Polyamines, a process for the production of polyamines and their use in the production of polyurethanes

Abstract

The invention relates to a simplified, economic process for the production of polyamines by the alkaline hydrolysis of compounds containing terminal aromatic and/or aliphatic isocyanate groups (including modified isocyanates or NCO-prepolymers and semi-prepolymers with NCO-contents of from 0.5 to 40% by weight), with strong aqueous bases, direct isolation of the polyamines from the carbamate stage being possible by thermal carbamate decomposition and/or solvent extraction. The invention also relates to the use of the aromatic and/or aliphatic polyamines containing primary NH2-groups obtainable by the process according to the invention for the production of polyurethanes, such as optionally cellular polyurethane plastics and polyurethane foams.

What is claimed is: 
     
       1. A process for the production of aromatic and/or aliphatic, primary polyamines by the hydrolysis of compounds containing isocyanate groups, comprising (I) converting aromatic and/or aliphatic compounds containing from 0.5 to 40% by weight of isocyanate groups .Iadd.other than distillation residues containing isocyanate groups obtained in the commercial production of TDI .Iaddend.into compounds containing carbamate groups by mixing said aromatic and/or aliphatic compounds with a strong aqueous base and at least a stoichiometric quantity of water and   (II) recovering polyamines directly from the compounds containing carbamate groups by thermal decomposition or by solvent extraction.   
     
     
       2. A process according to claim 1, characterized in that the aromatic and/or aliphatic compounds containing free NCO-groups are polyfunctional NCO-preadducts of polyisocyanates with relatively high molecular weight polyhydroxyl compounds from the series consisting of polyethers, polycarbonates, polyacetals, polythioethers, polysiloxanes or polybutadienes having molecular weights in the range of from 400 to 12,000 and/or with chain-extending agents containing NCO-reactive groups and having molecular weights in the range of from 18 to 399. 
     
     
       3. A process according to claim 1, characterized in that the aromatic and/or aliphatic compounds containing free NCO-groups are in solution in an NCO-inert solvent. 
     
     
       4. A process according to claim 1, characterized in that the base is an alkali hydroxide, alkaline earth hydroxide and/or quaternary tetraalkyl ammonium hydroxide. 
     
     
       5. A process according to claim 1, characterized in that the base is used in quantities of from 0.3:1 to 2:1 equivalents of base per NCO-group. 
     
     
       6. A process according to claim 1, characterized in that the base is used in the form of an aqueous solution. 
     
     
       7. A process according to claim 1, characterized in that step II is accomplished by heat treating the compounds containing carbamate groups at temperatures up to 200° C. and recovering the polyamines. 
     
     
       8. A process according to claim 1, characterized in that step II is accomplished by treating the compounds containing carbamate groups with one or more solvents and extracting the resulting polyamines. 
     
     
       9. A process according to claim 1, characterized in that step II is accomplished by heat treating the compounds containing carbamate groups at temperatures up to 200° C. in the presence of solvents and in a vacuum and extracting the resulting polyamines. 
     
     
       10. A process according to claim 8 or 9, characterized in that the solvents are water-immiscible organic solvents. 
     
     
       11. A process according to claim 1, characterized in that between steps I and II, the compounds containing carbamate groups are treated with between 0.01 and 0.99 equivalents of a proton donor, based on the quantity of base used in step I. 
     
     
       12. A process according to claim 1, characterized in that between 0.01 and 0.99 equivalents of a proton donor, based on the quantity of base used in step I, are added during step II. 
     
     
       13. A process according to claim 1, characterized in that in step II, the polyamines are separated off by phase separation, crystallization or extraction. 
     
     
       14. A process for the production of optionally cellular polyurethane plastics by reacting (a) polyisocyanates and/or blocked polyisocyanates with   (b) polyamines and   (c) optionally other low molecular weight and/or relatively high molecular weight compounds containing isocyanate-reactive groups and other known auxiliaries and additives, characterized in that the polyamines are produced by the hydrolysis of compounds containing isocyanate groups .Iadd.other than distillation residues containing isocyanate groups obtained in the commercial production of TDI .Iaddend.by converting them into compounds containing carbamate groups by mixing them with a base and at least a stoichiometric quantity of water, and recovering polyamines directly from the compounds containing carbamate groups by thermal decomposition or by solvent extraction. .Iadd.     
     
     
       15.  A continuous process for the production of aromatic and/or aliphatic primary amines by the hydrolysis of compounds containing isocyanate groups comprising (a) delivering an aromatic and/or aliphatic isocyanate compound containing from 0.5 to 40 wt. % isocyanate groups which isocyanate compound is a modified polyisocyanate and/or NCO-prepolymer and/or semiprepolymer into a reaction zone,   (b) delivering a solution of a strong base in at least a stoichiometric quantity of water into the same reaction zone to which the isocyanate is delivered in (a),   (c) intensively mixing the isocyanate and aqueous base present in the reaction zone,   (d) reacting the mixture of (c),   (e) discharging the mixture reacted in (d) from the reaction zone,   (f) repeating steps (a)-(e) until sufficient reaction mixture has been produced, and   (g) recovering polyamine directly from the mixture discharged in (e) by thermal decomposition or by solvent extraction..Iaddend. .Iadd.16. The process of claim 15 in which the isocyanate is a trimer of TDI..Iaddend.   
     
     
        .Iadd.17.  The process of claim 1 in which the isocyanate is a trimer of TDI..Iaddend. .Iadd.18. The process of claim 15 in which the temperature in the reaction zone is kept below 150° C..Iaddend. .Iadd.19. The process of claim 15 in which the polyisocyanate is delivered into the reaction zone at a temperature of from 20°-80° C. and the solution of the strong base is delivered into the reaction zone at a temperature of from -25° to 40° C..Iaddend. .Iadd.20. The process of claim 15 in which the strong base is selected from the group consisting of alkali metal hydroxides, alkaline earth metal hydroxides and tetraalkylammonium hydroxides..Iaddend. .Iadd.21. The process of claim 20 in which the base is used in a quantity such that the ratio of hydroxide to isocyanate groups is from 0.3:1 to 2:1..Iaddend. .Iadd.22. The process of claim 15 in which the isocyanate is an NCO-prepolymer..Iaddend. .Iadd.23. The process of claim 22 in which the base is an alkali metal hydroxide..Iaddend. .Iadd.24. The process of claim 23 in which the polyamine is recovered by heating the discharged mixture, cooling the heated mixture and filtering off the solid which formed on cooling..Iaddend.