CA2153862A1

CA2153862A1 - Process for producing precondensates of partially crystalline or amorphous,thermoplastically processable, partially aromatic polyamides or copolyamides

Info

Publication number: CA2153862A1
Application number: CA 2153862
Authority: CA
Inventors: Hanns-Jorg Liedloff; Manfred Schmid
Original assignee: EMS Inventa AG
Current assignee: Uhde Inventa Fischer AG
Priority date: 1994-07-14
Filing date: 1995-07-13
Publication date: 1996-01-15
Also published as: CZ288902B6; PL309677A1; EP0693515A1; JPH0853546A; EP0693515B1; JP3380654B2; CZ177895A3

Abstract

The invention relates to a process for producing precondensates of partially crystalline or amorphous, thermoplastically processable, partially aromatic polyamides or copolyamides, and the use of the higher molecular weight polyamides, accessible from the precondensates, for producing molding compositions, which are further processable by means of suitable processing techniques.

Description

21~ 3 8 6 2 Case95-E506 PROCESS FOR PRODUCING PRECONDENSATES OF PARTIALLY CRYSTALLINE OR
AMORPHOUS, THERMOPLASTICALLY PROCESSABLE PARTIALLY AROMATIC
POLYAMIDES OR COPOLYAMIDES

The invention relates to a processfor producing polymers of partially crystalline or amorphous, thermoplastically processable, partially aromatic polyamides or copolyamides, and to the use of the higher molecular weightpolyamides, accessible from the precondensates, for produciny molding compositions that are further processable by means of suitable processing techniques.
Partially aromatic polyamides with terephthalamlde and respectively isophthalamide units have already been ~nown since the beginning of the so-called "nylon age", in the form of their simply constructed representatives, for instance in the form of poly(hexamethylene terephthalamide). Nevertheless, it has taken another three to four decades of development until these polymers, which are extraordinarily interesting in terms of their properties, and recovering them, have become commercially available. Not until the 1970s could these products establish themselves on the market, in ever-increasing numbers of variants, with a steadily increasing growth rate.
The reason for the late appearance, compared with nylon-6, -66, -11 and -12, of the partially aromatic polyamides is that their production makes comparatively high and sometimes extreme demands of the process and of the necessary equipment or systems.
For the high-melting, partially crystalline poly(terephthalamides), methods and suitable equipment were not even available until the mid-1980s.
In amorphous, partially aromatic polyamides, which are accqssible in practically unlimited versatility from aromatic and optionally aliphatic dicarboxylic acids, aliphatic, cycloaliphatic or araliphatic diamines, and lactams or ~-amino acids, the situation proves to be more favorable in terms of the 21~3862 production process and the equipment. In that case, recourse can be made to the proven batch processes in conventional agitated autoclaves. Presently, virtually all the commercially available amorphous polyamides are produced industrially in batches, in suitably modified or expanded systems.
Suitably, a so-called dissolver is connected to the input side of the polycondensation reactor, and in it approximately equimolar quantities of dicarboxylic acid(s) and diamine(s) are converted into aqueous, possibly lactam-containing ~nylon~-salt solutions. Such solutions can be controlled as to their composition by using simple acid/base titration methods and can optionally be adjusted to the predetermined ratio of the amine and acid components by adding the missing proportion of acid or amine.
Batch processes generally have the advantage that a change in products can be done very quickly and without major effort.
In this sense, batch processes, in contrast to fully continuous methods, offer a high degree of flexibility.
However, batchwise production of amorphous partially aromatic polyamides is subject to limitations in terms of the attainable average molecular weight. Because of the typically very high structure-dictated melting viscosities of such polyamides, their polycondensation must be s topped at a very ear]y stage, to enable discharging the melt entirely from the autoclaves and processing it into granulate, for instance. In addition, to overcome the~often difficult problems of discharge, monofunctional cocomponents act as cnain regulators (or chain stoppers), such as monocarboxylic acids or monoamines, are used in the polycondensation.
Limiting the average molecular weight of these polymers to comparatively low values necessarily has a negative effect on their mechanical properties, technical processing properties, and other applications-oriented properties.
Meanwhile, there have been numerous attempts to circumvent these difficulties. Recent proposals involve the application of .
-two-stage methods, with a batchwise or continuously performed production of precondensates or prepolymers, and a final reaction stage that produces the final polymer. With amorphic partially aromatic polyamides, this latter stage typically comprises the condensation of the precondensate melt by means of continuous~
operation double- or single-screw extruders, with relatively short residence time- In these extruders, which are provided with one or more degassing openings and which can optionally be operated at reduced pressure, the condensation of the precondensates into high-molecular polyamides is carried on. In this connection, European Patent Disclosure EP A 410 649 and US Patent 4,963,646 are particularly informative. In both references, a batchwise process for precondensate (prepolymer~ production in combination with the above-described continuous-operation final reaction stage is proposed. In EP A 410 649, carboxyl-terminated polyamide prepolymers, with approximately equimolar quantities of diamine, are condensed in a double-screw extruder, with the splitoff of water, to make the high-molecular polyamide. To this end, a quantitatively controlled stream of prepolymer is continu-ously fed to the extruder , which after being melted and compressed mixes with the diamine metered by means of a pump, and is fed through a reaction zone and an ensuing degassing zone that is operated at reduced pressure. After passing through a further compression zone, the high-molecular polymer melt emerges through a nozzle, isIpulled off in the form of a strand, and is cooled and granulated.
US Patent 4,963,646 employs a similar mode of operation to EP A 410 649, but with the single difference that here a carboxyl-terminated polyamide prepolymer is reacted with an otherwise identically structured amino-terminated polyamide prepolymer. In the case of US Patent 4,963,646 as well, the condensation to the high-molecular polyamide is done in an extruder with a degassing zone; not only double-screw extruders but also single-screw extrudes can be used for this purpose.

.. ...

21~3~62 Both these patent disclosures evade the aforementioned problems involved with the single-stage batchwise production of amorphous partially aromatic polyamides. Each of the methods described are difficult, however, in the sense that the extruder must be supplied with two components in quantitative ratios that must be adhered to exactly and that are determined by the stoichiometry. This mode of operation thus makes extreme, and technically virtually unattainable, demands of the precision of two feed units that must be adapted precisely to one another. An even more difficult factor is that the extruder, with the homogeneous mixing of the two components and their polycondensation, must take on two tasks one after the other.
The temporal or spatial separation of these events along the extruder screw(s) , given the relatively short available residence time of nonnally approximately 1 to 5 minutes in conventional extruders, is not easy to attain. Problems of a similar nature to those occurring with the amorphous polyamides with terephthalamide and/or isophthalamide units also occur in the partially crystalline polyamides based on m-Xylylene diamine/adipic acid (PA-MXDA.6) or p-Xylylene diamine/adipic acid (PA-PXDA.6), and the copolyamides derived from them with arbitrary additional dicarboxylic acid and/or diamine components.
For the production of the most significant product of this series of partially aromatic polya~ides, PA-MXDA. 6, a conventional batch process is only limitedly suitable, especially when it is important to produce high-viscosity material with adequately hish viscosity. Because of the high melting point of PA-MXDA. 6, the postcondensation. of low-viscosity material in solid phase can be employed here at comparatively high process temperatures. With lower-melting-point copolyamides with MXDA units, however, this method has its limits.
Ccntinuous methods for producing precondensates of amorphous or partially crystalline, partially aromatic polyamides have also been proposed, in order to overcome the difficulties in the production of these polymers.

21S3~62 .
one such process,which is also said to be applicable to the production of other condensation pvlymers, is the subject of US
Patent ~,831,108. The sequence of process steps described there includes, for polyamides, the production of aqueous salt solution, a prereaction of these solutions in a tu~ular reactor through which there is a continuous flow, which reactor is operated at temperatures of around 300 C and, in order to maintain a closed liquid phase, at pressures above the respective water vapor pressure, and - in the next step - the controlled pressure relief of the prereacted solutions, while further condensations take place along with the formation of stable dispersions of polymer particles in a continuous vapor phase.
These dispersions are each delivered preferably directly to a double-screw extruder and there polycondensed to high-molecular polyamide (or other condensation polymers).
The applicant in the specification of 5,098,940 provides additionaL information on the process of US Patent 4,831,108;
according to this additional information, the salt solutions of diamines and dicarboxylic acids are preconcentrated by evaporating off some of the water. The prereaction of the salt solutions to make prepolymers is also no longer done in one tubular reactor but rather in two tubular reactors connected in series. What must be considered fundamentally novel compared with the process of US Patent 4,831,108, however, is the statement in US Patent 5, 098,940 that in the formation of the dispersions of polymer par~icles in a pressure-relieved continuous vapor phase, some of the water is let off in countercurrent via a regulating valve. Finally, in US Patent 5,098,940, further water is withdrawn from the dispersion of polymer particles and water vapor in the extruder, by degassing counter to the feed direction, before the polycondensation to high-molecular polyamides takes place downstream.
The process of US Patents 4,831,108 and 5,098,940 is extraordinarily pretent;ous and complex, especially with respect to regulating the very rapid process steps, fo1lo-~;ug~lirectly 21a3862 -on one another, in the tubular reactor, in the "dispersion phase"
and in the extruder. The direct coupling of all the process steps makes disruptions in operation still more difficult to control: even rearrangements and different products must be considered to be disruptions of this kind. With a view to a change in products, fully continuous methods are accordingly not as flexible as batch processes.
The object of the invention is therefore to furnish a process for producing precondensates of partially crystalline or amorphous, thermoplastically processable, partially aromatic polyamides or copolyamides that on the one hand neither has the disadvantages of the batch processes in the prior art nor the limitations of continuous processes in terms of rapidly changing from one product to another, but on the other hand makes use of the fundamental advantages of a batch process.
This object is attained by the method as defined by claim 1, the molding compositions as defined by claim 6, and the use thereof as defined by claim 7.
Advantageous embodiments of the invention are defined by the dependent claims.
The invention therefore relates in particular to a multi-step batch process that contains the following steps a) through e) a) a salt forming phase for producing salt(s) of diamine(s) and dicarboxylic acid(s) in an aqueous, 5 to 50 weight ~
solution containing the components, which is carried out in an agitatable and inertizable autoclave and optionally with partial prereaction to make low-molecular oligoamides at temperatures between 120-C and 220 C and at pressures of up to 23 bar;

b) optionally, the transfer of the solution from step a) to a second reaction vessel or an agitated autoclave, under the conditions prevailing at the end of its preparation;

.. . ..

, c) the reaction phase, during which the conversion to the precondensates is continued, by heating the reactor content to a predetermined temperature and controlled adjustment of the water vapor partial pressure to the predetermined value, which is maintained by the controlled venting of water vapor or optionally controlled feeding in of water vapor from a water vapor generator communicating with the autoclave;

d) a stationary phase to be maintained for at least 10 minutes, in which the temperature of the reactor content and the water vapor partial pressure - the latter by employing the provisions listed in c) above - are adjusted in controlled fashion, each to values which are contemplated for the transfer of the precondensates to the ensuing process step, with the specification that in the case of precondensates of partially crystalline polyamides or copolyamides having a melting point of 280 C and higher (maximum melting point, measured by differential scanning calorimetry), the temperature of the reactor content during this phases d) and phase c) must not exceed 265 C, and that for the aforementioned partially crystalline polyamides or copolyamides during phases d) and c), the values of Table must be adhered to with respect to the dependency of the minimum water vapor partial pressure PH 0 (minimum) to be employed 0n the temperature of the reactor content and on the amide group concentration of the polymer (in mmol/g, calculated for a condensed-out polymer with an average molecular wei:ght of at least 5000 g/mol);

. Table 1 Amide concentration Temperature PH 0 (minimum) (AC) [mmol/g] range [ C] [bar]

21S3~62 -I 10 > AC > 8 235-250 16 II 10 > AC > 8 250-260 19 III 8 > AC > 6 235-250 22 IV 8 > AC > 6 250-260 26 V 6 > AC 235-250 30 VI 6 > AC 250-260 32 e) a discharge phase, during which the precondensates, while the temperature prevailing at the end of phase d) is kept constant and the w~ter vapor partial pressure prevailing at that time is at least maintained by feeding water vapor from the aforementioned water vapor generator into the autoclave and all the discharge lines and units communicating with it, can be supplied either in the molten state directly, or after passing through the solid state and optionally passing through other process steps, to a final reaction apparatus.

This is done for the condensates of amorphous polyamides or copolyamides, or those that are partially crystalline with a melting point below 280 c, by introduction at constant temperature and constant pressure into a third autoclave acting as a buffer vessel, and from there to the final reaction apparatus by means of a suitable metering and feed unit via a melt line.

The precondensates, at a pressure of at least 16 bar, of partially crystalline polyamides or copolyamides with a melting point of 280 C and above are obtained in the form of solid particles by being sprayed into an inertized cyclone or spray tower, or a comparable apparatus, and are optionally dried and after remelting are fed into the final reaction apparatus by a suitable metering and feed unit.
The process steps a) through e) according to the invention can be carried out selectively in the presence of from 0.005 to ~153~62 1.5 weight %, referred to the total quantity of the polyamide-forming components, of an organic and/or inorganic phosphorus and/or tin and/or lead compound.
The process is applicable to the production of precondensates of partially crystalline or amorphous, thermoplastically processable, partially aromatic polyamides or copolyamides, which may comprise the following components:
A: from o to 100 mol ~ of at least one substituted or unsubstituted aromatic dicarboxylic acid having from 8 to 18 carbon atoms (referred to the total quantity of all the dicarboxylic acids A and B), B: from 0 to 100 mol % of at least one dicarboxylic acid having from 6 to 36 carbon atoms, selected from the group of straight- or branch-chained aliphatic and cycloaliphatic dicarboxylic acids (referred to the sum of A ~ B), C: from o to 100 mol % of at least one straight- or branch-chained aliphatic diamine having from 4 to 13 carbon--atoms (referred to the total quantity of all the diamines C + D + E), D: from 0 to 100 mol % of at least one cycloaliphatic diamine having from 6 to 26 carbon atoms (referred to the sum of C + D + E), E: from 0 to 100 mol % of at least one araliphatic diamine having from 8 to 26 carbon atoms (referred to the sum of C + D +
E), wherein molar quantity of the dicarboxylic acids (A and B) is approximately equal to the molar quantity of the diamines (C, D and E).
One skilled in the art is aware that because of the volatility of individual monomers, the molar quantity of the dicarboxyli.c acids (A + B) and the molar quantity of the diamines (C + D + E) can differ slightly from one another.
Further components F and/or G may be added to the components from the group A-E:
F: from o to 80 mol %, referred to the total quantity of components from the group A, B, C, D, E, F, of at least one 2153~62 polyamide-forming monomer from the lactam group or ~-amino acid having from 6 to 12 carbon atoms, and G: from O to 6 mol %, referred to the total quantity of components from the group A, B, C, D, F, G, of at least one c~nent selected from the group of aliphatic, cycloaliphatic or aromatic monoamines and aliphatic, cycloaliphatic or aromatic monocarboxylic acids.
The prerequisite, however, is that at least one of the components A or E must be present.
Moreover, selectively, at least one catalyst and/or process-or applications-dictated additive may be present.
The partially crystalline or amorphous, thermoplastically processable, high-molecular, partially aromatic polyamides, which can be produced from the precondensates prepared according to the invention, may be employed to produce molding compositions for arbitrary suitable processing techniques.
The process of the invention relates to amorphous and partially crystalline, partially aromatic polyamides or copolyamides. Because of this circumstance, it is appropriate to disclose discrimination criteria, which make it possible to assign a given polyamide composition to the group of amorphous or partially crystalline products, and optionally also to make predictions of its physical properties, and above all the melting point in the case of partially crystalline products and the glass transition temperature (Tg) of products of both groups. For the amorphous polyamides, valuable aid in this respect is offered for example by the article entitled "Structure Property Relationship in Amorphous Polyamides" by J. G. Dolden, in Polymer 1976, Vol. 17, pp. 875-892.
Predicting the partia] crystallinity of partia]ly aromatic copolyamides can be done with reliability at least for the group -known as isomorphic copolyamides. Examples of such systems are PA-66/6T, PA-46/4T, PA-106/lOT and PA-68/6PBDA based on hexamethylene amine (HMD)/adipic acid (ADS)/terephthalic acid (TPS), or tetramethylene diamine/ADS/TPS, or decamethylene diamille/ADS/TPS, and HMD/suberic acid/p-benzenediacetic acid (PBDA).
Further detail may be found in numerous publications, such as H. Plimmer et al in British Patent Application 604/49, Imperial Chemical Industries Ltd. (1949); R. Gabler, Swiss Yatent Disclosure CH-A 280 367, Inventa AG (1949); M. Levin and S. C.
Temin, J. Polm. Sci. 49, 241-249 (1961); T. Sakashita et al in US
Patent Application Serial No. 607,073, Mitsui Petrochemical Industries Ltd. (1985); S. Yamamoto and T. Tataka, European Patent Disclosure EP-A 0 449 466, Mitsui Petrochemical Industries, and British Patent Application 766 927, California Research Corporation (1945).
Information on non-isomorphic copolyamides, which in certain ranges of their composition may have amorphous structures, is found in some of the above publications and in A. J. Yu and R. D.
Evans, J. Am. Chem. Soc. 20 5261-5365 (1959) and F. B. Cramer and R. G. Beamann, J. Polym. Sci., 21, 237-250 (1959).
If no conclusive answer as to whether a given polyamide is partially crystalline or amorphous can be found by consulting the above publications and other work cited in them, then a preliminary trial preparation of the applicable product in a smaller laboratory autoclave is of help.
To that end, the various components are mixed together with water, and after being flushed with an inert gas are heated in the closed autoclave. Once a product temperature of 200 to 230 C
is reached, water vapor is vented by opening the exhaust gas valve, and the pressure is relieved to ambient pressure while further heating is done to 250 to 290-~. However, this is at the cost of the fact that in the course of this procedure, higher-melting partially crystalline polyamides or copolyamides can crystalline spontaneously under certain operating conditions and can block the agitator. The applicable product is taken from the autoclave and studied as to its Tg and its melting point, by means of differential scanning calorimetry (DSC). The DSC
measurement is suitably repeated from once to twice with the same 21~3862 specimen, in order to assure that the thermal performance of the particular polyamide remains constant.
In the simplest case, instead of an autoclave, an agitatable and inertizable vessel, such as a glass bulb, operated without pressure can be used to carry out the preliminary trial. The temperature at the end of reaction should once again be between 250 and 290 C.
The process according to the invention may be employed for the production of precondensates of arbitrary amorphous or crystalline partially aromatic polyamides or copolyamides.
Accordingly, the choice of components A-G may be varied within a very wide range:
O The substit~ted or unsubstituted aromatic dicarboxylic acids (A) having from 8 to 18 carbon atoms include the group comprising terephthalic acid, isophtha~ic acid, the alkyl- and aryl-substituted derivatives thereof, naphthalene dicarboxylic acids (-2,6-,-1,7-, etc.), diphenyldicarboxylic acids (-4,4-, 3,3-, etc.), and others. Terephthalic acid, isophthalic acid, 5-t-butylisophthalic acid and naphthalene-2,6-dicarboxylic acid) are preferred.
O Among the straight- or branch-chain aliphatic or cycloaliphatic dicarboxylic acids (B) having from 3 to 36 carbon atoms, those preferred are adipic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, brassylic acid, the trimethyl adipic acids, cis- and/or trans-cyclohexane-1,4-dicarboxylic akid, cis- and/or trans-cyclohexane-1,3-dicarboxylic acid, and dimerized fatty acids (such as Pripol 1013, Pripol 1009, Pripol 1008 made by UNICHEMA).
0 The straight- or branch-chain aliphatic diamines (C) having from 4 to 13 carbon atoms include the group comprising hexamethylene diamine ( 1,6-diaminohexane), 1,8-diamino~ctane, 1,10-diaminodecane, 1,12-diaminododecane, 1,4-diaminobutane, 2,2-dimethyl-1,3-diaminopropane, 2,2,4- and/or 2,4,4-trimethyl-1,6-diaminohexane, 2-methyl-1,5-diaminopentane, 5-methyl-1,9-diaminononane, and others. Those preferred are 1,6-.

.

diaminohexane, l,10-diaminodecane, 1,12-diaminododecane, and 2,2,4- or 2,4,4-trimethyl-1,6--diaminohexane.
0 Preferred representatives of the cycloaliphatic diamines (D) having from 6 to 26 carbon atoms are cis- and/or trans-1,4-diaminocylohexane, cis- and/or trans-1,3-diaminocylohexane, cis-and/or trans-1,4-bis(aminomethyl)cyclohexane, cis- and/or trans-1,3-bis~aminomethyljcyclohexane, 3(4),8(9)-bis(aminomethyl)tricyclo-[5,2-1.026]-decane, 2(3),5(6)-bis(aminomethyl)norbornane, 1,8-diamino-p-menthane, and 3-amino-3;5,5'-trimethylcyclohexylamine.
0 As preferred araliphatic (aliphatic/aromatic or cycloaliphatic/aromatic) diamines (E) having from 8 to 26 carbon atoms, in which an amino group may be connected directly to the aromatic radical, 1,4-bis(aminomethyl)benzene, l,3-bis(aminomethyl)benzene, and 4-(aminobenzyl)cyclohexylamine are used.
0 The preferred lactams or ~-amino acids (F) having from 6 to 12 carbon atoms are caprolactam, laurinlactam or ~-aminocaproic acid, ~-aminolauric acid and ~-aminoundecanoic acid, and ll- and 9-aminononanoic acid.
0 The preferred aliphatic, cycloaliphatic or aromatic monocarboxylic acids or monoamines (G) are acetic acid, propionic acid, butyric acid, caproic acid, lauric acid, stearic acid, 2-ethylhexanoic acid, cyclohexanoic acid, benzoic acid, the isomeric aminoalkanes having from 1 to 26 carbon atoms, such as n-butylamine, n-pentylamine, n-hexylamine, 2-ethylhexylamine, n~
dodecylamine, n-tetradecylamine, n-hexadecylamine, n-octadecylamine, and cycloaliphatic and araliphatic monoamines such as cyclohexylamine, methyl- and dimethylcyclohexylamines, benzylamine, and others.
With respect to the preferred embodiment of the process according to the invention, a distinction must be made between the following precondensates:
0 partially crystalline, partially aromatic polyamides or copolyamides having a melting point o~ 2~0 c and higher, and O the precondensates of amorphous polyamides or copolyamides, or those that are partially crystalline and melt at below 280 C.
However, in both cases, the process principle is the same, and in the phases that are decisive for the properties of the precondensates, that is, c) (reaction phase), d) (steady-state phase) and e) (discharge phase), it comprises keeping the temperature of the precondensate melt and the water vapor partial pressure of the gas chamber in contact with it in the respective reaction or buffer autoclave at the appropriate predetermined values in a controlled manner from the end of reaction phase c) on. Maintaining the water vapor partial pressure is done by venting off water vapor from the respective autoclave or by controlled feeding of water vapor into the autoclave or autoclaves from a water vapor generator communicating with it or them.
The speed with which the venting of the water vapor can proceed depends very strongly on the size and equi pmen t of the autoclave. In autoclaves with internal heating coils, heating and degassing can certainly be done faster than in those with double-jacket heating. Larger autoclaves with otherwise the same equipment take longer to heat tnan smaller ones (because of the less favorable ratio between surface area and volume).
In general, it is true that phase c), for economic reasons, should be kept as short as possible (with respect to the times for phase c)t g~ven in the examples, it should be noted that at 60-180 minutes as indicated they are very short, and are appropriate for the autoclave size (2.4 or 20 liters in volume, empty). In a 1500-liter autoclave, to be realistic, a duration of 5-8 hours would have to be expected for phase c).
The steady-state phase d) must be maintained for the period of at least 10 minutes and preferably at least 15 minutes, so that the precondensates reach a virtually stable state, in which no further substantial change in their properties occurs, and especially in their average molecular weight and the properties directly 21~3862 dependent on it.
This condition is not met by phase c), because here the ~alues for T and p, and hence the properties of the product, vary constantly.
During the discharge phase e), care must be taken that not only the autoclave but all the discharge lines and discharge units communicating with it be kept in controlled fashion at the same temperature and at least at the same water vapor partial pressure as in the autoclave.
The water vapor partial pressure should be adapted, before the end of the reaction phase c), to the particular total pressure measured in the gas chambers. The very complicated precise measurement of the water vapor partial pressure becomes unnecessary, because the partial pressures of the other gas ingredients, such as inert gas (such as nitrogen), relatively volatile raw materials (such as hexamethylene diamine) or the possible products of decomposition forming from the raw materials (such as NH3 from amines or C0z from carboxylic acids), is negligibly small compared with the total pressure. The proportion of inert gas - normally, nitrogen - decreases in any case sharply because of the requisite controlled opening of the pressure relief valve at the reaction autoclave during reaction phase c), and is almost completely positively displaced by the water vapor originating fr~m the salt forming step a) and formed in the reaction.
The afdre~entioned distinction between precondensates of partially crystalline, partially aromatic polyamides or copolyamides having a melting point of 280 C and above, on the one hand, and the precondensates of amorphous polyamides or copolyamides on the other, that is, those that are partially crystalline and melt at below 280 C, relates to the process parameters in steps c) through e) and the process sequences from the final precondensate to the corresponding high-molecular polyamide or copolyamide.
The preparation of the first--named group of precondensates . .

.

is subject to restrictions in the sense that the precondensate temperature during steps c) to e) must not exceed 265 C, and in the course of these process steps certain peripheral conditions with respect to the minimum water vapor partial pressure to be employed must be observed. The lower limits given above and in claim 1 for the water vapor partial pressure depend in turn on the temperature or on the temperature range selected, and surprisingly also depend on the amide group concentration ~C (for calculation of this, see below) of the applicable polyamide or copolyamide. A precise functional relationship between the minimum necessary water vapor partial pressure, the precondensate temperature, and the amide group concentration cannot be given.
However, it has been found, as will also be illustrated in the examples, that if the aforementioned peripheral conditions are adhered to, a reliable, disruption-free production of the precondensates of partially crystalline, partially aromatic polyamides or copolyamides that also melt at above 280 C is possible. From the minimum water vapor pressures required, which are each associated with the various temperature ranges, it can be concluded that higher temperatures also required higher pressures. At temperatures above 260C, still higher pressures than those shown in Table I must therefore be employed.
However, no attempt was made to list the minimum pressures, for instance for the temperature range of 260-270C, because - first, no certain data are available (except that at 270C, 30 ba~ is adequate for none of the cases I, II and III in Table I);
- second, pressures higher than 30 bar can be achieved in large autoclaves only at very high technological effort and expense.
Nevertheless, for the high melting products (melting point >
280OC), the maximum allowable temperature for the reactor content during phases c) and d) is believed to be 265C. This additional condition reflects nothing more than actual conditions in an autoclave process. For maintaining the particular minimum -required water vapor partial pressure, a water vapor generator from which in process steps c) through e), water vapor can be fed in controlled fashion into the autoclave and the discharge lines and units communicating with it is the most suitab]e. This provision is absolutely necessary in the discharge phase e), because the pressure drop in the gas space above the precondensate melt, which necessarily occurs from the increase in volume, must be compensated for.
During phases c) and d) an intervention need then be made, by connecting the steam generator, if leaks or defective pressure relief of the water vapor causes the water vapor partial pressure to threaten to drop below the lower limit that is supposed to be adhered to. As soon as operating states occur in the process steps in which either the water vapor partial pressure becomes too low or the precondensate temperature is too high, or even both occur, then the danger exists that the applicable precondensate will solidify rapidly and can no longer be discharged from the reactor via a melt line. The causes of these solidification phenomena, which are to be avoided in all circumstances, are unknown. Nor does the prior art provide any teaching in this respect at any point. However, in this connection, the only significant fact is that this problem has been recognized, and that with the method according to the invention a means for overcoming it has been provided.
Instead of a water vapor generator, a direct in~ection of water by meansAof a suitably controlled metering pump into the reactor would also be conceivable. However, operating in that way would have the disadvantage that because of the evaporation of the water that occurs in the reactor, energy is consumed, and consequently the temperature of the reactor conten~ is lowered in a way that is virtually impossible to control.
The precondensates having a melting point of 280 C and above and higher-melting polyamides or copolyamides are discharged by being sprayed into an inertized, optionaily cooled cyclone or spray to~er or some comparable apparatus; some of the water dissolved in the precondensate melts suddenly evaporates, and the precondensates are then in a finely dispersed, crystallized form.

Depending on the amount of water evaporated in this operation, the precondensate particles are simultaneously cooled to a more or less pronounced extent.
By means of a suitable feed system, the finely dispersed precondensate composition, optionally after further mechanical comminution and/or drying, is suitably re-melted and delivered, using a suitable metering and feed unit, to a continuously operating mechanically driven final reaction apparatus.
In the precondensates of amorphous polyamides or copolyamides, or those that are partially crystalline, partially aromatic and melt at below 280 C, there is greater freedom in terms of the choice of the temperature and the water vapor partial pressure in process steps c) through e) than is the case with the precondensation of products that melt at 280 C and higher.
In steps c) through e), the precondensate temperature may be varied between 230 C and 320 C; for the subgroup of precondensates involving the partially crystalline polyamides or copolyamides (having a melting point below 280 C), it is appropriate to adjust the precondensate temperature to be higher than the applicable melting temperature.
The water vapor partial pressure may also be varied over a comparably wide range in steps c) through e). Pressures of from 1.5 to 20 bar are usable. Preferably, work is done at water vapor partial pressures below 15 bar. The pressure range from 2 to 10 bar is especially preferably employed, in order to keep the water content of the precondensate melts as low as possible, and to assure high efficiency of the final reaction apparatus.
The precondensates of amorphous polyamides or copolyamides, or those that are partially crystalline and melt at below 280 C, are then transferred as a melt from the reactor into an autoclave, serving as a buffer vessel and operated under the same 21~3862 conditions as the reactor, and from there are supplied via a melt line directly to the final reaction apparatus, by means of a suitable feeding and metering apparatus, such as a spinning pump.
The provisions for maintaining the water vapor partial pressure in the reactor and in the buffer autoclave are the same as those described already above.
All the process steps according to the invention may be carried out with from 0.005 to 1.5 weight ~, referred to the total quantity of all the polyamide-forming components, of an inorganic and/or organic phosphorus and/or tin and/or lead compound as a catalyst.
Among the phosphorus compounds that may be employed are phosphoric acid, phosphorous acid,hypophosphorous acid, phenylphosphonic acid, phenylphosphinic acid, and salts thereof having 1- to 3-valent cations - such as the sodium, potassium, magnesium, calcium, zinc or aluminum cation - esters of phosphoric or phosphorous acid - such as triphenylphosphate, triphenylphosphite, tris-(nonylphenyl)phosphite, and others.
The tin compounds that may be employed include the following, for example: tin (II) oxide, tin (II) hydroxide, tin (II) salts of mono- or multivalent carboxylic acids, such as tin (II) dibenzoate, tin (II) di-(2-ethylhexanoate), tin (II) oxalate, and also dibutyltin oxide, butylstannic acid (H9C4-SnOOH), dibutyltindilaurate, and others.
Among the lead compounds that may be employed are, for example, lead (II) oxide, lead (II) hydroxide, lead (II) ace~ate, basic lead (II) acetate, lead (II) carbonate, and others.
Besides compounds of phosphorus, tin and lead, which can have a stabilizing effect on the precondensates and the applicable polyamides and/or that catalyze the formation of amide compounds, the usual additives may be used in all the p~ocess steps. These include antioxidants, such as sterically hindered phenol derivatives, aromatic amines, combinations of copper salts and alkali bromides or alkali iodides, light-protection agents, such as benzotriazole derivatives, 2,2,6,6-tetraalkylpiperidine derivatives, nickel chelating complexes, and the usual process additives based on fatty acid esters, fatty acid amides, fatty acid salts having from 1- to 3-valent cations, fatty alcohols, waxes, and others.
Finally, for the case of partially crystalline polyamides or copolyamides, the usual nucleation agents and crystallization accelerators are used in the usual quantities in all the process steps: these include finely dispersed minerals which are largely insoluble in the applicable precondensates and polyamides, such as mica, kaolin, talcum, montmorillonite, wollastonite and comparable materials, but also organic substances, such as polyamide-2.2.
The amorphous or partially crystalline, thermoplastically processable, partially aromatic polyamides or copolyamides that are accessible from precondensates by the process of the invention may be employed to produce molded parts by means of arbitrary suitable processing techniques. Suitable processing techniques include injection molding, multicomponent injection molding;
injection di-cast welding, extrusion, coextrusion, blow forming, deep drawing, and others.
For this purpose, reinforcing agents and fillers may be added to the aforementioned polyamides or copolyamides, examples being glass fibers, carbon fibers, mineral reinforcements and fillers, and other modification agents, such as flame-retardant additives or antistatic agents.
The fol~o~ing examples will explain the invention.

Examples The following abbreviations are used:
66: hexamethylene-adipamide units 6T: hexamethylene-tereph~halamide units 6I: hexamethylene-isophthalamide units 106: decamethylene-adipamide units lOT: decamethylene-terephthalamide units 12T: dodecamethylene-terephthalamide units 2153~62 Example 1.1-1.3 (CoPA 6T/6I (0.3/0.7 mol/mol; amorphous)) Salt forminq phase ( process step a)):
In a 2.4-1 double jacket reactor (steel), 294.0 g (2.5~ mol) of hexamethylene diamine is placed, in the form of a 50% aqueous solution. After the addition of 124.6 g (0.75 mol) of terephthalic acid, 290.8 g (1.75 mol) of isophthalic acid and 0.1 g of H3Po3, the reactor is closed. The reaction mixture is heated to 120-C (pressure = 1 bar). It is stirred for 30 minutes at 120-C and 1 bar, resulting in a clear solution of in-situ-formed nylon salts.
Transfer ( process step bl):
Omitted in the case of the 2.4-1 autoclave P Reaction phase ( process step c~):
The temperature of the reaction mixture from method step a) is raised in increments to 245 C. As soon as the pressure in the reactor has reached a value of 19 bar, enough water vapor is withdrawn from the reaction mixture, via a regulatable valve, so that the pressure is kept constant at 19 bar. This pressure is maintained for 1 hour each time. Next, the pressure in the autoclave is reduced by controlled pressure relief to 6 bar (Example 1.1), 4 bar (Example 1.2) and 3 bar (Example 1.3).
Since phase c) is a dynamic process, the values for T and p given in the examples that follow always correspond to the particular final state ~ofAthat phase.
Steady-state phase (.Prccess steP d)):
The conditions (245 C and 6 bar; 245 C and 4 bar; 245 C and 3 bar) established at the end of the reaction phase (method step c)) are maintained for 40 minutes. ~uring this period of time, samples of the applicable precondensate are taken at the beginning and every 10 minu-tes, in order to measure the relative viscosity of the solution (~rel) The results are summarized in Table II.

215~62 Table II: Relative Viscosity of Preconden~ates During the 8teady-state Phase (~rel (0~5% in m-cre901) ) Duration of the Example 1.1 Example 1.2 Example 1.3 Steady-State Phase - 6 bar - - 4 bar - - 3 bar -Start 1.090 1.253 1.282 10 minutes 1.092 1.265 1.294 20 minutes 1.092 1.271 1.305 30 minutes 1.092 1.272 1.307 40 minutes 1.093 1.272 1.310 Discharqe ~hase (process step e)):
During the discharge phase, which is 2 minutes long in each case, and which takes place under the conditions of process step d), a sample of the applicable precondensate is taken at the beginning and at the end, and the relative viscosity of the solution of the sample is determined.
able III: Relative Viscosity of Precondensates at 8tart and End of the Discharge Phase ~ rel ~0-5% in m-ore~ol) Discharge phase Example 1.1 Example 1.2 Example 1.3 i, Begin 1.093 1.274 1.311 End 1.092 1.274 1.312 The results of Example 1.1-1.3 show how the viscosity of the polymer precondensate can be adjusted via the water vapor pressure during the steady-state phase ( process step d)) and the discharge phase (process step e)). Once the steady-state phase ends, the reaction mixture has attained a virtually stable state.

21S3~62 .

In this form, the applicable precondensates can be supplied as a melt directly to a final reaction apparatus. The cons-tancy of the precondensate quality assures that the polycondensation in a final reaction also produces products of constant quality.

Example 2.1 - 2.3 (CoPA 6T/6I (0.3/0.7 mol/mol; amorphous)) Reaction volume = 130 liter Weight: - 16.180 kg (139.23 mol) hexamethylene amine - 16.165 kg (97.30 mol) isophthalic acid - 6.928 kg (41.70 mol) terephthalic acid - 0.008 kg H3P03 - 16.000 kg water (29 weight ~) P Salt forminq Phase (.process step a)~:
Temperature: 120-C
Pressure: 1 bar Residence time: 2 hours R Transfer Phase (process step b)):
Temperature: 120'C
Pressure: 1 bar Reaction Phase (process step c)):
Temperature: 245 C (at the end of the reaction phase) Pressure:~ 19 bar Residence time: 3 hours (at the end of the reaction phase) Pressure relief to: 4 bar SteadY-state phase (process step d~:
Temperature: 245'C
Pressure: 4 bar Residence time: 20 minutes Discharqe Phase (PrOCess step e)):
Temperature: 245'C
Pressure: 4 bar Three identical batches are processed. The viscosities of the solutions in Table IV illustrate the replicability of a desired precondensate viscosity, which is maintained over a 20-minute steady-state phase and over the discharge phase.

Table IV: Replicability o~ Target Viscosities Example 2.1 Example 2.2 Example 2.3 ~rel (0 5~
in m-cresol) 1.265 1.252 1.253 Example 3.1, 3.2 PA 12 T;
partially crystalline (AC = 6.06 mmol/g) Melting point: 301-C

Reaction volume = 2.4 li ter Weight: - 506.9 g (2.53 mol) dodecamethylene diamine - 415.4 g (2.50 mol) terephthalic acid - 0.1 g H3P03 ~ A - 500 g H20 (35 weight %) P Salt forminq Phase (proceSs steP a)):
Temperature: 180-C
Pressure: 8 bar Residence time: 30 minutes Transfer Phase t: process steP b)):
Cmitted for 2.4-liter autoclaves Reaction Phase ( process step c)):

2153~62 -Temperature: 245'C (at the end of the reaction phase) Pressure: 27 bar (at the end of the reaction phase) Residence time: 1 hour Example 3.1:
A controlled incremental pressure relief to a pressure of 6 bar (analogous to Example 1.1) fails, since the reaction mixture crystallizes spontaneously at approximately 20 bar and causes the stoppage of the agitator.

P SteadY-state Phase ( Process steP d~):
Example 3.2:
Temperature: 245 C
Pressure: 27 bar Residence time: 20 minutes Discharqe Phase ( Process step e)):
Example 3.2:
Temperature: 245 C
Pressure: 27 bar Product: ~ 1 = 1.071 (0.5% in m-cresol) Example 4.1, 4.2 CoPA lOT/106 (0.9/0.1 mol/mol) partially crys`talline (AC = 6.67 mmol/g) Melting point: 299 C

Reaction volume = 2.4 li ter Weight: - 436.0 g (2.530 mol) dodecamethylene diamine - 373.8 g (2.25 mol) terephthalic acid - 36.5 g (0.25 mol) adipic acid - 0.2 g NaHzPOzxH20 - 400 g H20 (32 weight ~) Salt forminq phase (.process steP al):
Temperature: 180-C
Pressure: 8 bar Residence time: 30 minutes Transfer Phase ( process step b~):
Omitted P Reaction phase (.~rocess step c)):
Temperature: 250 C (at the end of the reaction phase) Pressure: 32 bar (at the end of the reaction phase) Residence time: 1 hour Example 4.1:
A controlled incremental pressure relief to a pressure of 6 bar (analogous to Example 1.1~ fails, since the reaction mixture crystallizes spontaneously at approximately 14 bar and causes the stoppage of the agitator.

Steady-state Phase (process step d)):
ExamPle 4.2:
Temperature: 250 C
Pressure: 32 bar Reside~ce time: 20 minutes A

Discharge Phase ( processstep e)):
ExamPle 4.2:
Temperature: 250 C
Pressure: 32 bar P Product: ~rel = 1.071 (0 5% in m-cresol) Examples 3.1 and 3.2, and 4.1 and 4.2 (partially crystalline PA and CoPA, respectively), comparison to Example 1 (amorphous . .

~,s -CoPA), show that with partially crystalline PA or CoPA, at the end of the steady-state phase, the pressure cannot be reduced, since that causes uncontrollable crystallization and hence blockage of the agitator.
The discharge phase must therefore suitably be done under the conditions of the steady-state phase, when partially crystalline PA or CoPA with a melting point of more t.han 280C is used.

Examples 5.1-5.3 CoPA 6T/66 (0.6/0.4 mol/mol) partially crystalline (AC = 8.40 mmol/g) Melting point: 316-C

Reaction volume = 20 ].iter Weight: - 2700 g (23.234 mol) hexamethylene diam;ne - 2310 g (13.904 mol) terephthalic acid - 1350 g (9.238 mol) adipic acid - 20 g (0.164 mol) benzoic acid - 2 g NaHzPO2xH2O
- 2000 g HzO (24 weight %) Salt forminq phase ( process steP a)):
Tempera,ture: 180 C
Pressure: 6 bar Residence time: 2 hours Transfer Phase (.proc.ess steP b)):
Temperature: 180 C
Pressure: 6 bar P Reaction phase ( proceSs step c)):
Temperature: 241 C (Example 5.1) (at the end of the 243 C (Example 5.2) . .. . ... . ....

~15~62 ._ reaction phase) 247 C (Example 5.3) Pressure: 23 bar (Examples 5.1-5.3) (at the end of the reaction phase) Residence time: 90 minutes SteadY-state phase (process ste~ d)):
Temperature: 241-C (Example 5.1) 243 C (Example 5.2) 247 c (Example 5.3) Pressure: 23 bar (Examples 5.1-5.3) Residence time: 30 minutes Discharqe Phase (process step e)):
Temperature: 241-C (Example 5.1) 243 C (Example 5.2) 247 C (Example 5.3) Pressure: 23 bar (Examples 5.1-5.3) Product:

Example 5.1 Example 5.2 Example 5.3 ~rel = (0 5%
in m-cresol) 1.125 1.136 1.160 The Examples 5.1-5.3 show a desired viscosity of the polymer precondensate can be established via a targeted temperature adjustment in both the reaction phase and the steady-state phase.

Examples 6.1-6.3 CoPA 6T/66 (0.6/0.4 mol/mol) partially crystalline (AC = 8.40 mmol/g) Melting point: 316-C

Reaction volume = 20 liter 21538~2 Weight: identical to F.xample 5 Salt forminq phase (process step a)~:
identical to Example 5 Transfer Phase (process step b~:
identical to Example 5 Reaction ~hase (process step c)~:
Temperature: 241'C (at the end of the reaction phase) Pressure: 23 bar (Example 6.1) 22 bar (Example 6.2) 20 bar tExample 6.3) Residence time: 90 minutes SteadY-state Phase ~process step d~:
Temperature: 241'C
Pressure: 23 bar (Example 6.1) 22 bar (Example 6.2) 20 bar (Example 6.3) Residence time: 30 minutes Discharqe phase (Prcess step c~l:
Temperature: 241-C
Pressure: 23 bar (Example 6.1) 4 22 bar (Example 6.2) 20 bar (Example 6.3) Residence time: 30 minutes Discharqe Phase (Process step e~:

Temperature: 241-C
Pressure: 23 bar (Example 6.1) 22 bar (Example 6.2) 20 bar (Example 6.3) 21 538~2 Product:

Example 6.1 Example 6.2 Example 6.3 1 = (0~5~
in m-cresol) 1.128 1.145 1.157 The Examples 6.1-6.3 show a desired viscosity of the polymer precondensate can be established via a predetermined maximum pressure in both the reaction phase and the steady-state phase.

Examples 7.1, 7.2 CoPA 6T/66 (0.6/0.4 mol/mol) partially crystalline (AC = 8.40 mmol/g) Melting point: 316-C

Reaction volume = 20 liter Weight- identical to Example 5 Salt formin~ phase:
identical to Example 5 Transfer phase:
identical to Example 5 Reactio~ ~hase:
Temperature: 243 C (at the end of the reaction phase) Pressure: 23 bar (at the end of the reaction phase) Residence time: 90 minutes ~Example 7.1) 150 minutes (Example 7.2) SteadY-state Phase:
Temperature: 243'C
Pressure: 23 bar Residence time: 30 minutes (Example 7.1) 2153~62 30 minutes ~Example 7.2) Discharqe Phase:

Temperature: 243 C
Pressure: 23 bar Product:

Example 7.1 Example 7.2 ~r~1 = (0-5% in m-cresol) 1.131 1.173 The Examples 7.1 and 7.2 show a desired viscosity of the polymer precondensate can be established via controlling the residence time in the reaction phase.

Example 8 CoPA 6T/66 (0.6/0.4 mol/mol) partially crystalline (AC = 8.40 mmol/g) Melting point: 316-C

Reaction volume = 20 liter Weight: identical to Example 5 Salt forminq Phase:
identical to Example 5 Transfer phase:
identical to Example 5 Reaction Phase:
Temperature: 255 C (at the end of the reaction phase) Pressure: 27 bar (at the end of the reaction phase) 2133~62 -Residence time: 90 minutes Pressure relief to: 17 bar SteadY-state phase:
Temperature: 255 C
Pressure: 17 bar Residence time: 30 minutes Discharqe Phase:

Temperature: 255'C
Pressure: 17 bar Product:

Product partially crystallized in the reactor. Discharge of approximately 50~ of the expected quantity of product not possible.
Remaining product: ~rel = 1.211 (0.5% in m-cresol) Example 8 shows that if the required H20 partial pressure per Table I (Table II) is not attained, the reaction mixture crystallizes uncontrollably in the autoclave and can no longer be completely discharged from the reaction vessel.

Examples 9.1-9.3 CoPA 6T/6I (0.7/0.3 mol/mol) partially crystalline (AC = 8.12 mmol/g) Melting point: 320'c Reaction volume = 20 liter Weight: - 2500 g (21.513 mol) hexamethylene diamine - 2478 g (14.915 mol) terephthalic acid - 1062 g (6.392 mol) isophthalic acid - 15 g (0.250 mol) acetic acid . . . _ .

2153~62 2 y NaH2P02xH20 - 2000 g H20 (25 weight %) h Salt forminq Phase:
Temperature: 180-C
Pressure: 6 bar Residence time: 150 minutes P Transfer Phase:
Temperature: 180 c Pressure: 6 bar Reaction Phase:
Temperature: 243 C ~at the.end of the reaction phase) Pressure: 23 bar (at the end of the reaction phase) Residence time: 120 minutes SteadY-state phase:
Temperature: 243 C
Pressure: 23 bar Residence time: 30 minutes Discharqe phase:
Tempera~ture: 243 C
Pressure: 23 bar h Product:
Three identical batches were prepared. The precondensate viscosities given below illustrate the good replicability of a desired precondensate quality, under identical reaction conditions.

Example 9.1 Example 9.2 Example 9.3 ~rel = (0'5%

. . , _. _; .

21~3862 -in m-cresol) 1.092 1.085 1.088 The relative solution viscosities of the products are measured in accordance with DIN 53727 in 0.5% solutions in m-cresol at 20 C. The measurement of the melt temperatures ~maximums) is done with the aid of a DSC device, model 990, made by DuPont. In each case what was evaluated was the second heating course, picked up at a heating rate of lO C/min.
The amide concentrations AC (in mmol/g) given in the cases of polyamides or copolyamides with a melting point above 280 C
were calculated, each for a 100% conversion of the amide-forming components, by the following general formula:

n~c m~c mL m~5 AK - 1000 ( ~ + ~ _ + ~
M~C ML M~S

n~C~m~c m~
t~mb + ~m~ + ~mL + ~m~5 - MH 2 O (~
M~c M~s In which:

mA/c the mass mA of the amines or mc of the carboxylic acids in g, MA~C the molar masses MA of the amines or Mc of the carbo~xylic acid in g/moi, nA/c the functionality nA of the amines or nc of the carboxylic acids: l or 2, mL the masses of the lactams in g, ML the molar masses of the lactams in g/mol, m~S the masses of amino acids in g, M~S the molar masses of amino acids in g/mol, MH20 the molar mass of water in g/mol.

The factor 1000 is used for recalculation mol/g to mmol/g.

2153~S2 -The terms referring to lactams and amino acids are omitted in the examples to which that applies.
For the term nA/C mJVC nA ~ mA
, the term 1~ is used M~c M~

if the sum of carboxyl groups from the carboxylic acids is higher than the total number of amino groups from the amines.
Conversely, the following term is calculated:

n ~ m Mc 2153~62 -Tab1Q V: Temperature and Pressure Ranges of variouq Copolyami.des CoPA Amide concentration Product temperature Pressure (molar ratio) AC [mmol/g] range [ C] range [bar]

6T/66 8.44 243-250 16-23 (0.55:0.45?

6T/6I 8.12 243-250 16-23 (0.7:0-3) lOT/106 6.69 243-250 22-26 (0.85-0.15) 12T 6.06 243-250 22-26 4T 9.17 21~3862 . .

Table VI: Amide concentration (2 ami~e group~ per repetition unit), various polyamide~ in mmol/g of polymer CoPA Formula Molecu- Amide lar Concentration Weight mmol/g 6lan~ 11 o 246 8,1 6T N -- (CH2~ 6 N C ~ -- n 66 o o 226 8 85 H (CH2) 6 ~ N -- C -- (Ci{2 ) 4 -- C--H n lOT o o 392 6 62 ~ N (C~2)l0 N - C - ~ - C -106 o o 282 7.09 Il 11 ~ N -- (CH2) 10 ~ N -- C -- (C~2) 4 n 12T ~ o o 330 6 06 ~ N -- (C~2) 12 ENl C ~-- C--4T o o 218 9.17 ~ H (C~2) 4 -- N -- C -- ~ -- C---- N -- (C~{2) 4 -- N -- C -- (CE~2) 4 C n

Claims

1. A process for producing precondensates of partially crystalline or amorphous, thermoplastically processable, partially aromatic polyamides or copolyamides, which are based on monomer building blocks selected from the group A, B, C, D, E, as well as the components F and G, as follows:
A: from 0 to 100 mol % of at least one substituted or unsubstituted aromatic dicarboxylic acid having from 8 to 18 carbon atoms (referred to the total quantity of all the dicarboxylic acids A + B), B: from 0 to 100 mol % of at least one dicarboxylic acid having from 6 to 36 carbon atoms, selected from the group of straight- or branch-chained aliphatic and cycloaliphatic dicarboxylic acids (referred to the sum of A + B), C: from 0 to 100 mol % of at least one straight- or branch-chained aliphatic diamine having from 4 to 13 carbon atoms (referred to the total quantity of all the diamies C + D + E), D: from 0 to 100 mol % of at least one/cycloaliphatic diamine having from 6 to 26 carbon atoms (referred to the sum of C + D + E), E: from 0 to 100 mol % of at least one araliphatic diamine having from 6 to 26 carbon atoms (referred to the sum of C + D +
E), wherein the molar quantity of the dicarboxylic acids (A and B) is approximately equal to the molar quantity of the diamines (C, D and E), and F: from 0 to 80 mol %, referred to the total quantity of components from the group A, B, C, D, E, F, of at least one polyamide-forming monomer from the lactam group or .omega.-amino acid having from 6 to 12 carbon atoms, and G: from 0 to 6 mol %, referred to the total quantity of components from the group A, B, C, D, F, G, of at least one compound selected from the group of aliphatic, cycloaliphatic or aromatic monoamines and aliphatic, cycloaliphatic or aromatic monocarboxylic acids, wherein optionally at least one catalyst and optionally further processing- or application-dictated additives can be added, .on the specification that at least one of each of the components A or E must be present, and dicarboxylic acids (A, B) and diamines (C, D, E) are present in a virtually equimolar ratio, wherein the method includes the following steps:

a) a salt forming stage for producing salt(s) of diamine(s) and dicarboxylic acid(s) in an aqueous, 5 to 50 weight %
solution containing the components, which is carried out optionally with partial prereaction to make low-molecular oligoamides at temperatures between 120°C and 220°C and at pressures of up to 23 bar, b) optionally, the transfer of the solution from step a) to a second reaction vessel, or an agitated autoclave under the conditions prevailing upon completion of its manufacture, c) the reation phase, during which the conversion to the precondensates is continued by heating the reactor content to a predetermined temperature and by controlled adjustment of the water vapor partial pressure to the predetermined value, which is maintained by controlled venting of water vapor or optionally controlled feeding in of water vapor from a water vapor generator communicating with the autoclave, d) a stationary phase to be maintained for at least 10 minutes, in which the temperature of the reactor content and the water vapor partial pressure - the latter by employing the provisions listed in c) - are adjusted in controlled fashion in each case to the values that are provided for the conversion of the precondensates in the next process step, with the specification that in the case of precondensates of partially crystalline polyamides or copolyamides having a melting point of 280°C and higher (maximum melting point, measured by differential scanning calorimetry), the temperature of the reactor content during this phase d) and phase c) must not exceed 265°C, and that for the partially crystalline polyamides or copolyamides during phases d) and c), the following peripheral conditions (Table I) must be adhered to with respect to the dependency of the minimum water vapor partial pressure PH2O(minimum)to be employed on the temperature of the reactor content and on the amide group concentration of the polymer (in mmol/g, calculated for a condensed-out polymer with an average molecular weight of at least 5000 g/mol), Table 1 Amide concentration Temperature PH2O(minimum) (AC) [mmol/g] range [°C] [bar]
-----------------------------------------------------------I 10 > AC > 8 235-250 16 II 10 > AC > 8 250-260 19 III 8 > AC > 6 235-250 22 IV 8 > AC > 6 250-260 26 V 6 > AC 235-250 30 VI 6 > AC 250-260 32 e) a discharge step, during which the precondensates, while the temperature prevailing at the end of phase d) is kept constant and at least the water vapor partial pressure prevailing at that time is maintained by feeding water vapor from the aforementioned water vapor generator into the autoclave and all the discharge lines and discharge apparatuses communicating with it, can be supplied to a final reaction apparatus, either in the molten state via a buffer device directly or via a separator device and passage through the solid state, with subsequent selective drying and/or comminution and optionally further process steps.

2. The process of claim 1, characterized in that in the discharge step (e), prior to the introduction into a final reaction apparatus, - the precondensates of amorphous polyamides and copolyamides or partially crystalline polyamides and copolyamides with a melting point below 280°C are transferred to an inertized buffer vessel that is at constant temperature and constant pressure and from there are metered or fed onward, or - the precondensates of partially crystalline polyamides and copolyamides melting at 280°C and higher are sprayed at a pressure of at least 16 bar into an inertized separator device and obtained, in the form of solid particles, selectively dried and/or comminuted.

3. The process of claim 1 , characterized in that the separation of the precondensates of partially crystalline polyamides or copolyamides melting at 280°C and higher is done in a cyclone or spray tower or comparable apparatus.

4. The process of claim 1 , characterized in that from 0.005 to 1.5 weight % of catalyst, referred to the total quantity of components, selected from the group of organic or inorganic compounds of phosphorus, tin and lead, can be used.

5. The process of claim characterized in that an agitatable and inertizable autoclave is used as the reaction vessel.

6. Precondensates of partially crystalline or amorphous, thermoplastically processable, partially aromatic polyamides or copolyamides, which can be produced by the process` of one of claims 1-5.

7. The use of precondensates, which can be produced by the process of one of claims 1-5,for producing high-molecular polyamide molding compositions or molded parts.