Method and Device for the Extraction of Polyamide

专利摘要:
The present invention relates to a method for removing low molecular weight components from polyamide 6 or caprolactam based copolyamides by extraction. The present invention also relates to an apparatus for removing low molecular weight components from polyamide 6 or caprolactam based copolyamides by extraction. The invention also relates to a process for the preparation of polyamide 6 or caprolactam based copolyamides and to a device for carrying out the same.
公开号:KR20040011504A
申请号:KR10-2003-7015109
申请日:2002-05-08
公开日:2004-02-05
发明作者:하인리히 하웁트；디어터 괴벨스；콘라트 트리베네크；안드레아스 기팅거
申请人:바이엘 악티엔게젤샤프트；
IPC主号:

专利说明:

{Method and Device for the Extraction of Polyamide}
[4] Polyamides, their preparation and their use as industrial plastics are known. This is described, for example, in GW Becker and D. Braun in "Kunststoff-Handbuch", Volume 3, "Technische Thermoplaste", Part 4, "Polyamide", 1998 Hanser-Verlag Munich and Vienna. Publication].
[1] The present invention provides a process for removing low molecular weight components from polyamide 6 or caprolactam based copolyamides by extraction.
[2] The present invention also provides an apparatus for removing low molecular weight components from polyamide 6 and caprolactam based copolyamides by extraction.
[3] The invention also relates to a process for the preparation of polyamide 6 or caprolactam based copolyamides and to a device for carrying out the same.
[5] The present invention relates to polyamide 6 and caprolactam based copolyamides. Polyamide 6 is a homopolymer of caprolactam. The caprolactam based copolyamide according to the present invention is a copolyamide containing at least 50% by weight of monomer units derived from caprolactam. In addition, these caprolactam based copolyamides contain other repeating units bound by amide groups. For example, these repeating units may be repeating units derived from adipic acid and hexamethylene diamine, ie 6,6 polyamide units. They may also be other repeating units derived from other dicarboxylic acids and other diamines. Alternatively, they may be repeat units derived from aminocarboxylic acids, for example repeat units of polyamide 11 or polyamide 12.
[6] Polyamide 6 or caprolactam based copolyamides can be prepared by various methods. For example, these can be manufactured by hydrolytic polymerization of caprolactam. This is the main industrial method. This is also a preferred method according to the invention. Furthermore, these can be produced by alkali lactam polymerization. Processes for preparing polyamide 6 or caprolactam based copolyamides are described, for example, in "Kunststoff-Handbuch", Volume 3, "Technische Thermoplaste", Part 4, "Polyamide", pages 22-75. have.
[7] Typically polyamide 6 or caprolactam based copolyamides are prepared by hydrolytic polymerization of caprolactam. When preparing a caprolactam based copolyamide, the required comonomer is added. Preferably this comonomer is a mixture of dicarboxylic acids and diamines or aminocarboxylic acids or lactams.
[8] Hydrolytic polymerization, for example as described in "Kunststoff-Handbuch", Volume 3, "Technische Thermoplaste", Part 4, "Polyamide", Chapter 2.2.2.2.4, generally excludes ambient oxygen. It is usually carried out by polymerization under normal pressure by adding 1 to 5% by weight of water at a temperature of 240 to 270 ° C. Dehydration compounds, such as aminocarboxylic acids or AH salts (salts of adipic acid with hexamethylene diamine) can be used to initiate the reaction. Usually, it starts using water. The molecular weight of the polyamide is here defined by the water content, but in reality is conveniently stabilized by a regulator, for example a carboxylic acid or an amine.
[9] Typically polyamide 6 or caprolactam based copolyamides are prepared continuously. Typically, they are continuously produced in vertical tube reactors known as SC (SC = simplified continuous) tubes. Typical methods are as follows. Pour aqueous caprolactam (optionally with comonomer and optionally with another auxiliary material such as molecular weight regulator) onto the SC tube. Excess water is distilled off here to achieve a sufficiently high molecular weight. The melt is then flowed through the tube, typically for 15 to 30 hours at normal pressure, while maintaining a temperature of typically 240 to 270 ° C. The polyamide melt at the bottom of the SC tube is pressurized into a water bath through a circular cross section as a thread, for example using a gear pump, cooled and granulated.
[10] Low molecular weight compounds are formed as secondary products during polyamide 6 or caprolactam based copolyamide preparation. In particular, they are oligomeric compounds formed from caprolactam and optionally from comonomers. These low molecular weight compounds adversely affect the properties of polyamide 6 or caprolactam based copolyamides and are therefore typically removed. In particular, the cyclic dimer of caprolactam adversely affects the properties of polyamide 6 or caprolactam based copolyamides.
[11] Since the low molecular weight fraction diffuses on the surface to form a greasy film, the quality of products made from polyamides, for example injection molded articles or films, is lowered. In addition, the low molecular weight fraction diffused on the surface degrades the surface quality of the product made from the polyamide. Gloss decreases and color is impaired.
[12] In the case of polyamides which are processed for film production, especially low molecular weight compounds are required at low concentrations. Typically, immediately after polymerization polyamide 6 and caprolactam based copolyamides contain more than 5% by weight of low molecular weight compounds (caprolactam and oligomers thereof, and optionally oligomers of comonomers). In the case of polyamides processed for the production of injection molded articles, the concentration of low molecular weight compounds should typically be less than 1% by weight, preferably less than 0.5% by weight. Even higher requirements are required for polyamides that are processed for film production. In this case, the concentration of the low molecular weight compound should be 0.1 wt% or less, preferably 0.05 wt% or less.
[13] Low molecular weight compounds can be removed, for example, by extraction. Typically the extraction is carried out using water or a liquid containing mainly water.
[14] Typically, after polymerization and subsequent extraction, the polyamide 6 or caprolactam based copolyamide obtained is dried. This is done for example at a temperature of 90 to 130 ° C. in an inert gas stream. For example, nitrogen can be used. By increasing the drying temperature to, for example, 180 to 190 ° C., it is possible to further increase the molecular weight of the polyamide for certain applications by so-called postcondensation.
[15] Instead of the first stage SC tube, a device equipped with a multistage SC tube or an apparatus comprising an upstream low pressure prepolymerization stage may be used.
[16] According to the prior art, extraction of polyamide 6 or caprolactam based copolyamides is carried out batchwise or continuously using water at a temperature below the boiling point of water (ie below 100 ° C.) under atmospheric pressure.
[17] There is a disadvantage in the process for the preparation of polyamide 6 and caprolactam based copolyamides, including the extraction of polyamide 6 or caprolactam based copolyamides according to the prior art. In particular, one of the disadvantages of the known processes is that a long residence time is required in the extraction apparatus in order to prevent the low molecular weight fraction in the extracted polyamide from reaching a certain concentration. This means that the space-time yield for the extraction process is low. In addition, the extraction results by known industrial methods are often not good enough. In particular, the ratio of residual low molecular weight substances in the polyamide is very high. In particular, the proportion of cyclic dimers of residual caprolactam in the polyamide is very high.
[18] In addition, the extraction methods known in the prior art have the disadvantage that a very large amount of water per unit weight of the polyamide to be extracted is required. The use of less water for extraction is preferred because it simplifies the process, can reduce the design equipment, and reduces the cost of the process. It is advantageous to carry out the extraction process in a countercurrent system. Since the density of polyamide 6 and caprolactam based copolyamides is higher than that of the water or aqueous liquid used for extraction, countercurrent extraction is convenient for the polyamide to move down according to the gravitational effect, and the liquid used for extraction ( Typically water) is carried out in such a way that it moves up in the countercurrent to the polyamide in the reverse direction of gravity. In the case of using this process, if a small amount of water per unit weight of polyamide is used at the end of the extraction process, the higher the loading amount of the water containing the low molecular weight compound to be extracted, the lower the amount of water used. This load, including low molecular weight compounds, increases the density of the mixture of low molecular weight compounds and water extracted. As a result, by using the countercurrent method, a low density liquid layer (a low proportion of the compound and water to be extracted) is placed under the high density liquid layer (a high proportion of the low molecular weight compound and water to be extracted). As a result, the adverse effect of backmixing is caused because the high-density liquid layer located at the top passes through the gravity effect and breaks down into the low-density liquid layer located at the bottom. In this way the countercurrent method is impaired. The efficiency of the extraction process is reduced. Therefore, according to the present invention, a method of preventing the problem of extraction damage due to the density difference during the extraction process as described above is preferable.
[19] In the present invention, the construction yield is understood as the throughput of polyamide through the polyamide extraction unit per unit time and unit volume in the apparatus.
[20] It is therefore an object of the present invention to overcome the disadvantages of the prior art and to perform extraction with high construction yields, so that low molecular weight substances, in particular caprolactam and oligomers, can be contained in the polyamide after extraction, in a low concentration. It is to provide an improved method for extracting amide 6 or caprolactam based copolyamides.
[21] The purpose is to extract polyamide 6 or caprolactam based copolyamides at temperatures above the boiling point of the liquid under atmospheric pressure using a liquid containing at least 80% by weight of water. It is achieved by the extraction method of polyamide.
[22] The present invention also provides a polyamide comprising a preextractor (1), a pressure extractor (2), and an injector (5) which is located downstream of the preextractor and can carry the extracted polyamide from the preextractor to the pressure extractor, or And an apparatus for extracting caprolactam based copolyamides.
[23] The invention also provides an apparatus for producing polyamide 6 or caprolactam based copolyamides comprising the device according to the invention for the extraction of polyamide 6 or caprolactam based copolyamides.
[24] As in the case of this extraction method, the performance of the extraction process at temperatures above the boiling point of the liquid under atmospheric pressure shows that the extraction should be carried out under elevated pressure so that the extraction liquid does not evaporate.
[25] In the present invention, the term "under elevated pressure" means that the pressure is greater than 1 bar.
[26] There are many advantages to the method according to the invention. The extraction method according to the invention proceeds with high construction yields. The extraction process according to the invention requires only a small amount of water per unit weight of polyamide. This extraction method results in a low proportion of low molecular weight contaminants contained in polyamide 6 or caprolactam based copolyamides. In particular, the proportion of cyclic dimers of caprolactam in extracted polyamide 6 or extracted caprolactam based copolyamides is very low. Due to the high construction yields, industrial scale extraction processes can be carried out in small apparatus. Thus, the extraction method according to the invention is more economically viable and more cost effective than the prior art methods. In addition, the process according to the invention is carried out during extraction, as is usually the case when polyamide 6 or caprolactam based copolyamides, which are fed to the extraction process, usually in granular form, are contacted with an aqueous liquid for a long time at high temperature. The advantage is that they do not adhere together or form lumps. The method according to the invention achieves this advantage by limiting the upper limit of temperatures intentionally reached such that no sticking or lump formation occurs.
[27] The extraction method according to the invention has the advantage that when this method is carried out in a countercurrent system, it is not damaged by adverse backmixing due to the density difference of the extraction liquid.
[28] It is also advantageous that less water is consumed during extraction since the water must be retreated after extraction. Typically this is accomplished by evaporating off the water. The distilled water can then be reused in the extraction process as fresh water. A highly concentrated mixture of water, caprolactam, oligomers thereof and other low molecular weight compounds remaining in the distillation vessel can be fed to the polyamide manufacturing process or treated as waste.
[29] The extraction device according to the invention has many advantages. The continuous extraction method is easily performed without the problems associated with backmixing due to density differences.
[30] The extraction apparatus according to the invention enables high construction yields, low residual concentrations of low molecular weight compounds after extraction, and prevents adhesion or lump formation in the polyamide during extraction.
[31] Preferably the process according to the invention is carried out continuously.
[32] Preferably polyamide 6 or caprolactam based copolyamide and liquid are passed countercurrently to one another.
[33] Preferably, polyamide 6 or caprolactam based copolyamides are moved down according to the gravitational effect and the liquid is moved upwards in the reverse direction of gravity in countercurrent thereto.
[34] Preferably, the density difference of the liquid at the start of the extraction process and at the completion of the extraction process is kept sufficiently small so that the liquid does not adversely mix back substantially against the flow direction.
[35] Preferably, the extraction is carried out in two steps, in a second step which is also carried out at a temperature above the boiling point of the liquid by removing some of the extractable components in the first step, which may be carried out at temperatures below the boiling point of the liquid. Even when the liquid ratio of water to polyamide is low, the density difference is kept small, thereby maintaining a small density difference.
[36] Preference is given to a method wherein the amount of liquid used is 1 to 3 kg, preferably 2 to 3 kg, per kg of polyamide 6 or caprolactam based copolyamide to be extracted.
[37] Preferably the liquid consists essentially of water.
[38] Preferably the extraction process is carried out at a temperature of 100 to 130 ° C.
[39] A particularly preferred method is extraction, carried out at a temperature of 120 ° C. to 125 ° C., preferably with a liquid ratio of polyamide to liquid of 1 kg: 2 kg to 1 kg: 3 kg, preferably for 10 to 14 hours. Perform.
[40] In a preferred apparatus, a second injector 9 is located downstream of the pressure extractor so that the product can be carried out of the pressure extractor.
[41] In this case, a device comprising a pipe 4 for conveying the liquid from the upper end of the pressure extractor 2 to the pre-extractor 1 is preferred.
[42] Preferably the method according to the invention is carried out in a device according to the invention.
[43] The present invention also provides a process for the preparation of polyamide 6 or caprolactam based copolyamides comprising extraction by one of the processes according to the invention.
[44] Preferred polyamides according to the invention are selected from the group consisting of polyamide 6 and caprolactam based copolyamides containing at least 90% by weight monomer units, based on caprolactam. Preferably the remaining 10% by weight is derived from polyamide 6,6 repeat units of polyamide 11 or polyamide 12.
[45] According to the invention, polyamide 6 is particularly preferred.
[46] According to the invention, the extraction is carried out with a liquid consisting of preferably at least 80% by weight of water. Preferably extraction is carried out with water. Demineralized water is particularly preferred.
[47] Preferably the suspension of the polyamide granules in water which is preferably included in the process according to the invention is conveyed using a so-called injector. Injectors are pump compressors that operate using suction, also called ejectors. This belongs to the family of jett solid pumps. It uses water as the transport agent. The water transports the polyamide granules being conveyed. Polyamide granules come out of the injector as a suspension in water. Transport by the injector has the advantage that the material is transported without the problems caused by transporting it from the region under atmospheric pressure to the high pressure region. When using other conveying devices such as, for example, cellular wheel sluices, it is not possible to convey a suspension of polyamide granules in water from the low pressure region to the high pressure region. The amount carried by the injector during the transport process can be controlled by the flow rate of water or the back pressure downstream of the injector. In the process of the invention, pressure differentials of typically 1 to 2 bar, in particular 1.5 bar, are overcome during transport. In addition, the injector has the advantage that it can be manufactured in a simple and cost effective manner, with no moving parts and hardly worn. Surprisingly, there is no need to install a metering device upstream of the injector as required in the prior art to adjust the delivery rate.
[48] To date, it has not been described in the prior art that an injector can be used to deliver a suspension of plastic material granules, preferably polyamide granules, in water (if water is used as the transport medium). Furthermore, it has not been described that it is possible to transport from the low pressure region to the high pressure region. Furthermore, it has not been described that the conveying amount can be adjusted to the vehicle flow rate (ie the amount of water supplied as the transport stream per unit time), or to the pressure on the side of the injector from which the suspension flows. The plastic material granules to be conveyed may be anhydrous, ie dry or mixed with low proportions of water prior to transport.
[49] Thus, another aspect of the present invention is a method of conveying a suspension of plastic material granules, preferably polyamide granules, in water to an injector using water as the transport medium.
[50] Preferably the material is conveyed from the low pressure region to the high pressure region. The pressure difference is preferably 0.5 to 5 bar, particularly preferably 1 to 1.5 bar.
[51] In the case of transporting the material from the low pressure region to the high pressure region, a preferred embodiment of the method of the present invention comprises adjusting the transport amount by the transport flow rate of water. Another preferred embodiment of this method is to adjust the delivery amount by the pressure on the side of the injector from which the suspension is discharged. This can be achieved, for example, by using a pressure retention valve so that the transport can be regulated even if there is a pressure difference between the area in which the material is transported and the area into which the material is transported.
[52] The following figures show preferred embodiments of the invention.
[53] 1 shows a preferred extraction apparatus according to the invention for the extraction of polyamide 6 or caprolactam based copolyamides.
[54] The unextracted polyamide granules 3 from the polymerization process are fed to a preextractor 1 operated under atmospheric pressure. Water 4 coming from the pressure extractor 2 is used as the extraction medium. After separating the water in the device (7), the pressure extractor (2) (water traveling countercurrent to the polyamide granules) through the injector (5) operated with the polyamide granules using water (6) as the transport medium ( Is operated using 8). The extracted polyamide is discharged from the pressure extractor through the second injector 9 and dried. The amount carried by the injector can be adjusted by the flow rate of the transport medium or the pressure in the pipe used to discharge the suspension. For this purpose, pressure retention valves are mounted in these pipes (not shown).
[55] Since the apparatus according to FIG. 1 removes some of the low molecular weight compounds that occur in the preextractor 1, the pressure extractor 2 does not exhibit adverse backmixing due to density differences even when the liquid to water ratio of polyamide is low. There is an advantage.
[56] <Examples 1 and 2>
[57] Examples 1 and 2 below were obtained in a device according to FIG. 1 in a continuous operation. The numerical values used are in a range that includes values during the course of the experiment. Polyamide 6 having a concentration of low molecular weight compound (extract) of about 8.5 to 10% by weight was fed to the preextractor, which was operated at 95 ° C and atmospheric pressure. The residence time in the pressure extractor was 3 hours.
[58] Example 1
[59] After passing through the preextractor, the polyamide was transferred to a pressure extractor and operated at 100 to 120 ° C. The residence time in the pressure extractor was 6 hours. The ratio of water to polyamide was 1.3: 1. The extract concentration after the pressure extractor was 0.3 to 0.6% by weight. The dimer concentration of 0.6 to 1% by weight before the preextractor was reduced to 0.075 to 0.3% by weight after the pressure extractor.
[60] Example 2
[61] After passing through the preextractor, the polyamide was transferred to a pressure extractor and operated at 120 to 125 ° C. The residence time in the pressure extractor was 10 to 14 hours. The ratio of water to polyamide was 2.5: 1. The extract concentration after the pressure extractor was 0.25 to 0.4% by weight. The dimer concentration of 0.4 to 0.8 wt% before the preextractor was reduced to 0.01 to 0.03 wt% after the pressure extractor.
[62] In Examples 1 and 2, it has been shown that even a supply of water can attain a high quality extraction process that is at least sufficient for conventional applications in the field of injection molding. In Example 2, by increasing the amount of water, the temperature and the residence time, an extraction process of a quality suitable for use in the field of food packaging films, in particular where the extract concentration should be low, was obtained.
[63] <Other Embodiments>
[64] Trial series 3 to 6
[65] Laboratory scale experiments on the extraction of polyamide 6 (PA 6) with water and caprolactam containing water were carried out as follows.
[66] These experiments have demonstrated the advantages of the method according to the invention and the device according to the invention.
[67] This experiment was to determine the rate of extraction of the cyclic dimer of caprolactam from vacuum delactamated PA 6 compared to the case of unextracted PA 6. Vacuum delactamation means that some lactam is removed from PA 6 by vacuum distillation at elevated temperature.
[68] The experimental results can be summarized as follows.
[69] The extraction rates of dimers and oligomers from PA 6 (vacuum delactamated PA 6) with most monomeric caprolactam already removed vary greatly with temperature. In comparison with the extraction rate of the oligomer from caprolactam containing PA 6 (unextracted PA 6), the following results were obtained. At an extraction temperature of 95 ° C., dimers were extracted from vacuum delactamation PA 6 much slower than those extracted from unextracted PA 6, but at an extraction temperature of 125 ° C., the oligomers were equally rapidly from both types of PA 6. Extraction was in progress.
[70] This result is important for a two-stage extraction design consisting of a preliminary extraction step of a high proportion of caprolactam and a subsequent countercurrent extraction step under pressure for the final extraction, in particular for which the proportion of oligomers should be reduced to the required degree. This type of extraction design has the advantage that the problem of backmixing (due to density differences) that occurs during one-step aqueous extraction does not occur. This means that water consumption per unit weight of PA 6 extracted can be reduced, resulting in the final effect of saving energy and increasing construction yield in the extraction process.
[71] According to the results of the present invention, this extraction design can be realized even at 125 ° C. from the delactamized PA 6 since the extraction of the dimer proceeds sufficiently fast. Instead of an aqueous pre-extraction method, a lactam evaporation or vacuum de-lactamation method is also possible.
[72] Test Series 3: Extraction of Vacuum Decay Tamping Polyamide 6 at 95 ° C
[73] 50 g of vacuum delactamated PA 6 and 500 g of water were heated to 95 ° C. for 0.5, 1, 2, 4 and 8 hours with stirring. The granules were filtered off under suction and washed with 100 g of water. The concentration of monomers and dimers in the dried granules was measured by HPLC. The results are summarized in the table below.
[74]
[75] Test Series 4: Extraction of Vacuum Decay Tamping PA 6 at 125 ° C
[76] 50 g of vacuum delactamated PA 6 and 500 g of water were heated in an autoclave to 125 ° C. for 0.5, 1, 2, 4 and 8 hours. It was performed in the same manner as in test series 3. The measured monomer and dimer concentrations are summarized in the table below.
[77]
[78] Test Series 5: Extraction of Unextracted PA 6 at 95 ° C
[79] 50 g of PA 6 (not extracted) and 500 g of water were heated to 95 ° C. for 0.5, 1, 2, 4 and 8 hours with stirring. It was performed in the same manner as in test series 3. The measured monomer and dimer concentrations are summarized in the table below.
[80]
[81] Test Series 6: Extraction of Unextracted PA 6 at 125 ° C
[82] 50 g of PA 6 (unextracted) and 500 g of water were heated in an autoclave to 125 ° C. for 0.5, 1, 2, 4 and 8 hours. It was performed in the same manner as in test series 3. The measured monomer and dimer concentrations are summarized in the table below.
[83]
[84] <Other Embodiments>
[85] Trial series 7-9
[86] Test series 7 to 9 for extraction under elevated pressure were carried out in a temperature range of 95 to 125 ° C. 125 ° C. corresponded to an overpressure of about 2.5 bar.
[87] The starting material for these test series was unextracted PA 6, which was produced after polymerization. When the ratio of PA 6 to extract extracted is 1:10, the concentration of monomers and oligomers in the extraction medium was slightly higher during continuous extraction, so the extraction process was mainly determined by the extraction kinetics and the monomer and The distribution equilibrium of the oligomer was only important later in the extraction.
[88] Test Series 7: Extraction of Unextracted PA 6 at 95 ° C
[89] 50 g of PA 6 (not extracted) and 500 g of water were heated to 95 ° C. for 0.5, 1, 2, 4 and 8 hours with stirring. The granules were filtered off under suction and washed with water. The concentration of monomers and dimers in the granules dried at 90 ° C. was determined by HPLC. The results are summarized in the table below.
[90]
[91] Test Series 8: Extraction of Unextracted PA 6 at 110 ° C
[92] 50 g of PA 6 (not extracted) and 500 g of water were heated to 110 ° C. in an autoclave for 0.5, 1, 2, 4 and 8 hours. The same procedure as in test series 7 was performed. The measured monomer and dimer concentrations are summarized in the table below.
[93]
[94] Test Series 9: Extraction of Unextracted PA 6 at 125 ° C
[95] 50 g of PA 6 (unextracted) and 500 g of water were heated in an autoclave to 125 ° C. for 0.5, 1, 2, 4 and 8 hours. The same procedure as in test series 7 was performed. The measured monomer and dimer concentrations are summarized in the table below.
[96]
[97] From test series 7-9, it was very clear that the extraction rate increased significantly by increasing the extraction temperature from 95 ° C to 110 ° C and 125 ° C. This applies equally to monomeric caprolactam and dimers. Thus, under a given test batch, after one hour of extraction time at 125 ° C., the concentration of caprolactam was 0.36% and the dimer concentration was 0.073%, which was the extraction quality corresponding to the injection molding quality. On the other hand, similar values were obtained after only 4 to 8 hours at an extraction temperature of 95 ° C.
[98] In test series 7-9, the extraction rate increased significantly with increasing from 95 ° C to 110 ° C and 125 ° C. At a temperature of 135 ° C., agglomerates of granules were formed. Therefore, no extraction could be performed at 135 ° C.

权利要求:
Claims (9)
[1" claim-type="Currently amended] A method for extracting polyamide 6 or caprolactam based copolyamide, wherein the polyamide 6 or caprolactam based copolyamide is extracted at a temperature above the boiling point of the liquid under atmospheric pressure using a liquid composed of 80 wt% or more water.
[2" claim-type="Currently amended] 2. The method of claim 1, wherein the liquid and the polyamide are continuously operated in countercurrent, the liquid is moved upwards in the reverse direction of gravity, and at the beginning of extraction so that the liquid is not adversely mixed in a substantially opposite direction to the flow direction. A method of keeping the density difference of the liquid at the completion of extraction sufficiently small.
[3" claim-type="Currently amended] The liquid ratio of water to polyamide in a second stage as recited in claim 2, further comprising removing some of the extractable components in the first stage, which may also be carried out at a temperature below the boiling point of the liquid, to be carried out at a temperature above the boiling point of the liquid. A method of maintaining a small density difference by allowing the density difference to be kept small even when p is low.
[4" claim-type="Currently amended] Of a polyamide or caprolactam based copolyamide comprising a preextractor (1), a pressure extractor (2), and an injector (5) located downstream of the preextractor and carrying the extracted polyamide from the preextractor to the pressure extractor Extraction device.
[5" claim-type="Currently amended] 5. Device according to claim 4, wherein a second injector (9) is located downstream of the pressure extractor so that material can be conveyed out of the pressure extractor.
[6" claim-type="Currently amended] Device according to claim 4 or 5, comprising a pipe (4) for transporting the liquid from the top of the pressure extractor (2) to the preextractor (1).
[7" claim-type="Currently amended] Method according to any one of the preceding claims, carried out in an apparatus according to any one of claims 4 to 6.
[8" claim-type="Currently amended] A process for producing polyamide 6 or caprolactam based copolyamides, comprising the extraction method according to any one of claims 1 to 7.
[9" claim-type="Currently amended] An apparatus for producing polyamide 6 or caprolactam based copolyamides, comprising the apparatus according to any one of claims 4 to 6.

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US6699962B2|2004-03-02|

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JP2004528459A|2004-09-16|

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CN1509303A|2004-06-30|

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WO2002094908A1|2002-11-28|

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DE10124579A1|2002-12-05|

引用文献:

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公开号 | 申请日 | 公开日 | 申请人 | 专利标题

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法律状态:
2001-05-21|Priority to DE10124579.3

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2001-05-21|Priority to DE2001124579

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2002-05-08|Application filed by 바이엘 악티엔게젤샤프트

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2002-05-08|Priority to PCT/EP2002/005043

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2004-02-05|Publication of KR20040011504A

优先权:

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申请号 | 申请日 | 专利标题

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DE10124579.3|2001-05-21|

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DE2001124579|DE10124579A1|2001-05-21|2001-05-21|Process and device for extracting polyamide|

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PCT/EP2002/005043|WO2002094908A1|2001-05-21|2002-05-08|Method and device for the extraction of polyamide|