MX2008004948A - Polyamides formed from meta-xylylenediamine and adipic acid and having an amino end group content of less than 15 mmol/kg - Google Patents

Abstract

The present invention relates to novel and improved polyamides formed from meta-xylylenediamine and adipic acid with an amino end group content of less than 15 mmol/kg. Also found have been processes for preparing these polyamides from meta-xylylenediamine and adipic acid with an amino end group content of less than 15 mmol/kg, which is characterized in that salt solutions of adipic acid and m-xylylenediamine are reacted at temperatures of 80 to 300°C and a pressure of 1 to 20 bar with removal of water.

Description

POLYAMIDES FORMED OF META-XYLILENDIAMINE AND ADIPICO ACID AND THAT HAVE A CONTENT OF GROUP EXTREME AMINO LESS THAN 15 MMOL / KG DESCRIPTION The present invention relates to polyamides composed of meta-xylylenediamine and adipic acid and having an amino end group content of less than 15 mmol / g, and to process their preparation. US-A-2, 998, 463 discloses a process for suppressing degradation of amino end groups by the formation of xylylenetriamine. The reduction in amino end group degradation is achieved by a batch process with a two stage temperature / pressure profile in aqueous saline solution. In the mixture, a slight excess (O.β% molar) of adipic acid is used. The stability of poly (m-xylylene adipamide) is therefore prepared in the melt or while the solid phase condensations leave something that is convenient. WO-A-00/22043 discloses the preparation of a low molecular weight poly (m-xylylene-adipamide) with excess of acid end groups as a mixed component for polyethylene terphthalate. Poly (-xylylene dipamide) was prepared in a batch-environment process that is not suitable for industrial production. In addition, poly (m-xylylene adipamide) has a very high residual monomer content of adipic acid. US-B-6, 303, 741 describes the solid phase condensation of poly (m-x8? L? Leno-ad? Pam? Das) in a fusion process. The excesses of the acid end group after the melt polymerization are defined as follows: < CEG-AEG < 82; for the relative viscosity: 1.83 < RV < 2.28 (after the fusion polymerization). JP-A-2003/165838 and JP-A-2003/252986 refers to the two-step process for preparing polymers based on a starting mixture composed of the monomers and less than 20% by weight of water. Poly (m-xylylene adipamide) is obtained with the following ratio of end groups: CEG / AEG = 1.2. The ratio of the final end group is controlled at the end of the process by addition of regulator, more specifically acid anhydrides. The relative viscosity is 1.8 = RV = 3.6. It is an object of the present invention to remedy the disadvantages mentioned above. It has been found that this objective is achieved by novel and improved polyamides composed of meta-xylylenediamine and adipic acid and having an amino end group content better than 15 mmol / kg. Processes have also been found to prepare these polyamides composed of meta-xylylenediamma and adipic acid, which compose saline solutions of adipic acid and m-xylylenediamine, reacting at temperatures of 80 to 300 ° C and a pressure of 1 to 20 bar with removal of Water. The polyamide compositions of the invention characterize a) ba or triamine content (< 0.30% by weight, preferably < < < < 0.15% by weight), b) an optimized preparation process at minimum triamine contents (continuously and in the form of batches) which is based 50 to 70 ° by weight of aqueous saline solution and can be implemented industrially, c) a content of minimum amine end groups (AEG <15) and a relative viscosity in the scale of 1.55 to 2. 0, d) a high melting stability (? DopUn / ri5nUn < l .5,? .60m? N = melt viscosity after 60 min at 280 ° C in a rheometer,? 5m? N = v? Scos? melting capacity after 6m at 280 ° C in a rheometer) and high stability during solid-phase condensations (? RV <0.4 after 14 h at 230 ° C), e) high dispersibility in polyethylene terephthalates. The dispersibility of the polyamides in the polyethylene terephthalate matrix directly affects the mist of the containers or films produced from PeT / polyamide blends. The thinner the dispersion of the polyamide, the lower the mist. For example, single layer bottles composed of blends of the polyamides of the invention and polyethylene terephthalates which have been modified by isophthalic acid and alkali metal salts of sulfoisophthalic acid surprisingly have low haze values. The process according to the invention can be carried out in the following manner: The salt solutions, preferably solutions of aqueous salts, of adipic acid and [1,3-b? s- (ammomethyl) benzene] m-xylylenediamine can be reacted batchwise or preferably continuously at temperatures of 80 to 300 ° C, preferably 100 to 280 ° C. ° C, more preferably from 120 to 270 ° C, and a pressure of 1 to 20 bar, preferably from 1.5 to 10 bar, more preferably from 2 to 7 bar, in particular from 3 to 6 bar, in pressure vessels with removal of water. In the batchwise method, the reaction is generally carried out in one or more, i.e. 1 to 6, preferably 2 to 4, more preferably 2 or 3, in particular 2 pressure stages. In the one-step mode, the admixture of adipic acid and m-xylylene diamine can be concentrated to 80 to 100% by weight, preferably 90 to 100% by weight, more preferably 95 to 100% by weight, the removal of water at a temperature of 80 to 300 ° C, preferably 150 to 280 ° C. The mode with two pressure stages can be carried out so that, in the first pressure stage, which is generally carried out at a pressure of 1 to 3 bar, and the mixture of adipic acid and m-xylylenediamine is concentrated up to 80 98% by weight, preferably from 85 to 96% by weight, more preferably from 90 to 95% by weight, by the removal of water at a temperature of 80 to 150 ° C, preferably 100 to 140 ° C. In the second pressure stage, which is generally carried out at a pressure of 1 to 3 bar, the concentration can be carried out up to 95 to 100% by weight, preferably 98 to 100% by weight, more preferably 99 to 100% by weight, by removal of water at a temperature of 120 to 300 ° C, preferably 150 to 280 ° C and a pressure of 3.5 to 10 bar, preferably 4 to 6 bar. A particularly preferred embodiment of the batch reaction consists of working in a stirred steel autoclave at a pressure of 2 to 10 bar, preferably 3 to 8 bar and more preferably 4 to 6 bar. In this mode, a two-stage pressure profile is used. The mixture is first heated to internal temperature 120 ° C and, at a pressure of 2 bar, sufficient water is distilled so that a mixture of approximately 90% by weight is present. In the course of this, the internal temperature rises from 155 to 165 ° C. Subsequently, the mixture is heated to the white pressure, with particular reference to 4 bar. The temperature rises from 170 to 180 ° C at 4 bar. At 4 bar, the remaining water is distilled, in the course of which the temperature rises from 245 to 250 ° C. The tank then undergoes decompression at atmospheric pressure. If the relative viscosity required for the subsequent granulation has not yet been obtained, a post-condensation time in the nitrogen purge melt follows from 245 to 285 ° C with a variable duration of 5 to 30 minutes. After post-condensation, the polyamide is discharged through a water bath and the extrudate is granulated. An internal temperature of 265 ° C does not exceed the entire condensation process. As a result of a moderate temperature / pressure profile, the loss of meta-xylylenediamine during the polymerization process is below 0.15% by weight. A correction of the relationship of the extreme group in the final phase of the process by the addition of regulators, as described in JP-A-2003/165838 and JP-A-2003/25986, is therefore unnecessary. The relative viscosity of the polyamide compositions of the invention measured as a solution of 1% (lg / 100 ml) in 96% by weight of H2SO4 at 23 ° C, is in the range of 1.45 to 1.70. In the preferred continuous method, the reaction can be carried out in such a manner that the solutions of salts of adipic acid and m-xylylenediamine are heated to a temperature of 210 to 330 ° C, preferably 250 to 300 ° C, more preferably from 260 to 280 ° C, then the prepolymer is then separated in the form of batches, preferably continuously from reagent and water (referred to herein as steam), the meta-xylylenediamine removed, if it is preferably appropriate, it is generally returned quantitatively. Finally, the prepolymer can be polycondensed at a pressure of from 1 to 20 bar, preferably from 1.5 to 15 bar, more preferably from 2 to 10 bar, in particular from 4 to 6 bar and at a temperature from 230 to 330 ° C, preferably from 250 to 300 ° C, more preferably 260 to 280 ° C. A particular embodiment consists of heating the salt solution ba or a pressure of 2 to 10 bar, preferably of 4 to 6 bar, within a residence time of 60 seconds, the degree of reaction being at least 95% and the water content of the prepolymer being almost 7 $ by weight at the outlet of the evaporator zone. This was achieved by the salt solution passing through an evaporation zone that is tubular or designed with tubular or groove-like sections and filled with random packing and in which a two-phase flow is already formed as a result of heating and evaporation of water and most of the dissolving water is already derived in the gas phase. These short residence times generally suppress the formation of triamines substantially. The aqueous solutions generally have a monomer content of 30 to 70% by weight, in particular 45 to 65% by weight. In the particularly preferred embodiment, the aqueous salt solution can be advantageously passed at a temperature of 50 to 100 ° C in the form of batches, preferably continuously in an evaporator zone where the aqueous salt solution can be boiled at a temperature of 250 to 300 ° C, preferably 260 to 280 ° C, under a pressure of 2 to 10 bar, preferably 4 to 6 bar. The evaporation zone consists of one or more kidney tubes with random annular gaskets and having a ratio of 1 / d from 100: 1 to 200: 1, preferably from 120: 1 to 180: 1, more preferably 140: 1 to 160: 1, which has outputs of 1 to 10 kg of polymer per hour per tube, preferably 3 to 7 kg of polymer per hour per tube, more preferably 4 to 6 kg of polymer per hour per tube passed through the mime . The tubes are preferably passed through with a short residence time. The conversion at the outlet of the evaporator zone is generally from 80 to 100 °, preferably from 90 to 99.5%, more preferably from 95 to 99%, in particular from 96 to 98%, and the water content is generally on the scale from 0.01 to 10% by weight, preferably from 0.1 to 5% by weight, more preferably from 1 to 3% by weight, depending on the set pressure. The evaporator zone was advantageously configured as a tube bundle. It has been found that said particularly useful tube bundles are those in which the cross-section of the individual tubes has a tubular design and similar to periodic repetition groove. It has also been found to be advantageous to pass the mixture of prepolymers and steam, before the separation of the phases, immediately after the evaporator zone, through a tubular mass transfer zone which is provided with internal parts. In this case, the temperature and pressure conditions used in the evaporator zone are observed. Internal parts, for example, random packings such as Raschig rings, metal rings or especially random packages made of wire mesh, give rise to a large surface area. As a result, the phases, that is, prepolymer and vapor, come into intimate contact. This has the effect that the amount of meta-xylylenediamine released with steam is considerably reduced. The biphasic mixture of steam and prepolymer leaving the zone of the evaporator or mass transfer zone is separated. The separation proceeds generally by itself, belonging to the physical properties, in a container, the lower part of the container being advantageously designed as the polymerization zone. The vapors released consist essentially of vapor and traces of meta-xylylenediamma that have been released in the course of water evaporation. In general, only an extremely small amount of meta-xylylene-diamma is present in the gas phase (<; 0.1% by weight based on the step polymer). These vapors can be passed in a column and rectified in order to recover meta-xylylenediamine. Suitable columns, for example, are randomly packed columns, columns of bubble cover trays or columns of sieve trays having 5 to 15 theoretical plates. The column is operated appropriately under pressure conditions identical to the evaporator zone. Advantageously, the rectified meta-xylylenediamma can be fed to the downstream polymerization zone. The resulting prepolymer which, according to its degree of reaction, consists essentially of low molecular weight polyamide and any residual amount of unconverted salts and generally has a relative viscosity (measured as a solution with a concentration of 1 g per 100 g of solvent in 96% sulfuric acid) of less than or equal to 1.2 is passed in a polymerization zone. In the polymerization zone, the fusion obtained can generally be polycondensed at a temperature of 245 to 285 ° C, in particular of 255 to 275 °, and under a pressure of 2 to 10 bar, in particular of 4 to 6 bar. Advantageously, in a preferred process, the polyamide thus obtained can be passed in molten form through a discharge zone with simultaneous removal of the residual water present in the melt. The appropriate pits, for example, are ventilation extruders. Therefore, the free fusion of water can be carried out by processes known per se, for example, by forming pellets of spheres ba or water, forming strand pellets under water or forming strand pellets. The resulting pellet can be subjected to an extraction and this can be carried out either continuously in the form of batches. Suitable extractors include water, the polyamide can be subjected to solid phase condensation in an additional step. This can be carried out either in a vacuum or inert gas such as nitrogen or argon, preferably nitrogen. The temperature can vary within a wide range, generally between 120 to 230 ° C, preferably between 130 to 210 ° C and more preferably between 140 to 190 ° C. In a preferred process, the polyamide can be granulated with a granulation of spheres under water. The relative viscosity of the polyamides of the invention, measured in 1% solution (lg / 100 ml) in 96% by weight of sulfuric acid at 25 ° C, after leaving the discharge extruder, in the range of 1.45 to 1.55 . To establish the white viscosities, the resulting pellet finally, in solid phase, can be adjusted in the form of batches, preferably in agitators, or continuously, preferably in annealing towers, at a relative viscosity in the range of 1.55 to 2.0 at temperatures between 140 and 160 ° C. After the preparation process, the polyamide compositions of the invention have relative viscosities in the range of 1.55 to 2.0, preferably from 1.60 to 1.9 and more preferably from 0.65 to 1.75. After annealing, the value of the residual moisture content in the pellet is generally below 250 ppm. The molar ratio of adipic acid to meta-xylylenediamine may vary, and is generally from 1.5: 1 to 1,001: 1, preferably from 1.2: 1 to 1,005: 1, more preferably from 1.1: 1 to 1,007: 1, in particular 1.05 : 1 to 1.01: 1. The residual monomer content of adipic acid in the non-extracted polyamides of the invention is up to 600 ppm. With respect to the possible use in food packaging, the pellets of the polyamides can be subjected to extraction. This effectively decreases the residual monomer content.

After extraction, the residual monomer content of adipic acid in the polyamide is generally up to 500 ppm, for example from 1 to 400 ppm, preferably from 1 to 200 ppm, more preferably from 1 to 150 ppm. The residual monomer content of meta-xylylenediamine is generally below 1.01: 1. The residual monomer content of adipic acid in the non-extracted polyamides of the invention is up to 600 ppm. With respect to the possible use in the food packaging, the pellets of the polyamides can be subjected to an extraction. This effectively decreases the residual monomer content. After extraction, the residual monomer content of adipic acid in the polyamide is generally up to 500 ppm, for example from 1 to 400 ppm, preferably from 1 to 200 ppm, more preferably from 1 to 150 ppm. The residual monomer content of meta-xylylenediamine is generally below 10 ppm. Suitable polyamides generally all polyamides which are formed from 50 to 100% by weight, preferably from 70 to 100% by weight, more preferably from 85 to 100% by weight of units formed of meta-xylylenediamine and adipic acid, and also from 0 to 50% by weight, preferably 0 to 30% by weight, more preferably 0 to 15% by weight of the corresponding polyamide units and / or chain regulators if appropriate and / or stabilizers if appropriate. Suitable comonomers of meta-xylylenediamine, for example, are aliphatic, aromatic or arylaliphatic diamms such as ethylene diamine, butylene diamine, pentamethylenediamine, hexamethylenediamine, cyclohexanedia ma, octamethylenediamine, bis (4,4-amino-3, 3-met? l? clohex?) methane, bis (ammo) -cyclohexane, para-phenylenediamine, ortho-xylylenediamine and paa-xylylenediamine. Suitable comonomers of adipic acid are, for example, aliphatic, aromatic or apla-liiphatic dicarboxylic acids such as terephthalic acid, sulfoisophthalic acid and salts thereof, 2-d6-carboxylic acid, cyclohexanedicarboxylic acid, succinic acid, acid glutamic acid, aselaic acid and sebacic acid. Suitable chain regulators, for example, are monofunctional regulators such as triacetonadiamma compounds (see WO-A 95/28443), monocrboxylic acids such as acetic acid, propionic acid and benzoic acid and bases such as (mono) amines, for example Hexilamma or bentemina. In order to improve the properties of the polyamides of the invention, all the known additives, for example, nucleating agents, dyes, color pigments, flow improvers, UV absorption substances, leveling agents, oxygen scavengers, Inorganic or organic or impact modified fillers are suitable for modification. Suitable stabilizers are sterile hidden phenols, phosphorus compounds, described in the literature (Plastics Additives Handbook, 5th Edition, pages 97 -. 97-136; 2001), for example, phosphites and hypophosphites, and mixing these two classes of stabilizers. The polyamides generally comprise from 0 to 0.5% by weight, preferably from 0.001 to 0.1% by weight, more preferably from 0.01 to 0.05% by weight of stabilizers. Preferred dwarf form, the polyamide compositions of the invention comprise from 0 to 0.05% by weight, more preferably from 0 to 0.03% by weight of hyposophitic. In a particularly preferred embodiment, the content of secondary triamine in the polyamide is less than or equal to 0.3% by weight, preferably less than or equal to 0.15% by weight. This content can be determined, for example, indirectly via the so-called "triamine content" [content of (xylylenetriamine)? see following structural formula] (see examples).

The low contents of the amino end group can be controlled via the stequimetry of the two monomers to prepare the starting salt solution. In the polyamide compositions of the invention, the excesses of adipic acid can be on a scale of 60 to moles / kg to 150 mmoles / kg, preferably from 70 mmoles / kg to 130 mmoles / kg, more preferably from 80 to mols / kg to 110 mmoles / kg. The polyamides of the invention composed of meta-xylylenediamine and adipic acid are suitable for production or as a starting material, especially together with polyesters, for the production of molds, tubes, profiles, preforms, containers, plates, fibers, films, bottles and foams of any kind, for example, by extrusion processes, injection molding, calendering, blow molding, compression, concretion, and other common processes of thermoplastic processes. Suitable polyesters, for example, are polybutylene terephthalates, polyethylene naphthalates, polytrimethylene terephthalate and polyethylene terephthalate, and also the corresponding copolyesters. An additional property of the polyamide compositions of the invention is the surprisingly good dispersibility in a polyethylene terephthalate matrix. Particularly good results can be achieved in polyethylene terephthalates which have been modified by isophthalic acid and by alkali metal salts of sulfoisophthalic acid. The preferred use of the polyamides of the invention is in the preparation of mixtures with polyethylene terephthalate obtained in polyethylene terephthalates which have been modified by isophthalic acid and by alkali metal salts, of sulfoisophthalic acid. The preferred use of the polyamides of the invention is in the preparation of mixtures with polyethylene terephthalate which have been modified by isophthalic acid and by alkali metal salts of sulfoisophthalic acid. These are particularly suitable for producing transparent transparent and injection molded containers, especially preforms and bottles for the beverage industry. In this preferred embodiment, 0.01 and 15% by weight, preferably 0.02 to 10% by weight, more preferably 0.03 to 7% by weight of polyamide are present in the polyethylene terephthalate. A general process consists in the preparation of mixtures of granules of the modified polyethylene terephthalates and the polyamides of the invention. These "pepper / salt" mixtures can be converted directly into the injection molding machine for molds and preforms. The use of polyamides of the invention together with polyethylene terephthalates is not restricted solely to the preparation of mixtures of granules. An additional advantage of the polyamides of the invention lies in the high stability in relation to molecular weight and color. As a result, these polyamide compositions also survive the process operations in the presence of polyethylene terephthalate without forming genes and are notorious for high melt stability in the solid phase condensation process. In this case, the polyethylene terephthalates have been modified by isophthalic acid and by alkali metal salts of sulfoisophthalic acid. The operations of further processes in the melt are particularly extrusion processes for preparing granules of blends of polyamide / polyethylene terephthalate with polyamide isolated in a matrix of polyethylene terephthalate. A preferred use of the polyamides of the invention together with polyethylene terephthalates is the preparation of two component or multiple component granules. The biocomponent pellet, for example, may have a core / shell structure, the polyamide that forms the core and the polyethylene terephthalate surrounding the polyamide as the shell. The polyethylene terephthalates have advantageously been modified by isophthalic acid and by alkali metal salts of sulfoisophthalic acid. The two-component pellets can undergo solid-phase condensation (200-240 ° C, 10-14 h) in the additional process. Under this thermal stress, the polyamide compositions described in the gels literature as a result of xylylenetriamine formation or exhibit a high viscosity increase. As a result of the gels and the viscosity increase of the polyamide compositions during the process, pellets made from the available polyamide compositions known to date are less suitable for further processing to transparent films and containers, particularly bottles. The polyamide compositions described in this invention result in this problem. Belonging to the high stability of the polyamide compositions during the operation of the process, two-component pellets are obtained from which the highly transparent gel-free bottles are produced.

Examples Extreme groups (AEG = extreme ammo group content, CEG = extreme acid group content) As usual, the concentrations mentioned above were defined as the number of end groups (in moles or equivalents) per unit mass of polyamide, for example x mmol of end groups per kg of polyamide.

The determination of the extreme amino groups can be carried out, for example, by titration or a solution of the polyamide in the presence of an indicator. To this end, the polyamide was dissolved in a mixture of phenol and methanol (e.g., 75% by weight of phenol and 25% by weight of methanol) with heating. For example, the mixture can be kept under reflux at the boiling point until the polymer dissolved. The cooled solution was mixed with a suitable indicator or indicator mixture (eg, benzyl orange and methylene blue metabolic solution) and titrated with a solution of perchloric methanol in glycol until the color changed. The concentration of the amino end group was calculated from the consumption of perchloric acid. Alternatively, the titration can also be carried out potentiometrically with a solution of perchloric acid in ethylene glycol without indicator, as described in WO 02/26865 on page 11. The determination of the carboxyl end groups can be carried out, for example, likewise by extruding a solution of the polyamide using an indicator. To this end, polyamide was dissolved in benzyl alcohol (phenylmethanol) with heating, for example, to boiling, connecting a rinsing tube and introducing nitrogen gas. The still hot solution is mixed with a suitable indicator (eg propanolic solution of cresol red) and titrated immediately with a solution of alcoholic potassium hydroxide (KOH dissolved in a mixture of methanol, 1-propanol, 1 hexanol) until change color The carboxyl end group concentration was calculated from the KOH consumption. Alternatively, the titration can also be carried out conductometrically with a NaOH solution in benzyl alcohol without indicator, as described in WO 02/26865 on page 11-12.

Relative Viscosity VR The relative viscosity of the polyamide was carried out with the samples of 1 g of polyamide in 100 ml of 96% by weight of sulfuric acid and the measurement with the help of a viscometer of 50120 Ubbelohde 2 (from Schott) to DIN EN ISO 1628-1.

Intrinsic Viscosity VI The intrinsic viscosity of the slightly crystalline polyethylene terephthalates with an average molecular weight was determined by dissolving 0.1 g of the polymer (ground pellet) in 25 ml of a 60/40 mixture of phenol and tetrachloroethane. The viscosity of this solution was determined at 30 ° C with an Ubbelohde IB viscometer. The intrinsic viscosity was calculated via the relative viscosity with the help of the Millmeyer equation. To determine the intrinsic viscosity of high molecular weight or highly crystalline polyethylene terephthalates that are not soluble in the 60/40 solvent mixture, 0.1 g of the polymer (ground pellet) was dissolved in 25 ml of a 50/50 mixture of Tffluoroacetic acid and dichloromethane. The viscosity of this solution was determined at 30 ° C with an Ubbelohde OC viscometer. The intrinsic viscosity was calculated with the help of the Billmeyer equation and regression analysis (in relation to the phenol / tetrachloroethane 60/40 mixture). The regression calculation is: V.I. (phenol / tetrachloroethane 60/40) = 0.8229 x VI (trifluoroacetic acid / dichloromethane 50/50) + 0.0124.

Triamine content (xyl lentriamma) After dissociation of the sample matrix, the triamine was analyzed by means of capillary electrophoresis and UV detection. The quantification was carried out by the normal internal method. The internal normal used is N-methylimidazole. To prepare the sample, approx. 200 mg of the pellet were dissociated with 15 ml of IN H 2 SO at 180 degrees C for 4 h in an autoclave. 0.5 ml of the dissociation solution was mixed with 1 ml of normal internal solution, then the sulfate was precipitated with Ba (OH) 2 solution and adjusted to 50 ml with water. The aliq of these solutions were subjected to electrophoresis. For electrophoresis, a compact EC system of Biofocus, capillaries (fused silica, uncoated) and an electronic integrator were used. Electrophoresis conditions: capillary: fused silica, uncoated; total length 40 cm; separation length 35.5 cm; internal diameter 75 μm; cathode electrolyte: 20 mM NaH7P04 (pH 2.5 adjusted with H3P04); anode electrolyte: 20 mM NaH- > P04 (pH 2.5 adjusted with H3P04); Separation voltage: + 15 kV / + 375 V / cm. Temperature: 25 ° C; Detection: UV /? = 200 nm; Sample injection: 0.352 kg / cm2 * s.

Fusion Viscosity The melt viscosities were determined with the help of a controlled deformation rheometer (toracional rheometer) of TA - Instruments (ARES). Prior to measurement, the polyamide sample was dried in a normal manner at 80 ° C in a vacuum oven for > 3 d (days). The sample, directly outside the vacuum oven, was placed on the preheated lower plate of the rheometer, and its heating oven was closed. The top plate was then moved down until the measurement space of 1 mm was obtained. The melting time of 5 rain starts from here. The sample of supernatant between the two plates was separated with a spatula. After these 5 minutes of fusion time, the measurement starts and proceeds for a period of 70 min. Measuring conditions: measurement geometry: plate-plate 0 25 mm; measurement space; 1 mm; fusion time: 5 minutes; deformation: 30%.

Solid Phase Condensation Test To determine dRV, the polyamide samples were subjected to a solid phase condensation at 230 ° C for 14 h. To this end, 10 g of the polyamide pellet were introduced into an annealing tube and this was placed in an oil bath heated to 230 ° C. In the annealing tube, the pellet is under a nitrogen flow of 10 1 / h.

Mist measurement Measurements were made through the side walls of the bottles. A HunterLab ColorQUEST Sphere Spectrophotometer System equipped with a IBM PS / 2 Model 50Z computer, IBM Proprinter II printer. Several fasteners were used for specimens and green, gray and white hover plates. The HunterLab Spectrocolometer is an instrument to determine color and appearance. The light from the lamp is scattered in a circular hole and was passed through an object to a lens or reflected in an object to a lens. The lens collects the light and leads it to a diffraction grater that divides the light into its individual wavelength ranges. The scattered light is passed in a silicon diode array. The signals from the diodes pass through an amplifier in a converter and data is processed. The mist values are made available by the software. The ratio is calculated from the transmission of scattered light to the total light transmission. The multiplication by 100 gives the value of fog (0% represents transparent material, 100% opaque immaterial) the samples, which have to be prepared either to measure transmission or reflection, must be clean and free of all types of scratches or damage. In the case of transmission, the size of the sample should be adjusted to the size of the circular hole. Each sample is analyzed in four different points. To measure the thickness of the bottle walls, a Panametrics Magna-Mike 8000 Hall Effect Thickness Gauge was used.

Example 1: A shaking 10 1 autoclave (pear-shaped tank with lower valve) was charged at room temperature under a stream of nitrogen (ca. 10 1 / h) with 2121.4 g (14.52 moles, corresponds to an excess of acid) adipic acid of 100 mmoles (kg of adipic acid) of adipic acid, 1929.6 g (14.17 mmoles9 of meta-xylylenediamma and 1714.3 g of water.

As a result of the exothermic reaction of the formation of salts, the internal temperature rises to 90 ° C. With stirring (80 rpm), the mixture was heated to 136 ° C with the tank closed within a period of 60 min. At a pressure of 2 bar, then water was distilled within 75 min until a mixture of approximately 90% was obtained. The tank was closed again and, with additional heating, when obtaining a temperature of 170 ° C at 4 bar, the remaining water was distilled within 50 min. Subsequently, the tank was decompressed at atmospheric pressure within 2 min, in the course of which the temperature rises to 249 ° C. Upon obtaining the atmospheric pressure, postcondensation was carried out under a stream of nitrogen for 20 min; the temperature rises to 262 ° C. After an additional 10 minutes of post-condensation under reduced pressure (1000-200 mbar), polyamide was discharged through the lower valve, passed through a water bath as an extrudate and granulated. Subsequently, the drying was carried out at 105 ° C until a residual moisture content of less than 250 ppm was obtained. 3350 g of the pellet were obtained. After drying, a relative viscosity of 1601, an amino end group content of 10 mmole / kg and an acid end group content of 221 mmole (kg were measured.

Example 2: The condensation was carried out by the process described in example 1. The starting mixture used was 101.0 g (14.38 moles, corresponds to an excess of adipic acid of 60 mmoles (kg adipic acid) of adipic acid , 929.6 g (14.17 mmol) of meta-xililendiamma and 1714.3 g of water. 3200 g of the pellet obtained. After downloading, a relative viscosity of 1.913 was measured, a content of end amino group of 17 mmol / measured kg and an acid group content of 138 mmoles / kg A solid phase condemnation in a 185 ° agitator with nitrogen flow raised the relative viscosity to 1,990 after 8 h at an amino end group content of 9 mmoles (kg and a Acid end group content of 133 mmol (kg.

Example 3: The condensation was carried out by the process described in Example 1. The starting mixture used was 2111.2 g (14.45 moles, corresponds to an excess of adipic acid of 80 mmoles (kg of adipic acid) of adipic acid ., 1929.6 g (14.17 moles) of meta-xylylenediamine and 1714.3 g of water decompression tank at atmospheric pressure followed by postcondensation under a nitrogen stream for 30 minutes, then under reduced pressure (1000-200 mbar) for 15 minutes further, after the download and granulation. 3310 g of the pellet obtained. Before drying, a relative viscosity of 1.703, a content of end amino group of 11 mmol / kg and a content of end group of acid 200 was obtained mmoles / kg After drying, a relative viscosity of 1721, an amino end group content of 11 mmoles / kg and an acid end group content of 197 mmoles / kg were obtained.

Example 4 Condensation was carried out by the process described in example 1. The starting mixture used was 2111.2 g (14.45 mol, corresponds to an adipic acid excess of 80 mol / kg of adipic acid) of adipic acid, 1929.6 g (14.17 moles) of meta-xylylenediamine and 1714.3 g of water. Decompression of the tank at atmospheric pressure followed by postcondensation under a nitrogen stream for 30 min, then under reduced pressure (100-200 mbar) for an additional 5 minutes, then by discharge and granulation. 3380 g of the pellet were obtained. After a discharge, a relative viscosity of 1790, an amino end group content of 14 mmole / kg and an acid end group content of 183 mmole / kg were measured. After drying a relative viscosity of 1.1770, an amino end group content of 10 mmole / kg and an acid end group content of 180 mmole / kg was obtained.

Comparative Example la and b WO-A-00/22043 describes, in the example, the preparation of an acid-terminated polyamide of 50% by weight of a solution of salts of adipic acid and meta-xylylenediamine. For comparison, the example reproduced exactly according to the method specified in WO-A-00/222043 is very small for the specified batch. A mixture of 105 g of water and 89.4 g (0.612 mol, excess of 2 mol%) of adipic acid was introduced into a 500 ml flask, then washed with nitrogen for 30 min. 81.7 g (0.599 mmol) of meta-xylylenediamine were added rapidly. The flask was equipped with a nitrogen connection, a metal stirrer and a short condenser distillation head. The flask was then placed in a preheated metal / oil bath of 110 ° C for 30 minutes. Within 60 minutes, the temperature was stepped up to 275 ° C and a clear, slightly viscous polyamide was obtained. The inherent viscosity was IV = 0.42 (0.458), the relative viscosity RV = 1.52, the content of end amino group AEG = 28 mmol / kg (10 mmol / kg) and the content extremóte acid group CEG = 305 mmol / kg ( 220 mmole / kg). (The values in supports are those reported in WO 0022043). a) The method was repeated exactly once more. The inherent viscosity was VI = 0.38 (0.458), the relative viscosity VR = 1.47, the end-group content of AEG = 49 mmol / kg (10 mmol / kg) and the CEG acid end group = 318 mmol / kg (220 mmol / kg). The prepared polyamides were analyzed for their triamine content. The polyamide compositions of the invention prepared by the process in the form of batches characterize a tpamine content of less than 0.15% by weight. In addition, the prepared polyamides were analyzed for their residual monopoly content of adipic acid. The polyamide compositions of the invention prepared by the process in the form of batches, before extraction, characterize a residual content of adipic acid less than 500 ppm. The stability in the fusion was analyzed by rotational rheology measurements. The evolution of the melt viscosity was determined as a function of time. The parameter established for the fusion stability after 5 min.

The polyamide compositions of the invention characterize a very high stability and therefore are notorious for very low values of the quotient? O0m? N / ribpun the values are below 1.5. The stability during solid phase condensations (solid state polycondensation = SSP) were measured by determining the relative viscosities before and after the solid phase condensation. The solid phase condensations were carried out under a nitrogen stream at 230 ° C for 14 h. The parameter set for stability was the relative viscosity difference? VR = VR SSP • VRspues ssp • The polyamides of the invention are notorious for a relative viscosity difference of less than 0.4.

The results are compiled in table 1 All values in the table were determined after drying or condensation of the solid phase (* According to EP-A-0084661, EP-A-007100 and US-B-6,303,741, for example, MXD6007 was prepared in a fusion process and not via a homogeneous salt solution). Table 1 summarizes the most important results in relation to the synthesis. Examples 1-4 are the polyamide compositions of the invention in which the relative viscosity, the end groups varied and also the process conditions. MXD6007, commercially available from Mitsubishi Gas Chemical, was used as an additional comparative example. Unlike the polyamide compositions of the invention, the three comparative examples do not meet all the criteria simultaneously: AEG less than 15, triamma content less than 0.15,? 60 p.m./? 5 mia <0.05. 1.5 and? VR < 0.4.

Example 5 A homogeneous aqueous solution consisting of 103.0 kg / 704.76 mol corresponds to an excess of adipic acid of 110 mmol / kg) of adipic acid and 93.4 kg / 685.81 mol of meta-xylylenediamine and 193.2 kg of water was transported from a hot mother pot at about 90CC at a rate corresponding to a quantity of polyamide of 5 kg / hour by means of a measuring pump in a vertical tubular evaporator. The evaporator was heated with a heat transfer medium which was at a temperature of 275 ° C. The evaporator had a length of 4500 mm and a capacity of 5000 ml and a surface area of heat transfer of approximately 0.5 m2. The residence time in the evaporator was approximately 60 sec. The mixture of prepolymers and steam leaving the evaporator was at a temperature of 255 ° C and was separated into steam and melted in a separator. The melt was left in the separator for another 5 minutes and then transported by means of a discharge / vent extruder in an underwater sphere granulation. The zone of the separator and of the evaporator were kept under a pressure of 5 bar by means of a pressure retention device which was disposed downstream of the column. The steam removed in the separator was carried out in a column with random packing and approximately 10 theoretical plates, in which approximately 1.5 1 of the steam condenser was introduced per hour in the upper part to generate reflux. At the top of the column, a temperature of 155 ° C was established. The steam that flows out from under the decompression valve was condemned and had a meta-xylylenediamine content of 0.05% by weight. The bottoms of the column obtained were an aqueous solution of meta-xylylenediamine. Before entering the evaporator, this solution is added again to the solution of starting salts by means of a pump. Downstream of the evaporator, the prepolymer had a relative viscosity of 1.0-1.1, measured in 98% by weight of sulfuric acid at 25 ° C, and after analysis of the final group, had a conversion of 93 to 95%. The content of xylylenetriamine was from 0.20 to 0.24% by weight based on the polyamide. After the granulation, the polyamide had a very light intrinsic color and a relative viscosity of 1.50 to 1.55. The content of the ammo end group was 42 mmol / kg, the end group content of acid 235 mmol / kg. In the discharge extruder, the melt was decompressed at normal pressure and subjected to virtually no additional condensation with a residence time of less than 1 min. The polymer converted to granule form was subsequently extracted with water in a countercurrent unit of 90-105 ° C under the common conditions. Then, the resulting pellet was annealed to a relative extreme viscosity of 1.68 by a solid phase condensation at a temperature of 160 ° C for 30 h. After the heat treatment, the amino end group content was 13 mmol / kg, the end group content of acid 203 mmol / kg and the triamine content 0.14% by weight. The results are compiled in table 2.

Table 2 (** Values after solid phase condensation) The extremely good dispersion of the polyamides of the invention in modified polyethylene terephthalates manifests itself in low values that are measured in bottles that were produced from these mixtures.

For this purpose, mixtures of pellets of 2-10% polyamide and 90-98% polyethylene terephthalates were produced. The pellet mixtures were processed by injection molding machine at 420 ° C from Arbug for preforms of bottles weighing 28 g. With the help of a SIDEC SBOl blow molding machine, preforms for blow molding bottles having a volume of 660 ml at about 100 ° C at a pressure of 40 bar were used. Measurements of risk were taken in these bottles.

Table 3 reproduces the results of the experimental series with mixtures of pellets.

Table 3 For explanation: TPA = molar fraction in% of terephthalic acid in the polyethylene terephthalate acid fraction IPA = mole fraction in% isophthalic acid in the polyethylene terephthalate acid fraction LiSIPA = molar fraction in% of the Li salt of sulfoisophthalic acid in the acid fraction of polyethylene terephthalate. The identical experimental series were also carried out with the polyamide compositions of the invention which have been prepared in the continuous process. Table 4 summarizes the results.

Table 4 In addition, risk measurements were also carried out on bottles that were produced from two-component pellets having a core / shell structure.

The two-component pellets (core: polyamide, Shell: polyethylene terephthalate) were produced by a coextrusion process. For this purpose, a Haake single screw extruder was used for the polyamide and a Killion single screw extruder for the polyethylene terephthalate. The intrinsic viscosity of polyethylene terephthalate before coextrusion was VI = 0.54 - 0.56 fl / g. The process temperature was 270-280 ° C. The resulting two component pellets were subsequently subjected to solid phase condensation at 10-215 ° C with nitrogen flow for 12 hours. For this purpose, a Lara Kart Juchheim Laborgerate reactor was used. After solid phase condensation, the intrinsic viscosities of V.I. = 0.81-0.83 dl / g. After the solid phase condensation, the two-component pans were processed for bottle preforms with a weight of 49 g with the help of an injection molding machine 320. These preforms were then used to blow-mold the corresponding bottles with a volume of 1.5 1 with a SIDEC SBOl blow molding machine of approximately 100 ° C and a pressure of 40 bar.

Table 5 summarizes the results.

Table 5

Claims (4)

1. - A polyamide composed of meta-xylylenediamine and atypical acid, where the amino end group content is less than 15 mmol / kg, the relative viscosity is 1.55 to

2. 0 and the triamine content in the polyamide is less than or equal to 0.3 mol%. 2. The polyamide composed of meta-xylylenediamine and atypical acid according to claim 1, wherein the content of tpamine in the polyamide is less than or equal to 0.15 mol%.

3. A process for preparing polyamines according to claim 1 or 12, wherein the salt solutions of atypical acid and m-xylylenediamine are reacted in a molar ratio of 1.5: 1 to 1001: 1 at temperatures of 80 to 300 ° C and a pressure of 1 to 20 bar with removal of water.

4. The polyamide composed of meta-xylylenediamine and atypical acid according to claims 1 or 2, prepared by reacting solutions of salts of atypical acid and m-xylylenediamma in a molar ratio of 1.5: 1 to 1,001: 1 at temperatures of 80 to 300 ° C and a pressure of 1 to 20 bar with removal of water.