Process for producing polyamides from aminonitriles

Translation of description of equivalent WO 9808889 A2

METHOD FOR PRODUCING POLYAMIDE OFF

AMINONΓΠULEN

The present invention relates to a novel process for preparing polyamides from aminonitriles and water at elevated temperature and elevated pressure.

The US 2,245,129 describes a discontinuous two-stage preparation of polycaprolactam from ω-aminocapronitrile ( "ACN") and water at a temperature in the range of 150 to 300 ° C and a specific temperature program as a function of the amount of water added and a maximum pressure of , 30 bar. A disadvantage of this process is the long reaction times (20 h in the first stage), the low viscosity of the resulting polycaprolactam and the high content of volatile bases (essentially primary acid amides) compared with a polycaprolactam prepared from caprolactam.

In DE-C 35 34 817 US 4,568,736 and US 4,629,776 the problems described in US 2,245,129 are partially solved by the use of phosphorus and sulfur-containing catalysts. The use of the above mentioned catalysts improves the low space-time yield of the process described in US 2,245,129. However, the content of volatile bases of all products manufactured by the above method is still too high, so ό ^ ß the polyamides are difficult to process and have a reduced carboxyl end group. The products of the above-mentioned methods show due to the stoichiometric discrepancy between the amino and Carboxyi terminated an insufficient degree of polymerization and a slow increase in molecular weight during tempering. Furthermore, a complete separation of the catalysts is virtually impossible, so that the chemical and physical behavior of the polymers produced using the catalysts, such as type and quantity of end groups or Abknickverhalten is negatively affected during spinning.

In EP-A 0,479,306 is proposed with water to polycaprolactam in the reaction of ACN, continuous tension after reaching a reaction temperature of 200 to 260 ° C ammonia and water by develop- <img id="imgf000004_0001" he="3" wi="5" file="imgf000004_0001.tif" img-format="tif" img-content="drawing" orientation="portrait" inline="no" /> remove and simultaneously and continuously add water, wherein the pressure in the range of 14 to 24 x 10⁶ Pa (14 to 24 bar) is selected.

In EP-A 65 291 a continuous process for the production of polyamide 66 is described from dinitriles and diamines. The molecular weight is established via polycondensation.

Caprolactam does not occur as Zwischenprodulct on, probably however in the polymerization of ACN. Thus, because of the different FEN Reaktionsabläu- not possible in a transmission of the EP-A-mentioned procedure 65291 to the present problem.

The present invention is based on the object to provide a process for producing polyamides from aminonitriles available, which ensures an improved hydrolysis of Reaktonden, particularly the acid amide groups, and thus a higher carboxyl end group. The molecule-arge weight construction during the polymerization and the temperability of the product are improved compared with the method of the prior art in this way. Accordingly, the present invention relates to a process for preparing a polyamide by reacting at least one Amionitrüs with water, which comprises the following steps:

(1) reacting at least one aminonitrile with water at a

Temperature of 100 to 360 ° C, and a pressure of 0, 1 to 35 x 10⁶ Pa to obtain a reaction mixture is obtained,

(2) further reacting the reaction mixture at a temperature of 150 to 400 ° C and a pressure which is lower than the

Pressure in step 1, the temperature and the pressure are selected such that a first gas phase and a first liquid or a first solid phase or a mixture obtained from the first solid and first liquid phase, and the first gas phase from the first liquid or the first solid phase or the mixture of first liquid and first solid phase is separated, and

(3) admixing the first liquid or the first solid phase or the mixture of first liquid and first solid phase with a gaseous or liquid phase comprising water at a temperature of 150 to 360 ° C, and a pressure of 0, 1 to 30 x 10⁶ Pa to obtain a product mixture is obtained.

The present invention further relates to a process for preparing a polyamide by reacting at least one aminonitrile with water, comprising the following steps:

(1) reacting at least one aminonitrile with water at a temperature of 100 to 360 ° C, and a pressure of 0, 1 to 35 x 10⁶ Pa to obtain a reaction mixture is obtained, (2) further reacting the reaction mixture at a temperature of 150 to 400 ° C and a pressure which is lower than the pressure in step 1, the temperature and the pressure are selected such that a first gas phase and a first liquid or a first solid phase or a mixture of first solid and first liquid phase are obtained and the first gas phase from the first liquid or the first solid phase or the mixture of first liquid and first solid phase is separated, and

(3) admixing the first liquid or the first solid phase or the mixture of first liquid and first solid phase with a gaseous or liquid phase comprising water at a temperature of 150 to 360 ° C, and a pressure of 0.1 to 30 x 10⁶ Pa to obtain a product mixture is obtained.

(4) postcondensing the product mixture at a temperature of 200 to 350 ° C and a pressure which is lower than the pressure of stage 3, the temperature and the pressure are selected so as to, in that a second, containing water and ammonia gas phase and a second liquid or second solid phase or a mixture of second liquid and second solid phase, which (that) each entliält the polyamide, are obtained.

In addition, the invention provides a process for preparing a polyamide by reacting at least one aminonitrile with water, which comprises the following steps:

(1) reacting at least one aminonitrile with water at a temperature of 100 to 360 ° C, and a pressure of 0, 1 to 35 x 10⁶ Pa to obtain a reaction mixture is obtained, (2) further reacting the reaction mixture at a temperature of 150 to 400 ° C and a pressure which is lower than the pressure in step 1, the temperature and the pressure are selected such that a first gas phase and a first liquid or a first solid phase or a mixture of first solid and first liquid phase are obtained and the first gas phase from the first liquid or the first solid phase or the mixture of first liquid and first solid phase is separated, and

(4) postcondensing the first liquid or first solid phase or the mixture of first liquid and first solid phase at a temperature of 200 to 350 ° C and a pressure which is lower than the pressure of stage 3, the temperature and the pressure be chosen so that a second, water and ammonia-containing gas phase and a second liquid or second solid phase or a mixture of second liquid and second solid phase, which (that) each comprise the polyamide, are obtained,

provided.

The aminonitrile can piinzipiell any aminonitrile, ie compounds which have both at least one amino group and at least one nitrile group. Under these ω-amino nitriles are preferred, among the latter in particular ω-aminoalkyl nitriles having from 4 to 12 carbon atoms, more preferably 4 to 9 carbon atoms in the alkylene moiety, or an aminoalkylaryl nitrile are used with 8 to 13 C atoms, there being such preferably having between the aromatic unit and the amino and nitrile group an alkyl spacer with at least one carbon atom. Among the Arninoalkylarylnitrilen particularly preferred are those which have the amino group and nitrile group in the 1,4-position to each other. As ω-Aminoallcylnitril used is preferably a linear ω-aminoalkyl, where the alkylene radical (-CH₂-), More preferably 4-9 carbon atoms preferably contains 4 to 12 C-atoms, such as 6-amino-1 -cyanopentan (6-

Aminocapronitrile), 7-amino-l-cyanohexane, 8-amino-l-cyanoheptan, 9-amino-1-cyanooctan, 10- amino-1-cyanononan, particularly preferably 6-aminocapronitrile.

6-aminocapronitrile is customarily obtained by hydrogenation of adiponitrile according to known methods, described for example in DE-A 836.938, DE-A 848.654 or US 5,151,543.

Of course, can be used in mixtures of a plurality of aminonitriles or mixtures of an aminonitrile with further comonomers, such as caprolactam or the below-defined mixture.

In a particular embodiment, especially if copolyamides mΣ desired to prepare, are employed instead of pure <img id="imgf000008_0001" he="5" wi="33" file="imgf000008_0001.tif" img-format="tif" img-content="drawing" orientation="portrait" inline="no" /> following mixture:

From 50 to 99.99, preferably from 80 to 90 wt .-% 6-aminocapronitrile,

0.01 to 50, preferably from 1 to 30 wt .-% of at least one dicarboxylic acid selected from the group consisting of aliphatic C₄-Cι₀-α, ω-dicarboxylic acids, aromatic dicarboxylic acids, and Cg-C ^ C₅-C_8th-Cycloalkandi- Carboxylic acids, 0 to 50 preferably from 0.1 to 30 wt .-% of an α, ω-diamine having 4 to 10 carbon atoms,

0 to 50 preferably 0 to 30 wt .-% of an α, ω-C₂-C₁₂Dinitrile, as well as 0 to 50 preferably 0 to 30 wt .-% of a, ω-C₅-C₁₂Amino acid or the corresponding lactam,

wherein the sum of the individual weight percentages adding up to 100%. Suitable dicarboxylic acids include aliphatic C₄-C₁₀-Q:, Ω-dicarboxylic acids such as succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, preferably adipic acid and sebacic acid, particularly preferably adipic acid, and aromatic Cg-C₁₂Dicarboxylic acids such as terephthalic acid and C₅-cg-Cycloalkane as Cyclohexandicar- bonsäure use.

As α, ω-diamine having 4 to 10 carbon atoms can be amine tetramethylene, pentamethylene, hexamethylene, heptamethylenediamine, octamethylene, Nonamethylendi, amine and Decjunethylendiamin, preferably hexamethylenediamine, are running.

Furthermore, it is also possible to use salts of the aforementioned dicarboxylic acids and diamines, especially the salt of adipic acid and hexamethylenediamine, so-called AH salt.

As α, ω-C₂-C₁₂Dinitrile used is preferably an aliphatic dinitrile such as 1,4-dicyanobutane (adiponitrile), 1, 5-Dicyanpentan, 1,6-Dicyanhexan, 1,7- Dicyanheptan, 1.8-Dicyanoctan, 1, 9-Dicyannonan, 1 , 10-Dicyandecan, particularly preferably adiponitrile, a.

If desired, you can also use diamines, dinitriles and aminonitriles derived from branched alkylene or arylene or alkylarylene compounds.

As α, ω-C₅-C₁₂Amino acid can be 5-Aminopenüuιsäure, 6-Aminohexan- ωure, 7-aminoheptanoic, 8-Aminooct.ansäure, 9-Arrιinononansäure, 10- aminodecanoic acid, 11-Aminoundecatnsäure and 12-, aminododecanoic, preferably 6-aminohexanoic, running.

According to the invention in a er.sten stage (stage 1) involves heating an aminonitrile with water at a temperature of about 100 to about 360 ° C, preferably about 200 to about 350 ° C, especially from about 250 to about 300 ^CC., a pressure of about 0, 1 to about 35 x 10⁶ Pa, preferably about 4 to about 30 x 10⁶ Pa, especially about 6 to about 12 x 10⁶ Pa is set. The pressure and temperature can be matched to one another in this stage that a liquid or a solid PhΣise and a mixture of liquid or solid phase and a gaseous phase are obtained.

Erfindungsgem.äß, water is used in a molar ratio of amino alkylnitrile to water ranges from 1: 1 to 1:30, more preferably from 1: 2 to 1: 10, most preferably from 1: 2 to 1: 4, a wherein the use of water in excess, based on the aminoalkyl nitrile is preferred.

In this embodiment, the liquid or solid phase or the mixture of liquid and solid phase corresponds to the reaction mixture, whereas the gaseous phase is separated off. The gaseous phase immediately from the liquid or solid phase or the mixture of solid or liquid phase can be separated in this stage, or the forming within this stage reaction mixture can be present in two-gaseous, solid-gas or liquid / solid-gaseous present. Of course, pressure and temperature can also be coordinated with one another such that the reaction mixture present as a single solid or liquid.

The separation of Gaspliase can be accomplished by the use of stirred or unstirred separating tanks or tank batteries and by the use of VerdΣunpferappjiraten, eg circulatory evaporators or thin-film evaporators, eg. By film extruders, or by Ringscheibenre.aktoren that guarantee an enlarged phase interface Certain cases, recirculation of the reaction mixture or the use of a loop reactor may be necessary to increase the phase interface. 3 Furthermore, the removal of the gas phase by the addition of

Water vapor or inert gas are conveyed in the liquid phase.

Preferably is set at a preselected temperature of the pressure so that it is smaller than the equilibrium vapor pressure of ammonia, but greater than the equilibrium vapor pressure of the other components in the Re.aktionsgemisch at the predetermined temperature. In this way, especially .can the removal of ammonia and thus promotes the hydrolysis of the acid amide groups.

In stage 1, stirred tanks, flow pipes or tank batteries can be used. In a two-phase procedure, the use of tanks or a reaction column is preferred, while at a einphasigflüssigen driving style as a preferred embodiment a flow tube equipped with packing to use. The use of a tube bundle reactor, optionally equipped with packing elements, in the first process step is likewise possible and particularly advantageous in a two-phase procedure in order to improve the heat exchange and to reduce the axial back-mixing of the reactants on.

As packing elements, for example Raschig rings or Sulzer mixing elements can be used to ensure a narrow residence time distribution and in order to limit back-mixing.

In a further embodiment of the first stage reactor is flowed through from top to bottom, where it is again preferably equipped with packing elements which limit any axial back mixing of the reactants. This achieves the liberated in the reactor Ammonik gas which predominantly occurs immediately after entering the reactor, the shortest route, the gas phase at the top of the reactor. The disturbance of the flow profile in the further course of the reactor by ascending gas bubbles or convection is therefore low. HO

Bzgl. the residence time of the reaction mixture in the first step, there are no restrictions whatsoever; however, it is generally selected in the range from about 10 minutes to about 10 hours, preferably between about 30 minutes and about 6 hours.

Although related, the conversion of nitrile groups exist no restrictions in stage 1, is economic reasons especially dictate that the conversion of nitrile groups in step 1 be generally not less than about 70 mol%, preferably at least about 95 mol% and in particular about 97 to about 99 mol, each based on the moles of aminonitrile used.

The nitrile group conversion is customarily determined by means of IR spectroscopy (CN stretching vibration at 2247 wavenumbers), NMR or HPLC, preferably by IR spectroscopy.

In a further embodiment bevozugten the aminonitrile / water mixture is continuously heated with the aid of a heat exchanger, and the mixture thus heated vessel into a temperature to the same temperature reaction, preferably a pipe which may contain internals such as Sulzer mixing elements, if necessary, to avoid back-mixing, eingefülirt. Of course, the aminonitrile and the water can also be heated up separately.

Furthermore, it is not excluded ernndungsgemäß, the reaction in stage 1 in the presence of oxygen-containing phosphorus compounds, especially phosphoric acid, phosphorous acid and hypophosphorous acid and their alkali metal and alkaline earth metal salts such as Na and Ammoniumωlze₃PO₄, Close₂PO₄, N / A₂HPO₄, Close₂PO₃, N / A₂HPO₃, Close₂PO₂, K₃PO₄, KH₂PO₄, K₂HPO₄, KH₂PO₃, K₂HPO₃, KH₂PO₂ to carry out, where the molar ratio of ω - aminonitrile to phosphorus compounds is in the range of 0.01: selected 1: 1 to 1: 1, preferably from 0.01: 1 to 0.1. Furthermore, it is not excluded, also known metal oxides, such as

Titanium dioxides, zirconium oxide, Auluminiumoxid, lanthanum oxide, Magnesiuoxid, etc, preferably titanium dioxides, for heterogeneous catalysis in the individual process rensstufen use to promote the conversion, especially of the nitrile groups. The abovementioned metal oxides are not used in step 4, but can be used in steps 1 to 3, wherein the

Use is preferred in stage. 1

According to the invention the reaction mixture obtained in the first stage and in stage 2 at a temperature of about 150 to about 400 ° C, preferably a temperature in the range from about 220 to about 350 ° C and in particular in the range of about 250 to about 290 ° C a pressure which is lower than the pressure in step 1 is reacted further. Preferably, the pressure in the second stage is at least about 0.5 x 10⁶ Pa lower than the pressure in stage 1, wherein in general, the pressure in the range of about 0.05 to about 45 x 10⁶ Pa, preferably about 0.5 to about 15 x 10⁶ Pa, especially about 0.5 to about 5 x 10⁶ Pa.

Here, the temperature and the pressure are in stage 2 so chosen that a first gas phase and a first liquid or first solid phase or a mixture of first liquid and first solid phase are obtained and the first gas phase from the first liquid or first solid phase or the mixture of first liquid and first solid phase is separated.

The first gaseous phase, which consists of ammonia and water vapor substantially removed m.an generally continuously with the aid of a distillation device, such as a distillation column. The co-deposited in this distillation, if necessary, the organic components of the distillate, unreacted in the predominant extent aminonitrile, can be recycled completely or partially in step 1 and / or stage 2nd &lt;\ V ^' The residence time of the reaction mixture in step 2 is not subject to

However, limitations is generally ungefälir 10 minutes to about 5 hours, preferably 15 minutes to about 4 ungefa.hr

Hours.

The product line between the first and second stages optionally contains packing elements, for example Raschig rings or Sulzer mixing elements, which facilitate a controlled expansion of the reaction mixture into the gas phase.

In Stage 3, the first liquid or the first solid phase or mixture of first liquid and first solid phase with a gaseous or liquid phase comprising water is preferably added to water or water vapor. This is preferably done continuously. The amount of water added (as liquid) is preferably in the range of about 50 to about 1500 ml, more preferably about 100 to about 500 ml, based in each case on 1 kg of first liquid or first solid phase or the mixture of first liquid and first solid phase. This addition of water, the comparison in stage 2 ursachten water losses are compensated for in the first place and the hydrolysis of acid amide groups in the reaction mixture conveyed. This results in a further advantage of this invention that the mixture of the starting materials as used in step 1 can be used only with a small Wasserübschuß.

Preferably, the water-containing gaseous or liquid phase is preheated before being introduced into step 3 in a heat exchanger and then mixed with the first liquid or the first solid phase or the mixture of first solid and first liquid phase. Mixing elements can optionally be used in the reactor, which promote the mixing of the components. Step 3 is performed at a temperature of 150 to 400 ° C and a pressure of 0.1 to 30 x 10⁶ Pa operated.

The pressure and temperature can be coordinated so that the reaction mixture is present as a single liquid or solid phase. In another embodiment, pressure and temperature are selected so that a liquid or a solid phase or a mixture of solid and liquid phase and also a gaseous phase are obtained. In this embodiment, the liquid or solid phase or the mixture of liquid and solid phase corresponds to the product mixture, whereas the gaseous phase is separated off. Here, in the context of this step, the gaseous phase immediately be separated from the liquid or solid phase or the mixture of solid or liquid phase, or the forming within this stage reaction mixture present in two-gaseous, solid-gas or liquid / present solid-gaseous ,

At a preselected temperature, the pressure can be adjusted so that it is smaller than the Gleichgewichtsdampfdmck of ammonia, but greater than the Gleichgewichtsd-ampfdruck of the remaining components in the reaction mixture at the given temperature. In this way, the removal of ammonia, the hydrolysis of the acid amide groups may, in particular favoring and thus be accelerated.

The einsetzbΣiren in this stage apparatus / reactors with those of step 1, discussed above, identical.

In a preferred embodiment of the first stage reactor is flowed through from top to bottom in the two-phase procedure, where it is again preferably equipped with packing elements which limit any axial back-mixing of the reactants. This achieves the liberated in the reactor Ammonik gas which predominantly occurs immediately after entering the reactor, the shortest route, the gas phase at the top of the reactor sector. The disturbance of the flow profile in the further course of the reactor by ascending gas bubbles or convection is therefore low.

The residence time in this step is likewise not subject to any restrictions, economic reasons, however they generally range between about 10 minutes to about 3 hours, preferably between about 20 to about 90 minutes.

The product mixture obtained in step 3 may then be as described below, processed further.

In a preferred embodiment, the product mixture of step 3 in a fourth stage of condensation at a temperature of about 200 to about 350 ° C, preferably a temperature of about 220 to 300 ° C and especially about 250 to 270 ° C is subjected. Stage 4 is carried out at a pressure which is below the pressure of step 3, and preferably in a range of about 5 to 1000 x 10³ Pa, more preferably from about 10 to about 300 x 10³ Pa. In the context of this step the temperature and pressure are selected so that a second gas phase and a second liquid or solid phase or a mixture of second liquid and second solid phase which each comprise the polyamide, are obtained.

Preferably the condensation in stage 4 is carried out so that the relative viscosity (measured at a temperature of 25 ° C and a concentration of 1 g of polymer per 100 ml in 96 wt .-% strength sulfuric felωure) of the polyamide is in the range takes from about 1.6 to about 3.5.

In a preferred embodiment, can be obtained from the liquid phase, any water present cast as nitrogen by means of an inert gas. The residence time of the reaction mixture in step 4 depends especially on the desired relative viscosity, the temperature, the pressure and added in step 3 amount of water.

If step 3 is operated single-phase, so can in the product line between step 3 and step 4 may optionally contain packing elements, for example, be made Raschig rings or Sulzer mixing elements used, which allow a controlled expansion of the reaction mixture in the gas phase.

In a further embodiment according to the invention can be dispensed on stage 3 and for the preparation of the polyamide, the steps (1), (2) and (4) are executed.

This variant is preferably carried out as follows:

In step 1, at least one aminoalkyl nitrile with an excess of water to a temperature in the range of about 250 to about 350 ° C, more preferably about 270 to 300 ° C and a pressure of un- mately 4 to 30 x 10⁶ Pa, more preferably about 6 to 30 x 10⁶ Pa, in particular 7 to 13 x 10⁶ Pa, and particularly preferably about 8 to 12 x 10⁶ Pa heated, whereby the pressure and temperature adapts to each other so that the reaction mixture is present as a single liquid phase, and wherein the conversion of nitrile groups based not less than 95 mol%, more preferably in the range of 97 to 99 mol% based on the mole number of employed aminoalkylnitrile is, to obtain a reaction mixture is obtained.

The reaction mixture is in stage 2 at a temperature in the range of about 220 to about 300 ° C, more preferably about 250 to 270 ° C and a pressure in the range of about 1 to about 7 x 10⁶ treated Pa, more preferably from about 1 to about 4 x 10⁶ Pa, the pressure in the second stage at least 0.5 x 10⁶ Pa is lower than in stage 1. At the same time, the resulting first gas phase is separated from the first liquid phase.

The first liquid phase obtained in step 2, in step 3 at a temperature in the range of about 220 to 300 ° C, more preferably about 250 to 270 ° C and a pressure in the range of about 10 to about 300 x 10³ Pa, more preferably from about atmospheric pressure, treated, with the resulting second, water- and ammonia-containing gas phase is separated from the second liquid phase. Within this step, the relative viscosity (measured as defined above) of the resulting polyamide to a desired value in the range of about 1.6 to about 3.5 W.ahl adjusted by the temperature and residence time.

Subsequently, the resulting second liquid phase is discharged by conventional methods and, if desired, worked up.

The methods described above, that is the sequence according to the invention of steps (1) to (3) or (1), (2) and (4) or (1) to (4) may be either discontinuous, that is, in a reactor successively in time, or continuously, that is, at the same time carried out in successive reactors. Of course, it is also possible for a part of the steps, for example steps (1) and (2) continuously and the remaining (n) are performed discontinuously (n) stage.

In a further preferred embodiment of the present invention, at least one of the product obtained in the respective stages gas phases are recycled into at least one of the preceding stages.

It is further preferred that in step 1 or in step 3 or both in step 1 and in step 3, the temperature and the pressure are chosen such that a liquid or a solid phase or a mixture of liquid and solid phase and a gaseous phase are obtained, and the gaseous phase is separated off.

Further, one can under the Verfalirens invention also carry out a chain lengthening or branching or a combination of both. Given to the expert added substances known to a branching or chain-lengthening polymers in the individual stages. These substances are preferably added in step 3 or the fourth

Usable substances are:

Trifunctional amines or carboxylic acids as VernetKr. Examples of suitable at least trifunctional amines or carboxylic acids are described in EP-AO 345 648. The at least trifunctional amines have at least three amino groups which are capable of reacting with carboxylic acid groups. They preferably have no carboxylic acid groups. The at least trifunctional Garbonsäuren have at least three capable of reaction with amines carboxylic acid groups, which can, for example, be in the form of their derivatives such as esters. The carboxylic acids preferably do not capable of reaction with amino groups, carboxylic acid groups. Examples of suitable carboxylic acids are trimesic acid, trimerization-based fatty acids, which may be prepared for example from oleic acid and having from 50 to 60 carbon atoms, naphthalenepolycarboxylic as naphthalene 1,3, 5, 7-tetracarboxylic acid. Preferably, the carboxylic acids defined organic compounds and not polymeric compounds.

Amines having at least 3 amino groups are, for example Nitrilotrialkyla- min, especially nitrilotriethaneamine, dialkylene particular diethylenetriamine, trialkylenetetramines and tetraalkylenepentamines, the alkylation are lenreste preferably ethylene radicals. Furthermore, as amines Nevertheless dendrimers are used. Dendrimers preferably have the general formula I

(R₂N- (CH₂)_n)₂N- (CH₂)_x-N ((Ch₂)_n-NO₂)₂ (I)

in the

RH or - (CH ^ NR ^ with

R¹ H or - (CH₂)_n-NO²₂ With

R² H or - (CH₂)_n-NO³₂ With

R³ H or - (CH₂)_nNH₂ is,

n has an integral value from 2 to 6 and

x is an integer 2 to 14

Preferably, n is an integer of 3 or 4, especially 3, and x is an integer from 2 to 6, preferably from 2 to 4, especially 2. The radicals R may independently of each other have the meanings indicated. Preferably the radical R is a hydrogen atom or a radical - (CH₂)_nNH₂,

Suitable carboxylic acids are those having 3 to 10 Garbonsäuregruppen, preferably 3 or 4 carboxylic acid groups. Preferred carboxylic acids are those having aromatic and / or heterocyclic nuclei. Examples are benzyl, naphthyl, anthracene, biphenyl, triphenyl radicals or heterocycles such as pyridine, bipyridine, pyrrole, indole, furan, thiophene, purine, quinoline, phenanthrene, Poryphin, phthalocyanine, Naphthalocyarün. Preferred are 3,5,3 \ 5'-Bipheityltetracarborιsäure-Phtlιalocyanin, naphthalocyanine, 3,5,5 ', 5'-biphenyltetracarboxylic, 1,3,5,7-Naphthjüintetracarbonsäure, 2,4,6-pyridine -Λ3 Tricarboxylic, S ^ .S'S'-Bipyridyltetracarbonsäure, 3,5,3'5'-Benzophenontetra- carboxylic acid, 1,3,6,8-Akridintetracarbonsäure, particularly preferably 1,3,5-benzenetricarboxylic acid (trimesic acid) and 1, 2,4,5-benzene tetracarboxylic acid. Such compounds are commercially available or can be prepared by the method described in DE-A-4312182. When using ortho-substituted aromatic compounds imide formation is preferably prevented through the choice of suitable reaction temperatures.

These substances are at least trifunctional, preferably at least tetrafunctional. In this case, the number of functional groups 3 to 16, preferably 4 to 10, besondedrs preferably be 4 to 8. FIG. It can be used in the inventive process either at least trifunctional amines or at least trifunctional carboxylic acids, but not mixtures of such amines or carboxylic acids. However, small amounts of at least trifunctional amines can trifunktion rush carboxylic acids be included, and vice versa.

The substances are present in the amount from 1 to 50 .mu.mol / g of polyamide, preferably from 1 to 35, particularly preferably 1 to 20 .mu.mol / g of polyamide. The substances are preferably present in an amount of 3 to 150, particularly preferably 5 to 100, i nsbesondere 10 to 70 .mu.mol / g of polyamide of equivalents. The equivalents are based on the number of functional amino groups or Garbonsäuregruppen.

Bifunctional Garbonsäuren or difunctional amines as chain extenders. They thus have 2 carboxylic acid groups which can be reacted with amino groups, or 2 amino groups which can be reacted with carboxylic acids. The difunctional carboxylic acids or amines, besides the carboxylic acid groups or amino groups, no other functional groups that can react with amino groups or Garbonsäuregruppen. Preferably, they contain no functional zo ^'

Groups. Examples of suitable difunctional amines are those which form with difunctional carboxylic acids salts. They can be linear aliphatic, such as C_j,₁₄Alkylenediamine, preferably C ^ g-alkylenediamine, for example hexylenediamine. You can also be cycloaliphatic. Examples are isophoronediamine, dicycycan, laromine. Branched aliphatic diamines are likewise usable, an example being Vestamin TMD (Trimethylhexamethy- diamine, manufactured by Huls AG). In addition, the diamines may be aromatic-aliphatic, for example n-xylylenediamine may be used. The ges.amten amines can each by C ^ -, preferably C_j. ^ - Alkyl substituted on the carbon skeleton.

Difunctional carboxylic acids are for example those which form salts with difunkitionel- len diamines. They can be linear aliphatic dicarboxylic acids, preferably C_4:20Dicarboxylic acids are. Examples are adipic acid, azelaic acid, sebacic acid, suberic acid. They can also be aromatic. Examples are isophthalic acid, terephthalic acid, naphthalene dicarboxylic acid, as well as dimerized fatty acids.

The difunctional basic building blocks (c) are preferably used in amounts of from 1 to 55, particularly preferably 1 to 30, in particular 1 to 15 .mu.m / g of polyamide.

According to the invention carries the product mixture obtained in step 3 or the second liquid or second solid phase or the mixture of second liquid and second solid phase (from step 4), the PolyΣunid enthΣdten, preferably a polymer melt, by customary methods, for example by means of a pump from the reaction vessel. Then you can the polyamide obtained by known Mehtoden, for example, in DE-A 43 21 683 (page 3, line 54 to page 4, Z.3) are described in detail, worked up. Z. In a preferred embodiment can reduce the content of the present invention obtained polyamide 6 cyclic dimer further by first then extracted the Polyamit with an aqueous solution of caprolactam and then with water and / or gas phase extraction (for example, describe in EP-A 28 49 68) subjects. The products of that post-treatment low molecular weight constituents such as caprolactam and its linear and cyclic oligomers, can be recycled into the first and / or second and / or third stage.

The starting monomer or mixture of monomers in all the stages may be preferably in the fourth stage, conventional additives and fillers such as pigments, particularly titanium dioxide (anatase and / or rutile), silica, and talc, chain regulators such as aliphatic and aromatic carboxylic and dicarboxylic acids such as propionic acid, acetic acid acid, benzoic acid, terephthalic acid, and Triaceton- diamine, stabilizers such as copper (I) halides and alkali metal halides, nucleating agents such as magnesium silicate or boron nitride, catalysts, such as phosphorous acid, and also antioxidants in amounts ranging from 0.01 to 5, preferably from 0.2 to 2 .-%, based on the amount of monomers used, may be added.

The present invention provides a polyamide preparable by further relates to

(1) reacting at least one aminonitrile with water at a temperature of 100 to 360 ° C, and a pressure of 0, 1 to 35 x 10⁶ Pa to obtain a reaction mixture is obtained,

(2) further reacting the Umsemmgsgemischs at a temperature from 150 to 400 ° C and a pressure which is lower than the pressure in step 1, the temperature and pressure are selected such that a first gas phase and a first liquid or a first solid phase or a mixture of first solid and first liquid phase are obtained and the first gas phase from the first liquid or the first solid phase or the mixture of first liquid and first solid phase is separated, and

(3) admixing the first liquid or the first solid phase or the mixture of first liquid and first solid phase with a gaseous or liquid phase comprising water at a temperature of 150 to 360 ° C, and a pressure of 0, 1 to 30 x 10⁶ Pa to obtain a product mixture is obtained,

Polyamide producible by

(1) reacting at least one aminonitrile with water at a temperature of 100 to 360 ° C, and a pressure from 0.1 to 35 x 10⁶ Pa to obtain a reaction mixture is obtained,

(2) further reacting the reaction mixture at a temperature of 150 to 400 ° C and a pressure which is lower than the pressure in step 1, the temperature and pressure are selected such that a first gas phase and a first liquid or a first solid phase or a mixture of first solid and first liquid phase are obtained and the first gas phase from the first liquid or the first solid phase or the mixture of first liquid and first solid Pliase is separated off, and

(3) admixing the first liquid or the first solid phase or the mixture of first liquid and first solid phase with a gaseous or liquid phase comprising water at a temperature of 150 to 360 ° C, and a pressure of 0.1 to

30 x 10⁶ Pa to obtain a product mixture is obtained. (4) postcondensing the product mixture at a temperature of 200 to 350 ° C and a pressure which is lower than the pressure of stage 3, the temperature and the pressure are chosen such that a second, containing water and ammonia gas phase and a second liquid or second solid phase or a mixture of second liquid and second solid phase, which (that) each comprise the polyamide, are obtained, and

olyamid producible by

(1) reacting at least one aminonitrile with water at a temperature of 100 to 360 ° C, and a pressure of 0, 1 to 35 x 10⁶ Pa to obtain a reaction mixture is obtained,

(2) additional Umseming of the reaction mixture at a temperature from 150 to 400 ° C and a pressure which is lower than the pressure in step 1, the temperature and the pressure are selected such that a first gas phase and a first liquid or a first solid phase or a mixture of first solid and first liquid phase are obtained and the first gas phase from the first liquid or the first solid phase or the mixture of first liquid and first solid phase is separated, and

(4) postcondensing the first liquid or first solid Pliase or the mixture of first liquid and first solid phase at a temperature of 200 to 350 ° C and a pressure which is lower than the pressure of stage 3, the temperature and the pressure are gewϊüilt that a second, Wa.sser and Airimoniak-comprising gas phase and a second liquid or second solid

Phase or a mixture of second liquid and second solid phase, which (that) each comprise the polyamide, are obtained. According to the invention obtained according to the invention or polyamides, in particular polyamide-6 and its copolymers, can be used for the production of fibers and materials.

EXAMPLES

example 1

This example illustrates the present invention exemplified by the reaction of ACN.

The determination of the AEG (amino end) and CEG (Carboxylendgrup- pen) carried out according to the WO 95/01389 in the (p.6, Z.35 to p.7, Z.40) method described.

Determination of volatile bases was made by Parnas-Wagner by hydrolyzing the polyamide with HCl, liberation of the bases with NaOH, followed by steam distillation (after Parnas) of the released bases in a template with HCl and finally back titration of the excess HCl with NaOH. From the difference of inserted HCl in the template and zurücktitrierter HCl, the content of volatile bases (leaves in mg NH₃/ Kg) calculated.

The nitrile group conversion was by IR spectroscopy by FΗR basis of the characteristic CN group band at 2247 cm^*1 determined.

The relative viscosity (RV) was measured at a temperature of 25 ^CC and a concentration of lg of polymer per 100 ml in 96 wt .-% strength sulfuric feisäure determined. Z -m

In all listed attempts (250 ° C, l ^ Pa (Ibar) 3 h,) was in a laboratory autoclave discontinuously-condensed (step 4).

The results and experimental conditions are shown in Table 1 below.

example 2

In the table below, the experimental conditions are given in step 1 and 2. FIG. The temperature in the fourth step was 270 ° C, the pressure lO ^ a (1 bar) and the residence time 1.5 hours.

Level 1 Level 2

ACN / H₂0 Time TP ACN time TP RV flüs¬

[Mol] [min] (^β [Bar] sales [min] [° C] [bar] sige

bases

[mg

NH₃/ K gl

1: 6 200 250 90 97 240 252 36 2.14 240

AEG: 65 mmol / kg CEG: 55 mmol / kg AEG / CEG = 1.18

TABLE 1

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VD = residence is WZ = water additive in, based on the input current of the ACN / water mixture in stage 1

Z *

Comparative Examples

The table below gives the product ratios of products manufactured according to the prior art - Ex 1 of US 5,109,104 and Example 1 of US 2,245,129 -.. Again.

RV CEG [meq / royal liquid environments dev. Bases [mg NH3 / kg]

US 5 109 104 1.76 19 1910

US 2 245 129 1.82 10 3150