EP1280846A1

EP1280846A1 - Method for producing a polymer, using caprolactam

Info

Publication number: EP1280846A1
Application number: EP01943299A
Authority: EP
Inventors: Frank Ohlbach; Helmut Winterling; Andreas Ansmann; Rolf-Harmuth Fischer; Johann-Peter Melder; Stefan Maixner; Peter Bassler; Hermann Luyken
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 2000-05-03
Filing date: 2001-04-30
Publication date: 2003-02-05
Also published as: AR029914A1; MXPA02009715A; CN1172977C; CA2407814A1; CN1427861A; JP2003531935A; AU2001265912A1; WO2001083589A1; US20030135019A1; IL152051A0; DE10021191A1; US6878798B2; BR0110452A

Abstract

The invention relates to a method for producing a polymer. Said method is characterized as follows: a) a mixture (I) containing 6-aminocapronitrile and water is converted into a mixture (II) containing caprolactam, ammonia, water, high boilers and low boilers in the presence of a catalyst; then b) the ammonia is removed from mixture (II) to obtain a mixture (III) containing caprolactam, water, high boilers and low boilers; subsequently c) the water is completely or partially eliminated from mixture (III) to obtain a mixture (IV) containing caprolactam, high boilers and low boilers; and finally d) mixture (IV) is subjected to a polymerization reaction. The invention also relates to a polymer obtained according to said method, to its use in the production of fibres, flat material and moulded bodies that are obtained using a polymer of this type.

Description

Process for producing a polymer using caprolactam

description

The present invention relates to a method for producing a polymer using caprolactam, characterized in that

a) a mixture (I) containing 6-aminocapronitrile (α-aminocapronitrile, "ACN") and water to give a mixture (II) containing caprolactam, ammonia, water, high boilers and low boilers in the presence of a catalytically demanding reaction Solid, then

b) ammonia removed from mixture (II) to obtain a mixture (III) containing caprolactam, water, high boilers and low boilers, then

c) water completely or partially removed from mixture (III) to obtain a mixture (IV) containing caprolactam, high boilers and low boilers, and then

d) mixture (IV) feeds the polymerization reaction.

The present invention further relates to a polymer obtainable by this process, its use for the production of fibers, sheets and moldings, and fibers, sheets and moldings, obtainable using such a polymer.

Processes for the production of caprolactam and processes for the production of polymers using caprolactam are generally known.

For example, caprolactam can be produced by Beckmann rearrangement of cyclohexanonoxim with sulfuric acid or oleum. After neutralizing the mixture thus obtained with ammonia, the caprolactam can be obtained from the ammonium sulfate formed as a by-product by extraction with an organic solvent.

Depending on the processes for the preparation of the starting materials used to prepare the cyclohexanone oxime, such as cyclohexanone and hydroxylammonium sulfate, the oximation and rearrangement conditions, the crude caprolactam, which is produced by Beck- Depending on the processes for the preparation of the starting materials used to prepare the cyclohexanone oxime, such as cyclohexanone and hydroxylammonium sulfate, the oximation and rearrangement conditions, the crude caprolactam obtained by Beckmann rearrangement contains impurities, which can be found in Art and scope differ. Typical contaminants from crude caprolactam produced by the Beckmann rearrangement are C-methylcaprolactams, 6-methylvalerolactam and n-pentylacetamide.

Various processes have been described for purifying the crude caprolactam obtained in the Beckmann rearrangement.

According to DE-A-1253716, the crude caprolactam can be purified by hydrogenation in suspension in the presence of a catalyst and with the addition of an acid.

According to DE-A-1253716, the crude caprolactam can be purified by hydrogenation in suspension in the presence of a catalyst and with the addition of a base.

DD-A-75083 describes a process for the purification of crude caprolactam in which the crude caprolactam is first distilled and then, dissolved in an organic solvent, hydrogenated in the presence of a catalyst and then treated with an ion exchanger.

According to EP-A-411455, the characteristic important quality characteristics for caprolactam can be maintained by continuously hydrogenating the crude caprolactam in a liquid phase process.

Crude caprolactam, which by hydroformylation of 3-pentenoic acid and / or its esters to 5-formylvaleric acid (esters) as main products and 4- and 3-formylvaleric acid (esters) as by-products, extractive (WO 97/02228) or distillative ( WO 97/06126) separation of this branched formylvaleric acid (ester), aminating hydrogenation of 5-formylvaleric acid (esters) to 6-aminocaproic acid (esters) and / or β-aminocaproic acid amide and cyclization of 6-aminocaproic acid (esters) or 6-aminocaproic acid amide contains other typical impurities.

For example, from WO 99/48867, example 1, starting from 5-formylvaleric acid esters, according to WO 98/37063, example 9, crude caprolactam obtained from mixtures of 6-aminocaproic acid, 6-aminocaproic acid amide and corresponding oligomers with addition of 10 wt .-% water to crystallize. In this mann rearrangement was obtained, impurities that differ in type and extent.

Caprolactam can also be obtained by reacting ACN with water in the gas or liquid phase in the presence or absence of a catalyst to release ammonia.

The mixture obtained in this reaction contains, in addition to caprolactam, water, ammonia and any other liquid diluent, impurities with a boiling point above that of caprolactam ("high boilers") and those with a boiling point below that of caprolactam ("low boilers").

From US Pat. No. 5,496,941, example, it is known that after the separation of water, solvent, ammonia, low boilers and high boilers from a mixture, a crude caprolactam is obtained when ACN is reacted with water and solvent is obtained with a purity of 99.5%.

It is, for example from Ullmann's Encyclopedia of Industrial Chemistry, 5th Ed., Vol. A5, VCH Verlagsgesellschaft mbH, Weinheim (Germany), 1986, pages 46-48, or Kirk-Othmer, Encyclopedia of Chemical Technology, 4th Ed. , Vol. 4, John Wiley & Sons, New York, 1992, page 836, generally known that caprolactam used in the manufacture of polymers must be 99.9 to 99.94% pure, with the major impurity is usually water in an amount of 0.04 to 0.1%. Other impurities may only be contained in the range of a maximum of a few ppm.

DD-A-75083 describes a process for the purification of crude caprolactam in which the crude caprolactam is first distilled and then, dissolved in an organic solvent, hydrogenated in the presence of a catalyst and then treated with an ion exchanger. According to EP-A-411455, the characteristic important quality characteristics for caprolactam can be maintained by continuously hydrogenating the crude caprolactam in a liquid phase process.

Other purification methods are described for a crude caprolactam obtained from ACN, since the contaminants of such a crude caprolactam differ from those of a crude caprolactam obtained by Beckmann rearrangement, as described in US Pat. No. 5,496,941. clearly differentiates.

According to US Pat. No. 5,496,941, ACN is converted to caprolactam in a first step, low boilers, water, ammonia and, if appropriate, further solvents are separated off simultaneously, high boilers are separated off to give a crude caprolactam in a purity of 99.5%, this Crude caprolactam is hydrogenated in the presence of a catalyst, the product obtained is treated with an acidic ion exchanger or sulfuric acid and the product obtained is distilled in the presence of a base.

The cleaning processes mentioned have the disadvantage that they are technically complex and energy-intensive, in particular due to the numerous separation steps.

The present invention had for its object to provide a process which enables the production of polymers using caprolactam in a technically simple and energy-saving manner with comparable product indicators of the polymers compared to those polymers which are produced using caprolactam, the after was cleaned using a technically complex and energy-intensive process.

We have found that this object is achieved by the process defined at the outset, a polymer obtainable by this process, its use for the production of fibers, flat structures and moldings, and also fibers, flat structures and moldings obtainable using such a polymer.

According to step a), a mixture (I) containing 6-aminocapronitrile, water and optionally liquid diluent becomes a mixture (II) containing caprolactam, ammonia, water, optionally liquid diluent, high boilers and low boilers in the presence of a solid which catalytically promotes the reaction implemented. The ACN required for step a) can, as is generally known, from Ullmann's Encyclopedia of Industrial Chemistry, 5th Ed., Vol. A5, VCH Verlagsgesellschaft mbH, Weinheim (Germany), 1986, page 46, Fig. 8 Adiponitrile can be obtained.

Partial catalytic hydrogenation of adiponitrile in the presence of ammonia as a solvent and, for example, as a suspension catalyst rhodium on magnesium oxide (US Pat. No. 4,601,859), Raney Nickel (US Pat. No. 2,762,835, WO) is particularly suitable 92/21650), nickel on aluminum oxide (US-A-2, 208, 598) or as a fixed bed catalyst Cu-Co-Zn spinel (DE-B-954416, US-A-2,257,814) or iron (DE-A-42 35 466) or a method according to US-A-2, 245, 129, US-A-2, 301, 964, EP-A-150295, FR-A-2 029 540 or one in US-A-5, 496 , 941 described method.

The adiponitrile required for this reaction is produced industrially, for example by double hydrocyanation of butadiene in the presence of nickel-containing catalysts, and is commercially available, for example, from Aldrich-Chemie Gesellschaft mbH & Co. KG, Steinheim, Germany.

The reaction of mixture (I) to mixture (II) can be carried out in accordance with US Pat. No. 4,628,085 in the gas phase on silica gel at 300.degree.

This reaction can also be carried out according to US Pat. No. 4,625,023 in the gas phase over a silica gel or copper / chromium / barium titanium oxide catalyst.

According to FR-A-2029540, the reaction can be carried out in the presence of catalysts, metallic Zn or Cu powder or oxides, hydroxides, halides, cyanides of rubidium, lead, mercury or of the elements having an atomic number 21 to 30 as catalysts or 39 to 48 are used. The catalysts described are used as suspension catalysts in batch-operated stirred autoclaves.

The conversion of mixture (I) to mixture (II) can also take place, for example, according to EP-A-659 741, WO 96/22974, DE 19632006, WO 99/47500 or WO 99/28296.

The reaction can preferably be carried out in the gas phase at temperatures of generally 200 to 550 ° C., preferably 250 to 400 ° C. the pressure is generally in the range from 0.01 to 10 bar, preferably at normal pressure, care being taken that the reaction mixture is predominantly gaseous under the conditions used. The catalyst loads are usually 0.05 to 2, preferably 0.1 to 1.5, in particular 0.2 to 1 kg of 6-aminocapronitrile per liter of catalyst volume per hour.

The reaction can be carried out batchwise, preferably continuously.

Suitable reactors are advantageously those which are generally known for gas-phase reactions on moving or stationary solid catalysts. Preferably one

Fluidized bed reactor, preferably fixed bed reactor, such as a tray reactor, in particular a tubular reactor, can be used. Combinations of such reactors are also possible.

1 to 50, preferably 1 to 10, mol of water are generally used per mol of ACN.

The mixture (I) can also contain further organic compounds which are in gaseous form under the reaction conditions, such as alcohols, amines or aromatic or aliphatic hydrocarbons.

Examples of suitable catalytically active compounds of the catalysts are silicon dioxide as pyrogenically prepared silicon dioxide, as silica gel, diatomaceous earth, quartz or mixtures thereof, copper chromite, preferably aluminum oxide, titanium oxide, preferably titanium dioxide, lanthanum phosphates, lanthanum oxides, and also mixtures of such compounds.

Aluminum oxide is suitable in all modifications which can be obtained by heating the precursor compounds aluminum hydroxide (gibbsite, boehmite, pseudo-boehmite, bayerite and diaspor) at different temperatures. These include in particular gamma and alpha alumina and their mixtures.

Titanium dioxide is amorphous and suitable in all of its modifications, preferably anatase and rutile, and mixtures of such modifications.

Lanthanum phosphates are suitable in their various modifications, stoichiometric ratios between lanthanum and phosphate unit and degrees of condensation of the phosphate units (monophosphate, oligophosphates such as diphosphates or triphosphates, polyphosphates) individually or as a mixture. These compounds can be used in the form of powders, grits, grit, strands or pressed into tablets. The form of the compounds generally depends on the requirements of the particular reaction procedure, powder or semolina advantageously being used in a fluidized bed mode. In the fixed bed mode of operation, tablets or strands with diameters between 1 mm and 6 mm are usually used.

The compounds can be in pure form (content of the respective compounds> 80% by weight), as a mixture of the above-mentioned compounds, the sum of the above-mentioned compounds should be> 80% by weight, or as a supported catalyst, the above-mentioned Connections can usually be applied to a mechanically and chemically stable support with a high surface area.

The pure compounds can be prepared by precipitation from aqueous solutions, e.g. Titanium dioxide after the sulfate process or by other methods such as the pyrogenic production of fine aluminum oxide, titanium dioxide or zirconium dioxide powders, which are commercially available.

Several methods are available for producing mixtures of the different compounds. The compounds or their precursor compounds which can be converted into the oxides by calcining can e.g. be prepared from solution by co-precipitation. A very good distribution of the two compounds used is generally obtained. The compound or precursor mixtures can also be precipitated by precipitating one compound or precursor in the presence of the second compound or precursor present as a suspension of finely divided particles. Another method consists in mechanically mixing the compound or precursor powders, which mixture can be used as a starting material for the production of strands or tablets.

In principle, all methods described in the literature are suitable for the preparation of supported catalysts. For example, the compounds can be applied to the support in the form of their brine simply by soaking them. The volatile constituents of the sol are usually removed from the catalyst by drying and calcining. Such brines are commercially available for titanium dioxide and aluminum oxide.

Another possibility for applying layers of the catalytically active compounds consists in the hydrolysis or pyrolysis of organic or inorganic compounds. So a ke- Ramic support can be coated with titanium dioxide by hydrolysis of titanium isopropylate or other Ti alkoxides in a thin layer. Other suitable compounds include TiC14 and aluminum nitrate. Suitable carriers are powders, strands or tablets of the compounds mentioned themselves or other stable compounds such as steatite or silicon carbide. The carriers used can be designed to be macroporous in order to improve the mass transport.

The reaction can be carried out in the presence of a gas which is inert with respect to the conversion of mixture (I) to mixture (II), preferably argon, in particular nitrogen. The volume ratio of the inert gas to the gaseous ACN under the reaction conditions can advantageously be up to 100. A process as described in US Pat. No. 5,646,277 or US Pat. No. 5,739,324 is particularly preferred as step a).

In these processes, the reaction is carried out in the liquid phase at temperatures of generally 140 to 320 ° C, preferably 160 to 280 ° C; the pressure is generally in the range from 1 to 250 bar, preferably from 5 to 150 bar, care being taken that the reaction mixture is predominantly liquid under the conditions used. The residence times are generally in the range from 1 to 120, preferably 1 to 90 and in particular 1 to 60 minutes. In some cases, residence times of 1 to 10 minutes have proven to be completely sufficient.

The reaction can be carried out batchwise, preferably continuously. A stirred tank, autoclave, preferably a fixed-bed tubular reactor, can be used as the reactor. Combinations of such reactors are also possible.

In general, at least 0.1 mol, preferably 0.5 to 100 and in particular 1 to 20 mol of water are used per mol of ACN.

The ACN is advantageously in the form of a 1 to 50% by weight, in particular 5 to 50% by weight, particularly preferably 5 to 30% by weight solution in water, in which case the solvent is also the reactant, or used in mixtures containing water and a liquid diluent. Examples of liquid diluents are alkanols such as methanol, ethanol, n- and i-propanol, n-, i- and t-butanol and polyols such as diethylene glycol and tetraethylene glycol, hydrocarbons such as petroleum ether, benzene, toluene, xylene, lactams such as pyrrolidone or Caprolactam or alkyl-substituted lactams such as N-methylpyrrolidone, N-methylcaprolactam or N-ethylcaprolactam as well as carboxylic acid esters, preferably called carboxylic acids with 1 to 8 carbon atoms. Ammonia can also be present in the reaction. Mixtures of organic liquid diluents can of course also be used. Mixtures of water and alkanols in the weight ratio water / alkanol 1-75 / 25-99, preferably 1-50 / 50-99, have proven to be particularly advantageous in some cases.

In principle, it is also possible to use ACN as a reactant and solvent at the same time.

The following can be used as heterogeneous catalysts: acidic, basic or amphoteric oxides of the elements of the second, third or fourth main group of the periodic table, such as calcium oxide, magnesium oxide, boron oxide, aluminum oxide, tin oxide or silicon dioxide as pyrogenically produced silicon dioxide, as silica gel, Diatomaceous earth, quartz or mixtures thereof, furthermore oxides of metals of the second to sixth subgroup of the periodic table, such as titanium oxide, amorphous, as anatase or rutile, zirconium oxide, zinc oxide, manganese oxide or mixtures thereof. Oxides of lanthanides and actinides, such as cerium oxide, thorium oxide, praseodymium oxide, samarium oxide, rare earth mixed oxide, or mixtures thereof with the aforementioned oxides can also be used. Other catalysts can be, for example:

Vanadium oxide, niobium oxide, iron oxide, chromium oxide, molybdenum oxide, tungsten oxide or mixtures thereof. Mixtures of the oxides mentioned are also possible. Also some sulfides,

Selenides and tellurides such as zinc telluride, tin selenide, molybdenum sulfide, tungsten sulfide, sulfides of nickel, zinc and chromium can be used.

The abovementioned compounds can be doped with compounds of the 1st and 7th main groups of the periodic table or contain them.

Zeolites, phosphates and heteropolyacids, and acidic and alkaline ion exchangers such as Nafion are also suitable catalysts.

If appropriate, these catalysts can each contain up to 50% by weight of copper, tin, zinc, manganese, iron, cobalt, nickel, ruthenium, palladium, platinum, silver or rhodium. Heterogeneous catalysts based on titanium oxide, zirconium oxide, cerium oxide and aluminum oxide are considered as particularly preferred catalysts which have very high conversions, yields, selectivities and service lives under the reaction conditions described above. These can be in the form of powders, semolina,

Chippings, strands or pressed into tablets can be used. The form of the oxides generally depends on the requirements of the particular reaction procedure, powder or semolina being used in suspension. In the fixed bed mode, tablets or strands with diameters between 1 mm and 10 mm are usually used.

The oxides can be in pure form (content of the respective oxide> 80% by weight), as a mixture of the above-mentioned oxides, the sum of the above-mentioned oxides should be> 80% by weight, or as a supported catalyst, the above-mentioned Oxides can be applied to a mechanically and chemically stable support mostly with a high surface area.

The pure oxides can be prepared by precipitation from aqueous solutions, e.g. Titanium dioxide after the sulfate process or by other processes such as the pyrogenic production of fine aluminum oxide, titanium dioxide or zirconium dioxide powders, which can be obtained on loan.

Several methods are available for producing mixtures of the different oxides. The oxides or their precursor compounds which can be converted into the oxides by calcining can e.g. be prepared from solution by co-precipitation. A very good distribution of the two oxides used is generally obtained. The oxide or precursor mixture can also be precipitated by precipitation of one oxide or precursor in the presence of the second oxide or precursor which is present as a suspension of finely divided particles. Another method consists in mechanically mixing the oxide or precursor powders, which mixture can be used as a starting material for the production of strands or tablets.

In principle, all methods described in the literature are suitable for the preparation of supported catalysts. The oxides can be in the form of their brine by simply soaking them on the support be applied. The volatile constituents of the sol are usually removed from the catalyst by drying and calcining. Such brines are commercially available for titanium dioxide, aluminum oxide and zirconium dioxide. 5

Another possibility for applying layers of the active oxides is the hydrolysis or pyrolysis of organic or inorganic compounds. For example, a ceramic support can contain titanium dioxide by hydrolysis of titanium isopropylate or others

10 Ti alkoxides can be coated in a thin layer. Other suitable compounds include TiC14, zirconyl chloride, aluminum nitrate and cerium nitrate. Suitable carriers are powders, extrudates or tablets of the oxides mentioned themselves or other stable oxides such as silicon dioxide. The carriers used can be used for

15 improvement of the mass transport should be macroporous.

According to step b), ammonia is removed from mixture (II) to give a mixture (III) containing caprolactam, water, optionally liquid diluent, high boilers and low boilers.

In principle, the ammonia can be separated from mixture (II) by processes known per se for substance separation, such as extraction or preferably distillation, or a combination of such processes.

The distillation can advantageously be carried out at bottom temperatures of 60 to 220 ° C., in particular 100 to 220 ° C. Usually a pressure, measured at the head of the distillation device, of 2 to 30 bar absolute is set.

Conventional apparatuses are suitable for the distillation, as described, for example, in: Kirk-Othmer, Encyclopedia of Chemical Technology, 3rd Ed., Vol. 7, John Wiley & Sons, New York, 35 1979, pages 870-881 , such as sieve tray columns, bubble tray trays, packed columns or packed columns. The distillation can be carried out in several, such as 2 or 3 columns, advantageously in a single column.

40 According to step c), water is wholly or partly removed from mixture (III) and, if appropriate, liquid diluents to give a mixture (IV) comprising caprolactam, high boilers and low boilers.

5 If a liquid diluent was used in step a), water and liquid diluent can be separated off in step c) or the water before or after the liquid diluent.

In principle, the water and, if appropriate, the liquid diluent can be separated off from mixture (III) by processes known per se for the separation of materials, such as extraction, crystallization or preferably distillation, or a combination of such processes.

The distillation can advantageously be carried out at bottom temperatures of

Carry out 50 to 250 ° C, especially 100 to 230 ° C.

For the distillation, customary apparatuses are considered, as described, for example, in: Kirk-Othmer, Encyclopedia of Chemical Technology, 3rd Ed., Vol. 7, John Wiley & Sons, New York, 1979, pages 870-881 are, such as sieve tray columns, bubble tray trays, packed columns or packed columns. A heat-coupled, multi-stage separation of the water and optionally the liquid diluent is particularly preferred.

Before the mixture (IV) is fed in step d), the low boilers and high boilers are separated off, advantageously only the high boilers are separated off, in particular neither the low boilers nor the high boilers are separated off, particularly advantageously only the low boilers are separated off from the mixture ( IV) into consideration. If low boilers and high boilers are separated from the mixture, the low boilers can be separated off before, after or together with the high boilers.

In the case of separation of low boilers and high boilers or only high boilers or only low boilers, the removal can in principle be carried out by processes known per se for the separation of materials, such as extraction, crystallization or preferably distillation, or a combination of such processes.

The distillation can advantageously be carried out at bottom temperatures of 50 to 250 ° C., in particular 100 to 230 ° C. A pressure, measured at the top of the distillation apparatus, of 1 to 500, preferably 5 to 100, mbar absolute is usually established.

For the distillation, conventional apparatuses are considered, such as, for example, in: Kirk-Othmer, Encyclopedia of Chemical Technology, 3rd Ed., Vol. 7, John Wiley & Sons, New York, 1979, page 870-881 are described, such as sieve plate columns, bubble plate columns, packed columns or packed columns.

The distillation to remove the low boilers can advantageously be carried out in a number of columns, such as 2 or 3, in a single column.

The distillation to remove the high boilers can be carried out in several, such as 2 or 3 columns, advantageously in a single column.

According to step d), mixture (IV) is fed to a polymerization reaction.

The sum of the contents of high boilers and low boilers, water and organic diluents not being included, in the mixture (IV) used in step d) is advantageously at least 100 ppm by weight, preferably 200 ppm by weight, particularly preferably at least 500 wt . ppm, in particular at least 1000 ppm by weight based on the mixture (IV).

This step serves to produce the polymer obtainable by the process according to the invention.

Such a polymer is preferably a polyamide, the term polyamide being understood to mean homopolyamides, copolyamides, block polyamides, random polyamides and mixtures of such polyamides, in particular nylon 6 ("polycaprolactam") or nylon 66 (polyamide, built up in essentially from caprolactam, adipic acid and hexamethylenediamine).

To produce the polyamides, the caprolactam obtained in step c) can be used individually or in a mixture with other lactams, i.e. cyclic compounds which have at least one amide group in the cycle or aminocarboxylic acids, i.e. Compounds which have both at least one amino and at least one carboxyl group can be used.

Among the amino carboxylic acids, the omega-amino carboxylic acids are preferred, with the latter in particular using omega-amino carboxylic acids with 4 to 12 carbon atoms, more preferably 4 to 9 carbon atoms in the alkyl radical, or an aminoalkylaryl carboxylic acid with 8 to 13 carbon atoms in the alkyl radical , where preference is given to those which have an alkylene group with at least one carbon atom between the aromatic unit and the amino and carboxyl group. Aminoalkylarylcarboxylic acids include in particular preferred those which have the amino and carboxyl groups in the 1,4-position to one another.

The omega-aminocarboxylic acid used is more preferably linear omega-aminocarboxylic acids, the alkylene radical (-CH-) preferably containing 4 to 14, more preferably 4 to 9, carbon atoms, such as 4-amino-1-butanecarboxylic acid, 5-amino- l-pentanecarboxylic acid, 6-amino-l-pentanecarboxylic acid (6-aminocaproic acid), 7-amino-l-hexanecarboxylic acid, 8-amino-l-heptanecarboxylic acid, 9-amino-l-octanecarboxylic acid, 10-amino-1-nonancarboxylic acid, especially preferably 6-aminocaproic acid.

If lactams can be obtained from such aminocarboxylic acids by formation of a cyclic, preferably internal amide, the use of such lactams is advantageous, preference being given to using lactams of linear omega-aminocarboxylic acids, the alkylene radical (-CH--) of which is preferably 4 to 14 preferably contains 4 to 9 carbon atoms, such as the lactam of 4-amino-1-butane carboxylic acid, 5-amino-1-pentane carboxylic acid, 6-amino-1-pentane carboxylic acid (caprolactam), 7-amino-1-hexane - Carboxylic acid, 8-amino-l-heptane carboxylic acid, 9-amine-l-octane carboxylic acid, 10-amino-l-nonane carboxylic acid, particularly preferably caprolactam.

Mixtures of several lactams, several aminocarboxylic acids or mixtures of one or more lactams with one or more aminocarboxylic acids can of course also be used together with the caprolactam from step c).

If desired, lactams or aminocarboxylic acids derived from branched alkylene or arylene or alkylarylenes can also be used.

The caprolactam obtained from step c) can also be used together with a diamine or in a mixture with several diamines, ie compounds having at least two amino groups, such as aromatic amines, for example 1,4-phenylenediamine or 4,4'-diaminodiphenylpropane, or aliphatic amines , Among these, the alpha, omega-diamines are preferred, with the latter in particular alpha, omega-alkylenediamines having 3 to 14 C atoms, more preferably 3 to 10 C atoms in the alkylene radical, or alkylamino diamines having 9 to 14 C atoms are used in the alkyl radical, preference being given to those which have an alkylene group with at least one carbon atom between the aromatic unit and the two amino groups, such as p-xylylenediamine or preferably m-xylylenediamine. As alpha, omega-diamines, it is possible to use, more preferably, linear alpha, omega-diamines, the alkylene radical (—CH—) preferably containing 3 to 14, more preferably 3 to 10, carbon atoms, such as 1,3-diaminopropane , 1, 4-diaminobutane, 1, 5-diaminopentane, 1, 6-diaminohexane (hexamethylene diamine, HMD), 1, 7-diaminohept n, 1, 8-diaminooctane, 1, 9-diaminononane, 1, 10-diaminodecane, especially preferably hexamethylene diamine.

Hexamethylenediamine can be obtained by processes known per se by double catalytic hydrogenation of the nitrile groups of adiponitrile.

Mixtures of several diamines can of course also be used.

If desired, diamines derived from branched alkylene or arylene or alkylarylenes can also be used, such as 2-methyl-1,5-diaminopentane.

The caprolactam obtained from step c) can also be used together with a dicarboxylic acid or in a mixture with several dicarboxylic acids, ie compounds with at least two carboxyl groups. Among these, the alpha, omega-dicarboxylic acids are preferred, with the latter in particular alpha, omega-alkylenedi-carboxylic acids having 3 to 14 C atoms, more preferably 3 to 12 C atoms in the alkylene radical, or an aromatic Cs-C ^ -dicarboxylic acid such as isophthalic acid, in particular terephthalic acid, and a C ₅ -C ₈ cycloalkanedicarboxylic acid such as cyclohexanedicarboxylic acid.

The alpha, omega-dicarboxylic acids used are more preferably linear alpha, omega-dicarboxylic acids, the alkylene radical (-CH ₂ -) preferably containing 2 to 14, more preferably 3 to 12, carbon atoms, such as ethane-1,2-dicarboxylic acid (Succinic acid), propane-1, 3-dicarboxylic acid (glutaric acid), butane-1, 4-dicarboxylic acid (adipic acid), pentane-1, 5-dicarboxylic acid (pimelic acid), hexane-1, 6-dicarboxylic acid (suberic acid), Heptane-1, 7-dicarboxylic acid (azelaic acid), octane-1, 8-dicarboxylic acid (sebacic acid), nonane-1, 9-dicarboxylic acid, decane-1, 10-dicarboxylic acid, particularly preferably adipic acid.

Adipic acid can be obtained by processes known per se by oxidation of cyclohexane.

Mixtures of several dicarboxylic acids can of course also be used. Desired: you can also use dicarboxylic acids derived from branched alkylene or arylene or alkylarylenes.

The caprolactam obtained in step c) can also be used together with a diamine and a dicarboxylic acid or in a mixture with one or more diamines and one or more dicarboxylic acids.

In the preparation, the additives customary for the production of polymers, in particular polymides, such as chain regulators, heat or light stabilizers or pigments for matting or coloring can be used.

In the case of polyamides as polymer, chain regulators include, for example, monocarboxylic acids, such as propionic acid, benzoic acid, monoamines, such as 2, 2, 6, 6, tetramethyl-4-aminopiperidine, benzylamine, diamines, such as hexamethylene diamine, m-xylylenediamine, Dicarboxylic acids, such as terephthalic acid, naphthalenedicarboxylic acid, adipic acid, trifunctional amines, tricarboxylic acids, as heat or light stabilizers 2, 2, 6, 6-tetramethyl-4-aminopiperidine, variously substituted resorcinols, alkali metal halides, optionally in combination with Cu (I) halides, as a pigment for matting, for example titanium dioxide, zinc oxide, lead white and as a pigment for coloring, colored pigments such as chrome oxide green and phthalocyanines.

The process parameters for the production of the polymers according to the invention generally correspond to the process parameters for the production of polymers using pure caprolactam, which was obtained by a process according to the prior art. Any minor process deviations that occur can be easily determined by means of a few easy-to-carry out preliminary tests.

The polymers obtainable by the process according to the invention can be processed to produce fibers, fabrics and moldings. The process parameters for the production of fibers, fabrics and moldings from the polymers according to the invention generally correspond to the process parameters for the production of fibers, fabrics and moldings from polymers obtained using pure caprolactam, which was produced by a process according to the prior art. Any minor procedural deviations that occur can be easily determined by means of a few easy to carry out preliminary tests.

Claims

claims

1. A process for producing a polymer, characterized in that

a) a mixture (I) containing 6-aminocapronitrile and water to a mixture (II) containing caprolactam, ammonia, water, high boilers and low boilers in the presence of a catalyst, then

d) mixture (IV) feeds a polymerization reaction.

2. The method according to claim 1, wherein mixture (I) additionally contains an organic liquid diluent.

3. The method according to claim 2, wherein the liquid diluent in step c) is removed before, during or after the separation of the water from the mixture (III).

4. Process according to claims 1 to 3, wherein the low boilers are separated off between steps c) and d).

5. Process according to claims 1 to 3, wherein the high boilers are separated off between steps c) and d).

6. The method according to claims 1 to 3, wherein the low boilers and high boilers are separated off between steps c) and d).

7. The method according to claims 1 to 6, wherein the sum of the

Levels of high boilers and low boilers, calculated without water and any existing diluent, in the

Step d) mixture (IV) used is at least 100 ppm by weight.

8. Polymer obtainable by a process according to claims 1 to 7.

9. Use of the polymer according to claim 8 for the production of fibers, fabrics and moldings.

10. Fibers, fabrics and moldings obtainable using a polymer according to claim 8.