MXPA00007522A - Method for producing polyamides from amino carboxylic acid compounds - Google Patents

Abstract

The invention relates to a method for producing polyamides by reacting amino carboxylic acid compounds of general formula (I) H2N-(CH2)m-COR1 in which R1 represents OH, O-C1-12-alkyl or NR2R3 with R2 and R3, independent of one another, representing hydrogen, C1-12-alkyl or C5-8-cycloalkyl, and m represents a whole number between 3 and 12. Said compounds are optionally reacted in the mixture with amino nitriles and the hydrolysis products thereof and are optionally reacted in the presence of water. In addition, the compounds are reacted in liquid phase while being subjected to an increased pressure and an increased temperature, and in the presence of metal oxides as heterogeneous catalysts, whereby the metal oxides are placed inside a mold which permits mechanical separation from the reaction mixture and are removed from the reaction mixture during or after completion of the polymerization.

Description

PRODUCTION OF POLYAMIDES FROM AMINOCARBOXYLIC ACID COMPOUNDS This invention relates to the processes for producing polyamides from the aminocarboxylic acid compounds, to the polyamides obtained and to the uses thereof. The polyamides can be produced not only from the caprolacta but also, inter alia, from the aminocapronitrile. U.S. Patent No. 2,245,129, describes a preparation of polycaprolactam, for two-stage production batches, from aminocapronitrile ("ACN") and water, at a temperature that is in the range of 150 at 300"c, governed by a program with specific temperature as a function of the amount of water added, and a pressure of not more than 30 atmospheres.The disadvantages of eat» process are the long reaction times (20 hours in the first stage), the low viscosity of the resulting polycaprolacta and the high level of volatile bases (essentially the primary amido acids) as compared to a polycaprolactam produced from caprolactam, U.S. Patent No. 4,568,736, partially resolves The problems described in U.S. Patent No. 2,245,128, through the use of catalysts containing phosphorus and sulfur, the use of these catalysts improve the low yield. space-time of the process described in U.S. Patent No. 2,245,129. In any case, the level of volatile bases in all the products produced by this process is still very high, so that the polyamides are difficult to be processed and have a reduced extreme carboxyl group number. The stoichiometric discrepancy between the carboxyl and amino end groups in the products of the processes, is responsible for showing an insufficient degree of polymerization and a slow increase in molecular weight during tempering. Additionally, the complete removal of the catalysts is virtually impossible, so that the chemical and physical behavior of the polymers produced using the catalysts, such as the type and amount corresponding to the end groups or those of early separation behavior during the rotation , is adversely affected. It is an object of the present invention to provide a process for producing polyamides without the disadvantages of the above process. The process should provide polyamides in high conversions, and the properties of the polyamides should not be compromised by the presence of additional components that can not be separated from them. We have verified that this objective is achieved by a process to / produce polyamides by means of the reaction of the aminocarboxylic acid compounds of the general formula I: H N-ÍCH,) -C (0) RJ (I) wherein R is OH, s ~ C. / L -alkyl or NR R where Rly 7 are independently hydrogen, C /./ j.-alkyl or C, .g -cycloalkyl, and m is an integral from 3 to 12, optionally in a mixture with aminonitriles and their hydrolysis products, and optionally in the presence of water, in a liquid phase with elevated pressure and elevated temperature, in the presence of metal oxides such as heterogeneous catalysts, the metal oxides being used in a form that allows removal of the reaction mixture and being removed from the reaction mixture during or after the polymerization. In the process, the aminocarboxylic acid compounds or mixtures can be obtained by means of the complete or incomplete reaction of the aminonitriles with water, in a preceding step. The proportion of aminocarboxylic acid compound (s) in the mixture to be polymerized is preferably not less than 75% by weight, particularly preferably not less than 95% by weight. It has been found that the reaction of the aminocarboxylic acid compounds or mixtures comprising aminocarboxylic acid compounds and aminonitriles is derived in polyamide in a faster and improved manner. The use of homogeneous catalysts that impair the properties of the product is avoided. The initiator materials used in the process of the invention are the aminocarboxylic acid compounds of the general formula I: wherein R ^ is OH, -0-C.l -alkyl or -R ^ R? where R and R ^ are independently hydrogen, G ,. / ^ -alkil or Cr, 4 -cycloalkyl, and; m is 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12, optionally in a mixture with aminonitriles. Particularly preferable, the aminocarboxylic acid compounds are those wherein R is OH, -Q-C?. -alkyl such as -0-methyl, -0-ethyl, -0-n-propyl, -0-i-propyl, -0-n-butyl, -O-sec-butyl, -O-tert-butyl and - NR ^ R "7 such as - H ^, - NHMe, -NHEt, - NMe and -NEtt, and m is 5. Very particular preference is given to 6-aminocaproic acid, methyl 6-aminocaproate, ethyl 6-aminocaproate, 6-amino (N-methyl) caproamido, 6-amino (N, N-dimethyl) caproamide, 6-amino (N-ethyl) caproamide, 6-amino (N, N-diethyl) caproamide and 6-amino). -aminocaproamide The initiator compounds are commercially available or preparable, for example, as described in EP-A-0 234 285, and of the Industrial Engineering Chemical Process Description [Description of Chemical Process of Engineering Industrial], Dev. 17 (1978) 9-16. The inonitrile used can in principle be any type of aminonitrile, that is, any compound having at the same time at least one amino group and at least one nitrile group. The w-aminonitriles are preferred, especially the w-aminoalkyl nitriles having from 4 to 12 carbon atoms, preferably from 4 to 9 carbon atoms in the middle of the alkylene, or the aminoalkaryl nitriles having from 8 to 13 carbon atoms , the preferred nitrile aminoalkaryl are those having an alkyl-spacer of at least one carbon atom between the aromatic unit and the nitrile or amino group. Especially preferred nitrile alkoxylaryls are those having the amino group and the nitrile group in the 1,4-position relative to one another. The -aminoalkyl nitrile used is preferably a linear w-aminoalkyl nitrile wherein one-half of the alkylene (-CH-) preferably has from 4 to 12 carbon atoms, preferably still from 4 to 9 carbon atoms, such as the 6-amino -l-cyanopentane (6-aminocapronitrile), 7-amino-1-cyanohexane, 8-amino-1-cyanoheptane, 9-amino-1-cyanooctane, 10-amino-1-cyanononane, particularly preferably 6-aminocapronitrile. The 6-aminocapronitrile is customarily obtained by means of hydrogenation of the adiponitrile of compliance with known methods, described for example in DE-A 836,938, DE-A-848,654, or U.S. Patent No. 5,151,543. It is also possible to use mixtures of a plurality of aminonitriles. The catalysts used for the heterogeneous catalysis can be the known metal oxides, such as zirconium oxide, aluminum oxide, magnesium oxide, cerium oxide, lanthanum oxide and preferably titanium dioxides, as well as beta zeolites and sheet silicates for heterogeneous catalysts. Particular preference is given to the titanium dioxide in the polymorph anatase, in addition to the silica gel, the zeolites and the oxides of metals in paste, the pastes being, for example, ruthenium, copper or fluoride. The heterogeneous catalyst has a macroscopic shape that permits mechanical removal of the softened polymer from the catalyst, for example by means of sieves or filters. use of the catalyst in the form of an extruder or granular, or in a coated form on the packages and / or the internal parts In another embodiment, the aminocarboxylic acid compounds are reacted with the acidic co-catalysts dissolved homogeneously or with a mixture of different catalytically active compounds in the presence of the above-mentioned heterogene catalysts The preferred co-catalysts for this purpose are the acidic catalysts, such as the aforementioned carboxylic acids, the ter-phthalic acid, the adipic acid, the propionic acid and the isophthalic acid, or the oxygen-containing phosphorus compounds, especially the phosphoric acid, phosphorous acid, hypophosphorous acid, its salts of alkaline metals and alkaline earth metals and ammonium salts, sulfur compounds containing oxygen, especially sulfuric acid and sulfurous acid. Preference is given to the use of a Bronsted acid catalyst selected from a zeolite beta catalyst, from a silicate sheet catalyst or from a titanium dioxide catalyst comprising from 70 to 100% by weight of anastase and from 0 to 30 % by weight of rutile, wherein up to 40% by weight of the titanium dioxide can be replaced by tungsten oxide. The ratio dß anastasa in the titanium dioxide catalyst should be as high as possible. Preference is given to the use of a pure anatase catalyst. The catalyst preferably has a pore volume of from 0.1 to 5 ml / g., particularly preferably from 0.2 to 0.5 ml / gr. The average pore diameter is preferably in the range of 0.005 to 0.1 um, particularly and preferably within the range of 0.01 to 0.06 um. If highly viscous products are used, the average pore diameter should be large. The cutting hardness is preferably greater than 20 N, particularly preferably greater than 25 N. The BET surface area is preferably greater than 40 m / g, particularly greater than 100 ^ g. If the BET surface area is smaller, the bulk of the volume should be appropriately larger to ensure adequate catalytic activity. Particularly preferred catalysts have the following properties: 100% anatase; 0.3 ml / gr. of pore volume; 0.02 um average diameter of pore; 32 N is the cutting hardness; 116 m ^. of BET surface area or 64% by anatase weight; 16% by weight of rutile; 0.3 ml / gr. of pore volume; , 0.03 um average pore diameter; 26 N hardness of cut; 46 m / gr. of BET surface area. The catalysts can be prepared from commercial powders as available as for example from, Degussa, Finnti or Remira. When the oxide tungst? Is not used, up to 40% by weight, preferably up to 30% by weight, particularly preferably from 15 to 25% by weight titanium dioxide it is replaced by tungsten oxide. The catalysts can be prepared as described in Ertl, Knozinger, Weitkamp: ".. {annual heterogeneous catalysis.", VCH Weinheim, 1997, pages 88ff. Containers used in the reaction are packed with the catalyst material in such a way to maximize the catalyst surface area is available to all volume elements of the reaction solution. If desired, the reaction mixture can be re-circulated by pumping, to improve the exchange of the reactants on the surface of the catalyst. When the reaction mixture is reacted in the presence of a fixed channel catalyst, the temperature of the mixture is preferably within the range of 175 to 350.

C, preferably within the range of 200 to 300 ° C, particularly preferably within the range of 230 to 270 ° C. The lower temperature limit also depends on the degree of polymerization and the water content of the softened mixture, that a liquid-solid phase transition should be avoided In the absence of a fixed channel catalyst, the temperature of the reaction mixture is within the range of 200 to 350 ° C, preferably within the range of 220 at 300 * C, particularly preferable within the range of 240 to 280 In the process of the invention, said compounds or mixtures are reacted in the presence of metal oxide catalysts and optionally with water, to form polyamide The incorporations of the process are characterized by the temperature-time profiles and pressure-time, which depend on the reactants and the catalysts used.The dependence in time, of the pressure and temperature, depends directly on the reaction process, on the desired molecular weight distribution, or in the viscosity of the final product, and in the amount of water to be removed from the reaction mixture.The number of process steps and the water content in the reaction mixture depend on the composition and especially on the Amide and Nitrile Group Content of the Reaction Mixture: One- or two-stage additions are preferred when the reactants do not contain amides or nitriles, or The content of the amide or nitrile group of the reaction mixture is small and preferably less than 30 mole, still preferable less than 5 mole%, based on the monomers initiators. The incorporation of a step is particularly preferred for the case when only the aminocaproic acid has to be reacted. If the mixtures containing aminonitriles and / or amides are reacted, the incorporations of three and four stages will be particularly preferred.

Process dß Single Stage In the incorporation of a single stage, the pressure and temperature are preferably adjusted in such a way as to obtain a liquid phase comprising the reaction mixture and a gaseous phase that can be separated from it. The polycondensation of the mixtures which preferably have a high content of aminocaproic acid can then be carried out, for example, in a manner similar to the known continuous processes or batch production which are used for the polymerization of caprolactam and which is described in DE-A-44 13 177, DE -? - 14 95 198, DE-A-25 58 480, EP-A-0 020 946, and in "Polymerization Processes", pages 424 to 467, Interscience, New York, 1997, and in "Handbuch der Technisshen Poly erchemie", pages 546 to 554, VCH Verlagsgesellschaft, Weinheim, 1893, except that the above-mentioned lower reaction temperatures can be used. The water content of the reaction mixture depends, in particular, on the d-amide content of the mixture. When aminoalkanoic acids and especially aminocaproic acid are used exclusively, the reaction of. The reactants are preferably carried out without water.

Multi-Step Process In order to react a mixture of aminocarboxylic acid compounds and aminonitriles, the inventive incorporations of the process preferably have 2, 3 or 4 stages. The polymerization can be carried out in at least three stages, the first stage is carried out under an elevated pressure at which the reaction mixture, with the exception of the heterogeneous catalyst, is present as a single liquid phase and the last stage is carried out as a post-condensation under a pressure that is in the range from 0.01 x 10 to 10 x 10 Pa, it being possible for the heterogeneous catalyst to be present in either or both of the stages. Particular preference is granted to the incorporations that have 4 stages, when the amide and / or nitrile groups are present in the reaction mixture. The invention provides a process, preferably continuous, for producing the polyamide, by means of the reaction of at least one aminocarboxylic acid compound, optionally in a mixture, comprising the following steps: (1) reacting the acid compounds aminocarboxylic, optionally in a mixture, at a temperature of 175 to 300 C and at a pressure of 0.1 to 35 x 10 Pa, in a flow tube that could be packed with a Bronsted acid catalyst selected from a beta zeolite catalyst, of a silicate sheet catalyst or a titanium dioxide catalyst comprising from 70 to 100% by weight of anatase, and from 0 to 30% by weight of rutile, wherein up to 40% by weight of titanium dioxide it can be replaced by tungsten oxide to obtain a reaction mixture. (2) continue with the reaction procedure of the reaction mixture, at a temperature between 150 to 350 ° C and at a pressure that is lower than the pressure in stage 1, in a reaction that could be carried out in the presence of an acid catalyst Br-opstecl B & amp;; lmcsicmtula »pw-hiv ff Utt beta-seolite catalyst, a diesilic acid sheet catalyst or a titanium dioxide catalyst comprising from 70 to 100% by weight of anatase and from 0 to 30% by weight of rutile, where up to 40% of the titanium dioxide can be replaced by tungsten oxide, the temperature and the pressure being selected in such a way as to obtain a first phase of gas and a first phase of liquid or a first phase of solid, or a mixture d? the first phase of liquid and the first phase of solid, and wherein the first phase of gas is separated from the first phase of liquid or the first phase of solid, or the mixture of the first phase of liquid and the first phase of solid, and (3) mixing the first liquid phase or the first solid phase, or the mixture of the first liquid phase and the first solid phase with a liquid or gaseous phase comprising water at a temperature of 150 to 370 C and at a pressure of 0.1 to 30 x 10 Pa, to obtain a mixture as a product. The above process additionally and preferably comprises the following step: (4) post-condensate the produsto of the mixture at a temperature of 200 to 350 C and at a pressure that is lower than the pressure of stage 3, the temperature and the pressure are selected so as to obtain a second gas phase comprising water - and possibly ammonia - and a second liquid phase or a second solid phase, or a mixture of the second liquid phase and the second solid phase, One of which comprises polyamide.

The stages of the process correspond to the previous stages (1), (2), (3) and (4), to an incorporation of two stages of the process that combines stages (1) and (4), to an incorporation of three stages of the process that combines stages (1), (2) and (4), and an incorporation of four stages of the process that combines stages (1) to (4). The aforementioned processes, that is, the sequence of conformity to the invention of steps (1) and (4) or (1), (2) and (4) or (1) to (4), can be carried out by production batches, that is, in succession in a single reactor, or continuously, that is, simultaneously in successive reactors . It is also possible, of course, to carry out some of the stages (1) and (2) continuously and the rest in production lots. In an additional and alternative incorporation of the process to produce polyamides, the aminonitriles are reacted with water, completely or incompletely, in a preceding step and the product of the mixture is additionally reacted in the aforementioned steps (1) to (4) . The reaction of the invention, of the aminonitriles with water to form a mixture of aminocaproic acid compounds, can be carried out in any of the continuous stages or in production batches. The purpose is to achieve partial hydrolysis, with or without the polymerization of the nitriles. In a suitable embodiment, the reaction mixture can be mixed with water in a pressure vessel and heated. The molar ratio between aminonitrile and water should be within the range of 1: 0.1 to 1:10, preferably within the range of 1: 0.5 to 1: 6, particularly within the range of 1: 1 to 1: 4. The temperature during the reaction should be within the range of 150 to 300 ° C, preferably 200 to 280 ° C, particularly preferable within the range of 220 to 270 ° C. The temperature does not need to be kept constant during the reaction, but It can be sautéed, for example, in a possible and additional incorporation, the mixture of the reaction of the aminonitriles and a comparatively small amount of water, can be mixed is additional amount of water, at the rate of reaction speed. It is also possible to carry out comparatively low pressures in the autogenous system, it is additionally possible for the reaction of the invention to be carried out in a continuously stirred tank under super-atmospheric pressures. It is continuously monitored when it is introduced and stirred in the tank, while at the same time the reaction mixture is discharged via a valve. e pressure control. All the mentioned procedures can be operated with or without the catalyst. If the catalysts are used, the aforementioned Bronsted acid metal oxide catalysts are preferred. The product of the reaction obtained is often a mixture of oligomers and monomers that form polyamides, the proportion of which varies as a function of the process and the reaction conditions (water content)., pressure, temperature). It could be determined that the hydrolysis of the nitrile groups generally proceeds satisfactorily at the higher reaction temperatures, and with longer reaction or residence times. The reaction mixture of the aminonitriles, aminocarboxamides, aminocarboxylic acids and other compounds formed in the preceding step can then be converted into a multi-step process as described above, in polyamide. In this reaction, the aminocaproic acid compounds or their mixtures are reacted with water in a first stage, then partially and hydrolytically polymerized and further processed in subsequent stages of the reaction. The entire process consists of 3 or 4 stages, and it is preferable for the reaction mixture to form a single liquid phase in the first and in the third stage, and for a liquid phase comprising water, to be added to the liquid phase. third stage. Additionally, in the context of the process of the invention, it is also possible to carry out an elongation or ramified chain, or a combination of these. For this purpose, the branching of the polymer or the chain elongation of the connoid substances to a person trained in the art are added to the reaction mixture. The substances can be added not only to the initiator mixture, but also to the reaction mixture that is post-condensed. Useful substances (which can be used as a mixture) are: tri-funsional amines or carboxylic acids such as branching agents, or interconnecting agents. Examples of suitable and at least tri-functional carboxylic acids or amines are described in EP-A 345 648. Tri-functional amines have at least three groups of amines which are capable of reacting with the acid groups carboxylic They preferably do not have any carboxylic acid group which is capable of reacting with the amines and which may also be present, for example, in the form of their derivatives, such as esters. The carboxylic acids, preferably, do not contain any type of amines capable of reacting with the carboxylic acid groups. Examples of suitable carboxylic acids are trimesic acid, trimerized fatty acids, prepared for example from oleic acid and having from 50 to 60 carbon atoms, the naphthalene-polycarboxylic acids, such as naphthalene-1, 3, 5 , 7-tetracarboxylic. The carboxylic acids are preferably defined as organic compounds and not as polymeric compounds. Examples of amines having at least 3 amines groups in the nitrilotrialkilamine, especially the nitrilotrietanea ina, the dialkylenetriamines, especially the diethylenetriamine, the trialkylenetetramine and the tetraalkylenepentamines, the alkylenes medium, these preferably being the ethylenes medium. Traditionally, dendrimers can be used like amines. The dendrimers have the general formula I: (R_.N- (CHt) ^) a_N- (CH ,.) - ÍÍCH ^ - R-.) ,. (I) where R is H or - (CH -.) ^ - N ^, where Rxes H or -CCH ^ ^ -NR. , where ^ is H or - CHA ^ -NRÍ, where R * is H or - (CHa.) ^ - H ^, n is a whole number from 2 to 14.

Preferably, n is 3 or 4, especially 3, and x is an integral number from 2 to 6, preferably from 2 to 4, especially 2. The radicals R can also have the stated meanings, independently of one another.

Preferably, R is a hydrogen atom or a radical - (CHa.) --HH, .., 1 Suitable carboxylic acids are those having from 3 to 10 carboxylic acid groups. Preferred carboxylic acids are those having an aromatic and / or heterocyclic nucleus. Examples are benzyl, naphthyl, anthracene, biphenyl, triphenyl or histacyclic radicals such as pyridine, bipyridine, pyrrole, nature, furan, thiophene, purine, quinoline, phenanthrene, porphyrin, the eftalocianina, the naftalocianina. Preference is given to 3, 5, 3 ', 5' -biphenyltetracarboxylic acid, the phthalocyanine, the nataocyanin, the 3, 5, 3 ', 5'-biphenyltetracarboxylic acid, the 1,3,5,7-naphthalenetetracarboxylic acid, 2,4,6-pyridinetricarboxylic acid, 3, 5,3 ', 5'-bipyridyltetracarbesilic acid, 3, 5,3', 5'-bßnzofßnonetetracarboxylic acid, 1,3,6,8-acridinetetracarboxylic acid, Particularly preferred is 1,3-benzenetricarboxylic acid (trimesic acid) and 1,2,4,5-benzenotetracarboxylic acid. Said compounds are commercially available or can be prepared by means of the process described in DE-A-43 12 182. If the ortho-substituted aromatic compounds are used, the imide formation is preferably prevented through the choice of suitable temperatures. of reaction. These substances are at least "tri-functional, preferably at least tetra-functional. The number of functional groups can be from 3 to 16, preferably from 4 to 10, particularly preferably from 4 to 8. The processes of the invention r are carried out using at least tri-functional amines or at least tri-functional carboxylic acids , but not mixtures of said amines or said carboxylic acids. In any case, small amounts of the at least tri-functional amines can be present in the tri-functional carboxylic acids, and vice versa. The substances are present in an amount of 1 to 50 umol / gr. of polyamide. The substances are preferably present in an amount from 3 to 150, particularly preferably from 5 to 100, especially from 10 to 70 or 50 equivalents of polyamide / g. The equivalents are based on the number of functional amine groups or the carboxylic acid groups. The di-functional carboxylic acids are used as the chain extenders. These have 2 carboxylic acid groups which can be reacted with the amine groups, or 2 amine groups can be reacted with the carboxylic acids. The di-functional carboxylic acids or the amines, apart from the carboxylic acid groups or the amine groups, do not contain additional functional groups capable of reacting with the groups of amines or with the carboxylic acid groups. Preferably, they do not contain additional amounts of functional groups. Examples of suitable di-functional amines are those which form salts with the di-functional carboxylic acids. They may be linear aliphatic, such as C ¡_-y, -alkyleneamine, preferably C? _-Alkylenediamine, such as, for example, hexylene diamine. They can also be cyclo-aliphatic Examples are isophoronediamine, di-cyclic, laromine Branched aliphatic diamines are similarly usable, one example being Vesta ina TMD (tri-methyl hexamethylene diamine) Huís AG) They can also be diamines, complete amines can each be replaced by C /./, -alkyl, preferably C (.? -alkyl, which are radicals in the carbon skeleton. The di-functional carboxylic acids are, for example, those which form salts with the di-functional diamines, they can be aliphatic di-carboxylic acids, which preferably are CT, carboxylic acids, Examples are adipic acid, azelaic acid, sebacic acid, suberic acid They can also be aromatic Examples are isophthalic acid, terephthalic acid, naphthalenecarboxylic acid, as well as dimerized fatty acids.

The basic and di-functional constituent blocks are preferably used in amounts of 1 to 55, particularly preferably 1 to 30, especially 1 to 15 umol / g. of polyamide.

The initiator mixture and the reaction mixture can be mixed in all stages with the chain regulators, such as the dicarboxylic acids, the aromatic carboxylic acids and the aliphatic carboxylic acids, and the catalysts such as the phosphorus compounds that they contain oxygen, in amounts that are within the range of 0.01 to 5% by weight, preferably within the range of 0.2 to 3% by weight, based on the amount of monomers that make up the polyamide and the aminonitrile used. Suitable chain regulators include, for example, propionic acid, acetic acid, benzoic acid, terephthalic acid and triacetonadiamine. Additives and fillers such as pigments, dyes and stabilizers are generally added to the reaction mixture as a step prior to pelletization, preferably in the second, third and fourth stages. Particular preference is given to the use of filler add-ons and additives, provided that the reaction or polymer mixture is not found with fixed channel catalysts during the rest of the processing. One or more gums with a modified impact coefficient may be present in the compositions, as additives, in amounts of 0 to 40% by weight, preferably 1 to 30% by weight, based on the totality of the composition. The use, for example, of modifiers that are suitable for polyamides and / or polyarylene ethers is possible. The, gums that improve the hardness of. polyamides generally have two essential characteristics - they have an elastomeric portion having a glass transition temperature of less than -10"C, preferably less than -30" C, and they contain at least one functional group that is capable of interaction with polyamide. Suitable functional groups include, for example, the carboxylic acid, carboxylic anhydride, carboxylic ester, carboxylic amide, carboxylic imide, amino, hydroxyl, epidoxide, d-urethane and oxazoline groups. Examples of gums that improve the hardness of the mixtures include, for example: EP and EPDM gums grafted with the above functional groups. Suitable grafting reagents include, for example, maleic anhydride, itaconic acid, acrylic acid, glycidyl acrylate, and glycidyl methacrylate. These monomers can be grafted onto the polymer in the softened compound or in the solution, in the presence or in the absence of a free radical initiator, such as eumeno hydroperoxide. The copolymers of the α-olefins described under the polymers, especially including the ethylene copolymers, can also be used as gums instead of the polymers A, and can be mixed as such in the compositions of the invention.

An additional group of suitable elastomers are the coated core graft gums. These are gums of. graft that are produced in emulsion and which have at least one hard component and one soft component. A hard component is customarily a polymer having a glass transition temperature of at least 25"C, while a soft component is a polymer having a glass transition temperature of not more than 0" * C. These products have a structure made of a core and of at least one coating, the structure is the result of the order in which the monomers are added. The soft components are generally derived from butadiene, isoprene, alkyl acrylates, alkyl methacrylates or siloxanes and optionally and additionally, from the comonomers. Suitable siloxane cores can be prepared, for example, starting from cyclic oligomeric octamethyltetrasiloxane or tetravinyltetramethyltetrasiloxane. These can, for example, be reacted with the / -mercaptopropylmethyldimethoxysilane in a cationic polymerization with an open bond, preferably in the presence of sulfonic acids, to form the smooth siloxane cores. The siloxanes can also be interconnected by, for example, carrying out the polymerization reaction in the presence of silanes having hydrolysable groups such as halogen groups or alkoxy groups, such as tetraethoxysilane, methyltrimethoxysilane, or phenyltrimethoxysilane. Suitable comonomers here include, for example, styrene, acrylonitrile and interconnecting agents or graft monomers having more than one double polymerization linkage, such as diallyl phthalate, divinylbenzene, butanediol diacrylate or (iso) triallyl cyanurate. Hard components are usually derived from styrene, from t >; -methylstyrene and the copolymers thereof, the preferred comonomers are acronitrile, methacrylonitrile and methyl methacrylate. The coated core graft gums have a soft core and a hard coating or, a hard core, a first smooth coating and at least one additional hard coating. The incorporation of the functional groups such as the carbonyls, carboxylic acid, anhydride, amide, imide, carboxylic, amino, epoxy, oxazoline, urethane, urea, lactam or the halobenzyl groups, is here preferably effected by means of the addition of the suitably functionalized monomers during the polymerization of the last coating. Suitable functionalized monomers include, for example, maieic acid, maleic anhydride, mono or diesters or maleic acid, tert-butyl (et) acrylate, acrylic acid, glycidyl (meth) acrylate and vinyloxazoline. The proportion of monomers having functional groups is generally within the range of 0.1 to 25% by weight, preferably within the range of 0.25 to 15 X by weight, based on the total weight of the coated core graft gum. The weight ratio of the soft to hard components is generally within the range of 1: 9 to 9: 1, preferably within the range of 3: 7 to • 8: 2. Said gums, which improve the hardness of the polyamides, are known per se and are described in EP-A-0 208 187, for example. A further group of suitable impact modifiers are the thermoplastic polyester elastomers. Polyester elastomers are segmented copolyethers which contain long chain segments, generally derived from poly ether glycols (alkylenes), and chain segments derived from di-carboxylic acids and diols, with low molecular weight. Such products are known per se and are described in the literature, such as, for example, in U.S. Patent No. 3,651,014. The corresponding products are also commercially available under the names of Hytrel (DuPont), Arnitel (Akzo) and Pelprene (Toyobo Co. Ltd.) It will be appreciated that it is also possible to use mixtures of different gums. Further additives may be mentioned, for example, processing aids, stabilizers and oxidation retardants, agents against thermal decomposition and decay due to ultra violet light, lubricating agents, flame retardants. , dyes and pigments and plasticizers. The proportion of these is generally up to 40 X, preferably up to % by weight, based on the total weight of the composition.

The pigments and dyes are present in an amount of up to 4 X, preferably up to 0.5 to 3.5%, especially 0.5 to 3 X by weight. Pigments for the coloring of thermoplastics are commonly known, see for example R, Gachter and H. Muller, Taschenbuch der Kunststoffadditive, Carl Hanser Verlag, 1983, pages 494 to 510. The first preferred group of pigments to be mentioned as white pigments such as zinc oxide, zinc sulphide, white lead (2 Pb CO PbOH) ^), lithopone, white antimony and titanium dioxide. Of the two most common crystal polymorphs (rule and anatase) of titanium dioxide, the rutile form is preferred to be used as the white pigment for the molding compositions of the invention. The black pigments that can be used in accordance with the invention are black iron oxide (Fe. Oy), black spinel (Cu (Cr, Fe) t0y), black manganese (mixture of manganese dioxide, dioxide silicone and iron oxide d), black cobalt and black antimony and also, particularly preferred, black carbon, which is usually used in the form of an oven or black gas (see G. Benzing, Pig Entity Anstrich ittel, Expßrt-Verlag (1988), p.78ff). It will be appreciated that inorganic colored pigments, such as green chromium oxide or organic colored pigments such as azo pigments and phthalocinanines, can be used in accordance with the invention, to obtain certain shades. Said pigments are generally commercially available. The use of the aforementioned pigments or dyes in a mixture, for example, black carbon with copper phthalocyanines, could be of additional advantage, because this generally facilitates the dispersion of the color in the thermoplastic. Oxidation retardants and thermal stabilizers which may be added to the thermoplastic materials of the invention include, for example, the halides of metals of group I of the periodic table, for example, sodium halides, potassium halides. , the lithium halides, optionally in conjunction with copper (I) halides, such as, for example, chlorides, borides or iodides. Halides, especially copper, may also contain electron-rich p-binders. Examples of said copper complexes are the copper halide complexes with triphenylphosphine, for example. It is additionally possible to use zinc fluoride and zinc chloride. Other possibilities are the sterically clogged phenols, the hydroquinones, the substituted representatives of this group, the secondary aromatic amines, optionally in conjunction with the phosphorus-containing acids and salts thereof, and mixtures of these compounds, preferably in a concentration of up to 1% by weight, based on the weight of the mixture. Examples of Ultra Violet (UV) stabilizers are various substituted resorcinols, salicylates, benzotriazoles and benzophenones, which are generally used in amounts up to 2 X by weight. 1 Lubricating agents, which are generally included in the thermoplastic material in amounts of up to 1 X by weight, are stearic acid, stearyl alcohol, alkyl stearates and N-alkylstearamides and also esters of pentaerythritol with acids fatty with long link chains. It is also possible to use calcium, zinc or aluminum salts or stearic acid and also dialkyl ketones, such as, for example, distearyl ketone. Substances that are not homogeneously dissolved in the reaction mixture, such as pigments and fillers, are preferably added to the reaction mixture after the production steps that take place in the presence of a fixed channel catalyst . The polyamides of the invention, especially nylon-6 and the copolymers thereof, can be used to produce fibers, film sheets and molded articles. According to the invention, the mixture of the product obtained in stage 3, or the second liquid phase or second solid phase, or the mixture of the second liquid phase and the second solid phase (of stage 4) comprising the polyamide, preferably a softened polyamide compound is discharged from the reaction vessel by customary methods, such as, for example, with the aid of a pump. Subsequently, the obtained polia can be administered in a conventional manner as described in detail, for example, in DE-A 43 21 683 (page 3 line 54, page 4 line 3). In a preferred embodiment, the level of the cyclic dimer in the nylon-6 obtained in accordance with the invention can be further reduced by means of the extraction of the polyamide, first with an aqueous solution of caprolactam and then with water and / or subjecting it to a gas phase extraction (described in EP-A-0 284 968, for example). Low molecular weight constituents such as caprolactam and its linear and also cyclic oligomers obtained in the course of this post-treatment can be returned to the first and / or the second and / or the third stage. The following examples illustrate the invention.

Examples: Analysis v Sample Preparation The so-called relative viscosity (VR), a measure of the accumulation of moles and the degree of polymerization, was measured at 1% strength per weight of solution in the case of the extracted material and in 1.1 X strength. by weight of solution, in the case of the non-extracted polymer, in 96 X of resistance of the sulfuric acid, at 25 C using an Ubbelohde viscometer. The non-extracted polymers were dried under und. reduced pressure for 20 hours, prior to analysis. . The contents of the carboxyl and amine end groups were acidiometrically analyzed volumetrically. The amine groups were analyzed volumetrically with the perchloric acid at 70:30 (parts by weight) of phenol / methanol, as the solvent. The carboxyl end groups were analyzed volumetrically with a solution of potassium hydroxide, in benzyl alcohol as the solvent. For the extraction, 100 parts by weight of the polymer mixture were mixed by agitation with 400 parts by weight of diphosphate water at 100 C for 32 hours under reflux and, after being removed from the water, it was slightly dried, that is, without post-condensation, at 100 ~ C under reduced pressure for 20 hours. The separation of the mixtures of the reaction in individual substances and the analysis of the mass fractions, were carried out by means of liquid chromatography at high pressure (CLAP). The procedure is described in Anal. Chem. 43, 880 (1971). The products were first dissolved in a mixture of water, a buffer solution of sodium borate and acetonitrile, derivatized with OPA and then separated with a column of CLAP RP18. The concentrations were correlated via a series of calibrations. Procedure The catalyst particles were 100 X of Ti0u of commercial denomination Finnti, type S150, in the natase form and had an extruded length within the range of 2 to 14 mm, an extruded thickness of about 4 mm and a surface area specifies more than 100 m / gr. The purity of the aminocapronitrile used was 99.5 X. I Reaction by Production Batches of the Aminocarboxylic Acid Compounds Example 1-1 The tests were performed in an autoclave with and without (as a comparison) a catalyst bed, the channel completely covers the reaction mixture. Then, the aminocaproic acid was introduced and without the catalyst, the autoclave was sealed, vented and repeatedly purged with nitrogen. After 1.25 hours of heating at the desired reaction temperature of 230 ° C at a pressure of up to 18 atmospheres, manually controlled by means of a valve, the pressure in the autoclave was lowered to ambient pressure (around 1 atmosphere) in the course of 1 hour, so that the softened pre-polymer compound managed to post-condense. The product was extruded in the form of braids in a water bath.

Ex emp lo 1 -2 Properties Viscocity End groups End groups of relative polymer * Carboxyls Amines [meq / kg] [meq / kg] r with catalyst 2.09 112 70 without catalyst 1.80 99 126 (*) measurements taken in a non-extracted product Example 1-1 was repeated with a reaction temperature of 250 ° C. Result 1-2 Properties Viscocity End groups End groups of Polymer * relative Carboxyls Amines [meq / kg] [meq / kg] with catalyst 1.91 105 89 without catalyst 1.69 122 150 (*) measurements taken on a non-extracted product Preliminary Stage to Convert Aminonitriles into Mixtures of Aminocarboxylic acid Example 11-1 In a 2-liter pressure vessel equipped with a heating jacket and with a stirrer, 1400 gr. of a reaction mixture consisting of aminocapronitrile and water in a molar ratio of 1: 4, were stirred in a sealed reactor at 250 C. The autogenous pressure was 48 atmospheres. After 2 hours, the aminocapronitrile conversion was 96.6%; the analysis of the reaction mixture is reported in Table II.

Example II-2 In a 2 liter pressure vessel equipped with a heating jacket and with a stirrer, 1400 gr. of a reaction mixture consisting of aminocapronitrile and water in a molar ratio of 1: 1, were stirred in a sealed reactor at 250 C. The autogenous pressure was 30 atmospheres. After 200 minutes, the aminocapronitrile conversion was 36%; the analysis of the reaction mixture is reported in Table II.

Example II-3 In a 2 liter pressure vessel equipped with a heating jacket and with a stirrer, 1400 gr. of a reaction mixture consisting of aminocapronitrile and water in a molar ratio of 1: 4, were stirred in a sealed reactor at 230 ** C. The autogenous pressure was 39 atmospheres. After 3 hours, the aminocapronitrile conversion was 96 X; the analysis of the reaction mixture is reported in Table II.

Example TT-4 In a 2 liter pressure vessel equipped with a heating jacket and with a stirrer, 1400 gr. of a reaction mixture consisting of aminocapronitrile and water in a molar ratio of 1: 4, were stirred at 250 ° C. The autogenous pressure was 43 atmospheres.At the time of the 3-hour reaction, water was continuously introduced into the atmosphere. The reactor at a flow rate of 100 g / hr, a water / ammonia mixture was similarly continuously withdrawn from the gas phase, via an over-flow valve, and then 3 hours, the conversion of aminoc'apronitrile was greater than 99%, the analysis of the reaction mixture is reported in Table II.

Example II-5 4.5 g. of a reaction mixture comprising 2.7 g. of aminocapronitrile, 1.8 gr. of water and 0.5 gr. of a titanium dioxide catalyst (type P25 of the commercial name Degussa, granular powder) was added to an autoclave with 5.5 ml of capacity. The autoclave was sealed and left at 250 ° C in a d d oil bath for 2 hours.After the reaction, the autoclave was rapidly cooled and the reaction mixture was removed.The aminocapronitrile conversion was around d d 98 X; Analysis of the reaction mixture is reported in Table II.

Table II R_.f_ni t.Bdos He? «Reaction of the - Airiinonit ilos - in - the - Preliminary Eiana.

The ACN time: T [-C] ACN di-hexa ASC di tri ACSA di tri CL di tri oligos reaction H-0 ACN ACS ACS ACSA ACSA CL CL [min] II-l 120 1: 4 250 2.2 9.3 0.8 0.8 0.8 2.1 2.0 1.8 16.0 0.6 0.1 27.5 II-2 120 1: 1 250 30.9 25.5 0.1 0.1 0.1 0.9 0.6 0.2 9.1 < 0.1 < 0.1 II-3 180 1: 4 230 2.5 10.5 0.9 0.9 0.1 1.7 1.6 1.4 23.6 0.5 0.1 20.1 II-4 180 1: 4 250 0.1 0.8 1.0 1.1 0.50.6 0.5 17.0 1.0 0.2 41.2 II-5 120 1: 4 250 0.9 2.0 0.9 1.3 0.1 2.72.4 2.4 14.9 0.7 0.2 32.5 1T) ACN: aminocapronitrile ACS: aminocaproic acid ACSA: aminocaproamide CL: caprolactam di-hexa: dimer to hexamer di: dimer tri: trimer oligo: oligomer > 3 units The components are reported in percent by mass, based on the totality of the production batch. or m CN s Mixtures of acid compounds. aminocarboxylic acid prepared in the preliminary stage, were reacted in a four-stage mini-plant. The initiator mixtures were pumped with a water content of 50% by weight through the first stage, at a flow rate of 600 gr./hr. The first stage, with an empty volume of 1 liter and with an internal length of 1,000 mm, was completely charged with catalyst and was operated at a temperature of 240 C and a pressure of 55 atmospheres. The second stage used was a 2 liter separation vessel, where the reaction mixture was reacted at a temperature of 250 C and a pressure of 30 atmospheres. The third stage was a flow tube with 1 liter volume and 1,000 mm in length, loaded with Rasching rings of 6 mm diameter and 6 mm length (the reaction temperature of the mixture was 250 C, the pressure was of 35 atmospheres), inside which water was injected by pumping through the line of an additionally saline line, at a flow rate of 60 gr./hr. The fourth stage, in turn, consisted of a separation vessel (with a volume of 2 liters, with a temperature of the reaction mixture of 250 C, a pressure of 1.2 atmospheres), from which the polymer compound softened , produced, was extruded in the form of braids, by means of a booster pump. The polymers were produced without catalyst, for comparison purposes.

Table III Results; Continuous Conversion of Compound Mixtures. Laugh Acido? S LnafiLarb o x 1 licos___ P reí par ad_O_s_ in a Preliminary Stage. Agree 'n the E in TT' -1 to TT t? ..

Examples Con / Sin Catal iz, adi or Relative Viscocity II-l With 2.08 CII-1 Without 1.40 II-2 With 1.97 CII-2 Without 1.30 II-3- With 2.00 CII-3 Without 1.39 II-4 With 2.13 CII-4 Without 1.62

Claims (1)

1. CLAIMS The process for the production of polyamides by the reaction of aminocarboxylic acid compounds of the general formula IH? N-CCHz-COR1 wherein R1 is OH, O-alkyl 0-C2 or NR2R3, where R2 and R3 are, independently, hydrogen, C 1 -C 2 alkyl or Cs-Cs cycloalkyl, and m is an integer from 3 to 12, optionally in a mixture with aminonitriles and their hydrolysis products where the proportion of aminocarboxylic acid compound (s) in the initial mixture it is not less than 75% by weight, and optionally in the presence of water, in a liquid phase at a pressure of 0.1 to 35 x 106 Pa and at a temperature of 175 to 350 ° C in the presence of metal oxides as heterogeneous catalysts, the Metal oxides are used in a form that allows mechanical removal of the reaction mixture and are removed from the reaction mixture during or after polymerization. A process according to claim 1, wherein the aminocarboxylic acid is selected from 6-aminocaproic acid, methyl 6-aminocaproate, ethyl 6-aminocaproate, 6-amino (N-methyl) caproamide, 6-amino (N, N-dimethyl) caproamide, 6-amino (N-ethyl) caproamide, 6-aminocaproamide. A process according to claim 1 or according to claim 2, wherein the metal oxide catalysts are used in the form of granules, extrusion products, fixed beds or coated or internal packages. A process according to any of claims 1 to 3, wherein the metal oxide catalysts are selected from zirconium oxide, aluminum oxide, magnesium oxide, cerium oxide, lanthanum oxide, titanium dioxide, beta zeolites and sheet silicates. A process according to any of claims 1 to 4, wherein the metal oxide catalysts are used together with acid co-catalysts homogeneously dissolved in the reaction mixture. A process according to any of claims 1 to 5, wherein the polymerization is carried out in at least two stages, the first stage is carried out under a pressure of 0.1 to 35 x 106 Pa in which the mixture of the The reaction with the exception of the heterogeneous catalyst is present as a single liquid phase and the last step SB preferably carries out as a post-condensation under a pressure comprised within a range of 0.01 x 105 to 10 x 105 Pa, being possible that the heterogeneous catalyst is present in any of the stages or in both stages. A process according to any of claims 1 to 6, comprising the following steps: (1) reacting the aminocarboxylic acid compounds, optionally in a mixture with aminonitriles and their hydrolysis products, where the proportion of the The aminocarboxylic acid compound (s) in the initial mixture is not less than 75% by weight, and optionally in the presence of water at a temperature within a range of 175 to 350 ° C and under a pressure of 0.1 to 35 x 106 Pa in a flow tube which can be packed with a Brdnsted acid catalyst selected from a zeolite beta catalyst, a silicate sheet catalyst or a titanium dioxide catalyst comprising from 70 to 100% by weight of anatase and from 0 to 30% by weight of rutile wherein up to 40% by weight of the titanium dioxide can be replaced by tungsten oxide to obtain a reaction mixture, (2) further reacting the mixing the reaction at a temperature of 150 to 350 ° C and under a pressure that is lower than the pressure in step 1 in a reaction that can be carried out in the presence of a Brónsted acid catalyst selected from a beta zeolite catalyst, a sheet silicate catalyst or a titanium dioxide catalyst comprising from 70 to 100% by weight of anatase and from 0 to 30% by weight of rutile in which up to 40% by weight of the titanium dioxide can be replaced by tungsten oxide, the temperature and the pressure are selected such that a gas phase and a liquid or solid phase or a mixture of a solid and liquid phase are obtained, and the gas phase is separated from the liquid phase or the solid phase or of the mixture of the liquid and solid phase, and (3) mixing the liquid phase or the solid phase or the mixture of liquid and solid phase with a gaseous or liquid phase comprising water at a temperature of 150 to 370 ° C. and under a pressure of 0.1 to 30 x 106 Pa to obtain a mixture of products. A process according to claim 7, further comprising the following step: (4) subsequently condensing the product mixture at a temperature of 200 to 350 ° C and under a pressure that is lower than the pressure in step 3, the The temperature and the pressure are selected in order to obtain a gas phase comprising water and possibly ammonia and a liquid or solid phase or a mixture of a liquid and solid phase, comprising (each) the polyamide.