DE2703313A1 - PROCESS FOR THE PRODUCTION OF ORGANIC POLYAMINES - Google Patents

Description

Bayer Aktiengesellschaft 2703313

Central area of patents, trademarks and licenses

5090 Leverkusen, Bayerwerk Wr / be

Process for the production of organic polyamines

The present invention relates to a new process for the hydrolytic cleavage of undistillable organic ones Polyisocyanates, especially from distillation residues, such as those used in the work-up of organic products by distillation Polyisocyanates accumulate.

Organic polyisocyanates such as those used for the production of polyurethane plastics are known produced on an industrial scale by phosgenation of the corresponding polyamines. From the in this phosgenation reaction Accruing crude phosgenation products are used to manufacture the polyurethane plastics suitable pure polyisocyanates generally obtained by distillation. Fall in this distillation considerable amounts of distillation residues, which are not fed to a technically meaningful recovery could become. There has therefore been no shortage of attempts to hydrolyze these distillation residues in the corresponding, in the phosgenation as Aus

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to split the polyamines used as a starting material (cf. e.g. U.S. Patent 3,128,310 or U.S. Patent 3,331,876). These prior art processes, in which one for hydrolysis either pure water or aqueous solutions of alkali hydroxides are used, however, with considerable Associated disadvantages. For example, the poor compatibility of the distillation residues with water makes one more difficult Rapid and quantitative hydrolysis and degradation reaction to form uniform degradation products. A special one Serious disadvantage, which is particularly noticeable in the aforementioned processes of the prior art, is due to the fact that the polymeric by-products contain a wide variety of structures Distillation residues often have a softening behavior at higher temperatures, leading to strong clumping and leads to the formation of compact masses, whereby stirring processes are difficult or completely prevented. The hydrolytic degradation in the heterogeneous phase then proceeds extremely slowly and leads alongside technical ones Disruptions to inconsistent hydrolysis products. Aggravating with all neutral, alkaline or also acidic initiated Hydrolysis reactions also add to the fact that the often tarry residue polyisocyanates used have an NCO content between 5 to 20%, so that higher molecular weight, Highly cross-linked polyureas are formed, which in turn, due to their complete insolubility, undergo cleavage reactions extremely difficult, since the diffusion of the water necessary for splitting into the molecular areas of the polymers done extremely slowly. In the case of hydrolysis with caustic soda or potassium hydroxide, even under increased pressure,

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extremely long reaction times are also required for hydrolysis with sulfuric acid, with the polyisocyanates underlying diamines are obtained in poor yields. Even with 30 hours of hydrolysis 130 ° C are only relatively small amounts, often not more than 30 wt .-%, split to polyamines. Another disadvantage here is that these polyamine components are powdery until clumping remaining amounts of unhydrolyzed polymers are isolated in a laborious manner have to.

As the applicant's own experiments have shown, the reason for this is extremely slow Hydrolysis, inter alia, in that, for example, in all residue isocyanates, especially in residue isocyanates Toluylene diisocyanate production as well as in residue isocyanates of 4,4'-diisocyanatodiphenylmethane and Hexamethylene diisocyanate production of higher molecular weight Polyisocyanates containing biurethane groups in proportions of approx. 30-40% by weight, isocyanurate and polyisocyanurate polyisocyanates in proportions of approx. 20-30% by weight, polycarbodiimides, and their dimerization and trimerization products in proportions of about 10 to 15% by weight, as well as other cyclic or linear polymers, in particular the corresponding diisocyanatocarbodiimides, addition products of monomeric diisocyanates with carbodiimides and Contain polyisocyanates containing polyurethane groups. Since these polymeric compounds are either free or but have blocked isocyanate groups, they react in their treatment with hydrolytic agents

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according to prior art processes very rapidly with an increase in molecular weight and crosslinking reactions under polyurea bond, in particular during the heating-up period when carrying out the method of State of the art.

As a result, in the processes of the prior art, immediately insoluble products are extremely low Swellability in water arise, saponification is only very slow and uneconomical Reaction are accessible.

By the method of the present invention described in more detail below, these disadvantages could be overcome will.

The present invention is a process for the preparation of organic polyamines by hydrolytic Decomposition of undistillable polyisocyanates or distillation residues such as those used in distillation Work-up of organic polyisocyanates is obtained, characterized in that the undistillable polyisocyanates or distillation residues are optionally used after pretreatment with ammonia with conversion of the isocyanate groups present into Urea groups under pressure at a temperature of 100-3OO ° C with aqueous solutions of primary or secondary Amines, ammonia or compounds which split off ammonia under the reaction conditions for the reaction brings.

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The inventive method can be used for

a) any non-distillable organic polyisocyanates such as urethane groups, isocyanurate groups, Biureth groups, allophanate groups, urethdione groups, Carbodiimide groups or urethonimine groups organic polyisocyanates and especially for

b) any distillation residues, as they are in large-scale Accumulate distillative work-up of organic polyisocyanates.

An application of the method according to the invention for Non-distillable polyisocyanates mentioned under a) would be, for example, in the case of a desired work-up of technical defective parts, the properties of which do not correspond to the respective specifications, are conceivable.

Preferably in the method according to the invention used distillation residues are any distillation residues of the distillative Pure preparation of organic polyisocyanates, especially around the distillation residues that occur in the distillative Working up of crude technical diisocyanatotoluene, hexamethylene diisocyanate, 3,3,5-trimethyl-5-isocyanatomethyl-cyclohexyl isocyanate (IPDI), m-xylene diisocyanate, diisocyanatodiphenylmethane, or the aromatic mentioned Isocyanate-corresponding, perhydrogenated cyclcaliphatic diisocyanates are obtained. Preferably finds

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the inventive method application for the distillation residues, as in the work-up of the phosgenation products of 2,4- and / or 2,6-diaminotoluene by distillation attack.

The distillation residues to be used in the process according to the invention generally still have a free content, which is no longer readily available by distillation expellable diisocyanates of up to 35, preferably 8 to 30 wt .-% and a total NCO content of up to 30, preferably 10 to 25% by weight. Otherwise, the distillation residues consist primarily of Biuret groups, urea groups, isocyanurate groups, Oligomers containing carbodiimide groups, iminotriazine groups, urethonimine groups and / or urethdione groups or polymeric isocyanate group-containing compounds of the type already mentioned by way of example above.

In principle, it is possible with the method according to the invention also to use those distillation residues whose free isocyanate groups are caused by the action of water (Humidity in case of longer storage), amines or alcohols wholly or partly in urea or urethane groups have been convicted.

In carrying out the inventive method, the non-distillable polyisocyanates or particularly preferably used distillation residue under pressure at a temperature of 100-300 ⁰ C, preferably 150-250 ° C, more preferably 18O-22O ° C, flydrolysemitteln with the invention to be Implementation brought.

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Suitable "hydrolysis agents" according to the invention are:

1. Aqueous ammonia solutions or aqueous solutions below Compounds which release ammonia under the reaction conditions and have an ammonia content of 1-60% by weight (possibly under pressure) and preferably from 20 to 30% by weight or /. a content of ammonia-releasing compound, which corresponds to an ammonia content of preferably 1 to 30, preferably 20-25,% by weight. Suitable ammonia-releasing agents Compounds are in particular ammonium bicarbonate, amrionium carbonate, Ammonium carbamate or urea. The ammonia releasers mentioned by way of example are used often an advantage, as they have a solubilizing and clumping-preventing function. Yet is the use of aqueous ammonia solutions, especially ammonia solutions which are saturated at room temperature and normal pressure preferred over the use of the ammonia cleavers mentioned.

2. Aqueous solutions of water-soluble primary and / or secondary amino groups containing amines, the one considerably below the boiling point of that used in the phosgenation and thus in the case of the invention Process have diamines as the main product. This difference in boiling point is for convenience the pure preparation of the diamines obtained as the main product according to the invention by distillation advantageous. Suitable such water-soluble amines are e.g. methylamine, dimethylamine, ethylamine, diethylamine, Propylamine, di-n-propylamine, n-butylamine, ethylenediamine, Propylenediamine, aminoethanol and the like .. The two

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Amines mentioned by way of example generally come as 1 to 30, preferably 10-20% by weight, aqueous solutions for use. The use of such aqueous amine solutions is compared to the use of those mentioned under 1 Hydrolysis agents less preferred.

3. Aqueous solutions of organic diamines which, in terms of their constitution, have the constitution of the Phosgenation used and thus correspond to the polyamines formed as the main product according to the invention. This means that, for example, in the hydrolytic work-up of distillation residues of the hexamethylene diisocyanate an aqueous solution of hexamethylene diamine would be used. Because these polyamines often only have a limited solubility in water, it is advisable to use Solubilizers, for example acetone or methanol. The solutions generally have a content from 1 to 30, preferably from 10-20% by weight of polyamine. The use of these solutions is compared to the Use of the solutions mentioned under 2 is less preferred.

In the process according to the invention, per kg of distillation residue generally 1 to 10 1 hydrolysis agent used.

Since the distillation residues to be used in the process according to the invention are easy at elevated temperature tend to clump, it is often recommended that Distillation residues from pretreatment with ammonia

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to undergo so as to convert the NCO groups into urea groups to be transferred and at the same time to prevent a later agglomeration or clumping of the residues. This pretreatment can for example in the form of a gassing of the distillation residues with ammonia gas or with a Treatment with aqueous ammonia solution to proceed at temperatures which are below the softening point of the distillation residue. Such a pretreatment is particularly recommended in the case of distillation residues of IPDI or of m-xylene diisocyanate or of m-xylene diisocyanate. The most preferred Distillation residues from the diisocyanatoluene production to be used in the process according to the invention can be achieved with the process according to the invention, especially when using concentrated aqueous ammonia solutions and with rapid heating to the preferred hydrolysis temperature of 180-220 ° C., generally without saponify such a pretreatment smoothly, because when the hydrolysis temperature is reached, so does saponification It happens quickly that from the initially present mixture of the distillation residue introduced as a solid and the hydrolysis agent very quickly, often from around 100 ° C, a liquid mixture is formed.

As has also been shown, it is often advisable to use about 3-10% by weight, based on the distillation residue, of ε-cap rolactam when carrying out the process according to the invention, since this compound is not only a good solubilizer, but also a " Linearizing agent "represents cross-linked fractions in the distillation residue. It can also be of advantage to

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the implementation of the process according to the invention catalysts to be used for the cleavage of the particularly resistant isocyanurate ring. Such possibly in amounts of up to 10% by weight, based on the distillation residue, to be used Catalysts are, for example, sodium formate, potassium acetate, N-methyl diethanolamine, N-ethyl diethanolamine, permethylated diethylenetriamine or permethylated tetraethylene pentamine.

It is to be regarded as particularly surprising that when the method according to the invention is carried out, particularly rapid rates of hydrolysis can be achieved because it had to be expected that the residue isocyanate side due to their almost spontaneous reaction with ammonia or primary or secondary aliphatic amines or diamines react to form extremely stable polyureas or polybiurets with extensive crosslinking and therefore as a result complete insolubility would make the hydrolysis of the polymers extremely difficult. As completely surprising Finally, the fact that carbodiimide structures and segment structures like

a) -N = C = N-, - £ -N = C = N-R-J- £ and their polymers

as well as polyguanidines formed by NH ^ addition or crosslinked polyguanidines

b) also isocyanurate groups

O = C. C = O

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can be split so easily in an aqueous amine medium under pressure.

When carrying out the method according to the invention the urea, biuret, isocyanurate, uretdione cabodiimide present in the distillation residues and guanidine segments are always hydrolytically saponified in such a way that the carbon atom connecting the heteroatoms becomes carbon dioxide is eliminated.

When carrying out the method according to the invention therefore, if ammonia is used, it is converted into ammonium bicarbonate or ammonium carbonate, these salts remain in the aqueous solution due to their high solubility and from the resulting salts Di- or polyamines can be easily removed.

An advantageous variant of the method according to the invention consists in the fact that the thermally easily dissociable ammonium salts (NH, -Abspalter) in aqueous solution can be continuously reused for the hydrolysis of the residual isocyanates, so that, in principle, with a given amount of ammonia, any amount of residual isocyanates is always in circulation and their derivatives.

With a total oxygen content of about 16.1% of the residual isocyanate from TDI residue isocyanate, for example, when the residue isocyanate is broken down with a

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Liters of approx. 25% ammonia solution to approx. 6.01 C = O equivalents approx. 14.7 NH ₃ equivalents at 200 ° C. for action, ie approx. 2.43 NH equivalents are required per C = O equivalent used, which can bind the resulting COj as ammonium carbonate.

When carrying out the process according to the invention, it is also surprising that L- and β- methylbenzimidazolones can be isolated and separated almost quantitatively from tolylene diisocyanate residue isocyanates of the most varied isomer distributions in such a simple manner. In the distillation residues from the work-up of 2,4- and / or 2,6-diisocyanatotoluene by distillation, which are preferably to be used in the process according to the invention, these compounds are often present in considerable concentrations. They are not saponified to diaminotoluene under the reaction conditions of the process according to the invention, but since they are sparingly soluble in almost all solvents, they can be removed from the cleavage mixture by filtration or by extraction using sodium hydroxide solution and then worked up.

When carrying out the method according to the invention with Residual isocyanates from hexamethylene diisocyanate production can especially when these residues contain 2 to 10% by weight of monomeric chlorhexyl isocyanate, high conversion rates of the chlorhexyl isocyanate to hexamethylenediamine can be achieved, with in a side reaction also valuable constitutional polyamines

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H ₂ N- (CH ₂ Jg-NH- (CH ₂ ) ₆ -NH ₂ or H ₂ N- (CH ₂ ) g-NH- (CH ₂ ) g-NH- (CH ₂ ) g-NH ₂ are formed .

As already stated, the distillation residues to be used particularly preferably in the process according to the invention are those which are used in the preparation of the isomers Toluylene diisocyanates are obtained after the toluene diisocyanate has been distilled off. These tolylene diisocyanates are known those which contain a ratio of 2,4: 2,6 isomers such as 80:20, 70:30 and 65:35% by weight, respectively. the Residual isocyanates are preferred with a monomer content of 1-methylbenzene-2,4- or 2,6-diisocyanate from 8 to 30% by weight removed from the distillation devices and, if desired, flaked or ground. These residue isocyanates generally have a total NCO content of 15 to 24% in solid form.

The process according to the invention can be carried out either batchwise or continuously. in the The first case is expediently carried out in suitable autoclaves. Served in a continuous way of working one expediently a suitable tubular reactor in which the present in the form of a slurry Mixture of distillation residue and hydrolysis agent is introduced continuously. After separation the one taken from the autoclave or the one from the tubular reactor leaving mixture in an organic phase containing the process products according to the invention and a the aqueous phase containing the hydrolysis agent can be the latter

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be returned in a circle to the beginning of the process. The separation of the single-phase or two-phase reaction mixture obtained in the process according to the invention takes place in an in a known manner, for example by crystallizing out the polyamines formed and making them pure Filtration and, if appropriate, subsequent distillation, or by extraction of those present in the reaction mixture Polyamines with cosolvents such as. B. methylene chloride, Dichloroethane, chlorobenzene or dichlorobenzene and subsequent purification of the polyamines by working up by distillation the organic phase obtained in this way, or else by concentrating the aqueous reaction mixture by distilling off of the water, possibly the release of the organic polyamines, which may be present as a salt, by adding strong bases such as B. sodium hydroxide solution and subsequent purification by distillation of the organic polyamines. It is fundamental also possible the organic ones obtained with the extraction method Solution, for example in chlorobenzene, directly, without having to carry out further work-up to a phosgenation reaction. Regardless of the methods mentioned for working up the process products obtained according to the invention, it can be said that in the work-up and purification of the polyamines formed in the process according to the invention only a residue of approx. 5-15% by weight, based on the distillation residue used, remains. This means that with the method according to the invention a possibility has been opened up which allows 85-95% by weight of the distillation residue obtained in the industrial production of polyisocyanates to break down into valuable organic intermediates. The method according to the invention is therefore a real recycling process, which increases the scarcity of raw materials helps to relieve, and which, since the distillation residues no longer have to be burned, to relieve the burden on the environment contributes.

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Example 1 ^ ®

The residue polyisocyanate used in this example is used in the industrial phosgenation of 1-methylbenzene-2,4-diamine and 1-methylbenzene-2,6-diamine in the isomer ratio 80/20 received. 1-methylbenzene-2,4- and 1-methylbenzene-2,6-diisocyanate are distilled from distillation stills to such an extent that the viscous residue is still a Has a content of about 22% NCO. The resulting, glass-like solidifying melt is pressed into pans and pulverized the residue isocyanate mixture. It has a content of 15% by weight of monomeric tolylene diisocyanates. 85% by weight consist of higher molecular weight biuret polyisocyanates, isocyanurate isocyanates, polycarbodiimides, Methyl benzimidazolone adducts with toluene diisocyanates and uretdione, carbodiimide or uretone imine groups containing higher molecular weight polyisocyanates. NCO content: 21.8%.

600 g of comminuted material from the distillation residue were stirred in 1 liter of concentrated aqueous ammonia solution in a 3 liter autoclave at 200 ° C. for 2.5 hours. It was let down, cooled, stirred with dichloromethane and filtered. 144.4 g of residue with a melting point of 284-289 ° C. were obtained; this residue was dissolved in dilute sodium hydroxide solution for purification. Insoluble material "-10.6 g with a melting point of> 320 ° C. was filtered off. When the sodium hydroxide solution was acidified, tfL ~ ^and β-methylbenzimidazolone were obtained as a mixture (40% β and 60% β according to 220 MH-NMR) from Melting point 284-289 ° C. The mixture of dichloromethane and water / NH3 obtained in the first filtrate was separated and the NH / water solution was extracted thoroughly with dichloromethane

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Dichloromethane solutions were extracted with dilute sodium hydroxide solution (from this a further 6.9 g of L- and β-methylbenzimidazolone were obtained), then washed once with water, dried and evaporated: 316 g of crude amine. Distillation in vacuo (boiling point ₂₁ 175-185 ° C.) gave 284.4 g of a mixture of 2,4- and 2,6-toluenediamine (melting point 86-91 ° C.). The composition was determined by capillary gas chromatography to be 13.1% 2,6- and 86.9% 2,4-tolylenediamine (these values were also confirmed by the NMR spectrum).

When the amine mixture was distilled, 30 g of dark product remained. The total amount of waste is thus in this case 40.6 g based on the residue used, d.s. ~ 7% real waste.

When the aqueous NH ₃ solution was evaporated, 41 g of solid were obtained, which consists predominantly of urea and ammonium salts.

Example 2

The residual isocyanate mixture used in this example is used in the industrial phosgenation of 1-methylbenzene-2,4-diamine and 1-methylbenzene-2,6-diamine in an isomer ratio of 65/35% by weight. The monomers are distilled Diisocyanates in an isomer ratio of 65/35 in vacuo from distillation stills to such an extent that the viscous residue still has an NCO content of 23%, the resulting glass-like solidifying melt is pressed into pans and pulverizes the residue isocyanate mixture. It owns a content of about 12 wt .-% of monomeric toluene diisocyanates and consists essentially of higher

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molecular biuret polyisocyanates, polyisocyanates containing isocyanurate groups and higher molecular weight uretdione carbodiimide or polyisocyanates containing uretonimine groups of the aforementioned higher molecular weight polyisocyanates.

600 g of the distillation residue were stirred in 1 liter of a concentrated aqueous ammonia solution at 20O ⁰ C for 2.5 hours. The further work-up was carried out as in Example 1.

Result:

Yield of tolylenediamine, 364 g consisting of

74.5% L ¹ LrH and 25.1% | "l | ^NH 2

NH ₀

2 δ

Yield of oi, - and ß-methylbenzimidazolone, consisting of 90.33 g the end

CH-

^0Η 3γΓΝ ^ ^ΝΗ \ _{= ο r}

Total amount of real waste 37.2 g ds ~ 6% based on the residue used.

Example 3

600 g of the distillation residue from the production of 2,4-toluene diisocyanate, and which is 22 % by weight

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Containing NCO groups and 15 wt .-% free diisocyanate, were in 1 liter of a concentrated aqueous ammonia solution Stirred at 2OO ° C for 2 hours. The further work-up was carried out as in Example 1.

Result:

Yield of 2,4-toluenediamine: 363.7 g to 99%

Yield of ((.- and ß-methylbenzimidazolone: 25.5 g consisting of

20%

and 80%

Total amount of real waste: 35.1, d.s. ^ 6% related used residue.

Example 4

As described in Example 1, 300 g of the distillation residue used there are obtained using a solution hydrolyzed by 240 g of urea in 400 ml of water for 3 hours at 200 ° C. After working up as in As described in Example 1, 127.1 g of distilled diamine were obtained. The yield of methylbenzimidazolones was 58.9 g.

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Example 5

The procedure is as in Example 4, but as a hydrolysis agent the solution of 30 g of ammonium carbonate in 400 ml of water was used. There were 141.7 g of diamine and 58.55 g Obtain methylbenzimidazolones.

Example 6

The residual isocyanate mixture used in this example fell upon distillation of the phosgenation product Hexamethylenediamine and is a black liquid with an NCO content of 30.8% by weight.

Option A:

2OO parts by weight of this residue isocyanate mixture initially with vigorous stirring over the course of 2 hours in 1200 parts by weight of about 25% strength aqueous ammonia solution added dropwise at 2O-25 ° C and turned into a powdery, NH - C-NH-

Group-owning by-product of the residue isocyanate implemented. The aqueous dispersion obtained, which contains about 270 parts by weight of free ammonia, is then hydrolytically split into polyamines in a 3 liter autoclave for 4 hours at 200.degree. The autoclave is allowed to cool to room temperature and, after filtering the contents of the autoclave, only 2 parts by weight of brown-black insoluble residues are obtained. The insoluble Ruckstandsisocy anat-NH , used for the hydrolysis conversion product has thus been hydrolyzed into water-soluble polyamines in a yield of about 99%, based on the residue isocyanate mixture used. In the brown solution there are salts of carbonic acid with ammonia or betaine-like

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Salts of hexamethylenediamine, of H ₃ N- (CH ₂ ) gN- (CH ₂ ) g-NH ₂

and higher molecular weight polyamines (= solution A).

Solution A is concentrated in a water jet vacuum, ammonium carbonate and ammonium bicarbonate thermally dissociating and being enriched in the distillate. The betaine-like salts of the polyamines formed remain in the sump. After the liquid distillation bottoms have been concentrated to about 310 parts by weight, 200 parts by weight of solid sodium hydroxide are dissolved in it. This binds the bound CO ₂ in the betaines as sodium carbonate. The water present in the distillation residue is removed by azeotropic distillation with 800 parts by volume of toluene and the polyamines dissolved in toluene are then concentrated by distillation in vacuo. A slightly yellowish polyamine mixture is obtained in a yield of 120 parts by weight.

62 parts by weight of pure hexamethylenediamine can be distilled off from this polyamine mixture in the vacuum distillation. Sp. 85 ° C / 13 torr. 58 parts by weight of golden-yellow polyamine mixtures made from homologous polymer polyamines remain in the residue the constitution

H ₂ N- (CH ₂₎ g-NH- _(CH2) 5-NH ₂

H ₂ N- (CH ₂ ) ₆ -N- (CH ₂ ) ₆ -N- (CH ₃ ) ^ NH ₃ HH

exist. These polyamines with primary and secondary NH ^. _a groups are valuable crosslinkers for epoxy resins and porj isocyanates.

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Variant B;

An equal amount of a solution A prepared as described above can be used for pressure hydrolysis without further work-up of a further 400 parts by weight of the isolated insoluble residue isocyanate-ammonia reaction product is used will. Here, the hydrolysis by ammonia, ammonium carbonate present and the carbonic acid salts of the Executed under variant A isolated polyamines. The preparation of the approach is carried out exactly according to variant A. Zur To bind the carbon dioxide from the carbonic acid salts of the polyamines, 600 parts by weight of solid sodium hydroxide are added. The polyamines are worked up, extracted and isolated exactly as described for variant A. Yield to pure hexamethylenediamine: 182 parts by weight. Yield of polymer-homologous polyamine mixtures: 174 parts by weight.

Example 7

The procedure is exactly as described in Example 6, variant A, but replacing ammonia

a) by 16 moles of methylamine

b) by 16 moles of ethylamine.

The hydrolysis, extraction and isolation of the polyamines takes place exactly as in Example 6, variant A. a *) Yield of hexamethylenediamine: 59 parts by weight

Yield of homologous polymer polyamines: 57 parts by weight b ¹ ) Yield of hexamethylenediamine: 60 parts by weight Yield of homologous polymer polyamines: 59 parts by weight.

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Example 8

The procedure is exactly as described in Example 6, variant A, but using 200 parts by weight of a liquid, brown-black Residue isocyanates, which in the technical phosgenation of 3, SjS-trimethyl-S-amino-methyl-cyclohexylamine

= Isophoronediamine

is obtained. The residue isocyanate has an NCO content of 18.2%. Hydrolytic splitting of this residual isocyanate after the NCO groups have reacted with ammonia and work-up and isolation of the polyamines is carried out according to Example 6, variant A. The insoluble black residues after filtration are only 6 parts by weight, i.e. H. approx. 97% by weight of the residual isocyanate are hydrolyzed.

Yield of 3, SjS-trimethyl-S-amino-methyl-cyclohexylamine (= isophoronediamine): 71 parts by weight, temperature 99 ° C./0.3 Torr. Yield of higher molecular weight, nondestillable honey-like polyamines: 76 parts by weight.

Example 9

From a technically inferior, higher molecular weight biuret polyisocyanate, which is made from hexamethylene diisocyanate and tert. Butanol was produced in a molar ratio of 8: 1 and through improper storage as a result of further reaction of the NCO groups with atmospheric moisture in a higher molecular biuret poly-

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Isocyanate with a viscosity of 150,000 cP / 40 ° C has been converted, 2OO parts by weight are exactly according to the example 6, variant A reacted with ammonia and then hydrolyzed under pressure. Insoluble parts after filtration: 1.8 parts by weight, i.e. H. the hydrolysis of the biuret polyisocyanate used takes place to about 99%.

The processing, extraction and isolation of the hexamethylenediamine and the higher molecular weight polymer homologous polyamines are carried out exactly as in Example 6, variant A. Yield of hexamethylenediamine:
59 parts by weight, bp 85 ° C / 13 Torr.

Yield of polymer-homologous polyamine mixtures of the constitution

H ₂ N- (CH ₂ ) ₆ -N- (CH ₂ ) ₆ -NH ₂
H

HN- (CH-), -N- (CH-) C-NH- (CH-) -.- NH-: 2 26 _H 26 262

54 parts by weight Example 10

The black-brown residue isocyanate mixture used in this example was obtained in the technical phosgenation of aniline-formaldehyde condensates and removal of 4,4'-diisocyanatodiphenylmethane by distillation. Improper storage of the isocyanate residue for 3 months and the reaction of the NCO groups with atmospheric moisture result in the formation of polyurea, which results in viscous polyisocyanates. NCO content 21.5%.

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200 weight tie. this isocyanate residue is converted into a polyurea mixture with aqueous ammonia solution, exactly as in example k, variant A, and then hydrolyzed under pressure in an autoclave. After the autoclave has cooled down, the aromatic polyamine mixtures obtained by hydrolysis are used. the carbon dioxide formed by hydrolysis does not form any easily soluble betaine-like salts, filtered off and dried. Yield: 145 parts by weight. By fractional crystallization from a little benzene, 19 parts by weight. k , k '-diaminodiphenylmethane can be isolated. Mp. 9 "5 ⁰ C. 126 weight parts. Of the aforementioned yield consist somereneemisehen ans] and polynuclear aromatic polyamines linked methyl.

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Claims (4)

Claims 1) Process for the production of organic polyamines by hydrolytic decomposition of undistillable Polyisocyanates or distillation residues such as those used in the work-up of organic polyisocyanates by distillation incurred ,, characterized in that one the undistillable polyisocyanates or distillation residues, optionally after pretreatment with ammonia with conversion of the isocyanate groups present into urea groups under pressure at a Temperature of 100-3OO C with aqueous solutions of primary or secondary amines, of ammonia or of brings ammonia-releasing compounds to reaction under the reaction conditions. 2) Method according to claim 1, characterized in that that the reaction is carried out in the presence of up to 10% by weight, based on non-distillable polyisocyanate, or on the distillation residue on £ -caprolactam. 3) Process according to claim 1 and 2, characterized in that the reaction is carried out in the presence of the splitting of isocyanurate rings accelerating catalysts. 4) Use of the polyamines accessible according to claims 1-3 as raw material for the production of organic Polyisocyanates by phosgenation of the polyamines present in the resulting polyamine mixture with exclusively primary amino groups. Le A 17 767 - 25 - 809831/0107