Process for the preparation of a polyamide elastomer and polyamide elastomer

Abstract

The application relates to the field of high polymer material preparation, and discloses a preparation method of a polyamide elastomer and the polyamide elastomer. The preparation method of the polyamide elastomer comprises the following steps: (1) contacting a diacid monoester with polyhydric alcohol to perform an ester exchange reaction in the presence of an ester exchange catalyst, so as to obtain an intermediate product containing carboxyl groups at one end and hydroxyl groups at the other end; and (2) contacting the intermediate product with a polyamide monomer to perform a reaction, so as to obtain the polyamide elastomer. The preparation method is simple, and the polyamide elastomer prepared by the method has the advantages of good batch stability, high tensile strength and good elastic performance.

Description

Technical Field

[0001] This invention relates to the field of polymer material preparation, specifically to a method for preparing a polyamide elastomer and the polyamide elastomer itself. Background Technology

[0002] Thermoplastic polyamide elastomer (TPAE) is a segmented block copolymer. It consists of multiple alternating blocks, with each repeating block composed of monomer units with completely different chemical structures. One type of block is a hard segment, whose homopolymer has a high glass transition temperature (Tg) or melting point (Tm); the other is a soft segment, which can be either a crystalline or amorphous polymer. In thermoplastic polyamide elastomers, soft and hard segments are alternately linked, forming alternating block copolymers. The soft segments impart flexibility and extensibility to the polymer, while the glassy or semi-crystalline hard segments provide better mechanical properties.

[0003] TPAE has excellent corrosion resistance and good processing performance, and is mainly used in sporting goods, hoses, automobiles, wire and cable sheaths, medical supplies, sealing materials, etc.

[0004] Currently, polyamide elastomers are usually prepared by copolymerization of polyamide as the hard segment and polyether or polyester as the soft segment. During the synthesis process, it is necessary to ensure the equimolar ratio of the soft and hard segments. If there is a slight deviation, the degree of polymerization will not meet the requirements.

[0005] CN1055666639B discloses a method for preparing a polyamide 1012-based thermoplastic elastomer, which uses polyamide 1012 as the hard segment and polyether or polyester diol as the soft segment to synthesize a polyamide 1012 elastomer; CN109206613A discloses a method for preparing a polyamide 6 elastomer, which uses polyamide 6 as the hard segment and amino-terminated polyether as the soft segment to synthesize a nylon 6 elastomer.

[0006] The above-mentioned method for preparing polyamide elastomers is problematic because polyamide prepolymers and polyethers (or polyesters) are macromolecules with specific molecular weight distributions. Simply weighing them makes it difficult to achieve an equimolar ratio of soft and hard segments. An excess of either will result in a low degree of polymerization, poor material properties, and potential problems such as oligomer precipitation and degradation in later stages, making it difficult to meet practical requirements.

[0007] Therefore, researching and developing a method for preparing polyamide elastomers is of great significance. Summary of the Invention

[0008] The purpose of this invention is to overcome the defects of low degree of polymerization and poor performance caused by the non-equimolar reaction of soft and hard segments in the synthesis process of polyamide elastomers in the existing technology. This invention provides a method for preparing polyamide elastomers and a polyamide elastomer. The preparation method is simple, and the polyamide elastomer prepared has the advantages of good batch stability, high tensile strength and good elastic properties.

[0009] To achieve the above objectives, a first aspect of the present invention provides a method for preparing a polyamide elastomer, wherein the preparation method includes:

[0010] (1) In the presence of an ester exchange catalyst, a dicarboxylic acid monoester is contacted with a polyol to carry out an ester exchange reaction, and an intermediate product containing a carboxyl group at one end and a hydroxyl group at the other end is obtained.

[0011] (2) The intermediate product and the polyamide monomer are reacted to obtain a polyamide elastomer.

[0012] A second aspect of the present invention provides a polyamide elastomer prepared by the preparation method described above.

[0013] The above-described technical solution provides a simple preparation method with a short reaction time, overcoming the problems of low polymerization degree and poor material properties caused by the equimolar ratio of soft and hard segments in existing processes. This polyamide elastomer exhibits advantages such as good batch stability, high tensile strength, and excellent elasticity. It can be widely used in the automotive, sporting goods, medical supplies, and electronic components industries. Detailed Implementation

[0014] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0015] The first aspect of this invention provides a method for preparing a polyamide elastomer, wherein the preparation method includes:

[0016] (1) In the presence of an ester exchange catalyst, a dicarboxylic acid monoester is contacted with a polyol to carry out an ester exchange reaction, and an intermediate product containing a carboxyl group at one end and a hydroxyl group at the other end is obtained.

[0017] (2) The intermediate product and the polyamide monomer are reacted to obtain a polyamide elastomer.

[0018] The inventors of this invention unexpectedly discovered that relying solely on precise weighing cannot guarantee an equimolar ratio of soft and hard segments in the reaction. Due to the molecular weight distribution of the raw materials, one side will inevitably be in excess, adversely affecting the product. Solving this problem is key to producing a product with excellent performance and stable quality. The inventors of this invention use a transesterification reaction between a dicarboxylic acid monoester and a polyol to prepare an intermediate product containing both terminal carboxyl and terminal hydroxyl groups. This intermediate product can undergo esterification reactions with the terminal carboxyl groups of polyamide segments, as well as amidation reactions with the terminal amino groups of polyamide segments, and can also undergo esterification reactions itself to increase the molecular chain length. This cleverly bypasses the problem of an equimolar ratio of soft and hard segments, resulting in a product with excellent performance.

[0019] According to the present invention, the dicarboxylic acid monoester has the structure shown in formula (1);

[0020] HOOC-R1-COOR2, Equation (1);

[0021] R1 is C2-C 12 R2 is a straight-chain alkylene, branched alkylene, or aromatic compound group; R2 is methyl, ethyl, or propyl.

[0022] According to the present invention, more preferably, the dicarboxylic acid monoester is selected from aliphatic dicarboxylic acid monoesters and / or aromatic dicarboxylic acid monoesters; in the present invention, the ester group is selected from methyl esters, ethyl esters or propyl esters.

[0023] In this invention, the aliphatic dicarboxylic acid monoester is selected from one or more of bisacrylic acid monoester, sebacic acid monoester, glutaric acid monoester, and octanoic acid monoester; the aromatic dicarboxylic acid monoester is selected from terephthalic acid monoester and / or terephthalic acid monoester.

[0024] According to the present invention, more preferably, the dicarboxylic acid monoester is a straight-chain aliphatic dicarboxylic acid monomethyl ester; most preferably, the dicarboxylic acid monoester is adipic acid monomethyl ester (chemical formula C7H). 12 O4 (molecular weight 160.17).

[0025] According to the present invention, using the aforementioned diacid monoester, on the one hand, the diacid monoester has a low boiling point, and excess is evaporated by raising the temperature; on the other hand, the diacid monoester contains a carboxyl functional group. In this application, the terminal carboxyl functional group of the diacid monoester does not participate in the reaction, but only undergoes transesterification to generate a new ester. According to the present invention, using monomethyl adipic acid, which is the product of the esterification reaction of adipic acid and methanol, the transesterification reaction of monomethyl adipic acid with polyethylene glycol causes the ester bond of monomethyl adipic acid to break again. After breaking, methanol, with its low boiling point and high volatility, is removed, and then a new ester bond is formed with polyethylene glycol. This results in an intermediate product with a carboxyl group at one end, an ester bond in the middle, and a hydroxyl group at the other end of polyethylene glycol. Based on the same principle, using the diacid monoesters defined in this application can also yield an intermediate product with a carboxyl group at one end, an ester bond in the middle, and a hydroxyl group at the other end.

[0026] According to the present invention, the polyol is a polyether polyol and / or a polyester polyol; preferably, the polyol has a molecular weight of 1,000-20,000, more preferably 1,000-3,000, and even more preferably 1,500-2,500.

[0027] According to the present invention, preferably, the polyether polyol is selected from one or more of polyethylene glycol, polypropylene glycol, polybutylene glycol and polytetrahydrofuran ether diol; more preferably, the polyester polyol is polycaprolactone diol.

[0028] According to the present invention, the molar ratio of the diacid monoester to the polyol is (1-1.05):1, preferably (1-1.02):1. In the present invention, preferably, using an excess of diacid monoester can fully complete the transesterification reaction in step (1); if the amount of diacid monoester is too low, the transesterification reaction cannot be completed, a large amount of polyol will remain, and the molar ratio of soft and hard segments cannot be guaranteed, resulting in low degree of polymerization and poor mechanical properties of the product; in the present invention, preferably, using a slightly excess of diacid monoester can theoretically perfectly solve the problem of low degree of polymerization and poor mechanical properties caused by the ratio of soft and hard segments; however, the adipic acid monoester cannot be in excess, as excessive excess can easily generate intermediate products with carboxyl groups at both ends.

[0029] According to the present invention, the polyamide monomer is selected from one or more of lactams, ω-aminocarboxylic acids, ω-aminocarboxylic acid salts, and diamine / dicarboxylic acid mixtures. In the present invention, preferably, the diamine / dicarboxylic acid mixture is an equimolar mixture of diamines / dicarboxylic acids.

[0030] Preferably, the polyamide monomer is selected from one or more of the following: autolactam, undecyllactam, dodecyllactam, aminocaproic acid, aminoundecanoic acid, aminododecanic acid, nylon 66 salt, nylon 612 salt, nylon 56 salt, nylon 1212 salt, nylon 1213 salt, nylon 1012 salt, and nylon 1010 salt.

[0031] Preferably, based on the total weight of the polyamide elastomer, the amount of polyamide is 20-90 wt% and the amount of polyol is 10-80 wt%; preferably, based on the total weight of the polyamide elastomer, the amount of polyamide is 40-80 wt% and the amount of polyol is 20-60 wt%; more preferably, based on the total weight of the polyamide elastomer, the amount of polyamide is 50-70 wt% and the amount of polyol is 30-50 wt%.

[0032] According to the present invention, when the polyamide monomer is a lactam (caprolactam, undecanolactam or dodecalactam), the preparation method further includes: in step (2), adding a ring-opening agent, that is, reacting the intermediate product, the polyamide monomer and the ring-opening agent to obtain a polyamide elastomer.

[0033] According to the present invention, the ring-opening agent is selected from one or more of water, amino acids, sulfuric acid, phosphoric acid, hypophosphoric acid and their salts; wherein the amino acid is selected from one or more of aminocaproic acid, aminoundecanoic acid and aminododecanoic acid; in the present invention, if no ring-opening agent is added, the lactam cannot participate in the reaction through ring opening; if it is not a lactam and ring opening is not required, then no ring-opening agent needs to be added.

[0034] According to the present invention, when water is used as the ring-opening agent, it is preferable to add a larger amount. Preferably, based on the total weight of the polyamide monomer, the amount of the ring-reducing agent is 0.1-20 wt%, more preferably 2-10 wt%, and more preferably 3-5 wt%. When acid and its salt are used as the ring-opening agent, it is generally at the ppm level, and the amount used is relatively small.

[0035] According to the present invention, the transesterification catalyst is selected from one or more of tetrabutyl titanate, antimony trioxide and antimony polyethylene glycol; preferably, the amount of the transesterification catalyst is 0.1-5 wt%, based on the total amount of the dicarboxylic acid monoester and the polyol.

[0036] According to the present invention, in step (1), the conditions for the transesterification reaction include: a temperature of 80-160°C, a pressure of -0.04 MPa to 0 MPa, and a time of 4-20 h; preferably, the conditions for the transesterification reaction include: a temperature of 100-150°C, a pressure of atmospheric pressure of -0.02 MPa to 0 MPa, and a time of 8-18 h.

[0037] According to the present invention, in a preferred embodiment, the transesterification reaction further includes removing excess diacid monoester, which has a low boiling point and excess is removed by increasing the temperature; in the present invention, in step (1), after the transesterification reaction is completed, the temperature is further increased to 160-210°C to remove excess diacid monoester; preferably, after the transesterification reaction is completed, the temperature is further increased to 180-200°C to remove excess diacid monoester.

[0038] According to the present invention, in step (2), the reaction conditions include: a temperature of 220-280°C, a vacuum pressure of -0.02MPa to -0.099MPa, and a time of ≥2h; preferably, the reaction conditions include: a temperature of 240-260°C, a vacuum pressure of -0.06MPa to -0.095MPa, and a time of 3-8h.

[0039] A second aspect of the present invention provides a polyamide elastomer prepared by the preparation method described above.

[0040] According to the present invention, the polyamide elastomer comprises polyamide structural unit blocks provided by polyamide and polyol structural unit blocks provided by polyol, wherein, based on the total weight of the polyamide elastomer, the content of the polyamide blocks is 20-90 wt% and the content of the polyol blocks is 10-80 wt%; preferably, based on the total weight of the polyamide elastomer, the content of the polyamide blocks is 40-80 wt% and the content of the polyol blocks is 20-60 wt%; preferably, based on the total weight of the polyamide elastomer, the content of the polyamide blocks is 50-70 wt% and the content of the polyol blocks is 30-50 wt%.

[0041] According to a particularly preferred embodiment of the present invention, a method for preparing a polyamide elastomer, wherein the preparation method comprises:

[0042] (1) In the presence of a transesterification catalyst (tetrabutyl titanate), a diacid monoester (monomethyl adipate) is contacted with a polyol (one or more of polytetrahydrofuran ether glycol, polyethylene glycol, and polypropylene glycol) to carry out a transesterification reaction. The conditions for the transesterification reaction include: a temperature of 100-150°C, a pressure of 0 MPa, and a time of 8-18 h; the molar ratio of the diacid monoester to the polyol is (1-1.02):1; and the amount of the transesterification catalyst is 0.1-5 wt%, based on the total amount of the diacid monoester and the polyol. An intermediate product containing a carboxyl group at one end and a hydroxyl group at the other end is obtained.

[0043] (2) The intermediate product is reacted with a polyamide monomer (one or more of caprolactam, nylon 1012 salt and aminododecanoic acid), wherein the reaction conditions include: temperature of 240-260℃, vacuum pressure of -0.06MPa to -0.095MPa, and time of 3-8h; to obtain a polyamide elastomer.

[0044] The present invention will be described in detail below through embodiments.

[0045] In the following examples and comparative examples:

[0046] Tensile strength and elongation at break were measured in accordance with GT / B 1040-2006;

[0047] Hardness was measured according to GT / B 2411-2008;

[0048] Example 1

[0049] This embodiment illustrates a polyamide elastomer prepared using the preparation method of the present invention.

[0050] (1) Add excess dicarboxylic acid monoester, polymer polyol and transesterification catalyst to a stainless steel reactor in the proportions shown in Table 1. The transesterification reaction is carried out at 130℃ and 0MPa for 12 hours. After completion, the temperature is raised to 190℃ and maintained for 1 hour to remove excess dicarboxylic acid monoester and obtain intermediate product A.

[0051] (2) Add the polyamide monomer and ring-opening agent together to the reactor containing intermediate product A in step (1), heat to 250°C, evacuate to -0.08MPa, and react for 4 hours;

[0052] As a result, a polyamide elastomer was prepared.

[0053] Example 2

[0054] This embodiment illustrates a polyamide elastomer prepared using the preparation method of the present invention.

[0055] (1) Add excess dicarboxylic acid monoester, polymer polyol and transesterification catalyst to a stainless steel reactor in the proportions shown in Table 1. The transesterification reaction is carried out at 100℃ and 0MPa for 18 hours. After completion, the temperature is raised to 180℃ and maintained for 1 hour to remove excess dicarboxylic acid monoester and obtain intermediate product A.

[0056] (2) Add the polyamide monomer and ring-opening agent together to the reactor containing intermediate product A in step (1), heat to 240°C, evacuate to -0.095MPa, and react for 3 hours;

[0057] As a result, a polyamide elastomer was prepared.

[0058] Example 3

[0059] This embodiment illustrates a polyamide elastomer prepared using the preparation method of the present invention.

[0060] (1) Add excess dicarboxylic acid monoester, polymer polyol and transesterification catalyst to a stainless steel reactor in the proportions shown in Table 1. The transesterification reaction is carried out at 150°C and 0MPa for 8 hours. After the reaction is completed, the temperature is raised to 200°C and maintained for 1 hour to remove excess dicarboxylic acid monoester and obtain intermediate product A.

[0061] (2) Add the polyamide monomer and ring-opening agent together to the reactor containing intermediate product A in step (1), heat to 260°C, evacuate to -0.06MPa, and react for 8 hours;

[0062] As a result, a polyamide elastomer was prepared.

[0063] Example 4

[0064] This embodiment illustrates a polyamide elastomer prepared using the preparation method of the present invention.

[0065] (1) Add excess dicarboxylic acid monoester, polymer polyol and transesterification catalyst to a stainless steel reactor in the proportions shown in Table 1. The transesterification reaction is carried out at 90℃ and 0MPa for 6 hours. After the reaction is completed, the temperature is raised to 170℃ and maintained for 1 hour to remove excess dicarboxylic acid monoester and obtain intermediate product A.

[0066] (2) Add the polyamide monomer and ring-opening agent together to the reactor containing intermediate product A in step (1), heat to 230°C, evacuate to -0.04MPa, and react for 2.5h;

[0067] As a result, a polyamide elastomer was prepared.

[0068] Example 5

[0069] This embodiment illustrates a polyamide elastomer prepared using the preparation method of the present invention.

[0070] (1) Add excess dicarboxylic acid monoester, polymer polyol and transesterification catalyst to a stainless steel reactor in the proportions shown in Table 1. The transesterification reaction is carried out at 80°C and 0MPa for 20 hours. After the reaction is completed, the temperature is raised to 160°C and maintained for 1 hour to remove excess dicarboxylic acid monoester and obtain intermediate product A.

[0071] (2) Add the polyamide monomer and ring-opening agent together to the reactor containing intermediate product A in step (1), heat to 280°C, evacuate to -0.05MPa, and react for 2 hours;

[0072] As a result, a polyamide elastomer was prepared.

[0073] Example 6

[0074] This embodiment illustrates a polyamide elastomer prepared using the preparation method of the present invention.

[0075] (1) Add excess dicarboxylic acid monoester, polymer polyol and transesterification catalyst to a stainless steel reactor in the proportions shown in Table 1. The transesterification reaction is carried out at 160℃ and 0MPa for 4 hours. After the reaction is completed, the temperature is raised to 210℃ and maintained for 1 hour to remove excess dicarboxylic acid monoester and obtain intermediate product A.

[0076] (2) Add the polyamide monomer and ring-opening agent together to the reactor containing intermediate product A in step (1), heat to 220°C, evacuate to -0.02MPa, and react for 2.8h;

[0077] As a result, a polyamide elastomer was prepared.

[0078] Comparative Example 1

[0079] The polyamide elastomer was prepared using the same method as in Example 1, except that the amount of monomethyl adipic acid added was not within the range specified in this application, i.e., the molar ratio of monomethyl adipic acid to polymer polyol was 0.52:1.

[0080] As a result, a polyamide elastomer was prepared.

[0081] Comparative Example 2

[0082] The polyamide elastomer was prepared using the same method as in Example 1, except that “dicarboxylic acid methyl ester” was replaced with “monocarboxylic acid methyl ester”, specifically, the monocarboxylic acid methyl ester was methyl hexanoate.

[0083] As a result, a polyamide elastomer was prepared.

[0084] Comparative Example 3

[0085] The polyamide elastomer was prepared using the same method as in Example 1, except that the amount of polyamide monomer added was 5 wt% of the total weight of the elastomer, i.e., 5 ÷ (3 + 95 + 0.5 + 5 + 3) = 4.6%, approximately 5%.

[0086] As a result, a polyamide elastomer was prepared.

[0087] Comparative Example 4

[0088] Polyamide elastomers were prepared using the same method as in Example 1, except that a conventional route was adopted, without the addition of monomethyl adipic acid, and equimolar amounts of adipic acid were used for end capping.

[0089] As a result, a polyamide elastomer was prepared.

[0090] Table 1

[0091]

[0092]

[0093] Note: In specific embodiments 1-6:

[0094] 1. All dicarboxylic acid monoesters are selected from monomethyl adipic acid; the polymer polyols are selected from one or more of polyethylene glycol, polypropylene glycol, and polytetrahydrofuran glycol (see Table 1 for details); the molecular weight of all polymer polyols is 2000.

[0095] 2. Tetrabutyl titanate was used as the transesterification catalyst.

[0096] 3. The polyamide monomers are selected from one or more of the following: autolactam, nylon 1012 salt, and aminododecanic acid (see Table 1 for details);

[0097] 4. Water is used as the ring-opening agent;

[0098] 5. The unit for component dosage is g;

[0099] 6. Examples 1-6 are denoted as S1-S6, and Comparative Examples 1-4 are denoted as DS1-DS4.

[0100] Test case

[0101] The polyamide elastomers prepared in the examples and comparative examples were subjected to performance tests, and the results are shown in Table 2.

[0102] Table 2

[0103]

[0104]

[0105] As can be seen from the results in Table 2, the polyamide elastomers prepared by the method of the present invention in Examples 1-6 have significantly better tensile strength and elongation at break.

[0106] In Comparative Example 1, due to the lack of sufficient dicarboxylic acid monoesters, the transesterification reaction could not be completed effectively, and the soft and hard segments could not react in equal molar amounts, resulting in a low degree of polymerization and poor mechanical properties of the product.

[0107] Comparative Example 2 uses monocarboxylic acid methyl ester for transesterification, generating a product with a hydroxyl group at one end. This cannot guarantee equimolar reactions of soft and hard segments, nor can it effectively promote molecular chain growth through self-reaction, resulting in a low degree of polymerization and poor mechanical properties of the product.

[0108] Comparative Example 3 had insufficient product strength due to too little polyamide hard segment content.

[0109] Comparative Example 4: Due to traditional techniques, adipic acid is used to end-cap the polyamide, and the end-carboxyl polyamide is copolymerized with polyols to prepare polyamide elastomers. However, the problem of equal molar ratio of soft and hard segments cannot be solved, resulting in a low degree of polymerization and poor performance of the product.

[0110] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for preparing a polyamide elastomer, characterized in that, The preparation method includes: (1) Under the condition of the presence of an ester exchange catalyst, a diacid monoester is contacted with a polyol to carry out an ester exchange reaction to obtain an intermediate product containing a carboxyl group at one end and a hydroxyl group at the other end; wherein the molar ratio of the diacid monoester to the polyol is (1-1.05):

1. (2) The intermediate product, polyamide monomer and ring-opening agent are reacted to obtain polyamide elastomer; The amount of polyamide monomer used is 20-90 wt%, based on the total weight of the polyamide elastomer.

2. The preparation method according to claim 1, wherein, The dicarboxylic acid monoester has the structure shown in formula (1); HOOC-R1-COOR2, Equation (1); Where R1 is C2-C 12 R2 is a straight-chain alkylene, branched alkylene, or aromatic compound group; R2 is methyl, ethyl, or propyl.

3. The preparation method according to claim 1 or 2, wherein, The dicarboxylic acid monoester is an aliphatic dicarboxylic acid monoester and / or an aromatic dicarboxylic acid monoester.

4. The preparation method according to claim 3, wherein, The aliphatic dicarboxylic acid monoester is selected from one or more of the following: succinic acid monoester, sebacic acid monoester, glutaric acid monoester, and octanoic acid monoester.

5. The preparation method according to claim 3, wherein, The aromatic dicarboxylic acid monoester is terephthalic acid monoester and / or terephthalic acid monoester.

6. The preparation method according to claim 1 or 2, wherein, The dicarboxylic acid monoester is a dicarboxylic acid monomethyl ester.

7. The preparation method according to claim 1, wherein, The polyol is a polyether polyol and / or a polyester polyol.

8. The preparation method according to claim 1 or 7, wherein, The molecular weight of the polyol is 1000-20000.

9. The preparation method according to claim 8, wherein, The molecular weight of the polyol is 1000-3000.

10. The preparation method according to claim 7, wherein, The polyether polyol is selected from one or more of polyethylene glycol, polypropylene glycol, polybutylene glycol, and polytetrahydrofuran ether diol.

11. The preparation method according to claim 7, wherein, The polyester polyol is polycaprolactone diol.

12. The preparation method according to claim 1, wherein, The molar ratio of the dicarboxylic acid monoester to the polyol is (1-1.02):

1.

13. The preparation method according to claim 1, wherein, The polyamide monomer is selected from one or more of lactams, ω-aminocarboxylic acids, ω-aminocarboxylic acid salts, and diamine / dicarboxylic acid mixtures.

14. The preparation method according to claim 13, wherein, The polyamide monomer is selected from one or more of the following: autolactam, undecyllactam, dodecyllactam, aminocaproic acid, aminoundecanoic acid, aminododecanoic acid, nylon 66 salt, nylon 612 salt, nylon 56 salt, nylon 1212 salt, nylon 1213 salt, nylon 1012 salt, and nylon 1010 salt.

15. The preparation method according to claim 1, wherein, Based on the total weight of the polyamide elastomer, the amount of polyamide monomer used is 40-80 wt%.

16. The preparation method according to claim 1, wherein, The ring-opening agent is selected from one or more of water, amino acids, sulfuric acid, phosphoric acid, hypophosphoric acid and their salts.

17. The preparation method according to claim 16, wherein, The amino acid is selected from one or more of aminohexanoic acid, aminoundecanoic acid, and aminododecanoic acid.

18. The preparation method according to claim 1, wherein, The transesterification catalyst is selected from one or more of tetrabutyl titanate, antimony trioxide, and antimony polyethylene glycol.

19. The preparation method according to claim 1 or 18, wherein, Based on the total amount of the dicarboxylic acid monoester and the polyol, the amount of the transesterification catalyst is 0.1-5 wt%.

20. The preparation method according to claim 1, wherein, In step (1), the conditions for the transesterification reaction include: a temperature of 80-160℃ and a time of 4-20h.

21. The preparation method according to claim 1, wherein, In step (2), the reaction conditions include: a temperature of 220-280℃, a vacuum pressure of -0.02MPa to -0.099MPa, and a time of ≥2h.

22. A polyamide elastomer prepared by the preparation method according to any one of claims 1-21.

23. The polyamide elastomer according to claim 22, wherein, The polyamide elastomer comprises polyamide structural unit blocks provided by polyamide and polyol structural unit blocks provided by polyol, and based on the total weight of the polyamide elastomer, the content of the polyamide blocks is 20-90 wt% and the content of the polyol blocks is 10-80 wt%.

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