Aconitic acid-based polyester plasticizer and its preparation method

Abstract

This invention discloses an aconitic acid-based polyester plasticizer and its preparation method, relating to the field of plasticizer composite materials technology. The molecular structure of the plasticizer is as follows: R1 and R2 are independently selected from alkyl groups containing 1 to 4 carbon atoms, and the number of structural units n is 1 to 20. The aconitic acid-based polyester plasticizer provided by this invention avoids the cross-linking phenomenon in the preparation of polyester materials from tricarboxylic acids, giving it good flowability and plasticizing properties when plasticizing plastic matrices. Simultaneously, the reactant is derived from biomass, the preparation process is mild, equipment requirements are low, and the yield is high.

Description

Technical Field

[0001] This application relates to an aconitine-based polyester plasticizer and its preparation method, belonging to the field of plasticizer composite material technology. Background Technology

[0002] Plasticizers are substances that can be added to polymer materials to improve their processability and plasticity. They are among the most widely used and consumed polymer material additives, and are extensively applied in plastic products used in construction, medical, electronics, toys and other fields.

[0003] Developing bio-based materials and additives has become an effective way to replace traditional toxic petroleum-based products, especially in the plasticizer industry. Bio-based plasticizers not only have non-toxic and environmentally friendly properties, but their raw materials are also derived from biomass, reducing dependence on petroleum and accelerating the carbon cycle. Therefore, several bio-based environmentally friendly plasticizers, such as citrate esters and epoxy vegetable oil esters, have been developed. However, most plasticizers have small molecular weights and are prone to migrating from the matrix material to the outside environment, making it difficult to ensure long-term stable use of the material. Therefore, developing a bio-based plasticizer with a certain molecular weight has become an urgent need in the polar plastics industry. Chinese patent CN112126070B discloses a hyperbranched polymeric glycerol ester bio-based plasticizer, its preparation method, and its application. Using bio-based glycerol as a raw material, the preparation of polymeric glycerol, the preparation of hyperbranched polymeric glycerol, and the preparation of hyperbranched polymeric glycerol esters are carried out to obtain the hyperbranched polymeric glycerol ester plasticizer. However, the plasticizer provided by this invention has a branched and cross-linked molecular structure, resulting in poor flowability in composite materials and making it difficult to achieve efficient plasticizing effects. In addition, Chinese patent CN113801484B discloses a low-odor, non-toxic, non-benzene environmentally friendly composite plasticizer. By adding winterized epoxy oil and epoxy fatty acid methyl ester to the plasticizer system, a composite oxidant and deodorizer are combined to achieve an integrated plasticizing and stabilizing effect, thereby enhancing its application value. However, its composite plasticizers are all small molecules and still possess a certain degree of outward migration.

[0004] Therefore, the difficulty in balancing plasticizing performance and safety is one of the main pain points in the bio-based plasticizer market. How to reduce the migration of plasticizers while ensuring sufficient bio-carbon content and high plasticizing efficiency is a problem that urgently needs to be solved. Summary of the Invention

[0005] To address the aforementioned issues, this application provides an aconitic acid-based polyester plasticizer and its preparation method. This plasticizer is prepared via a two-step process of cyclization and esterification. The polar ester and carbonyl groups in its structure provide good compatibility with polar materials, and its linear structure gives it good molecular mobility. At the same time, its high molecular weight makes it different from traditional small-molecule plasticizers, making it more difficult to migrate to the outside world, effectively improving the biocarbon content and long-term stability of the plasticized material.

[0006] One of the objectives of this application is to provide an aconitic acid-based polyester plasticizer, the molecular structure of which is as follows:

[0007]

[0008] Among them, R1 and R2 are independently selected from alkyl groups containing 1 to 4 carbon atoms, and the number of structural units n is 1 to 20.

[0009] Preferably, R1 is an alkyl group with 1 to 3 carbon atoms, R2 is an alkyl group with 2 to 4 carbon atoms, and the number of structural units n is 5 to 10.

[0010] Optionally, the plasticizer has a number-average molecular weight range of 300–3000 g / mol and a molecular weight distribution of 1–2.

[0011] Preferably, the number average molecular weight of the plasticizer is in the range of 500 to 2000 g / mol, more preferably 1000 g / mol.

[0012] The molecular weight of a plasticizer is a crucial factor in balancing plasticizing efficiency and stability. When the plasticizer is a small molecule, the friction between it and the matrix material's molecular chains is low, and its molecular mobility is strong. As long as it has good compatibility with the matrix material, it can effectively plasticize. However, the strong mobility of small molecules makes them more prone to migrating from the material to the outside, leading to unstable long-term use. When the plasticizer is a long-chain macromolecule, the friction between it and the matrix material's molecular chains is high, and its molecular mobility decreases. Although it can maintain good stability, the aggregation of large plasticizer molecules and the "phase separation" with the matrix material can easily lead to poor plasticizing effect. Based on past experience with polyester plasticizers, when the number-average molecular weight of the plasticizer is between 300 and 3000 g / mol, the plasticizer molecules can be uniformly dispersed to effectively plasticize the matrix material while maintaining good migration resistance.

[0013] The second objective of this application is to provide a method for preparing an aconitic acid-based polyester plasticizer, wherein the process of preparing the plasticizer includes a cyclization step and an esterification step;

[0014] The cyclization reaction steps are as follows:

[0015] (1) Mix 1 equivalent of aconitic acid with 1 equivalent of amino acid according to the equivalent ratio;

[0016] (2) After adding the above raw materials, raise the reaction temperature to 150°C and stir until the two materials melt during the heating process;

[0017] (3) After the reaction temperature is raised to 150℃, stir the mixture for 4-5 hours.

[0018] (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.

[0019] (5) Cool to room temperature to obtain a cyclic dicarboxylic acid product.

[0020] The cyclization process is a crucial step in preparing polyester plasticizer precursors, and its purity significantly impacts subsequent esterification steps. The inventors discovered that a 1:1 equivalence ratio of aconitic acid to amino acids effectively avoids purity deviations caused by excess of any one raw material. Furthermore, conducting the cyclization reaction at 150°C, a relatively high temperature, ensures sufficient reaction between aconitic acid and amino acids. The reaction temperature, reaction time, and feed equivalence involved in the cyclization reaction are all carefully selected to ensure stable esterification in the next step; arbitrary adjustments can easily lead to poor subsequent esterification or reduced purity and performance of the final product.

[0021] The esterification reaction steps are as follows:

[0022] (1) Mix cyclic dicarboxylic acid, diol and catalyst, with an acid-to-alcohol molar ratio of 1:(1-1.5) and a catalyst dosage of 0.1-1 mol%.

[0023] (2) Prepolymerization was carried out at a reaction temperature of 150-180℃ for 2-4 hours;

[0024] (3) Condensation polymerization was carried out at a reaction temperature of 180-250℃ for 1-4 hours;

[0025] (4) Acetic acid was then added and the reaction was capped at a temperature of 140-180℃ for 2-4 hours.

[0026] (5) After the reaction is complete, cool to room temperature to obtain the final product.

[0027] The esterification process aims to dehydrate and condense cyclic dicarboxylic acids with diols, and is a crucial step in controlling the molecular weight of the final product. Therefore, the temperature and polymerization time must be within the aforementioned conditions to achieve a molecular weight range of 300–3000 g / mol. While esterification products can still be obtained outside this range, their molecular weight and purity are difficult to guarantee, significantly impacting the final plasticizing properties and migration resistance. Therefore, to ensure the molecular weight remains within this range, the prepolymerization and polycondensation times are shorter than the melt polycondensation times for typical materials.

[0028] Optionally, in the cyclization step, the amino acid includes one or more of glycine, β-alanine, and γ-aminobutyric acid.

[0029] Preferably, the amino acid includes one or more of glycine and β-alanine.

[0030] The raw materials involved 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 after cyclization serves as the main structure of the plasticizer. In addition to giving the plasticizer the function of being green, environmentally friendly and having a high biocarbon content, its polarity is also further enhanced. When aconitic acid is used as the main structure, it only has three polar ester groups, while the cyclic dicarboxylic acid has two polar ester groups and two polar carbonyl groups. The higher polarity gives it better compatibility with polar materials and higher plasticizing efficiency.

[0031] Optionally, the diol is one or more of ethylene glycol, 1,3-propanediol, and 1,4-butanediol.

[0032] These diols can be obtained through bio-fermentation, making them green and environmentally friendly bio-based raw materials. The inventors also discovered that these diols all have a straight-chain structure. In the final polyester plasticizer structure, the straight-chain structure of the diols effectively reduces the steric hindrance of the molecular chain side groups, giving the polyester plasticizer good mobility and providing a "lubricating" function between the host materials, further improving the plasticizing properties of the materials. Good chain mobility and compatibility jointly enhance the plasticizing efficiency of the plasticizer; the two are not simply additive but rather work synergistically.

[0033] 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.

[0034] Optionally, in the esterification step, the capping agent includes one or more of acetic acid and acetic anhydride.

[0035] Preferably, the capping agent is acetic acid.

[0036] The inventors discovered that by deliberately increasing the equivalent amount of diol in the esterification step, the polyester molecules can be capped with diol, thereby controlling the molecular weight to prevent further increase. At the same time, the introduction of acetic acid for final capping can further introduce polar carbonyl groups into the molecular structure. If alcohol is used for capping, the increase in polarity is not significant. The increase in polarity can better promote the compatibility between polyester and matrix materials. This capping step is a unique design based on the application direction of polyester materials (plasticizer).

[0037] The aconitine-based polyester plasticizer, except for the catalyst, uses all raw materials derived from biomass, and the final plasticizer product has a biocarbon content of 100%.

[0038] Biocarbon content is gradually guiding the direction of materials development. The biocarbon content in a product includes the sum of biocarbon in the matrix and additives. The aconitine-based polyester plasticizer in this application has 100% biocarbon, which reduces the pressure on the biocarbon content of the main material.

[0039] The third objective of this application is to provide an application of aconitate, wherein the aconitate-based polyester has good compatibility with polar materials such as PVC, PLA, nitrile rubber, and chloroprene rubber, and can be used as a plasticizer thereon.

[0040] Optionally, the plasticizer can effectively reduce the glass transition temperature (T0) of the material. g It has high hardness and is difficult to migrate out of the material.

[0041] The fourth objective of this application is to provide a method for preparing the aconitine-based polyester plasticized polar material as described in any of the above claims, comprising the following steps:

[0042] S1: The base material, aconitic acid-based polyester plasticizer, and additives are mixed to obtain a premix;

[0043] S2: Add the premixed material to a mixer or screw extruder and mix to obtain a compound or compounded granules;

[0044] S3: Place the compound or compounded granules in a vulcanizing machine to form the mixture.

[0045] The beneficial effects of this application include, but are not limited to:

[0046] 1. The aconitine-based polyester plasticizer of this application has strong structural tunability. The ratio of linear alkyl groups and polar groups can be adjusted by amino acids and diols. The polarity is adjustable and can meet the plasticizing requirements of most polar materials.

[0047] 2. The aconitine-based polyester plasticizer of this application is made from biomass and obtained through synthetic biology technology. It is non-toxic and environmentally friendly, and its biocarbon content is 100%.

[0048] 3. The aconitine-based polyester plasticizer of this application is an oligopolyester. Compared with traditional small molecule plasticizers, the long chain increases intermolecular friction and has the characteristic of being resistant to migration. Compared with ordinary linear polyester plasticizers, the rigidity of the ring structure can effectively reduce the interaction between molecular chains of the main material and improve the plasticizing effect. Compared with branched polyester plasticizers, the linear structure has stronger mobility and prevents the plasticizing performance from decreasing due to plasticizer agglomeration.

[0049] 4. In the preparation process of the aconitic acid-based polyester plasticizer of this application, the experimental conditions are adjusted according to the target structure. Through targeted design of conditions such as reaction temperature, reaction time, and feed equivalent, a high-purity polyester plasticizer product is finally obtained. Detailed Implementation

[0050] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0051] The raw materials used in the embodiments of this application were all obtained through synthetic biology techniques.

[0052] Example 1

[0053] This embodiment provides an aconitic acid-based polyester plasticizer, the structure of which is as follows:

[0054]

[0055] The number-average molecular weight was determined to be 1300 g / mol by gel permeation chromatography.

[0056] Its preparation method includes the following steps:

[0057] (1) In an equivalent ratio, 1 equivalent of aconitic acid and 1 equivalent of amino acid were mixed and stirred in a reactor. The reaction temperature was then raised to 150°C and stirred for 4 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 a cyclic dicarboxylic acid product.

[0058] (2) A cyclic dicarboxylic acid, a diol, and tetrabutyl titanate were mixed with an acid-to-alcohol molar ratio of 1:1.1 and a tetrabutyl titanate dosage of 0.1 mol%. Prepolymerization was carried out at a reaction temperature of 150°C for 2 hours, followed by condensation polymerization at a reaction temperature of 180°C for 1 hour. Acetic acid was then added and end-capped at a reaction temperature of 180°C for 2 hours. After the reaction was completed, the mixture was cooled to room temperature to obtain the final product.

[0059] In step (1), the amino acid is glycine, and in step (2), the diol is ethylene glycol.

[0060] Example 2

[0061] The difference between this embodiment and Example 1 is that the amino acid in step (1) is β-alanine, and the diol in step (2) is 1,3-propanediol. The remaining experimental conditions and steps are the same as in Example 1. The structure of the aconitine polylactic acid ester prepared in this embodiment is as follows:

[0062]

[0063] The number-average molecular weight was determined to be 1500 g / mol by gel permeation chromatography.

[0064] Example 3

[0065] The difference between this embodiment and Example 1 is that the amino acid in step (1) is γ-aminobutyric acid, and the diol in step (2) is 1,4-butanediol. The remaining experimental conditions and steps are the same as in Example 1. The structure of the aconitine polylactic acid ester prepared in this embodiment is as follows:

[0066]

[0067] The number-average molecular weight was determined to be 2100 g / mol by gel permeation chromatography.

[0068] Example 4

[0069] The difference between this embodiment and Example 1 is that the amino acid in step (1) is glycine, the diol in step (2) is 1,3-propanediol, the acid-to-alcohol molar ratio in the esterification step is 1:1, and the remaining experimental conditions and steps are the same as in Example 1. The structure of the aconitine polylactic acid ester prepared in this embodiment is as follows:

[0070]

[0071] The number-average molecular weight was determined to be 3000 g / mol by gel permeation chromatography.

[0072] Example 5

[0073] The difference between this embodiment and Example 1 is that the amino acid in step (1) is glycine, the diol in step (2) is 1,4-butanediol, and the acid-to-alcohol molar ratio in the esterification step is 1:1.5. The remaining experimental conditions and steps are the same as in Example 1. The structure of the aconitine polylactic acid ester prepared in this embodiment is as follows:

[0074]

[0075] The number-average molecular weight was determined to be 300 g / mol by gel permeation chromatography.

[0076] Comparative Example 1

[0077] The difference between this comparative example and Example 1 is that the acid-to-alcohol molar ratio in the esterification step is 1:2. All other experimental conditions and steps are the same as in Example 1. The structure of the aconitine polylactic acid ester prepared in this example is as follows:

[0078]

[0079] The number-average molecular weight was determined to be 30,000 g / mol by gel permeation chromatography.

[0080] Comparative Example 2

[0081] The difference between this comparative example and Example 1 is that the acid-to-alcohol molar ratio is 1.5:1, and the capping agent is ethanol. All other experimental conditions and procedures are the same as in Example 1. The structure of the aconitine polylactic acid ester prepared in this example is as follows:

[0082]

[0083] The number-average molecular weight was determined to be 1300 g / mol by gel permeation chromatography.

[0084] Comparative Example 3

[0085] The difference between this comparative example and Example 1 is that the amino acid used is valine with a side group. All other experimental conditions and procedures are the same as in Example 1. The structure of the aconitine polylactic acid ester prepared in this example is as follows:

[0086]

[0087] The number-average molecular weight was determined to be 1300 g / mol by gel permeation chromatography.

[0088] Comparative Example 4

[0089] The difference between this comparative example and Example 1 is that the cyclization reaction temperature is 130°C, while the remaining experimental conditions and steps are the same as in Example 1. The structure of the aconitine polylactic acid ester prepared in this example is as follows:

[0090]

[0091] The number-average molecular weight was determined to be 1300 g / mol by gel permeation chromatography.

[0092] Comparative Example 5

[0093] The difference between this comparative example and Example 1 is that the cyclization reaction temperature is 170°C, while the remaining experimental conditions and steps are the same as in Example 1. The structure of the aconitine polylactic acid ester prepared in this example is as follows:

[0094]

[0095] The number-average molecular weight was determined to be 1300 g / mol by gel permeation chromatography.

[0096] Comparative Example 6

[0097] The difference between this comparative example and Example 1 is that the prepolymerization temperature in the esterification reaction is 120°C and the polycondensation temperature is 150°C. All other experimental conditions and steps are the same as in Example 1. The structure of the aconitine polylactic acid ester prepared in this example is as follows:

[0098]

[0099] The number-average molecular weight was determined to be 1100 g / mol by gel permeation chromatography.

[0100] Comparative Example 7

[0101] The difference between this comparative example and Example 1 is that the prepolymerization temperature in the esterification reaction is 200℃ and the polycondensation temperature is 270℃. All other experimental conditions and steps are the same as in Example 1. The structure of the aconitine polylactic acid ester prepared in this example is as follows:

[0102]

[0103] The number-average molecular weight was determined to be 1700 g / mol by gel permeation chromatography.

[0104] Test Example 1

[0105] The purity, color, yield, and triester conversion of the aconitine-based polyester plasticizer prepared in the above examples and the comparative examples were tested. The specific test results are shown in Table 1 below, and the test methods are as follows:

[0106] 1. Molecular weight test: Samples were prepared and tested according to GB / T 27843 "Determination of low molecular weight components in polymers by gel permeation chromatography (GPC)".

[0107] 2. Purity: High-performance liquid chromatography (HPLC) was used. The instrument sensitivity and stability of the tester should comply with GB / T16631-2008. Column: C18 column; Injector: 10 μL microsyringe; Solvent: Acetonitrile (HPLC grade); Acquisition time: 15 min; Mobile phase: 80% acetonitrile (HPLC grade), 20% deionized water; Injection volume: 1 μL; Wavelength: 230 nm.

[0108] Experiment: Adjust the instrument according to the above specifications. After the baseline stabilizes, inject 0.2 μL of sample using a microsyringe. At the same time, start the integrator or chromatography workstation. The instrument will automatically provide the area percentage of each component.

[0109] Purity calculation formula: Purity = (Integrated area of ​​aconitine polylactic acid ester / Total integrated area) × 100%.

[0110] 3. Color: In accordance with GB / T 1664-1995 "Determination of Appearance and Color of Plasticizers", solutions of different standard color numbers were prepared and compared with the samples in colorimetric tubes.

[0111] 4. Yield: The efficiency of the reaction synthesis route is characterized by the yield. The yield calculation formula is: Yield = (mass of the final product / mass of the theoretically obtained polylactic acid ester) × 100%.

[0112] Table 1

[0113] Sample number Molecular weight (g / mol) purity(%) Colorimetric (Pt-Co) Yield (%) Example 1 1300 99.3 25 97.8 Example 2 1500 99.5 25 98.1 Example 3 2100 99.2 25 98.3 Example 4 3000 99.7 25 97.7 Example 5 300 99.3 25 98.6 Comparative Example 1 30000 92.4 140 89.5 Comparative Example 2 1300 99.1 30 96.6 Comparative Example 3 1300 99.0 30 88.6 Comparative Example 4 1300 79.7 50 75.1 Comparative Example 5 1300 74.2 260 69.3 Comparative Example 6 1100 86.7 40 83.2 Comparative Example 7 1700 87.4 430 83.5

[0114] As shown in Table 1, adjusting the acid-alcohol ratio, esterification reaction temperature, and the structure of the amino acid and diol can effectively control the number-average molecular weight of aconitine-based polyester plasticizer to 300-3000 g / mol. Within this range, the plasticizer effectively balances plasticizing and stability properties. However, according to the comparative examples, exceeding the reaction conditions protected in this application results in increased molecular weight, darker product color, and reduced product purity and yield. These phenomena, besides reducing product quality and production efficiency, also adversely affect the subsequent use of the product.

[0115] The aconitine-based polyester prepared in the above embodiments and comparative examples was added to the polar materials as a plasticizer. The formulation for preparing PVC plastic included 100 parts of PVC resin, 35 parts of plasticizer, and 2 parts of heat stabilizer. The formulation for preparing PLA plastic included 100 parts of PLA resin and 20 parts of plasticizer.

[0116] The formulation for preparing chloroprene rubber includes 100 parts chloroprene rubber, 15 parts plasticizer, 5 parts zinc oxide, 4 parts magnesium oxide and 0.5 parts stearic acid, and is processed according to GB / T 21462-2008 standard.

[0117] The processing method is as follows:

[0118] S1: Mix the raw materials to obtain a premix;

[0119] S2: Add the premixed material to the mixer and mix to obtain the compound material;

[0120] S3: The mixture is placed in a flat vulcanizing machine to form the product.

[0121] Application Examples 1-5:

[0122] Application Examples 1-5 were prepared using the above-described PVC formulation and processing method. The difference between each application example is that the plasticizer used corresponds to the product in Examples 1-5, while the other components and preparation methods are the same.

[0123] Application Example 6:

[0124] In this application example, the PLA is prepared using the above-described formulation and processing method, and the plasticizer used corresponds to the product in Example 1.

[0125] Application Example 7:

[0126] In this application example, the chloroprene rubber was prepared using the above-described chloroprene rubber formulation and processing method, and the plasticizer used corresponds to the product in Example 1.

[0127] Application Comparative Examples 1-7

[0128] The difference between Comparative Examples 1-7 and Application Example 1 is that the plasticizers used are respectively corresponding to the products in Comparative Examples 1-7, while the other components and preparation methods are the same.

[0129] Application Comparative Example 8

[0130] The difference between this comparative example and application example 1 is that the plasticizer used is dioctyl phthalate (DOP), while the other components and preparation methods are the same.

[0131] Application Comparison Example 9

[0132] The difference between this comparative example and application example 1 is that the plasticizer used is acetyl tributyl citrate (ATBC), while the other components and preparation methods are the same.

[0133] Application Comparison Example 10

[0134] The difference between this comparative example and application example 1 is that the plasticizer used is tributyl aconitate (TBA), while the other components and preparation methods are the same.

[0135] Application Comparative Example 11

[0136] The difference between this comparative example and application example 1 is that the plasticizer used is polybutylene adipate (PBGA) with a number average molecular weight of 1300 g / mol, while the other components and preparation methods are the same.

[0137] Application Comparative Example 12

[0138] The difference between this comparative example and application example 6 is that the plasticizer used is dioctyl phthalate (DOP), while the other components and preparation methods are the same.

[0139] Application Comparative Example 13

[0140] The difference between this comparative example and application example 7 is that the plasticizer used is dioctyl phthalate (DOP), while the other components and preparation methods are the same.

[0141] Test Example 2

[0142] The specific test results of the properties of the plasticized composite material are shown in Tables 2 and 3 below. The test methods are as follows:

[0143] 1. Bio-based carbon content: Samples were prepared and tested according to GB / T 39715.2-2021 "Bio-based content of plastics - Part 2: Determination of bio-based carbon content". Each sample was tested according to the oxalic acid standard reference material, and the test time was 4-8 hours.

[0144] 2. Hardness: Prepare and test specimens according to GB / T531-2008 "Indentation Hardness Test Method, Shore Hardness Tester Method". Select 3 points for each group of specimens, measure each point once, and take the median value.

[0145] 3.100% constant tensile stress and elongation at break: According to GB / T1040–2006 "Test for tensile properties of plastics", the tensile speed is 50 mm / min and the temperature is 25℃.

[0146] 4. Glass transition temperature (Tg): The glass transition temperature was tested using a dynamic mechanical analyzer. Test conditions: nitrogen was used as the carrier gas, the test temperature range was -40 to 80℃, the heating rate was 3℃ / min, and the frequency was 1Hz.

[0147] 5. Volatilization loss rate: The test was conducted according to HG / T 4458–2012 "Determination of loss of plasticizer in plastics - Activated carbon method", with a test temperature of 70℃ and a test time of 24h.

[0148] 6. Water extraction rate: The test was conducted in accordance with the standard "ISO 175-2011 Plastics - Test method for determination of the immersion effect of liquid chemicals". The test temperature was room temperature, the test time was 72 hours, and the extracted solvent was deionized water.

[0149] 7. Ethanol extraction rate: The test was conducted in accordance with the standard "ISO 175-2011 Plastics - Test method for determination of the immersion effect of liquid chemicals". The test temperature was room temperature, the test time was 72 hours, and the extracted solvent was ethanol.

[0150] 8. Petroleum ether extraction rate: The test was conducted in accordance with the standard "ISO 175-2011 Plastics - Test method for determination of the immersion effect of liquid chemicals". The test temperature was room temperature, the test time was 72 hours, and the extracted solvent was petroleum ether.

[0151] 9. Migration rate: The test was conducted in accordance with HG / T 4458–2012 "Determination of migration of plasticizers in plastics". The test temperature was 50℃ and the test time was 48h. The absorbent sheet material was polyethylene (PE) without additives.

[0152] Table 2

[0153]

[0154] Table 3

[0155]

[0156] Table 2 tests are mainly used to evaluate the plasticizing performance of plasticizers. According to the table, the aconitic acid-based polyester plasticizer involved in this application has a biomass-derived raw material with a bio-carbon content of 100%, which is far higher than that of traditional petroleum-based plasticizers DOP (0%), bio-based environmentally friendly plasticizers ATBC / TBA (30% / 33%), and other polyester plasticizers with similar molecular weights, PBGA (40%). Regarding plasticizing performance, a comparison of application examples 1-5 and application comparative example 1 reveals that as the molecular weight of the plasticizer increases, the plasticizing efficiency slightly decreases within 3000 g / mol. With further increases in molecular weight, the plasticizing efficiency significantly decreases (hardness, 100% tensile stress, and glass transition temperature increase, while elongation at break decreases).

[0157] Based on the comparison of Application Comparative Examples 2-3 and Application Example 1, it can be found that if the carbonyl group is capped, the number of polar "carbonyl" groups will be reduced, thus reducing the plasticizing performance of the material. Similarly, the introduction of side groups on amino acids will reduce the flexibility of alkyl groups, thereby reducing the overall molecular chain mobility and resulting in a decrease in the plasticizing performance of the material. Therefore, the amino acid containing straight-chain alkyl groups and the synthesis method using acetic acid capping involved in this application can effectively improve the plasticizing efficiency of the material.

[0158] Based on the comparison of Application Example 1 and Application Comparative Examples 8-11, Application Examples 6-7 and Application Comparative Examples 12-13, it was found that, regardless of whether it is PVC, PLA or chloroprene rubber, aconitic acid-based polyester plasticizer has a plasticizing effect comparable to or better than traditional petroleum-based plasticizers, bio-based environmentally friendly plasticizers and polyester plasticizers with similar molecular weight.

[0159] Table 3 tests are mainly used to evaluate the stability of plasticizers. According to application examples 1-7 and application comparative examples 1-3, aconitic acid-based polyester plasticizers have good stability, and it is difficult for plasticizers with a molecular weight exceeding 1000 g / mol to migrate to the outside world.

[0160] Based on the comparison of Application Example 1 and Application Comparative Examples 4-7, it was found that in the preparation process of aconitic acid-based polyester, the problem of low product purity caused by reaction conditions will greatly affect the stability of the product. The main reason is that most impurities are unreacted or side-reacted small molecules that are very easy to migrate to the outside world.

[0161] Based on the comparison of Application Example 1 and Application Comparative Examples 8-11, Application Examples 6-7 and Application Comparative Examples 12-13, it was found that compared with commercial plasticizers, aconitic acid-based polyester plasticizers can better balance plasticizing efficiency and stability in PVC, PLA, and chloroprene rubber. Small molecule plasticizers are prone to migration to the outside world, while polyester plasticizers with similar molecular weight and acyclic structure are more likely to migrate to liquid and solid environments because of the smaller interaction force between them and the molecular chains of the host material.

[0162] The above description is merely an embodiment of this application, and the scope of protection of this application is not limited to these specific embodiments, but is determined by the claims of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the technical concept and principles of this application should be included within the scope of protection of this application.

Claims

1. A polyester plasticizer based on aconitine, characterized in that: The molecular structure of the plasticizer is as follows: Among them, R1 and R2 are independently selected from alkyl groups containing 1 to 4 carbon atoms, and the number of structural units n is 1 to 20; The preparation method of the aconitine-based polyester plasticizer includes a cyclization reaction step and an esterification reaction step; The cyclization reaction steps are as follows: (1) Mix 1 equivalent of aconitic acid with 1 equivalent of amino acid according to the equivalent ratio; (2) After adding the above raw materials, raise the reaction temperature to 150°C and stir until the two materials melt during the heating process; (3) After the reaction temperature is raised to 150 °C, stir and melt for 4-5 h; (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 esterification reaction steps are as follows: (1) Mix the cyclic dicarboxylic acid, diol, and catalyst, with an acid-to-alcohol molar ratio of 1:(1~1.5) and a catalyst dosage of 0.1~1 mol%. (2) Prepolymerization was carried out at a reaction temperature of 150-180 °C for 2-4 h; (3) Condensation polymerization was carried out at a reaction temperature of 180-250 °C for 1-4 h; (4) Then add the capping agent and cap the reaction at a temperature of 140-180 °C for 2-4 h; (5) After the reaction is complete, cool to room temperature to obtain the plasticizer product; The amino acid includes one or more of glycine, β-alanine, and γ-aminobutyric acid.

2. The aconitine-based polyester plasticizer as described in claim 1, characterized in that: The plasticizer has a number-average molecular weight range of 300~3000 g / mol and a molecular weight distribution of 1~2.

3. A method for preparing an aconitic acid-based polyester plasticizer as described in any one of claims 1 to 2, characterized in that: This includes cyclization and esterification steps; The cyclization reaction steps are as follows: (1) Mix 1 equivalent of aconitic acid with 1 equivalent of amino acid according to the equivalent ratio; (2) After adding the above raw materials, raise the reaction temperature to 150°C and stir until the two materials melt during the heating process; (3) After the reaction temperature is raised to 150 °C, stir and melt for 4-5 h; (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 esterification reaction steps are as follows: (1) Mix the cyclic dicarboxylic acid, diol, and catalyst, with an acid-to-alcohol molar ratio of 1:(1~1.5) and a catalyst dosage of 0.1~1 mol%. (2) Prepolymerization was carried out at a reaction temperature of 150-180 °C for 2-4 h; (3) Condensation polymerization was carried out at a reaction temperature of 180-250 °C for 1-4 h; (4) Then add the capping agent and cap the reaction at a temperature of 140-180 °C for 2-4 h; (5) After the reaction is complete, cool to room temperature to obtain the plasticizer product.

4. The method for preparing an aconitine-based polyester plasticizer as described in claim 3, characterized in that: The amino acid includes one or more of glycine, β-alanine, and γ-aminobutyric acid.

5. The method for preparing an aconitine-based polyester plasticizer as described in claim 3, characterized in that: The diol is one or more of ethylene glycol, 1,3-propanediol, and 1,4-butanediol.

6. The method for preparing an aconitine-based polyester plasticizer as described in claim 3, characterized in that: The capping agent is one or more of acetic acid and acetic anhydride.

7. The method for preparing an aconitine-based polyester plasticizer as described in claim 3, 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. The method for preparing an aconitine-based polyester plasticizer as described in claim 3, characterized in that: The plasticizer product has a biocarbon content of 100%.

9. The application of an aconitic acid-based polyester plasticizer as described in any one of claims 1 to 2, characterized in that: This technology is applied to the modification of polar materials, wherein the polar materials include at least PVC, PLA, nitrile rubber, and chloroprene rubber.

10. A method for preparing an aconitine-based polyester plasticized polar material, characterized in that, Includes the following steps: S1: A premix is ​​obtained by mixing the substrate, the aconitic acid-based polyester plasticizer as described in any one of claims 1 to 2, and the additives. S2: Add the premixed material to a mixer or screw extruder and mix to obtain a compound or compounded granules; S3: The mixture or granulated material is formed in a flat vulcanizing machine.

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