A method for refining lauroyl lysine

Abstract

The present application relates to the chemical product refining technical field, specifically to a kind of lauroyl lysine's refining method, the refining method includes the following steps: S1, lauroyl lysine is added to solvent, heating stirring dissolves, obtain lauroyl lysine dissolving solution, the solvent is the mixture of glacial acetic acid and alcohol additive;S2, slowly adjust the vacuum degree of system in step S1, while the lauroyl lysine dissolving solution is cooled crystallization, after crystallization, hot solid-liquid separation is carried out to obtain solid;S3, the solid obtained in step S2 is added to water and washed, then filtered, dried, to obtain the lauroyl lysine after refining.The lauroyl lysine product obtained by the refining method has a layered structure, which can improve the softness of the powder, skin-friendly and hydrophobic, reduce the pearlescent effect.Moreover, the refining method is simple to operate, the solvent can be recycled, the yield is high, and is suitable for industrial application.

Description

Technical Field

[0001] This invention relates to a method for refining lauroyl lysine, belonging to the field of chemical refining technology. Background Technology

[0002] Lauroyl lysine (also known as: N) ε Lauroyl lysine (L-lauroyl lysine) belongs to the amino acid derivative class and is a hydrophobic powder. Its unique plate-like crystalline structure gives it excellent skin-friendly properties, making it an ideal cosmetic matrix or skin feel modifier for use in foundations and cleansers. It can also be used in color cosmetics and cosmetic powder processing, imparting a good skin-friendly feel and hydrophobicity to the powder. Currently, lauroyl lysine production companies are mainly concentrated in the United States and Japan. Domestic demand for this product mainly relies on imports, while foreign companies sell it to the domestic market at high prices. Therefore, lauroyl lysine has a large market prospect in the Chinese market.

[0003] Currently, domestically produced lauroyl lysine exhibits diverse morphologies, making it difficult to obtain well-formed, plate-like crystals that impart good skin-friendliness and hydrophobicity, thus limiting its application. Chinese patent application CN114026062A discloses: N ε A method for manufacturing long-chain acyl lysine crystals and a composition containing the crystals, the technical solution being: dissolving N in an aqueous solution of an acidic or alkaline organic solvent. ε A solution of long-chain acyl lysine was obtained, and the solution was added dropwise to an acidic solution at a temperature below 20°C, so that N ε -Long-chain acyl lysine crystal crystallization yields N ε - Long-chain acyl lysine, when mixed with other powders, can improve the water repellency and oil repellency of the powder. However, this method has limitations in the preparation of N... ε The process of producing long-chain acyl lysine generates a large amount of solvent-containing wastewater and salt-containing wastewater. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a method for refining lauroyl lysine. This refining method can improve the skin-friendliness and hydrophobicity of lauroyl lysine powder, reduce the pearlescent effect, and is simple to operate. The solvent can be recycled, the yield is high, and the refined solid lauroyl lysine has good application performance.

[0005] The technical solution of the present invention to solve the above-mentioned technical problems is as follows: a method for purifying lauroyl lysine, the purification method comprising the following steps:

[0006] S1. Lauroyl lysine is added to a solvent, heated and stirred to dissolve, to obtain a lauroyl lysine solution. The solvent is a mixture of glacial acetic acid and alcohol additives.

[0007] S2. Slowly adjust the vacuum level of the system in step S1, and at the same time cool down the lauroyl lysine solution to allow it to crystallize. After crystallization, separate the solid and liquid while it is still hot to obtain a solid.

[0008] S3. The solid obtained in step S2 is washed in water, then filtered and dried to obtain refined lauroyl lysine.

[0009] Furthermore, in step S1, the alcohol additive is one or a combination of methanol, anhydrous ethanol, isopropanol, glycerol, and polyethylene glycol.

[0010] Furthermore, in step S1, the mass ratio of lauroyl lysine to glacial acetic acid is 1:(3-15); the mass ratio of lauroyl lysine to alcohol additive is 1:(0.01-0.5).

[0011] Preferably, in step S1, the mass ratio of lauroyl lysine to glacial acetic acid is 1:(3-12); the mass ratio of lauroyl lysine to alcohol additive is 1:(0.05-0.2).

[0012] Furthermore, in step S1, the heating temperature is 60-105℃, and the temperature state of the heating system does not exceed the micro-reflux state. The micro-reflux state means that the reflux liquid flows back in droplet form and does not flow down in a stream.

[0013] Furthermore, in step S2, the vacuum level in the system is adjusted at a rate of 0.05-0.1 MPa / h, the cooling rate is 10-30 °C / h, and the system is in a state of micro-reflux or non-reflux.

[0014] Furthermore, in step S2, when crystallization is complete, the vacuum level in the system is 0.01-0.1 MPa.

[0015] Preferably, in step S2, when crystallization is complete, the vacuum level in the system is 0.02-0.1 MPa.

[0016] Furthermore, in step S2, the final crystallization temperature is 20-50℃.

[0017] Furthermore, in step S2, after the system reaches the final crystallization temperature, it is kept at that temperature for 0.5-2 hours, and then filtered while still hot.

[0018] Furthermore, in step S3, the temperature at which the solid is added to the water for washing is 20-90°C.

[0019] Preferably, in step S3, the temperature at which the solid is added to the water for washing is 30-70°C.

[0020] Furthermore, in step S3, during washing, the mass ratio of solid to water is 1:(3-5).

[0021] The beneficial effects of this invention are:

[0022] (1) In the refining method of the present invention, by adding alcohol additives, the solvent environment of the system is changed to a certain extent, thereby controlling the formation of product crystal shape.

[0023] (2) By controlling the crystallization rate of the product under vacuum conditions, the reflection on the product surface is weakened, thereby reducing the pearlescent effect.

[0024] (3) The lauroyl lysine product has a layered structure, which can improve the softness and skin affinity of the powder and reduce the pearlescent effect.

[0025] (4) The purification method described in this invention is simple to operate, the solvent can be recycled, and the yield is high. The solid lauroyl lysine obtained by the purification method has good properties, which is conducive to the realization of industrial production. Attached Figure Description

[0026] Figure 1 The image shown is an electron microscope image of the purified prelauroyl lysine in the example.

[0027] Figure 2 Here is an electron micrograph of lauroyl lysine after purification in Example 1;

[0028] Figure 3 This is an electron micrograph of lauroyl lysine after purification in Example 2;

[0029] Figure 4 This is an electron micrograph of lauroyl lysine after purification in Example 3;

[0030] Figure 5 This is an electron micrograph of lauroyl lysine after purification in Example 4;

[0031] Figure 6 This is an electron micrograph of lauroyl lysine after purification in Example 5;

[0032] Figure 7 This is an electron micrograph of lauroyl lysine after purification in Example 6;

[0033] Figure 8 Electron micrograph of lauroyl lysine after purification in Comparative Example 1;

[0034] Figure 9 Electron micrograph of lauroyl lysine after purification in Comparative Example 2;

[0035] Figure 10 Electron micrograph of lauroyl lysine after purification in Comparative Example 3;

[0036] Figure 11 Electron micrograph of lauroyl lysine after purification, Comparative Example 4;

[0037] Figure 12 The images show the hydrophobic effects of the refined lauroyl lysine products from Examples 1, 2, and 5.

[0038] Figure 13 The images show the hydrophobic effects of the refined lauroyl lysine products from Comparative Examples 1, 2, and 3. Detailed Implementation

[0039] The specific embodiments of the present invention will be described in detail below. The present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed.

[0040] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used is for describing particular embodiments only and is not intended to limit the invention.

[0041] A method for purifying lauroyl lysine, the purification method comprising the following steps:

[0042] S1. Lauroyl lysine is added to a solvent, heated and stirred to dissolve, to obtain a lauroyl lysine solution. The solvent is a mixture of glacial acetic acid and alcohol additives.

[0043] S2. Slowly adjust the vacuum level of the system in step S1, and at the same time cool down the lauroyl lysine solution to allow it to crystallize. After crystallization, separate the solid and liquid while it is still hot to obtain a solid.

[0044] S3. The solid obtained in step S2 is washed in water, then filtered and dried to obtain refined lauroyl lysine.

[0045] Specifically, in step S1, the alcohol additive is one or more of methanol, anhydrous ethanol, isopropanol, glycerol and polyethylene glycol.

[0046] Specifically, in step S1, the mass ratio of lauroyl lysine to glacial acetic acid is 1:(3-15); the mass ratio of lauroyl lysine to alcohol additive is 1:(0.01-0.5).

[0047] Specifically, in step S1, the heating temperature is 60-105℃, and the temperature state of the heating system does not exceed the micro-reflux state.

[0048] Specifically, in step S2, the vacuum level is adjusted at a rate of 0.05-0.1 MPa / h, and the cooling rate is 10-30℃ / h, resulting in a micro-reflux or non-reflux state within the system. By controlling the adjustment rates of vacuum level and temperature, boiling over is avoided within the system.

[0049] Specifically, in step S2, when crystallization is complete, the vacuum level in the system is 0.02-0.1 MPa.

[0050] Specifically, in step S2, the final crystallization temperature is 20-50℃.

[0051] Specifically, in step S2, after the system reaches the final crystallization temperature, it is kept at that temperature for 0.5-2 hours, and then filtered while still hot.

[0052] Specifically, in step S3, the temperature at which the solid is added to the water for washing is 20-90℃.

[0053] Specifically, in step S3, during washing, the mass ratio of solid to water is 1:(3-5).

[0054] In this embodiment of the invention, the lauroyl lysine raw material used for purifying lauroyl lysine is prepared by conventional methods. Specifically, the lauroyl lysine before purification is prepared using the method disclosed in CN115160173B. The electron micrograph of the lauroyl lysine before purification is shown below. Figure 1 As shown, its pearlescent effect and skin-friendly properties are the blank example data in Table 1.

[0055] Example 1

[0056] (1) Add 40g of lauroyl lysine, 400g of glacial acetic acid and 5g of methanol to the flask, heat to 80℃ to dissolve them completely, and keep warm and stir for 1h to obtain lauroyl lysine solution.

[0057] (2) Subsequently, the vacuum level of the system was slowly adjusted (the adjustment rate of the vacuum level in the system was 0.05 MPa / h), and the system was cooled (the cooling rate was 20℃ / h) to allow lauroyl lysine to crystallize. When the system temperature dropped to 40℃, the vacuum level was 0.05 MPa. Then, the system was kept at this temperature and stirred for 1 hour. After stirring, the lauroyl lysine filter cake was obtained by filtration.

[0058] (3) The above filter cake was put into a flask, 120g of pure water was added, and it was boiled at 35℃ for 1 hour. Then it was filtered and dried to obtain 39.5g of lauroyl lysine, with a yield of 98.8%.

[0059] The electron micrograph of the purified lauroyl lysine in this embodiment is shown below. Figure 2 As shown.

[0060] Example 2

[0061] (1) Add 40g of lauroyl lysine, 400g of glacial acetic acid and 3g of anhydrous ethanol to the flask, heat to 80℃ to dissolve completely, keep warm and stir for 1h to obtain lauroyl lysine solution.

[0062] (2) Subsequently, the vacuum level of the system was slowly adjusted (the adjustment rate of the vacuum level in the system was 0.05 MPa / h), and the system was cooled (the cooling rate was 10℃ / h) to allow lauroyl lysine to crystallize. When the system temperature dropped to 40℃, the vacuum level was 0.06 MPa. Then, the system was kept at this temperature and stirred for 1 hour. After stirring, the lauroyl lysine filter cake was obtained by filtration.

[0063] (3) The above filter cake was put into a flask, 120g of pure water was added, and it was boiled at 35℃ for 1 hour. Then it was filtered and dried to obtain 39.4g of lauroyl lysine, with a yield of 98.5%.

[0064] The electron micrograph of the purified lauroyl lysine in this embodiment is shown below. Figure 3 As shown.

[0065] Example 3

[0066] (1) Add 40g of lauroyl lysine, 400g of glacial acetic acid, 0.5g of polyethylene glycol and 8g of methanol to the flask, heat to 80℃ to dissolve them completely, and keep warm and stir for 1h to obtain lauroyl lysine solution.

[0067] (2) Subsequently, the vacuum level of the system was slowly adjusted (the adjustment rate of the vacuum level in the system was 0.05 MPa / h), and the system was cooled (the cooling rate was 30℃ / h) to allow lauroyl lysine to crystallize. When the system temperature dropped to 50℃, the vacuum level was 0.08 MPa. Then, the system was kept at this temperature and stirred for 1 hour. After stirring, the lauroyl lysine filter cake was obtained by filtration.

[0068] (3) The above filter cake was put into a flask, 120g of pure water was added, and it was boiled at 45℃ for 1 hour. Then it was filtered and dried to obtain 39.2g of lauroyl lysine, with a yield of 98.1%.

[0069] The electron micrograph of the purified lauroyl lysine in this embodiment is shown below. Figure 4 As shown.

[0070] Example 4

[0071] (1) Add 40g of lauroyl lysine, 400g of glacial acetic acid, 0.5g of polyethylene glycol and 8g of anhydrous ethanol to the flask, heat to 80℃ to dissolve them completely, and keep warm and stir for 1h to obtain lauroyl lysine solution.

[0072] (2) The vacuum level of the system was then slowly adjusted (the adjustment rate of the vacuum level in the system was 0.06 MPa / h), and the system was cooled (the cooling rate was 15℃ / h) to allow lauroyl lysine to crystallize. When the system temperature dropped to 50℃, the vacuum level was 0.075 MPa. The system was then kept at this temperature and stirred for 1 hour. After stirring, the lauroyl lysine filter cake was obtained by filtration.

[0073] (3) The above filter cake was put into a flask, 120g of pure water was added, and the mixture was boiled at 45℃ for 1 hour. Then it was filtered and dried to obtain 39.6g of lauroyl lysine, with a yield of 99%.

[0074] The electron micrograph of the purified lauroyl lysine in this embodiment is shown below. Figure 5 As shown.

[0075] Example 5

[0076] (1) Add 40g of lauroyl lysine, 160g of glacial acetic acid and 4g of polyethylene glycol to the flask, heat to 100℃ to dissolve them completely, and keep warm and stir for 1h to obtain lauroyl lysine solution.

[0077] (2) The vacuum level of the system was then slowly adjusted (the adjustment rate of the vacuum level in the system was 0.1 MPa / h), and the system was cooled (the cooling rate was 20℃ / h) to allow lauroyl lysine to crystallize. When the system temperature dropped to 40℃, the vacuum level was 0.095 MPa. The system was then kept at this temperature and stirred for 2 hours. After stirring, the lauroyl lysine filter cake was obtained by filtration.

[0078] (3) The above filter cake was put into a flask, 120g of pure water was added, and it was boiled at 40℃ for 1h. Then it was filtered and dried to obtain 39.4g of lauroyl lysine, with a yield of 98.6%.

[0079] The electron micrograph of the purified lauroyl lysine in this embodiment is shown below. Figure 6 As shown.

[0080] Example 6

[0081] (1) Add 40g of lauroyl lysine, 240g of glacial acetic acid, 4g of polyethylene glycol and 0.5g of methanol to the flask, heat to 95℃ to dissolve them completely, and keep warm and stir for 1h to obtain lauroyl lysine solution.

[0082] (2) Then, the vacuum degree of the system was slowly adjusted (the adjustment rate of the vacuum degree in the system was 0.1 MPa / h), and the system was cooled (the cooling rate was 10℃ / h) to allow lauroyl lysine to crystallize. When the system temperature dropped to 30℃, the vacuum degree was 0.085 MPa. Then, the system was kept at this temperature and stirred for 1 hour. After stirring, the lauroyl lysine filter cake was obtained by filtration.

[0083] (3) The above filter cake was put into a flask, 120g of pure water was added, and it was boiled at 40℃ for 1h. Then it was filtered and dried to obtain 39.4g of lauroyl lysine, with a yield of 98.6%.

[0084] The electron micrograph of the purified lauroyl lysine in this embodiment is shown below. Figure 7 As shown.

[0085] Example 7

[0086] (1) Add 40g of lauroyl lysine, 120g of glacial acetic acid, 18g of polyethylene glycol and 2g of glycerol to the flask, heat to 105℃ to dissolve them completely, and keep warm and stir for 1h to obtain lauroyl lysine solution.

[0087] (2) The vacuum level of the system was then slowly adjusted (the adjustment rate of the vacuum level in the system was 0.05 MPa / h), and the system was cooled (the cooling rate was 25℃ / h) to allow lauroyl lysine to crystallize. When the system temperature dropped to 30℃, the vacuum level was 0.01 MPa. The system was then kept at this temperature and stirred for 0.5 h. After stirring, the lauroyl lysine filter cake was obtained by filtration.

[0088] (3) The above filter cake was put into a flask, 150g of pure water was added, and the mixture was kept at 20℃ and stirred for 1h. Then it was filtered and dried to obtain 39.2g of lauroyl lysine, with a yield of 98.0%.

[0089] Example 8

[0090] (1) Add 40g of lauroyl lysine, 600g of glacial acetic acid and 0.4g of methanol to the flask, heat to 60℃ to dissolve them completely, and keep warm and stir for 1h to obtain lauroyl lysine solution.

[0091] (2) The vacuum level of the system was then slowly adjusted (the adjustment rate of the vacuum level in the system was 0.08 MPa / h), and the system was cooled (the cooling rate was 10℃ / h) to allow lauroyl lysine to crystallize. When the system temperature dropped to 20℃, the vacuum level was 0.02 MPa. The system was then kept warm and stirred for 1.5 h. After stirring, the lauroyl lysine filter cake was obtained by filtration.

[0092] (3) The above filter cake was put into a flask, 150g of pure water was added, and the mixture was kept at 90℃ and stirred for 1h. Then it was filtered and dried to obtain 39.0g of lauroyl lysine, with a yield of 97.5%.

[0093] Comparative Example 1

[0094] Lauroyl lysine was purified using the same method as in Example 5, except that polyethylene glycol was not added in step (1), i.e. no alcohol additives were added; and the entire process in step (2) was carried out under normal pressure.

[0095] After purification, this comparative example yielded 37.2g of lauroyl lysine, with a yield of 93%.

[0096] Electron micrograph of purified lauroyl lysine in this comparative example is shown below. Figure 8 As shown.

[0097] Comparative Example 2

[0098] Lauroyl lysine was purified using the same method as in Example 5, except that the entire process in step (2) was carried out under normal pressure.

[0099] After purification, this comparative example yielded 37.8 g of lauroyl lysine, with a yield of 94.6%.

[0100] Electron micrograph of purified lauroyl lysine in this comparative example is shown below. Figure 9 As shown.

[0101] Comparative Example 3

[0102] Lauroyl lysine was purified using the same method as in Example 5, except that polyethylene glycol was not added in step (1), i.e. no alcohol additives were added.

[0103] After purification, this comparative example yielded 37.4 g of lauroyl lysine, with a yield of 93.5%.

[0104] Electron micrograph of purified lauroyl lysine in this comparative example is shown below. Figure 10 As shown.

[0105] Comparative Example 4

[0106] Lauroyl lysine was purified using the same method as in Example 5, except that in step (1), the amount of polyethylene glycol added was 40g, which increased the amount of alcohol additive.

[0107] After purification, this comparative example yielded 37.0 g of lauroyl lysine, with a yield of 92.5%.

[0108] Electron micrograph of purified lauroyl lysine in this comparative example is shown below. Figure 11 As shown.

[0109] The refined lauroyl lysine from each example and comparative example was applied to the forearms of 10 participants. The pearlescent effect of each product was observed and the softness and skin-friendliness of the product were felt. The specific results are shown in Table 1 below.

[0110] The pearlescent effect was categorized into three cases: pearlescent effect, weak pearlescent effect, and no pearlescent effect. The proportion of people in each case out of the total number of test participants was calculated (referred to as the average point). The average point for the pearlescent effect was 0-0.3, represented by √; the average point for the weak pearlescent effect was 0.3-0.6, represented by ○; and the average point for the no pearlescent effect was 0.6-1, represented by ×.

[0111] The skin-friendly properties were categorized into three levels: poor skin-friendly, good skin-friendly, and excellent skin-friendly. The proportion of people in each level was calculated (referred to as the average point). The average point for poor skin-friendly properties was 0-0.3, represented by -; the average point for good skin-friendly properties was 0.3-0.6, represented by +; and the average point for excellent skin-friendly properties was 0.6-1, represented by *.

[0112] Table 1. Pearlescent effect and skin-friendly properties of the products

[0113]

[0114] pass Figure 1 and Figure 2-7 The electron micrographs clearly show that the purification method described in this invention can produce high-quality lauroyl lysine with a sheet-like structure. Furthermore, the experimental data from Examples 1-8 in Table 1 demonstrate that the lauroyl lysine obtained using the purification method described in this invention has good skin-friendliness and no pearlescent effect.

[0115] A comparison of experimental data from Comparative Examples 1-3 and Example 5 shows that if no alcohol additives are added or negative pressure conditions are used during the refining process of lauroyl lysine, the product's softness and skin-friendliness will decrease, and it will have a pearlescent effect. Furthermore, from... Figures 8-9 The electron micrographs also show that if alcohol additives are not added or negative pressure conditions are not used during the purification process, a good lauroyl lysine product with a lamellar structure cannot be obtained. This is because reasonably changing the solvent environment of the system and the precipitation rate of crystals can effectively control the shape of the crystals and the reflective effect of the crystal surface.

[0116] A comparison of the experimental data from Comparative Example 4 and Example 5 shows that excessive use of alcohol additives during the refining process leads to a decrease in product yield and also reduces the product's softness and skin-friendliness, resulting in a pearlescent effect. Excessive additive use also causes the product to have a strip-like shape. Therefore, using the alcohol additive dosage specified in this invention is more conducive to obtaining a high-quality lauroyl lysine product.

[0117] Furthermore, the lauroyl lysine product obtained using the purification method described in this invention exhibits better hydrophobicity. The same mass of lauroyl lysine products purified in Examples 1, 2, and 5 were placed in beakers containing the same amount of water. After sonication for 30 minutes, the distribution of lauroyl lysine at the bottom of the beakers and in the water was observed. Figure 12 As shown. The same method was used to determine the hydrophobicity of the purified lauroyl lysine products from Comparative Examples 1, 2, and 3, as shown. Figure 13 As shown.

[0118] The less lauroyl lysine distributed at the bottom of the beaker and in the water, the worse the dispersibility of the lauroyl lysine product in water, and the better its hydrophobic effect. Figure 12 and Figure 13 Data comparison shows that the lauroyl lysine products obtained by the purification method described in this invention in Examples 1, 2 and 5 have better hydrophobicity.

[0119] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are exhaustively listed. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0120] For those skilled in the art, various modifications and improvements can be made without departing from the concept of the present invention, and these modifications and improvements are all within the scope of protection of the present invention. The scope of protection of the present invention is defined by the appended claims.

Claims

1. A purification method of lauroyl lysine, characterized by, The refining method comprises the following steps: S1, adding lauroyl lysine into a solvent, heating and stirring to dissolve, to obtain a lauroyl lysine solution, wherein the solvent is a mixture of glacial acetic acid and an alcohol additive; S2, slowly adjusting the vacuum degree of the system in step S1, while cooling and crystallizing the lauroyl lysine solution, after the crystallization is completed, hot solid-liquid separation is performed to obtain a solid; S3, adding the solid obtained in step S2 into water for washing, then filtering and drying to obtain refined lauroyl lysine; In step S1, the mass ratio of lauroyl lysine to glacial acetic acid is 1: (3-15), and the mass ratio of lauroyl lysine to the alcohol additive is 1: (0.01-0.5); In step S2, the adjusting speed of the vacuum degree in the system is 0.05-0.1 Mpa / h, the cooling speed is 10-30℃ / h, and the system is in a micro-reflux or non-reflux state; In step S2, the vacuum degree in the system at the end of crystallization is 0.01-0.1 Mpa; In step S2, the final crystallization temperature is 20-50℃; In step S1, the alcohol additive is one or a combination of multiple of methanol, anhydrous ethanol, isopropyl alcohol, glycerol and polyethylene glycol.

2. The purification method of lauroyl lysine according to claim 1, characterized in that, In step S1, the heating temperature is 60-105℃, and the temperature state of the heating system does not exceed a micro-reflux state.

3. The method of purifying lauroyl lysine according to claim 1, wherein In step S2, after the system reaches the final crystallization temperature, it is kept for 0.5-2h, and then hot filtration is performed.

4. The method of purifying lauroyl lysine according to claim 1, wherein In step S3, the temperature for adding the solid into water for washing is 20-90℃.

5. The method of purifying lauroyl lysine according to claim 1, wherein In step S3, during washing, the mass ratio of the solid to water is 1: (3-5).

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