Process for manufacturing laurolactam, its synthesis device, laurolactam composition manufactured using the same, and process for manufacturing polylaurolactam using the same

Abstract

The present invention relates to a manufacturing method of laurolactam, a synthetic device thereof, a laurolactam composition manufactured using the same, and a manufacturing method of polylaurolactam using the same, the manufacturing method of laurolactam comprising the steps of: a) synthesizing laurolactam by Beckmann rearrangement of cyclododecanone oxime in the presence of a catalyst; b) mixing the laurolactam synthesized in the step a) with a good solvent to remove the catalyst; and c) mixing the laurolactam from which the catalyst is removed in the step b) with a poor solvent to perform recrystallization.

Description

Technical Field

[0001] This invention relates to a method for manufacturing laurolactam, an apparatus for synthesizing it, a laurolactam composition manufactured therefrom, and a method for manufacturing polylaurolactam using the composition.

[0002] In addition, the present invention provides a new method for manufacturing laurolactam, which improves the disadvantage that when using existing catalysts and co-catalysts, namely a mixed catalyst of TCT (cyanuric chloride, trichlorotriazine) and ZnCl2, it is not easy to remove the above-mentioned catalyst components from the manufactured laurolactam. Background Technology

[0003] Typically, the industrial synthesis of cyclic amide monomers, such as laurolactam, involves synthesizing cyclododecanone oxime via the Beckmann rearrangement reaction.

[0004] Such polyamide polymers, such as polylaurolamide, can be synthesized by anionic polymerization. The purity of the laurolactam monomer has a significant impact on the polymerization reaction activity, so the purity of the monomer is a very important factor.

[0005] Previously, for the monomers of laurolactam produced by the Beckmann rearrangement reaction, the solvent was removed by distillation after the reaction, and then the high molecular weight substances (Heavies) were removed in solid and / or liquid states to purify the laurolactam. However, the problem still exists that trace amounts of catalyst remain in the final laurolactam product, causing a sharp decrease in the activity of the anionic polymerization reaction.

[0006] Therefore, there is a need for a method to purify laurolactam to high purity by removing the catalyst remaining after the Beckmann rearrangement reaction through a simple process and to improve the anionic polymerization activity of laurolactam monomers, etc.

[0007] As one of the methods described above, the applicant of this application studied the following method in the previously filed application 2019-161182: cyclododecanone oxime was synthesized into laurolactam via a Beckmann rearrangement in the presence of TCT and ZnCl2 catalysts. After removing the catalyst by adding a good solvent (such as ethanol), the catalyst was recrystallized by mixing with a poor solvent (water) to recover the monomer that had been partially removed from the catalyst.

[0008] However, in the aforementioned patent, when a poor solvent is added to a good solvent for recrystallization, a viscous catalyst substance still exists at the interface. Even after recrystallization, the catalyst still exists in the monomer at a concentration of more than 90 ppm. This poses a problem that when the recrystallized monomer is subjected to anionic polymerization, the anionic reaction sites are damaged, making it impossible to increase the degree of polymerization or reducing the conversion rate. Summary of the Invention

[0009] The purpose of this invention is to provide a new method for purifying laurolactam, which produces laurolactam from cyclododecanone oxime via a Beckmann rearrangement reaction. When the synthesized laurolactam is treated with the aforementioned good and bad solvents, recrystallization is performed without the presence of viscous substances, thereby maintaining the residual amount of catalyst at less than 20 ppm, preferably less than 10 ppm, and more preferably less than 1 ppm.

[0010] In addition, an apparatus for synthesizing the aforementioned laurolactam is provided.

[0011] In addition, laurolactam synthesized by the above-described method for manufacturing laurolactam is provided with a catalyst component maintained at 10 ppm or less.

[0012] In addition, a method is provided for producing polylaurolactam by anionic polymerization of synthesized laurolactam with high conversion rate.

[0013] One specific example provides a method for manufacturing laurolactam, comprising the following steps: a) synthesizing laurolactam from cyclododecanoxime via Beckmann rearrangement in the presence of a TCT catalyst without the use of a co-catalyst; b) mixing the laurolactam synthesized in step a) with a good solvent to remove the catalyst; and c) mixing the laurolactam from step b) with a poor solvent for recrystallization.

[0014] The Beckmann rearrangement reaction in step a) above can be carried out in a solvent containing isopropylcyclohexane (IPCH) and a catalyst to synthesize cyclododecanone oxime into laurolactam. The catalyst used is only cyanuric chloride (TCT) and does not contain the co-catalyst zinc chloride (ZnCl2) used by the applicant in Korean Patent Application No. 2019-161823, which has been filed but not yet published.

[0015] Step a) above may also include the step of distilling the synthesized laurolactam to remove the solvent.

[0016] Step b) above can remove the catalyst by taking advantage of the difference in solubility of the catalyst and laurolactam in a good solvent.

[0017] The aforementioned good solvent can be a C1 to C4 hydrocarbon organic solvent containing one or more functional groups selected from hydroxyl, amine and mercapto groups.

[0018] Step c) above can utilize the difference in solubility of laurolactam in good solvents and in bad solvents to recrystallize laurolactam.

[0019] The aforementioned good and bad solvents can be miscible.

[0020] The aforementioned unsuitable solvents can be distilled water or deionized water.

[0021] The aforementioned good and bad solvents can be injected at a weight ratio of 1:1.5 to 1:3.

[0022] It may also include the steps of evaporating the recrystallized laurolactam, removing the heavy substances in a liquid and / or solid state, and separating the laurolactam in a gaseous state.

[0023] Another specific example provides a laurolactam synthesis apparatus, comprising: a first reactor for synthesizing laurolactam from cyclododecanone oxime via a Beckmann rearrangement in the presence of a TCT catalyst; an evaporator for removing the solvent from the laurolactam synthesized in the first reactor; a second reactor for mixing the laurolactam from which the solvent has been removed in the evaporator with a good solvent to remove the catalyst; and a third reactor for recrystallizing the laurolactam from which the catalyst has been removed in the second reactor with a poor solvent.

[0024] It may also include a filter to remove the catalyst that precipitates in the second reactor described above.

[0025] It may also include a film evaporator to separate the polymeric substances (heavies) from the recrystallized laurolactam.

[0026] Another specific example provides a laurolactam composition synthesized using the above-described method for manufacturing laurolactam.

[0027] In the above laurolactam composition, the catalyst used in the Beckmann rearrangement reaction may be included in less than 5% by weight relative to the total weight of the laurolactam composition.

[0028] Another specific example provides a method for manufacturing polylaurolactam, wherein the above-mentioned laurolactam composition is anionicly polymerized in the presence of an anionic initiator to produce polylaurolactam.

[0029] The aforementioned anionic initiators may include one or more selected from NaH, n-BuLi, KH and LiH.

[0030] The above anionic polymerization can be carried out at 250 to 350°C for 10 to 60 minutes.

[0031] The weight-average molecular weight of the polymerized polylaurolactam can be greater than 6000.

[0032] After synthesizing laurolactam via the Beckmann rearrangement reaction, residual catalysts and solvents in the reaction products can be effectively removed through a simple process.

[0033] Anionic polymerization can be carried out with high conversion rates using purified laurolactam monomers. Detailed Implementation

[0034] The present invention will now be described in detail. Unless otherwise defined, the terminology used in this specification should be interpreted as that commonly understood by those skilled in the art. Regarding the figures and embodiments of this specification, to facilitate understanding and implementation of the invention by those skilled in the art, content that may obscure the main points of the invention may be omitted; the invention is not limited to the figures and embodiments.

[0035] Unless otherwise specified, the singular forms of the terms used in this invention may be interpreted to include the plural forms.

[0036] In the description of this invention, a catalyst refers to a catalyst system that uses only a TCT catalyst and does not contain a co-catalyst.

[0037] The following describes a method for manufacturing laurolactam based on a specific example.

[0038] The above-mentioned method for manufacturing laurolactam includes the following steps: a) synthesizing laurolactam from cyclododecanone oxime via Beckmann rearrangement in the presence of a TCT catalyst; b) mixing the laurolactam synthesized in step a) with a good solvent to remove the catalyst; and c) mixing the laurolactam from step b) with a poor solvent for recrystallization.

[0039] Step a) above is the process of synthesizing laurolactam from cyclododecanone oxime via a Beckmann rearrangement reaction in the presence of a TCT catalyst. The Beckmann rearrangement reaction can be carried out in a solvent using a cyanuric chloride (TCT) catalyst to synthesize laurolactam from cyclododecanone oxime.

[0040] Specifically, the Beckmann rearrangement reaction in step a) above can be carried out at a temperature of 70 to 130°C, preferably 90 to 110°C, more preferably 95 to 100°C, for 1 to 20 minutes, preferably 5 to 20 minutes, more preferably 5 to 15 minutes. If the reaction temperature is too high, a large amount of byproducts such as heavy molecules are generated; if it is too low, the reaction rate is not fast enough, making it unsuitable for commercial applications. Furthermore, when the reaction time is less than 1 minute, the cyclododecanone oxime cannot be sufficiently rearranged to laurolactam; when it is greater than 20 minutes, too many side reactions occur, making these conditions undesirable.

[0041] On the other hand, the Beckmann rearrangement refers to a rearrangement reaction in which a ketoxime is replaced by an amide. In particular, in this invention, it can refer to the reaction in which the above-mentioned cyclododecanone oxime is rearranged into laurolactam.

[0042] The catalyst described above is cyanuric chloride (TCT). Specifically, relative to 100 parts by weight of cyclododecanone oxime, the catalyst may be present in 0.1 to 10 parts by weight, preferably 0.1 to 5 parts by weight, and more preferably 0.5 to 2 parts by weight. If the content of the catalyst is too low, the Beckmann rearrangement reaction cannot proceed sufficiently; if the content of the catalyst is too high, the catalyst residue remains in a high concentration in the reaction product after the reaction is completed, making it difficult to effectively remove it in the purification step.

[0043] As the solvent described above, an organic solvent containing, for example, isopropylcyclohexane (IPCH) is preferred. This solvent, due to its highly nonpolar nature, can be used to successfully produce laurolactam from cyclododecanone oxime using the Beckmann rearrangement reaction. Taking advantage of the significant difference in boiling point between the solvent and the reaction product, the reaction product can be distilled, thereby easily removing the solvent. Therefore, high-purity laurolactam can be produced efficiently.

[0044] For every 100 parts by weight of cyclododecanone oxime, 30 to 50 parts by weight of an organic solvent containing the aforementioned IPCH can be used. When the content is within the above range, the Beckmann rearrangement of cyclododecanone oxime is facilitated, and the solvent can be easily removed by distillation of the reaction product. Therefore, high-purity laurolactam can be efficiently produced.

[0045] Next, step b) above is to mix the laurolactam synthesized in step a) above with a good solvent to remove the catalyst. The good solvent can be a C1 to C4 hydrocarbon organic solvent, preferably a C1 to C4 hydrocarbon organic solvent containing one or more functional groups selected from hydroxyl, amino and mercapto groups, and more preferably a C1 to C4 hydrocarbon or C1 to C4 alcohol containing hydroxyl groups.

[0046] When the above-mentioned good solvent is mixed, the catalyst can be removed by taking advantage of the difference in solubility of the catalyst and laurolactam in the good solvent. Specifically, the above-mentioned catalyst is insoluble in the good solvent and precipitates as solid particles. Conversely, laurolactam has a high solubility in the good solvent and is therefore practically completely dissolved in the good solvent, thus not precipitating. Then, the catalyst precipitated in particle form can be easily removed by a filter. At this time, if too little good solvent is injected, some laurolactam remains undissolved and exists as a solid, thus being removed in the filter along with the residual catalyst. Therefore, the laurolactam yield decreases, and the portion of laurolactam that is not dissolved in the good solvent agglomerates with the residual catalyst and remains through the filter. Conversely, if too much good solvent is injected, the recrystallization of laurolactam in the subsequent step c) may be difficult. Therefore, the laurolactam synthesized in step a) and the above-mentioned good solvent can be mixed in a weight ratio of 1:4 to 1:7, preferably 1:5 to 1:7, and more preferably 1:6 to 1:7.

[0047] On the other hand, in the specification of this invention, a good solvent refers to a solvent that has a high affinity for laurolactam (solute) and can dissolve it well, while a poor solvent can refer to a solvent that has a low affinity for laurolactam and cannot dissolve it well.

[0048] Next, in step c), the laurolactam from step b) (where the catalyst has been removed) is recrystallized by mixing it with a poor solvent. The poor solvent can be a substance miscible with the good solvent; specifically, it can be distilled water or deionized water. When mixing with the poor solvent, the difference in solubility of laurolactam in the good solvent and the poor solvent can be utilized to recrystallize the laurolactam. Specifically, laurolactam has the characteristic of high solubility in the good solvent and low solubility in the poor solvent. When the poor solvent is mixed with the good solvent containing dissolved laurolactam from step b), as the concentration of the good solvent decreases, the solubility of laurolactam decreases, resulting in the recrystallization of laurolactam as a solid.

[0049] The aforementioned good solvent and poor solvent can be injected in a weight ratio of, for example, 1:1.5 to 1:3, preferably 1:2 to 1:3, and more preferably 1:2 to 1:2.5. When an excess of good solvent is injected relative to the poor solvent, some laurolactam cannot precipitate as a solid and may exist in a state dissolved in the good solvent. The yield of purified laurolactam may become lower, which is therefore not preferred.

[0050] Next, the following steps can be performed: evaporating the recrystallized laurolactam, removing the heavy molecules in a liquid and / or solid state, and separating the laurolactam in a gaseous state. As a result, high-purity laurolactam can be purified, which is therefore preferred.

[0051] The evaporation described above can be carried out, for example, in a film evaporator, but the present invention is not limited thereto.

[0052] On the other hand, a thin-film evaporator is an evaporation device used to obtain a desired substance with high purity from a mixture of substances (liquids) through a distillation reaction. That is, by using physical force to form a thin film (membrane) from the liquid mixture to maximize the surface area of ​​the mixture, the evaporation rate can be increased, and the substance can be separated with high purity.

[0053] Furthermore, the present invention can provide a laurolactam synthesis apparatus according to the above-described laurolactam manufacturing method. In this case, since the technical concept is substantially the same as that mentioned in the above-described laurolactam manufacturing method, the substances used, reaction conditions, etc., should naturally be interpreted as substantially the same as those described above.

[0054] The laurolactam synthesis apparatus described above according to another specific example will now be described.

[0055] The laurolactam synthesis apparatus according to the present invention comprises: a first reactor for synthesizing laurolactam from cyclododecanoxime via a Beckmann rearrangement reaction in the presence of a catalyst; an evaporator for removing solvent from the laurolactam synthesized in the first reactor; a second reactor for mixing the laurolactam from which the solvent has been removed in the evaporator with a good solvent to remove the catalyst; and a third reactor for recrystallizing the laurolactam from which the catalyst has been removed in the second reactor with a poor solvent.

[0056] The laurolactam synthesis apparatus described above may also include a filter to remove the catalyst solids precipitated in the second reactor.

[0057] The aforementioned laurolactam synthesis apparatus may also include a film evaporator to separate the heavies from the recrystallized laurolactam.

[0058] The "reactor," "(thin-film) evaporator," and "filter" mentioned in this invention can be any known reactor, (thin-film) evaporator, and filter, and their specifications and dimensions can be appropriately adjusted according to the scale of the process and the environment, and are therefore not limited. Furthermore, each reactor, (thin-film) evaporator, and filter can be equipped with various inlet pipes, outlet pipes, etc., for material inflow or outflow, and the use of various devices for adjusting their inflow and outflow rates, as well as various devices for controlling them, are matters that can be appropriately adjusted by those skilled in the art.

[0059] Below, a laurolactam composition synthesized by the above-described method for manufacturing laurolactam according to another specific example is provided.

[0060] The conversion rate of cyclododecanone oxime in the above laurolactam composition can be 98 to 99%, preferably 99 to 99.5%, more preferably 99.5% to 99.9%, and the selectivity of laurolactam can be 97 to 98%, preferably 98 to 99%, more preferably 99 to 99.5%.

[0061] Furthermore, in the above-mentioned laurolactam composition, relative to the total weight of the laurolactam composition, it may contain less than 5% by weight of the catalyst used in the Beckmann rearrangement reaction, preferably less than 5% by weight, more preferably less than 3% by weight, and most preferably less than 1% by weight or less or 0.5% by weight. When the content of the catalyst exceeds the above-mentioned range, the activity of the anionic initiator used in the anionic polymerization decreases significantly, and therefore the polymerization reaction is not easy to proceed.

[0062] On the other hand, the content of the catalyst contained in the above laurolactam composition can be determined by an ICP (Inductively Coupled Plasma Spectrometer) analyzer.

[0063] Below, another specific example provides a method for manufacturing polylaurolactam, which may include anionic polymerization of the laurolactam composition in the presence of an anionic initiator.

[0064] The polymerization (comonomer) of purified laurolactam and any new monomer can be carried out at 200 to 350°C for 10 to 60 minutes. Specifically, the above polymerization reaction can be carried out at 200 to 300°C, preferably 220 to 250°C, for 10 to 60 minutes, more preferably 10 to 50 minutes, and more preferably 20 to 40 minutes.

[0065] The polymerized polylaurolactam can be a laurolactam-containing polymer, such as a polyamide or a polyether-block amide, preferably polyamide 12 (nylon 12).

[0066] The aforementioned anionic initiator may specifically include one or more selected from NaH, LiH, KH, and n-BuLi. It is known that the catalyst used in the Beckmann rearrangement reaction according to a specific embodiment of the present invention significantly reduces the activity of the aforementioned anionic initiator (killing it). However, the method for producing laurolactam according to a specific embodiment of the present invention and the laurolactam composition utilizing it very effectively remove the aforementioned catalyst, thus allowing the laurolactam monomer to undergo anionic polymerization with a high degree of polymerization in the presence of the aforementioned anionic initiator.

[0067] The above-described anionic polymerization can be carried out in a batch reactor or a continuous reactor (CSTR, PFR, or PBR), preferably in a continuous reactor, but the invention is not limited thereto.

[0068] The weight-average molecular weight of the polymerized polylaurolamide can be greater than 6,000, preferably 6,500 to 14,000, and more preferably 8,000 to 12,000 or 9,000 to 11,000.

[0069] The present invention will now be described in detail through embodiments, but these are only for the purpose of further explaining the invention, and the scope of the invention is not limited to the embodiments described below.

[0070] Example 1

[0071] In a 100 mL round-bottom flask, 3 g of cyclododecanone oxime, 12 g of isopropylcyclohexane, and 0.045 g of cyanuric chloride were added. The mixture was then heated to 95 °C using a heating jacket and stirred at at least 200 rpm. The reaction was completed in 5 minutes, with a conversion rate of over 99% for cyclododecanone oxime and a selectivity of over 99% for laurolactam.

[0072] 100g of the prepared product was injected into an evaporator and distilled at 150°C to remove IPCH through the top of the evaporator. 700g of ethanol was added to the resulting brown solid (laurolactam before purification) and dissolved in a flask. The suspended solid (catalyst) was removed using a 0.22μm filter. 1600g of water was added to the dissolved laurolactam (LL), and the LL solid was recrystallized. The recrystallized LL was filtered to separate the solids. Heavies were removed from the bottom using a thin-film evaporator, and LL was separated from the top. The residual catalyst content and LL yield were determined and recorded in Table 1 below. There were no viscous or non-separating substances between the recrystallized interfaces.

[0073] Next, using the manufactured LL, 50g of LL and catalyst were added to a 100ml round-bottom flask in a weight ratio of LL:NaH:EBS (ethylene bis stearamide):TEOS (tetraethyl orthosilicate):CO2 = 100:0.6:0.36:0.15:0.15, and an anionic polymerization reaction was carried out at 240°C for 30 minutes to produce PA12 (polyamide 12). The degree of polymerization of PA12 is recorded in Table 1 below.

[0074] Example 2

[0075] Except for injecting 300g of ethanol, the same method as in Example 1 was used to separate LL, and the residual catalyst content and LL yield were determined, as shown in Table 1 below.

[0076] Next, anionic polymerization was carried out using the same method as in Example 1 to produce PA12, and the degree of polymerization of PA12 is recorded in Table 1 below.

[0077] Example 3

[0078] Except for injecting 700g of water into laurolactam (LL) dissolved in ethanol, the same method as in Example 1 was used to separate LL, and the residual catalyst content and LL yield were determined and recorded in Table 1 below.

[0079] Next, anionic polymerization was carried out using the same method as in Example 1 to produce PA12, and the degree of polymerization of PA12 is recorded in Table 1 below.

[0080] Comparative Example 1

[0081] 100 g of the product from Manufacturing Example 1 was injected into an evaporator and distilled at 150 °C to remove IPCH through the top of the evaporator. The resulting brown solid was removed from the bottom using a thin-film evaporator to remove the heavy molecules, and the LL was separated from the top. The residual catalyst content and LL yield were determined and recorded in Table 1 below.

[0082] Next, anionic polymerization was carried out using the same method as in Example 1 to produce PA12, and the degree of polymerization of PA12 is recorded in Table 1 below.

[0083] Comparative Example 2

[0084] Except that water was not injected into laurolactam (LL) dissolved in ethanol, the same method as in Example 1 was used to separate LL, and the residual catalyst content and LL yield were determined and recorded in Table 1 below.

[0085] Next, anionic polymerization was carried out using the same method as in Example 1 to produce PA12, and the degree of polymerization of PA12 is recorded in Table 1 below.

[0086] Comparative Example 3

[0087] As a catalyst in Example 1, 0.045 g of cyanuric chloride and 0.03 g of zinc chloride were added for the reaction, and otherwise the reaction was carried out by the same method. The results are shown in Table 1.

[0088] Next, anionic polymerization was carried out using the same method as in Example 1 to produce PA12, and the degree of polymerization of PA12 is recorded in Table 1 below.

[0089] *Method for determining residual catalyst content

[0090] Laurolactam is a solid at room temperature, making it indistinguishable from the solid catalyst used during synthesis. However, when dissolved at 150°C, the catalyst exists as a black solid, thus confirming whether any solid catalyst remains. In Example 1, residual catalyst in the laurolactam was separated as a solid at high temperature and its weight measured, or its content was determined using a solvent capable of dissolving laurolactam.

[0091] *Yield determination method for laurolactam

[0092] 100g of the product from Manufacturing Example 1 was analyzed by GC to determine the content of laurolactam (L1), the content of laurolactam obtained from the top of the thin-film evaporator of Example 1 was determined (L2), and the yield of laurolactam (L2 / L1*100, %) was calculated.

[0093] *Method for determining the molecular weight (degree of polymerization) of PA12

[0094] The stirrer torque value was calculated from the polymerization reactor after the anionic polymerization reaction. The weight-average molecular weight of PA12 was then calculated by performing the inverse operation on the above value.

[0095] *Residual catalyst analysis methods

[0096] The residual catalyst components, specifically the Cl anion content, were analyzed using Combustion IC (combustion ion chromatography). The chloride, generated by the combustion of Ar / O2 gas and absorbed in H2O2 solution, was separated using an ion exchange column in the ion chromatograph and then quantitatively analyzed using a suppression-detection system.

[0097] [Table 1]

[0098]

[0099] Referring to Table 1, in Examples 1 to 3, residual catalyst was actually removed, and anionic polymerization was carried out using purified laurolactam, resulting in the production of PA12. However, in Comparative Example 3, which used a co-catalyst in conjunction with the catalyst composition of Example 1, a relatively large amount of catalyst composition remained at 94 ppm, and the molecular weight during anionic polymerization was also lower than that of the present invention.

[0100] As described above, this invention has been illustrated with specific details and limited embodiments, but this is only provided to facilitate a more comprehensive understanding of the invention. The invention is not limited to the above-described embodiments, and various modifications and variations can be made based on such description by those skilled in the art. Therefore, the spirit of the invention should not be limited to the described embodiments, not only to the scope of the invention claimed below, but also to all scopes equivalent to or having equivalent variations to the scope of the invention claimed.

Claims

1. A method for manufacturing laurolactam, comprising the following steps: a-1) The step of synthesizing cyclododecanone oxime to laurolactam via a Beckmann rearrangement reaction in the presence of cyanuric chloride (TCT) catalyst, wherein the Beckmann rearrangement reaction in step a-1) is the synthesis of cyclododecanone oxime to laurolactam using only cyanuric chloride (TCT) catalyst in the absence of a co-catalyst in a solvent containing isopropylcyclohexane (IPCH). a-2) The step of removing the solvent by distillation of the synthesized laurolactam; b) The synthesized laurolactam from steps a-2) is mixed with a good solvent having a high affinity for laurolactam to remove the catalyst, wherein the good solvent is a C1 to C4 alcohol containing hydroxyl groups, and The laurolactam synthesized in wherein a-1) is mixed with the good solvent at a weight ratio of 1:4 to 1:7; and c) A recrystallization step in which the laurolactam from step b) has had the catalyst removed is mixed with a poor solvent having low affinity for laurolactam, wherein the poor solvent is distilled water or deionized water. The good solvent and the bad solvent are injected in a weight ratio of 1:1.5 to 1:

3.

2. The method for manufacturing laurolactam according to claim 1, characterized in that, Step b) utilizes the difference in solubility of the catalyst and laurolactam in a good solvent to remove the catalyst.

3. The method for manufacturing laurolactam according to claim 1, characterized in that, Step c) utilizes the difference in solubility of laurolactam in good solvents and in bad solvents to recrystallize laurolactam.

4. The method for manufacturing laurolactam according to claim 1, characterized in that, The good solvent and the bad solvent are miscible.

5. The method for manufacturing laurolactam according to claim 1, wherein, It also includes the following steps: The steps include evaporating the recrystallized laurolactam to remove the polymer in a liquid and / or solid state, and separating the laurolactam in a gaseous state.

6. The method for manufacturing laurolactam according to claim 1, further comprising anionicly polymerizing the manufactured laurolactam in the presence of an anionic initiator to produce polylaurolactam.

7. The method for manufacturing laurolactam according to claim 6, wherein, The anionic initiator includes one or more selected from NaH, n-BuLi, KH and LiH.

8. The method for manufacturing laurolactam according to claim 6, wherein, The anionic polymerization was carried out at 200 to 350°C for 10 to 60 minutes.

9. The method for manufacturing laurolactam according to claim 6, wherein, The weight-average molecular weight of the polymerized polylaurolamide is greater than 6000.

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