constant reaction time, or that the reaction time can be shortened for semi-batch processes by starting the reaction more quickly, and the throughput for cascade processes can be increased for a constant catalyst quantity. In the first case, the lower consumption of catalyst means that fewer stoppers are needed to stop the reaction, and less catalyst is present in the product, which improves product quality (less tendency to discoloration). A reduced reaction time means a more economical process. In addition, the reaction process can be better adapted to the quality of the diisocyanate used (in relation to acidic components), since the amounts of catalyst and alcohol added can be controlled independently of one another. The invention relates to a process for the preparation of polyisocyanates P containing isocyanurate groups by trimerization A) at least one organic di- or polyisocyanate having independently aliphatically, cycloaliphatically and/or araliphatically bound isocyanate groups, in the presence of B) at least one trimerization catalyst selected from the group consisting of quaternary tetraalkylammonium hydroxides, quaternary trialkylarylammonium hydroxides and hydroxyalkyl-substituted quaternary ammonium hydroxides of the choline type and C) at least one alcohol as solvent, comprising or consisting of the following steps I) placing component A in a reactor, II) adding the total amount of catalyst component B, as well as a first portion of component C (CTI), and trimerizing component A until a degree of trimerization T g in the range of > 0.5 to < 25%, preferably > 0.5 to < 20%, is obtained, where T g = (NCOo - NCOt) / NCOo, where NCOo corresponds to the amount of free NCO groups originally present in component A and NCOt corresponds to the amount of free NCO groups in the reaction solution at time t, determined by NCO titration according to M105-ISO 11909, III) Adding a second portion of component C (CT2) while continuing the trimerization of component A. The above method is hereinafter referred to as Embodiment 1. It is also possible to initially add the alcoholic catalyst solution in a high concentration and then add catalyst solution at a lower concentration after the start of the reaction. The invention therefore also relates to a process for the preparation of polyisocyanates P' containing isocyanurate groups by trimerization A‘) at least one organic di- or polyisocyanate having independently aliphatically, cycloaliphatically and/or araliphatically bound isocyanate groups, in the presence B‘) at least one trimerization catalyst selected from the group consisting of quaternary tetraalkylammonium hydroxides, quaternary trialkylarylammonium hydroxides and hydroxyalkyl-substituted quaternary ammonium hydroxides of the choline type and C‘) at least one alcohol as solvent, comprising or consisting of the following steps T) introducing component A' into a reactor, IF) Adding a first portion of the catalyst component B' and a first portion of component C'(C'TI), wherein catalyst component B'TI is used in amounts of > 0.6 to < 8 wt. %, preferably > 0.8 to < 5 wt. %, particularly preferably > 0.8 to < 2 wt. %, based on the first portion of component C'(C'TI) used in step IT, and trimerization of component A' until a degree of trimerization is obtained T g ' in the range from > 0.5 to < 25 %, preferably from > 0.5 to < 20 %, where T g ' = (NCOo - NCOt) / NCOo, where NCOo corresponds to the amount of free NCO groups originally present in the submitted component A’ and NCOt corresponds to the amount of free NCO groups in the reaction solution at time t, determined by NCO titration according to M105-ISO 11909, IIF) Adding a second portion of the catalyst component B'(B' T 2), as well as a second portion of the component C'(C'T2), wherein the catalyst component B' T