A bio-based polyester material based on aconitic acid

Abstract

This invention belongs to the field of polyester material technology and discloses a bio-based polyester material prepared based on aconitine. The preparation process includes the following steps: (1) preparing a dicarboxylic acid monomer with a cyclic structure by reacting aconitine with one or more amino acids and their derivatives; (2) obtaining a polyester material by polycondensation of the dicarboxylic acid monomer prepared in (1) with diols of different structures; the resulting polyester material has a high glass transition temperature and thermal decomposition temperature. The bio-based polyester material provided by this invention avoids the problem of high conversion rate due to crosslinking in the preparation of polyester materials from bio-based polyacids, and the resulting polyester material has a high molecular weight (M). n ): 3000 g / mol–30000 g / mol, narrow molecular weight distribution 1–5, high glass transition temperature (T g ): 60-250℃ and thermal decomposition temperature (T) d5 ): 250-500℃; at the same time, the raw materials for the reaction are derived from bio-based sources, the preparation process is mild, the operation is simple and easy, the cost is controllable, and the yield is high.

Description

Technical Field

[0001] This invention belongs to the field of polyester materials, specifically, it relates to a bio-based polyester material prepared based on aconitine. Background Technology

[0002] Currently, commercially available plastics such as polyethylene terephthalate (PET), polyethylene (PE), polyvinyl chloride (PVC), polypropylene (PP), and polystyrene (PS) are all derived from non-recyclable petroleum resources. Petroleum-based plastics dominate the plastics market due to their low production costs and wide range of applications, accounting for over 70% of total plastic production annually. However, improper disposal of waste plastics will have a significant impact on the environment. In 2017, only 9% of the 438 billion kilograms of waste plastic generated globally was recycled, with approximately 2% entering the ecosystem. Furthermore, these plastics do not hydrolyze naturally and eventually enter our food chain as microplastics, thus endangering human health and safety. Therefore, there is an urgent need to develop renewable polymers to alleviate concerns about the depletion of fossil fuels and human health.

[0003] Bio-based plastics were commercially produced in the late 1980s. In 2021, bioplastic production reached 2.42 million kilograms, accounting for only 1% of total plastic production. The slow development of bioplastics is due to high production costs and low glass transition temperatures, limiting their further applications. For example, polylactic acid (PLA) has the same cost as PET, but its glass transition temperature (Tg) is much lower. g The temperature is only 55℃, while PET can reach 72℃.

[0004] In fact, polyester materials have attracted much attention due to the presence of easily hydrolyzable ester groups, and a large amount of bio-renewable energy can be used to synthesize polyesters. For example, US patent application US2423093A reported the preparation of ethylene glycol-isopropylene glycol-sebacic acid-aconitine polyester materials using aconitine, endowing the materials with special properties and expanding their application range. However, the flexible methylene groups in these bio-based monomers impart low TT to the materials. g This limits the application of materials in daily life.

[0005] Therefore, it is necessary to develop a biodegradable, high-T... g Polyester materials have important research significance for the development of sustainable materials and the utilization of biological resources. Summary of the Invention

[0006] One objective of this invention is to provide a bio-based polyester material prepared based on aconitine, the molecular structure of which is as follows:

[0007]

[0008] Where 0≤n≤10, m≥20, and m and n are both integers; R is an independent alkyl group selected from alkyl groups containing 1 to 4 carbon atoms.

[0009] Optionally, the glass transition temperature (T) of the polyester material described in this invention... g The temperature range is 60-250℃, and the thermal decomposition temperature (T) is... d5 The temperature range is 250-500℃, the molecular weight range is 3000-30000g / mol, and the molecular weight distribution is 1-5.

[0010] The second objective of this application is to provide a method for preparing a bio-based polyester material based on aconitine, including a cyclization step and an esterification step;

[0011] The cyclization reaction steps are as follows:

[0012] (1) Mix 1 equivalent of aconitic acid with 1-5 equivalents of amino acids according to the equivalent ratio;

[0013] (2) After adding the above raw materials, raise the reaction temperature to 150-200℃, and stir during the heating process until aconitic acid and the corresponding amino acids are completely melted;

[0014] (3) After the reaction temperature is raised to 150-200℃, stir the mixture for 5-8 hours.

[0015] (4) After the reaction is complete, vacuum the system at 150°C and 0.05 mbar for 5 hours to remove all the water generated in the reaction.

[0016] (5) Cool to room temperature to obtain a cyclic dicarboxylic acid product.

[0017] Preferably, in the cyclization reaction of the present invention, the equivalent ratio of aconitic acid to amino acid is 1:(1-5), the reaction temperature is 150-200℃, and the reaction time is 5-8h.

[0018] Cyclization is a crucial step in the synthesis of aconitic acid-based bio-based polyester materials. The degree of cyclization and purity of the cyclic dicarboxylic acid product in the polymerization precursor directly affect the molecular weight, glass transition temperature, and other properties of the polyester material in subsequent polymerization processes. The inventors discovered that aconitic acid to amino acid equivalent ratio of 1:(1-5) effectively avoids the problem of insufficient raw material purity leading to incorrect reactant ratios. Furthermore, cyclization is carried out at 150-200℃, which effectively enhances the cyclization efficiency of aconitic acid and amino acids, ensuring a complete cyclization reaction. The reaction temperature, reaction time, and feed equivalent ratios involved in the cyclization reaction are carefully selected to ensure stable esterification in the subsequent step. Arbitrary adjustments can easily lead to poor subsequent esterification or reduced purity and performance of the final product.

[0019] The polymerization reaction steps are as follows:

[0020] (1) Mix cyclic dicarboxylic acid, diol and catalyst, with an acid-to-alcohol molar ratio of 1:(1.5-3) and a catalyst dosage of 1-10 mol%.

[0021] (2) Prepolymerization is carried out at a reaction temperature of 180-250℃ for 5-20 hours;

[0022] (3) Condensation polymerization was carried out at a reaction temperature of 250-300℃ for 10-30 h.

[0023] (4) After the reaction is complete, cool to room temperature to obtain the final product.

[0024] Preferably, in the polymerization reaction of the present invention, the equivalence ratio of cyclic dicarboxylic acid to diol is 1:(1.5-3), and the amount of catalyst used is 1-10 mol% of the amount of dicarboxylic acid.

[0025] Preferably, in the prepolymerization reaction described in this invention, the reaction temperature is 180-250℃ and the reaction time is 5-20h.

[0026] Preferably, in the condensation polymerization reaction described in this invention, the reaction temperature is 250-300℃ and the reaction time is 10-30h.

[0027] The polymerization process primarily utilizes the dehydration condensation of cyclic dicarboxylic acids and diols to obtain polyester products. Effective control of the degree of polymerization allows for the design of the final polyester product's molecular weight. Because the resulting polyester product has a relatively high molecular weight, it is crucial to maintain an equivalence ratio of cyclic dicarboxylic acid to diol of 1:(1.5-3), and the reaction must be carried out at higher temperatures and longer reaction times. This ensures that the carboxyl groups on the cyclic dicarboxylic acid are esterified as much as possible, resulting in a higher degree of polymerization and a final polyester molecular weight range of 3000-30000 g / mol. When the reaction conditions are outside this range, although a certain amount of polyester product can still be obtained, the molecular weight and purity cannot be guaranteed. Furthermore, the molecular structure of the polyester product will change, affecting its glass transition temperature and thermal decomposition temperature. Therefore, to obtain polyester products with higher molecular weights, this polymerization reaction needs to be carried out under specific catalytic ratios, higher temperatures, and longer reaction times.

[0028] Optionally, the amino acid includes one or more of the following: carbamic acid, glycine, β-alanine, γ-aminobutyric acid, 5-aminovaleric acid, 6-aminohexanoic acid, 7-aminoheptanoic acid, 8-aminooctanoic acid, 9-aminononanoic acid, 10-aminodecanoic acid, 11-aminoundecanoic acid, and 12-aminododecanoic acid.

[0029] Preferably, the amino acid includes one or more of carbamic acid, 6-aminohexanoic acid, and 12-aminododecanoic acid.

[0030] The main reactants in the cyclization reaction are aconitic acid and amino acids, both of which are extracted from bio-fermentation or biomass and are green and environmentally friendly bio-based raw materials. The cyclic dicarboxylic acid obtained by the cyclization reaction is the main polymer of the polyester product in the polymerization step. Compared with aconitic acid, cyclic dicarboxylic acid contains more esterification reaction sites, which is more conducive to obtaining high molecular weight polyester products.

[0031] Optionally, the diol is one or more of ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, heptahydrin, octanediol, nonanediol, decanediol, 1,2-cyclopentanediol, and isosorbide.

[0032] Preferably, the diol is one or more of ethylene glycol, hexanediol, and isosorbide.

[0033] These diols can be obtained through bio-fermentation and are green and environmentally friendly bio-based raw materials. Increasing the amount of diol added can effectively improve esterification efficiency and promote the formation of high molecular weight polyester products.

[0034] Optionally, the catalyst is one or more of zinc acetate, antimony trioxide, p-toluenesulfonic acid, concentrated sulfuric acid, stannous octoate, disodium hydrogen phosphate, potassium carbonate, and tetrabutyl titanate.

[0035] Preferably, the catalyst is one or more of zinc acetate, p-toluenesulfonic acid, and potassium carbonate.

[0036] The aconitine-based polyester product, except for the catalyst, uses all raw materials derived from biomass, and the final plasticizer product has a biocarbon content of 100%.

[0037] Biocarbon content is increasingly guiding the direction of materials development. For example, French Decree 2016-379 requires that single-use plastic bags have a biocarbon content of at least 30% from January 1, 2017, with the testing standard being ISO 16620-2. The minimum biocarbon content required for these plastic bags will increase to 40% in 2018, 50% in 2020, and 60% in 2025. The biocarbon content in a product includes the sum of biocarbon from the matrix and additives. The aconitine-based polyester in this application has 100% biocarbon, meeting relevant policy requirements while reducing pressure on the biocarbon content of the main material.

[0038] The third objective of this application is to provide an application of a bio-based polyester material prepared based on aconitine, which has adjustable rigidity and flexibility and can be used as a special engineering plastic in aerospace and other fields.

[0039] The beneficial effects of this application include, but are not limited to:

[0040] 1. The aconitine-based bio-based polyester of this application overcomes the limitation of the tricarboxylic acid reaction system in achieving high conversion rates due to crosslinking issues. The resulting polymer has a high molecular weight and molecular weight distribution, and the material exhibits high Tg. g and T d5 .

[0041] 2. The aconitine-based bio-based polyester of this application is made from biomass and obtained through synthetic biology technology. It is non-toxic and environmentally friendly, and has a biocarbon content of 100%.

[0042] 3. The aconitine-based bio-based polyester of this application has a mild preparation process, is simple and easy to operate, has controllable cost, and has a high yield. Detailed Implementation

[0043] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0044] The raw materials used in the embodiments of this application were all obtained through synthetic biology techniques.

[0045] Example 1:

[0046] Cycloning process:

[0047] Aconitic acid and carbamic acid were mixed in a 1:1 equivalent ratio, and the reaction temperature was raised to 150°C and stirred for 5 hours. After the reaction was completed, the mixture was evacuated at 150°C and a vacuum of 0.05 mbar for 5 hours to remove all the water generated in the reaction. The mixture was then cooled to room temperature to obtain the cyclic dicarboxylic acid monomer product with a yield of 95%.

[0048] Aggregation process:

[0049] The obtained cyclic dicarboxylic acid monomer was mixed with ethylene glycol at a 1:1.5 equivalent ratio, and then 1 mol% of zinc acetate catalyst was added. The reaction temperature was then raised to 180℃ for prepolymerization. After reacting for 5 h, the reaction temperature was raised to 250℃ for condensation polymerization. After reacting for 10 h, the final product, polyester, was obtained.

[0050] Experimental results: The conversion rate of cyclic dicarboxylic acid was 97%, the molecular weight of the obtained polyester was 3000 g / mol, the molecular weight distribution was 1, and the T of the polyester material was... g At 60℃, T d5 The temperature is 250℃.

[0051] Example 2:

[0052] Cycloning process:

[0053] Aconitic acid and 6-aminohexanoic acid were mixed in a 1:3 equivalent ratio, and the reaction temperature was raised to 170°C and stirred for 6 hours. After the reaction was completed, the mixture was evacuated at 150°C and a vacuum of 0.05 mbar for 5 hours to remove all the water generated in the reaction. The mixture was then cooled to room temperature to obtain the cyclic dicarboxylic acid monomer product with a yield of 96%.

[0054] Aggregation process:

[0055] The obtained cyclic dicarboxylic acid monomer was mixed with hexanediol at a 1:2 equivalent ratio, and then 5 mol% of p-toluenesulfonic acid catalyst was added. The reaction temperature was then raised to 220℃ for prepolymerization, and after reacting for 10 h, the reaction temperature was raised to 270℃ for condensation polymerization, and after reacting for 20 h, the final product polyester was obtained.

[0056] Experimental results: The conversion rate of cyclic dicarboxylic acid was 97%, the molecular weight of the obtained polyester was 10000 g / mol, the molecular weight distribution was 3.2, and the T of the polyester material was... g The temperature is 170℃, T d5 It is 370℃.

[0057] Example 3:

[0058] Cycloning process:

[0059] Aconitic acid and 12-aminododecanoic acid were mixed in a 1:5 equivalent ratio, and the reaction temperature was raised to 200℃ and stirred for 8 hours. After the reaction was completed, the mixture was evacuated at 150℃ and a vacuum of 0.05 mbar for 5 hours to remove all the water generated in the reaction. The mixture was then cooled to room temperature to obtain the cyclic dicarboxylic acid monomer product with a yield of 94%.

[0060] Aggregation process:

[0061] The obtained cyclic dicarboxylic acid monomer was mixed with isosorbide in a 1:3 equivalent ratio, and then 10 mol% potassium carbonate catalyst was added. The reaction temperature was then raised to 250℃ for prepolymerization. After reacting for 20 h, the reaction temperature was raised to 300℃ for condensation polymerization. After reacting for 30 h, the final product polyester was obtained.

[0062] Experimental results: The conversion rate of cyclic dicarboxylic acid was 95%, the molecular weight of the obtained polyester was 30000 g / mol, the molecular weight distribution was 5, and the T of the polyester material was... g At 250℃, T d5 It is 500℃.

[0063] Comparative Example 1:

[0064] Cycloning process:

[0065] Aconitic acid and carbamic acid were mixed at a 1:0.5 equivalent ratio, and the reaction temperature was raised to 100℃ and stirred for 1 h. After the reaction was completed, the mixture was evacuated at 150℃ and a vacuum of 0.05 mbar for 5 h to remove all the water generated in the reaction. The mixture was then cooled to room temperature to obtain the cyclic dicarboxylic acid monomer product with a yield of 50%.

[0066] Aggregation process:

[0067] The obtained cyclic dicarboxylic acid monomer was mixed with ethylene glycol at a 1:1 equivalent ratio, and then 0.1 mol% zinc acetate catalyst was added. The reaction temperature was then raised to 150°C for prepolymerization. After reacting for 5 hours, the reaction temperature was raised to 200°C for condensation polymerization. After reacting for 10 hours, the final product, polyester, was obtained.

[0068] Experimental results: The conversion rate of cyclic dicarboxylic acid was 97%, the molecular weight of the obtained polyester was 3000 g / mol, the molecular weight distribution was 1, and the T of the polyester material was... g At 60℃, T d5 The temperature is 250℃.

[0069] Comparative Example 2:

[0070] Cycloning process:

[0071] Aconitic acid and carbamic acid were mixed in a 1:1 equivalent ratio, and the reaction temperature was raised to 100°C and stirred for 1 hour. After the reaction was completed, the mixture was evacuated at 150°C and a vacuum of 0.05 mbar for 5 hours to remove all the water generated in the reaction. The mixture was then cooled to room temperature to obtain the cyclic dicarboxylic acid monomer product with a yield of 97%.

[0072] Aggregation process:

[0073] The obtained cyclic dicarboxylic acid monomer was mixed with ethylene glycol at a 1:0.5 equivalent ratio, and then 0.1 mol% zinc acetate catalyst was added. The reaction temperature was then raised to 150 °C for prepolymerization. After reacting for 5 h, the reaction temperature was raised to 200 °C for condensation polymerization. After reacting for 10 h, the final product polyester was obtained.

[0074] Experimental results: The conversion rate of cyclic dicarboxylic acid was 32%, the molecular weight of the obtained polyester was 700 g / mol, the molecular weight distribution was 1, and the T of the polyester material was... g At 40℃, T d5 It is 230℃.

[0075] Comparative Example 3:

[0076] Cycloning process:

[0077] Aconitic acid and carbamic acid were mixed in a 1:1 equivalent ratio, and the reaction temperature was raised to 100°C and stirred for 1 hour. After the reaction was completed, the mixture was evacuated at 150°C and a vacuum of 0.05 mbar for 5 hours to remove all the water generated in the reaction. The mixture was then cooled to room temperature to obtain the cyclic dicarboxylic acid monomer product with a yield of 98%.

[0078] Aggregation process:

[0079] The obtained cyclic dicarboxylic acid monomer was mixed with ethylene glycol at a 1:1 equivalent ratio, and then 0.05 mol% zinc acetate catalyst was added. The reaction temperature was then raised to 150 °C for prepolymerization. After reacting for 5 h, the reaction temperature was raised to 200 °C for condensation polymerization. After reacting for 10 h, the final product, polyester, was obtained.

[0080] Experimental results: The conversion rate of cyclic dicarboxylic acid was 47%, the molecular weight of the obtained polyester was 1200 g / mol, the molecular weight distribution was 3.2, and the T of the polyester material was... g At 30℃, T d5 The temperature is 150℃.

[0081] Comparative Example 4:

[0082] Cycloning process:

[0083] Aconitic acid and carbamic acid were mixed in a 1:1 equivalent ratio, and the reaction temperature was raised to 100°C and stirred for 1 hour. After the reaction was completed, the mixture was evacuated at 150°C and a vacuum of 0.05 mbar for 5 hours to remove all the water generated in the reaction. The mixture was then cooled to room temperature to obtain the cyclic dicarboxylic acid monomer product with a yield of 95%.

[0084] Aggregation process:

[0085] The obtained cyclic dicarboxylic acid monomer was mixed with ethylene glycol at a 1:1 equivalent ratio, and then 0.1 mol% zinc acetate catalyst was added. The reaction temperature was then raised to 100℃ for prepolymerization. After reacting for 5 h, the reaction temperature was raised to 200℃ for condensation polymerization. After reacting for 10 h, the final product polyester was obtained.

[0086] Experimental results: The conversion rate of cyclic dicarboxylic acid was 52%, the molecular weight of the obtained polyester was 1700 g / mol, the molecular weight distribution was 6.3, and the T of the polyester material was... g At 45℃, T d5 The temperature is 132℃.

[0087] Comparative Example 5:

[0088] Cycloning process:

[0089] Aconitic acid and carbamic acid were mixed in a 1:1 equivalent ratio, and the reaction temperature was raised to 100°C and stirred for 1 hour. After the reaction was completed, the mixture was evacuated at 150°C and a vacuum of 0.05 mbar for 5 hours to remove all the water generated in the reaction. The mixture was then cooled to room temperature to obtain the cyclic dicarboxylic acid monomer product with a yield of 94%.

[0090] Aggregation process:

[0091] The obtained cyclic dicarboxylic acid monomer was mixed with ethylene glycol at a 1:1 equivalent ratio, and then 0.1 mol% zinc acetate catalyst was added. The reaction temperature was then raised to 150°C for prepolymerization. After reacting for 2 hours, the reaction temperature was raised to 200°C for condensation polymerization. After reacting for 10 hours, the final product, polyester, was obtained.

[0092] Experimental results: The conversion rate of cyclic dicarboxylic acid was 18%, the molecular weight of the obtained polyester was 1450 g / mol, the molecular weight distribution was 5.2, and the T of the polyester material was... g The temperature was 53℃, T d5 It is 123℃.

[0093] Comparative Example 6:

[0094] Cycloning process:

[0095] Aconitic acid and carbamic acid were mixed in a 1:1 equivalent ratio, and the reaction temperature was raised to 100°C and stirred for 1 hour. After the reaction was completed, the mixture was evacuated at 150°C and a vacuum of 0.05 mbar for 5 hours to remove all the water generated in the reaction. The mixture was then cooled to room temperature to obtain the cyclic dicarboxylic acid monomer product with a yield of 97%.

[0096] Aggregation process:

[0097] The obtained cyclic dicarboxylic acid monomer was mixed with ethylene glycol at a 1:1 equivalent ratio, and then 0.1 mol% zinc acetate catalyst was added. The reaction temperature was then raised to 150°C for prepolymerization. After reacting for 5 hours, the reaction temperature was raised to 100°C for condensation polymerization. After reacting for 10 hours, the final product, polyester, was obtained.

[0098] Experimental results: The conversion rate of cyclic dicarboxylic acid was 85%, the molecular weight of the obtained polyester was 2400 g / mol, the molecular weight distribution was 7.1, and the T of the polyester material was... g The temperature is 44℃, T d5 The temperature is 115℃.

[0099] Comparative Example 7:

[0100] Cycloning process:

[0101] Aconitic acid and carbamic acid were mixed in a 1:1 equivalent ratio, and the reaction temperature was raised to 100°C and stirred for 1 hour. After the reaction was completed, the mixture was evacuated at 150°C and a vacuum of 0.05 mbar for 5 hours to remove all the water generated in the reaction. The mixture was then cooled to room temperature to obtain the cyclic dicarboxylic acid monomer product with a yield of 97%.

[0102] Aggregation process:

[0103] The obtained cyclic dicarboxylic acid monomer was mixed with ethylene glycol at a 1:1 equivalent ratio, and then 0.1 mol% zinc acetate catalyst was added. The reaction temperature was then raised to 150°C for prepolymerization. After reacting for 5 hours, the reaction temperature was raised to 200°C for condensation polymerization. After reacting for 3 hours, the final product, polyester, was obtained.

[0104] Experimental results: The conversion rate of cyclic dicarboxylic acid was 78%, the molecular weight of the obtained polyester was 2100 g / mol, the molecular weight distribution was 8.2, and the T of the polyester material was... g The temperature is 34℃, T d5 The temperature is 185℃.

[0105] Experimental and test performance results

[0106] The test data for the polyester material are recorded in Table 1 below.

[0107] Table 1

[0108]

[0109]

[0110] As shown in Table 1, the molecular weight of aconitine-based polyester products can be controlled by adjusting the ratio of aconitine to amino acids, the acid-alcohol ratio, the amount of catalyst, and the reaction temperature and time. Ultimately, the molecular weight of the polyester product can be controlled between 3000 and 30000 g / mol. Within this molecular weight range, the polyester product exhibits a high glass transition temperature (60-250℃) and a high thermal decomposition temperature (250-500℃). However, when the reaction conditions are not within the specified range, the comparative experiments show that the polyester product exhibits a decrease in molecular weight and a lower conversion rate of cyclic dicarboxylic acids. This decrease in molecular weight and cyclic dicarboxylic acid conversion rate leads to structural changes in the polyester product, ultimately resulting in a significant reduction in both the glass transition temperature and the thermal decomposition temperature. These changes in product properties will also have a certain impact on the subsequent application of the product.

Claims

1. A bio-based polyester material prepared on the basis of aconitic acid, characterized by: The molecular structure of polyester material is as follows: Where 0≤n≤10, m≥20, and m and n are both integers; R is an independent alkyl group selected from alkyl groups containing 1 to 4 carbon atoms; The molecular weight range of polyester materials is 3000-30000 g / mol, and the molecular weight distribution is 1-5; The preparation method of the bio-based polyester material includes a cyclization step and a polymerization step; The cyclization reaction steps are as follows: (1) Mix 1 equivalent of aconitic acid with 1-5 equivalents of amino acids according to the equivalent ratio; (2) After adding the above raw materials, raise the reaction temperature to 150-200 ℃, and stir during the heating process until aconitine and the corresponding amino acids are completely melted; (3) After the reaction temperature is raised to 150-200 ℃, stir for 5-8 h to melt the mixture; (4) After the reaction is complete, the water generated by the reaction is removed by evacuating the vacuum at 150 °C and 0.05 mbar for 5 h. (5) Cool to room temperature to obtain a cyclic dicarboxylic acid product; The polymerization reaction steps are as follows: (1) Mix the cyclic dicarboxylic acid, diol, and catalyst. The molar ratio of the cyclic dicarboxylic acid to the diol is 1:(1.5-3), and the amount of catalyst is 1-10 mol%. (2) Prepolymerization is carried out at a reaction temperature of 180-250 ℃ for 5-20 h; (3) Condensation polymerization was carried out at a reaction temperature of 250-300 ℃ for 10-30 h; (4) After the reaction is complete, cool to room temperature to obtain the final product.

2. The bio-based polyester material prepared based on aconitine as described in claim 1, characterized in that: The glass transition temperature range of polyester materials is 60-250 ℃.

3. The bio-based polyester material prepared based on aconitine as described in claim 1, characterized in that: The thermal decomposition temperature range of polyester materials is 250-500 ℃.

4. A method for preparing a bio-based polyester material based on aconitine as described in any one of claims 1-3, characterized in that: This includes cyclization and polymerization steps; The cyclization reaction steps are as follows: (1) Mix 1 equivalent of aconitic acid with 1-5 equivalents of amino acids according to the equivalent ratio; (2) After adding the above raw materials, raise the reaction temperature to 150-200 ℃, and stir during the heating process until aconitine and the corresponding amino acids are completely melted; (3) After the reaction temperature is raised to 150-200 ℃, stir for 5-8 h to melt the mixture; (4) After the reaction is complete, the water generated by the reaction is removed by evacuating the vacuum at 150 °C and 0.05 mbar for 5 h. (5) Cool to room temperature to obtain a cyclic dicarboxylic acid product; The polymerization reaction steps are as follows: (1) Mix the cyclic dicarboxylic acid, diol, and catalyst. The molar ratio of the cyclic dicarboxylic acid to the diol is 1:(1.5-3), and the amount of catalyst is 1-10 mol%. (2) Prepolymerization is carried out at a reaction temperature of 180-250 ℃ for 5-20 h; (3) Condensation polymerization was carried out at a reaction temperature of 250-300 ℃ for 10-30 h; (4) After the reaction is complete, cool to room temperature to obtain the final product.

5. The method for preparing a bio-based polyester material based on aconitine as described in claim 4, characterized in that: The amino acids include one or more of the following: carbamic acid, glycine, β-alanine, γ-aminobutyric acid, 5-aminovaleric acid, 6-aminohexanoic acid, 7-aminoheptanoic acid, 8-aminooctanoic acid, 9-aminononanoic acid, 10-aminodecanoic acid, 11-aminoundecanoic acid, and 12-aminododecanoic acid.

6. The method for preparing a bio-based polyester material based on aconitine as described in claim 4, characterized in that: The diol is one or more of ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, heptanediol, octanediol, nonanediol, decanediol, 1,2-cyclopentanediol, and isosorbide.

7. The method for preparing a bio-based polyester material based on aconitine as described in claim 4, characterized in that: The catalyst is one or more of the following: zinc acetate, antimony trioxide, p-toluenesulfonic acid, concentrated sulfuric acid, stannous octoate, disodium hydrogen phosphate, potassium carbonate, and tetrabutyl titanate.

8. A method for preparing a bio-based polyester material based on aconitine as described in any one of claims 4 to 7, characterized in that: All raw materials except the catalyst are derived from biomass, and the final polyester product has a biocarbon content of 100%.

9. An application of a bio-based polyester material prepared based on aconitine as described in any one of claims 1-3, characterized in that: Used in the aerospace field.

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