A bio-based polyamide elastomer and a method of making the same

Abstract

This invention belongs to the field of polymer synthetic chemistry and discloses a bio-based polyamide elastomer and its preparation method. The method includes first adding sebacic acid, decanediamine, and deionized water to a reaction vessel for reaction, then adding polytrimethylene ether glycol and a catalyst to the reaction vessel for polycondensation to obtain the bio-based polyamide elastomer. The bio-based polyamide elastomer method of this invention is suitable for industrial production and has advantages such as environmental friendliness, simple operation, easy processing, readily available raw materials, and stable yield. Furthermore, this type of copolymer exhibits good thermodynamic properties, mechanical properties, and good processability.

Description

Technical Field

[0001] This invention relates to the field of polymer synthetic chemistry, specifically to a bio-based polyamide elastomer and its preparation method. Background Technology

[0002] Thermoplastic polyamide elastomers (TPAEs), as a high-end category with outstanding performance among thermoplastic elastomers, are block copolymers composed of polyamide hard segments and flexible soft segments linked by chemical bonds. With the rapid development of emerging industries such as new energy and high-end manufacturing, market demand for high-performance TPAE products will gradually increase. Currently, commercially produced TPAE products globally primarily rely on petroleum-based raw materials for their polyamide hard segments, with PA6 and PA12 accounting for over 90% of products. However, the existing petroleum-based TPAE system faces two major difficulties that seriously affect the sustainable development of the industry and the self-sufficiency and controllability of the domestic supply chain. First, its raw materials depend on non-renewable fossil resources, resulting in low biocarbon content and insufficient environmental friendliness. PA6 and PA12 monomers are both derived from petroleum refining products, leading to high carbon emissions and significant environmental impact during production. Furthermore, the products are difficult to biodegrade naturally, which contradicts the "dual carbon" goals and the requirements of a circular economy. Stricter environmental regulations further limit their application scenarios. Second, the core technologies for high-end products are controlled by overseas companies. PA12-based TPAEs occupy a major share of the high-end market due to their excellent performance. However, the synthesis technology of the core monomer dodecyl lactam is mastered by foreign countries. Domestic PA12 production capacity is limited and raw materials rely on imports, which restricts the independent production of high-end TPAEs and makes it difficult to meet the demand for domestic substitution. PA6-based TPAEs, which have achieved large-scale domestic production, are only suitable for low- and mid-end scenarios due to defects such as high water absorption and poor dimensional stability in humid and hot environments. They cannot meet the strict requirements of high-end fields.

[0003] To address the resource and environmental issues of petroleum-based polyamide materials, bio-based polyamide materials made from renewable biomass have become a global research and industrialization hotspot in the field of polymer materials. In the bio-based polyamide elastomer copolymerized from PA1010 and polytrimethylene ether glycol proposed in this patent, PA1010 is a fully bio-based polyamide material with completely independent intellectual property rights in my country and has achieved full-chain domestic mass production. Its key raw materials, sebacic acid and sebacic diamine, are both deep-processed products from non-grain crop castor oil, not relying on fossil resources. The carbon emissions during production are significantly lower than those of petroleum-based polyamides. Furthermore, the material itself possesses low water absorption, excellent low-temperature resistance, dimensional stability, and mechanical properties similar to PA12, making it an ideal domestic bio-based matrix material to replace imported PA12. Polytrimethylene ether glycol, as a fully bio-based flexible soft segment raw material, has a much lower environmental footprint than traditional petroleum-based polyethers and exhibits good compatibility with polyamide segments, giving the elastomer material excellent flexibility, resilience, and low-temperature toughness. It achieves 100% bio-based substitution from the raw material end and solves the problems of insufficient performance of existing products, complex synthesis process, high production cost, and poor domestic self-control, providing a green, sustainable, high-performance, and cost-controllable domestic polyamide elastomer material for the high-end manufacturing field. Summary of the Invention

[0004] Purpose of the invention: The technical problem to be solved by the present invention is to address the shortcomings of existing technologies that have low bio-carbon content and poor mechanical properties in most polyamide elastomers, and to provide a bio-based polyamide elastomer and its preparation method.

[0005] To solve the above-mentioned technical problems, the present invention discloses the following technical solution:

[0006] In a first aspect, the present invention provides a bio-based polyamide elastomer, with the general formula shown in Formula I:

[0007]

[0008] in,

[0009] R is selected from C8 alkyl groups;

[0010] n is any integer from 2 to 20;

[0011] m is selected from any integer between 5 and 70.

[0012] Secondly, the preparation method shown in Formula I provided by the present invention includes the following specific process steps and conditions:

[0013] Sebacic acid and decanediamine were added in a specific molar ratio along with deionized water and sealed in a high-pressure reactor. The reactor was heated to temperature T1 to initiate the reaction, maintained for time A1, and then heated further until temperature T2 was reached. The pressure was then maintained at P1 for a reaction time A2. Subsequently, the pressure was gradually reduced to atmospheric pressure, and the reactor was stirred and evacuated for time A3. The temperature was then lowered to T3, and polytrimethylene ether glycol and a catalyst were added to the high-pressure reactor. The reactor was heated to temperature T4 and stirred for a period of time, then evacuated under negative pressure and stirred for time A4. After the reaction was completed, the reactor was cooled in deionized water to obtain a polyamide block copolymer. This copolymer not only possesses excellent mechanical properties, heat resistance, and chemical stability, but also exhibits good low-temperature flexibility and resilience.

[0014] The molecular weight of the polytrimethylene ether glycol is 500–5000 g / mol.

[0015] The molar ratio of sebacic acid, sebacic acid diamine, and polytrimethylene ether glycol is 100:(1-100):(1-100).

[0016] The deionized water comprises 5-40 wt%.

[0017] The catalyst is tetrabutyl titanate, tetraisopropyl titanate, dibutyltin dilaurate, stannous octoate, zirconium n-butoxide, and antimony trioxide, preferably zirconium n-butoxide, and the amount of catalyst is 500-10000 ppm.

[0018] Wherein, the temperature of T1 is 80–120℃, the reaction time of A1 is 1–3 h, and the pressure of P1 is 1.0–3 MPa. The temperature of T2 is 220–280℃, and the reaction time of A2 is 1.5–4 h. The reaction time of A3 is 0.5–2 h, the temperature of T3 is 80–160℃, the temperature of T4 is 240–300℃, and the reaction time of A4 is 5–24 h.

[0019] The bio-based polyamide elastomer prepared by this invention has excellent thermal properties, and the 5% thermal decomposition temperature (T) d，5％ The maximum thermal decomposition temperature is 380–400℃. d，max The melting temperature is 420–450℃, and the melting temperature (T) is... m The crystallization temperature is 160–200℃ (T). c The temperature range is 140–160℃, the tensile strength is 10–50 MPa, the elongation at break is 100–1500%, the elastic recovery rate is 85–95%, the impact strength is NB (non-fracture), the Shore hardness is D is 30–80, and the melt index (235℃) is 5–80 g / 10 min.

[0020] Beneficial effects:

[0021] (1) Achieving 100% bio-based construction. Compared with mainstream polyamide elastomers on the market that use PA6 and PA12 as hard segments, the raw materials of this invention are completely free from dependence on petroleum-based monomers, which can effectively reduce the environmental pollution caused by traditional petroleum-based polyamide materials, meet the development needs of green materials in the global circular economy, and have environmental compatibility far superior to existing petroleum-based polyamide elastomers;

[0022] (2) Superior performance compared to traditional polytetramethylene ether glycol system, with excellent thermal stability and mechanical properties that are precisely adjustable. Using polytrimethylene ether glycol as the soft segment and PA1010 as the hard segment to construct a block copolymer, compared to the traditional polytetramethylene ether glycol soft segment system, the odd-numbered carbon chain structure of polytrimethylene ether glycol gives the material a lower tendency for soft segment crystallization, a faster elastic recovery rate and a smaller permanent deformation, resulting in a comprehensive improvement in resilience, flexural fatigue resistance and hydrolysis resistance; at the same time, it maintains the inherent high thermal stability, excellent tensile strength and toughness of polyamide elastomers, and by controlling the hard segment / soft segment ratio, molecular weight and chain segment distribution, key indicators such as hardness, modulus and low-temperature toughness can be adjusted over a wide range to meet the differentiated application needs of multiple fields;

[0023] (3) The one-pot two-step feeding synthesis method is simple and easy to understand, with low cost, strong controllability, and is convenient for large-scale industrial production. It has strong practical application feasibility and economic benefits. Attached Figure Description

[0024] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, and the advantages of the present invention in the above and / or other aspects will become clearer.

[0025] Table 1 shows the performance tests of the polyamides prepared in Examples 1-10 and Comparative Example 1.

[0026] Figure 1 Bio-based polyamide elastomer of Example 1 1 H NMR spectrum.

[0027] Figure 2 The image shows the TGA diagram of the bio-based polyamide elastomer from Example 1.

[0028] Figure 3 This is a DSC diagram of the bio-based polyamide elastomer from Example 1.

[0029] Figure 4 This is a tensile test diagram of the bio-based polyamide elastomer in Example 1.

[0030] Figure 5 This is a cyclic tensile test diagram of the bio-based polyamide elastomer in Example 1. Detailed Implementation

[0031] The present invention can be better understood from the following embodiments. However, those skilled in the art will readily understand that the descriptions in the embodiments are for illustrative purposes only and should not, and will not, limit the invention as detailed in the claims.

[0032] Unless otherwise specified, the experimental methods described in the following examples are conventional methods; unless otherwise specified, the reagents and materials are commercially available.

[0033] In the following examples, a 400MHz Bruker nuclear magnetic resonance instrument was used to measure the product: a polyamide sample was placed in an NMR tube, deuterated trifluoroacetic acid was added, and the sample was measured after shaking until it was completely dissolved.

[0034] The thermal stability (T) of the polymer in this invention d，5％ T d，max The results were measured using a TGA-550 instrument. 4–8 mg of the polymerization product was weighed and placed in a platinum pan under a nitrogen protective atmosphere (gas flow rate of 50 mL / min). -1 The program is set to first heat up, then cool down, and finally heat up again. The initial temperature is -30℃, and the final temperature is the temperature at which the sample degrades by 0.5% under thermogravimetric analysis. Cooling involves lowering the sample from the highest temperature back to -30℃. The time interval is 10℃ per minute. -1 The melting point was obtained from the second temperature scan curve.

[0035] The melting temperature (T) of the polymer in this invention m ), crystallization temperature (T) c The measurements were taken using a DSC-250 instrument. The heating and cooling processes of the polymer were measured under a nitrogen protective atmosphere at a gas flow rate of 50 mL / min. -1 Weigh 4–8 mg of sample into a sample pan, raise the temperature from 30°C to 250°C at a rate of 10°C / min, hold for 3 minutes, then cool from 250°C to 30°C at a rate of 10°C / min, and finally raise the temperature back to 250°C.

[0036] The melt index test of the polymer in this invention is as follows: After the sample is thoroughly dried, the melt indexer barrel is preheated to the standard temperature of 235°C and maintained at a constant temperature. 3-8g of the dried sample is weighed and added to the barrel. The material is compacted using the piston rod within 1 minute to remove residual air bubbles. A 2.16kg weight is then applied to extrude the melt through the die, discarding any sample strips containing air bubbles from the initial stage. After the extrusion stabilizes, sample strips are cut at 30-60s intervals, controlling the length to be between 10-20mm. The mass of at least three air-free sample strips is accurately weighed, and the melt index is calculated. The final result is expressed in g / 10min.

[0037] In this invention, the mechanical properties of the polymer samples were tested using an electronic universal testing machine (TMG104). The tensile test conditions were in accordance with the national standard GB / T1040.1-2006, with a tensile rate of 50 mm / min and a test temperature of room temperature.

[0038] Example 1

[0039] 45.2 g of sebacic acid, 27.1 g of decanediamine, and 14.4 g of deionized water were sequentially added to a high-pressure reactor, which was then sealed. The reactor was heated to 120°C and maintained at this temperature for 1 hour to allow the reaction to proceed. The temperature was then further increased to 240°C, and the pressure was maintained at 1.75 MPa for 2 hours. Initially, the pressure was gradually reduced to atmospheric pressure, and the reactor was stirred and evacuated for 1 hour. The temperature was then lowered to 120°C, and 64.8 g of polytrimethylene ether glycol and 0.54 g of zirconium butoxide were added to the high-pressure reactor. The temperature was then increased to 260°C and stirred for a period of time. Finally, a vacuum was applied and the reactor was stirred for 10 hours.

[0040] After the polycondensation is complete, stop stirring, drain the polymer product into cooling water, wash it three times with anhydrous ethanol, place it in a vacuum drying oven at 60°C, and dry it for 12 hours to obtain bio-based polyamide elastomer with a melt index of 20.5 g / 10 min.

[0041] Example 2

[0042] 42.5g of sebacic acid, 30.5g of decanediamine, and 14.6g of deionized water were sequentially added to a high-pressure reactor, which was then sealed. The reactor was heated to 90°C and maintained at that temperature for 1 hour to allow the reaction to proceed. The temperature was then further increased to 230°C, and the pressure was maintained at 1.7MPa for 1.5 hours. Initially, the pressure was gradually reduced to atmospheric pressure, and the reactor was stirred and evacuated for 1 hour. The temperature was then lowered to 120°C, and 32.4g of polytrimethylene ether glycol and 0.42g of zirconium n-butoxide were added to the high-pressure reactor. The temperature was then increased to 270°C and stirred for a period of time. Finally, a vacuum was applied and the reactor was stirred for 10 hours.

[0043] After the polycondensation is complete, stop stirring, drain the polymer product into cooling water, wash it three times with anhydrous ethanol, place it in a vacuum drying oven at 60°C, and dry it for 12 hours to obtain bio-based polyamide elastomer with a melt index of 24.3 g / 10 min.

[0044] Example 3

[0045] 50.6 g of sebacic acid, 38.4 g of decanediamine, and 17.8 g of deionized water were sequentially added to a high-pressure reactor, which was then sealed. The reactor was heated to 90°C and maintained at that temperature for 1 hour to allow the reaction to proceed. The temperature was then further increased to 230°C, and the pressure was maintained at 1.7 MPa for 1.5 hours. Initially, the pressure was gradually reduced to atmospheric pressure, and the reactor was stirred and evacuated for 1 hour. The temperature was then lowered to 120°C, and 26.5 g of polytrimethylene ether glycol and 0.46 g of zirconium butoxide were added to the high-pressure reactor. The temperature was then increased to 260°C and stirred for a period of time. Finally, a vacuum was applied and the reactor was stirred for 11 hours.

[0046] After the polycondensation is complete, stop stirring, drain the polymer product into cooling water, wash it three times with anhydrous ethanol, place it in a vacuum drying oven at 60°C, and dry it for 12 hours to obtain bio-based polyamide elastomer with a melt index of 19.2 g / 10 min.

[0047] Example 4

[0048] 54.8 g of sebacic acid, 42.9 g of decanediamine, and 19.5 g of deionized water were sequentially added to a high-pressure reactor, which was then sealed. The reactor was heated to 90°C and maintained at that temperature for 1 hour to allow the reaction to proceed. The temperature was then further increased to 230°C, and the pressure was maintained at 1.7 MPa for 1.5 hours. Initially, the pressure was gradually reduced to atmospheric pressure, and the reactor was stirred and evacuated for 1 hour. The temperature was then lowered to 120°C, and 21.6 g of polytrimethylene ether glycol and 0.47 g of zirconium butoxide were added to the high-pressure reactor. The temperature was then increased to 260°C and stirred for a period of time. Finally, a vacuum was applied and the reactor was stirred for 10 hours.

[0049] After the polycondensation is complete, stop stirring, drain the polymer product into cooling water, wash it three times with anhydrous ethanol, place it in a vacuum drying oven at 60°C, and dry it for 12 hours to obtain bio-based polyamide elastomer with a melt index of 15.4 g / 10 min.

[0050] Example 5

[0051] 45.2 g of sebacic acid, 27.1 g of decanediamine, and 14.4 g of deionized water were sequentially added to a high-pressure reactor, which was then sealed. The reactor was heated to 120°C and maintained at this temperature for 1 hour to allow the reaction to proceed. The temperature was then further increased to 240°C, and the pressure was maintained at 1.75 MPa for 2 hours. Initially, the pressure was gradually reduced to atmospheric pressure, and the reactor was stirred and evacuated for 1 hour. The temperature was then lowered to 120°C, and 137.8 g of polytrimethylene ether glycol and 0.84 g of zirconium n-butoxide were added to the high-pressure reactor. The temperature was then increased to 260°C and stirred for a period of time. Finally, a vacuum was applied and the reactor was stirred for 10 hours.

[0052] After the polycondensation is complete, stop stirring, drain the polymer product into cooling water, wash it three times with anhydrous ethanol, place it in a vacuum drying oven at 60°C, and dry it for 12 hours to obtain bio-based polyamide elastomer with a melt index of 27.8 g / 10 min.

[0053] Example 6

[0054] 42.5g of sebacic acid, 30.5g of decanediamine, and 14.6g of deionized water were sequentially added to a high-pressure reactor, which was then sealed. The reactor was heated to 100°C and maintained at this temperature for 1 hour to allow the reaction to proceed. The temperature was then further increased to 240°C, and the pressure was maintained at 1.8MPa for 2 hours. Initially, the pressure was gradually reduced to atmospheric pressure, and the reactor was stirred and evacuated for 0.5 hours. The temperature was then lowered to 120°C, and 68.9g of polytrimethylene ether glycol and 0.57g of zirconium n-butoxide were added to the high-pressure reactor. The temperature was then increased to 260°C and stirred for a period of time. Finally, a vacuum was applied and the reactor was stirred for 10 hours.

[0055] After the polycondensation is complete, stop stirring, drain the polymer product into cooling water, wash it three times with anhydrous ethanol, place it in a vacuum drying oven at 60°C, and dry it for 12 hours to obtain bio-based polyamide elastomer with a melt index of 26.3 g / 10 min.

[0056] Example 7

[0057] 50.6 g of sebacic acid, 38.4 g of decanediamine, and 17.8 g of deionized water were sequentially added to a high-pressure reactor, which was then sealed. The reactor was heated to 90°C and maintained at that temperature for 1 hour to allow the reaction to proceed. The temperature was then further increased to 230°C, and the pressure was maintained at 1.7 MPa for 1.5 hours. Initially, the pressure was gradually reduced to atmospheric pressure, and the reactor was stirred and evacuated for 1 hour. The temperature was then lowered to 120°C, and 56.5 g of polytrimethylene ether glycol and 0.58 g of zirconium butoxide were added to the high-pressure reactor. The temperature was then increased to 260°C and stirred for a period of time. Finally, a vacuum was applied and the reactor was stirred for 10 hours.

[0058] After the polycondensation is complete, stop stirring, drain the polymer product into cooling water, wash it three times with anhydrous ethanol, place it in a vacuum drying oven at 60°C, and dry it for 12 hours to obtain bio-based polyamide elastomer with a melt index of 22.6 g / 10 min.

[0059] Example 8

[0060] 54.8 g of sebacic acid, 42.9 g of decanediamine, and 19.5 g of deionized water were sequentially added to a high-pressure reactor, which was then sealed. The reactor was heated to 90°C and maintained at that temperature for 1 hour to allow the reaction to proceed. The temperature was then further increased to 230°C, and the pressure was maintained at 1.7 MPa for 1.5 hours. Initially, the pressure was gradually reduced to atmospheric pressure, and the reactor was stirred and evacuated for 1 hour. The temperature was then lowered to 120°C, and 45.9 g of polytrimethylene ether glycol and 0.57 g of zirconium butoxide were added to the high-pressure reactor. The temperature was then increased to 260°C and stirred for a period of time. Finally, a vacuum was applied and the reactor was stirred for 10 hours.

[0061] After the polycondensation is complete, stop stirring, drain the polymer product into cooling water, wash it three times with anhydrous ethanol, place it in a vacuum drying oven at 60°C, and dry it for 12 hours to obtain bio-based polyamide elastomer with a melt index of 17.7 g / 10 min.

[0062] Example 9

[0063] 45.2 g of sebacic acid, 27.1 g of decanediamine, and 14.4 g of deionized water were sequentially added to a high-pressure reactor, which was then sealed. The reactor was heated to 120°C and maintained at this temperature for 1 hour to allow the reaction to proceed. The temperature was then further increased to 240°C, and the pressure was maintained at 1.75 MPa for 2 hours. Initially, the pressure was gradually reduced to atmospheric pressure, and the reactor was stirred and evacuated for 1 hour. The temperature was then lowered to 120°C, and 64.8 g of polytrimethylene ether glycol and 0.54 g of zirconium butoxide were added to the high-pressure reactor. The temperature was then increased to 260°C and stirred for a period of time. Finally, a vacuum was applied and the reactor was stirred for 9 hours.

[0064] After the polycondensation is complete, stop stirring, drain the polymer product into cooling water, wash it three times with anhydrous ethanol, place it in a vacuum drying oven at 60°C, and dry it for 12 hours to obtain bio-based polyamide elastomer with a melt index of 23.2 g / 10 min.

[0065] Example 10

[0066] 45.2 g of sebacic acid, 27.1 g of decanediamine, and 14.4 g of deionized water were sequentially added to a high-pressure reactor, which was then sealed. The reactor was heated to 120°C and maintained at this temperature for 1 hour to allow the reaction to proceed. The temperature was then further increased to 240°C, and the pressure was maintained at 1.75 MPa for 2 hours. Initially, the pressure was gradually reduced to atmospheric pressure, and the reactor was stirred and evacuated for 1 hour. The temperature was then lowered to 120°C, and 64.8 g of polytrimethylene ether glycol and 0.54 g of zirconium butoxide were added to the high-pressure reactor. The temperature was then increased to 260°C and stirred for a period of time. Finally, a vacuum was applied and the reactor was stirred for 12 hours.

[0067] After the polycondensation is complete, stop stirring, drain the polymer product into cooling water, wash it three times with anhydrous ethanol, place it in a vacuum drying oven at 60°C, and dry it for 12 hours to obtain bio-based polyamide elastomer with a melt index of 18.1 g / 10 min.

[0068] Comparative Example 1

[0069] 42.5g of sebacic acid, 30.5g of decanediamine, and 14.6g of deionized water were sequentially added to a high-pressure reactor, which was then sealed. The reactor was heated to 100°C and maintained at this temperature for 1 hour to allow the reaction to proceed. The temperature was then further increased to 240°C, and the pressure was maintained at 1.8MPa for 2 hours. Initially, the pressure was gradually reduced to atmospheric pressure, and the reactor was stirred and evacuated for 0.5 hours. The temperature was then lowered to 120°C, and 68.9g of polytetramethylene ether glycol and 0.57g of zirconium n-butoxide were added to the high-pressure reactor. The temperature was then increased to 260°C and stirred for a period of time. Finally, a vacuum was applied and the reactor was stirred for 10 hours.

[0070] After polycondensation is complete, stirring is stopped, the polymer product is drained into cooling water, washed three times with anhydrous ethanol, and then placed in a vacuum drying oven at 60°C for 12 hours to obtain bio-based polyamide elastomer with a melt index of 24.5 g / 10 min.

[0071] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

[0072] Table 1. Physicochemical parameters of polyamides prepared in Examples 1-10 and Comparative Example 1

[0073]

Claims

1. A bio-based polyamide elastomer, characterized in that, The structure of the bio-based polyamide elastomer is shown in Formula I; in, R is selected from C8 alkyl groups; n is any integer from 2 to 20; m is any integer from 5 to 70.

2. The method for preparing the bio-based polyamide elastomer according to claim 1, characterized in that, Includes the following steps: Sebacic acid and decanediamine were added in a specific molar ratio along with deionized water. The mixture was sealed in a high-pressure reactor and heated to temperature T1 to initiate the reaction. After maintaining the temperature for time A1, the temperature was further increased until it reached T2, at which point the pressure was maintained at P1 for a reaction time A2. Then, the pressure was gradually reduced to atmospheric pressure, and the reactor was stirred and evacuated for time A3. The temperature was lowered to T3, and polytrimethylene ether glycol and a catalyst were added to the high-pressure reactor. The temperature was raised to T4 and stirred for a period of time. A vacuum was then created, and the reactor was stirred for time A4. After the reaction was completed, the mixture was cooled in deionized water to obtain a bio-based polyamide elastomer.

3. The preparation method according to claim 2, characterized in that, The molecular weight of the polytrimethylene ether diol is 500–5000 g / mol.

4. The preparation method according to claim 2, characterized in that, The molar ratio of sebacic acid, sebacic diamine, and polytrimethylene ether glycol is 100:(1-100):(1-100).

5. The preparation method according to claim 2, characterized in that, The deionized water is 5-40 wt%.

6. The preparation method according to claim 2, characterized in that, The catalyst is tetrabutyl titanate, tetraisopropyl titanate, dibutyltin dilaurate, stannous octoate, zirconium n-butoxide, and antimony trioxide, preferably zirconium n-butoxide, and the amount of catalyst is 500-10000 ppm.

7. The preparation method according to claim 2, characterized in that, The T1 temperature is 80–120℃, the A1 reaction time is 1–3 h, the P1 pressure is 1.0–3 MPa, the T2 temperature is 220–280℃, the A2 reaction time is 1.5–4 h, the A3 reaction time is 0.5–2 h, the T3 temperature is 80–160℃, the T4 temperature is 240–300℃, and the A4 reaction time is 5–24 h.

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