Bio-based polyester elastomers prepared from a single diol and methods of making and using the same

Abstract

The application provides a kind of single diol preparation of bio-based polyester elastomer and its preparation method and application.The bio-based polyester elastomer is prepared from raw materials including dihydric alcohol, dibasic acid A, dibasic acid B, itaconic acid, catalyst, antioxidant and polymerization inhibitor;The dihydric alcohol is one of 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol;Under the protection of inert gas, the raw materials are mixed according to the amount, esterification is carried out, the catalyst is added after cooling, and the bio-based polyester elastomer is obtained after pre-polycondensation and final polycondensation.The bio-based polyester elastomer prepared has low glass transition temperature and stable chemical structure, and the product has excellent performance after being compounded and reinforced with white carbon black, and if applied to industrial production of single diol, it is beneficial to recycling and can reduce production cost to a certain extent.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, and more specifically, to a bio-based polyester elastomer prepared from a single diol, its preparation method, and its application. Background Technology

[0002] Elastomers, due to their unique high elasticity, have wide applications in various fields. However, apart from natural rubber, most elastomers are currently derived from petrochemical resources and are non-degradable, causing increasingly serious environmental pollution. Therefore, the development of biodegradable elastomers applicable to engineering fields is of great significance. Bio-based polyester engineering elastomers are polyester elastomer materials that can be chemically cross-linked using traditional elastomer processing methods and are biodegradable. ① The monomers used are all mass-produced industrial bio-based monomers, which are readily available; ② After being reinforced and chemically cross-linked with nanomaterials, the synthesized polyester elastomer exhibits good stability under normal use and can be completely degraded into water and carbon dioxide through soil composting; ③ The processing and molding technology of the synthesized polyester elastomer is similar to that of traditional rubber; ④ The physical and mechanical properties of the reinforced and cross-linked polyester elastomer are comparable to those of traditional non-degradable synthetic rubber.

[0003] From a molecular design strategy perspective, the main method for disrupting the crystallization of bio-based polyester engineered elastomers is through multi-component copolymerization (copolymerization using multiple glycol and diacid monomers). Chinese patents CN101450985A, CN113136027A, and CN112708115A disclose methods for preparing polyester elastomers by copolymerization using two or more glycol monomers. However, in industrial production using multi-component copolymerization, the alcohol-acid ratio during the esterification stage often needs to be greater than 1.5:1. These excess glycol monomers are removed during the polycondensation stage. However, the multiple glycol monomers used in the above-mentioned works have similar boiling points (differences of 10-30°C), making it difficult to control the removal ratio during the polycondensation stage. Therefore, it is difficult for polyester elastomers synthesized in different batches to achieve a stable chemical structure. Moreover, in large-scale industrial production, it is necessary to fractionate and recover the glycols removed during the polycondensation stage. Different types of glycols with similar boiling points also greatly increase the difficulty of this fractionation process. Using monomers with side groups, such as 2,3-butanediol, 1,2-propanediol, and lactic acid, will increase the glass transition temperature of polyester elastomers, limiting the range of applications of the products.

[0004] The purpose of using multiple diol copolymerization in existing technologies is to create a variety of structural units with different structures in the molecular chain by adding multiple components. This hybridization disrupts the crystallization behavior of the polyester, or by introducing diols with side groups to disrupt the regularity of the molecular chain. However, if a single, side-group-free diol is used to replace multiple diols in the copolymerization of polyester elastomers, it is difficult to disrupt the polyester's crystallinity. Therefore, a molecular design strategy is needed to design a polyester elastomer prepared from a single, side-group-free diol that can disrupt polyester crystallinity, has a more stable chemical structure, and exhibits better elastomer properties. Summary of the Invention

[0005] To address the technical problems existing in the prior art, this invention provides a bio-based polyester elastomer prepared from a single diol, its preparation method, and its application.

[0006] This invention uses only a single unbranched diol and three polybasic acids to copolymerize a bio-based polyester elastomer. It utilizes the "odd-even effect" in polyester, that is, the crystallization ability of polyester synthesized using monomers with an odd number of carbon atoms is generally weaker than that of monomers with an even number of carbon atoms. By using diacid and diol monomers with an odd number of carbon atoms for copolymerization, most structural units of the resulting bio-based polyester elastomer contain odd-numbered carbon atom segments (from diols or diacids with odd-numbered carbon atoms), which disrupts polyester crystallization. The resulting bio-based polyester elastomer has good elastomer properties.

[0007] This invention uses only a single type of unbranched diol monomer, resulting in a more stable chemical structure for the bio-based polyester elastomer, and the diol is easier to recycle and reuse, thus reducing costs.

[0008] One of the objectives of this invention is to provide a bio-based polyester elastomer prepared from a single diol.

[0009] The structural formula of the bio-based polyester elastomer is:

[0010]

[0011] a, b, and c are all integers greater than 0;

[0012] a: (a+b) is 0.1~0.9;

[0013] b: (a+b) ranges from 0.1 to 0.9;

[0014] c: (a+b+c) is 0.05~0.3; preferably 0.1~0.2;

[0015] R1, R2, and R3 are each independently selected from unbranched chain alkyl groups having 2 to 10 carbon atoms;

[0016] The number of carbon atoms in R1 is preferably 2 to 6;

[0017] The number of carbon atoms in R2 is preferably 2 to 8; more preferably 2 to 3.

[0018] The number of carbon atoms in R3 is preferably 2 to 8; more preferably 3 to 5.

[0019] If the number of carbon atoms in R1 is even, then the number of carbon atoms in R2 and R3 is odd.

[0020] If the number of carbon atoms in R1 is odd, then the number of carbon atoms in R2 and R3 can be either odd or even.

[0021] Both the "odd-even segment" and "odd-odd segment" of polyester can weaken crystallization to some extent. In the bio-based polyester elastomer, except for the structural unit with itaconic acid as the crosslinking point, all other structural units have an odd number of carbon atom segments. If the number of carbon atoms in R1 is odd, then the structural unit with the R1 group will have an odd number of carbon atom segments. If the number of carbon atoms in R1 is even, the number of carbon atoms in R2 and R3 will both be odd, ensuring that the structural unit has an odd number of carbon atom segments. When the number of carbon atoms in R1 is even, the number of carbon atoms in itaconic acid is even. However, the amount of itaconic acid is small and it has side groups, which has a certain inhibitory effect on the crystallization of polyester segments and has no promoting effect on the crystallization behavior of molecular chains.

[0022] In a preferred embodiment of the present invention,

[0023] The bio-based polyester elastomer is prepared from raw materials including diol, diacid A, diacid B, itaconic acid, catalyst, antioxidant and polymerization inhibitor.

[0024] The diol is one of 1,2-ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, and 1,6-hexanediol.

[0025] In a preferred embodiment of the present invention,

[0026] The molar ratio of the diol to the total molar ratio of diacid A, diacid B, and itaconic acid is (1.05–1.5):1; preferably (1.1–1.2):1; and / or,

[0027] Itaconic acid comprises 5-30% of the total molar fraction of dicarboxylic acid A, dicarboxylic acid B, and itaconic acid; preferably 10-20%; and / or,

[0028] The molar ratio of dicarboxylic acid A to dicarboxylic acid B is 1:(0.11–9); and / or,

[0029] The amount of catalyst used is 0.05–0.5% of the total monomer mass of the reaction; preferably 0.1–0.2%; and / or,

[0030] The amount of antioxidant used is 0.01–0.2% of the total monomer mass; preferably 0.01–0.1%; and / or,

[0031] The amount of polymerization inhibitor used is 0.01 to 0.2% of the total monomer mass in the reaction; preferably 0.04 to 0.1%.

[0032] In a preferred embodiment of the present invention,

[0033] When the diol is 1,3-propanediol or 1,5-pentanediol, the dicarboxylic acid A and dicarboxylic acid B are respectively one of 1,4-succinic acid, 1,5-pentanenic acid, 1,6-adipic acid, 1,7-heptanenic acid, 1,8-octanoic acid, 1,9-azelaic acid, and 1,10-sebacic acid; dicarboxylic acid A and dicarboxylic acid B are not the same;

[0034] The diol is 1,2-ethylene glycol, 1,4-butanediol, or 1,6-hexanediol, and the diacid A and diacid B are one of 1,5-pentanoic acid, 1,7-heptanoic acid, or 1,9-azelaic acid; diacid A and diacid B are not the same.

[0035] In a preferred embodiment of the present invention,

[0036] The catalyst is at least one of alkylaluminum, organotin compounds, and titanates having 1 to 12 carbon atoms; preferably at least one of tetrabutyl titanate and aluminum acetylacetonate; and / or,

[0037] The antioxidant is at least one selected from phosphoric acid, triphenyl phosphate, trimethyl phosphate, phosphorous acid, trimethyl phosphite, and triphenyl phosphite; and / or,

[0038] The polymerization inhibitor is at least one of phenolic polymerization inhibitors, ether polymerization inhibitors, quinone polymerization inhibitors, and aromatic amine polymerization inhibitors; preferably at least one of hydroquinone, p-tert-butylcatechol, p-hydroxyanisole, benzoquinone, diphenylamine, and p-phenylenediamine.

[0039] The second objective of this invention is to provide a method for preparing a bio-based polyester elastomer made from a single diol, comprising:

[0040] Under the protection of an inert gas, the raw materials are mixed according to the specified amount and subjected to an esterification reaction. After the reaction is completed, the temperature is lowered and a catalyst is added. After pre-condensation and final condensation, the bio-based polyester elastomer is obtained.

[0041] The polymerization is carried out in a reactor equipped with a mechanical stirrer.

[0042] In a preferred embodiment of the present invention,

[0043] The inert gas is nitrogen or argon; and / or,

[0044] The esterification reaction temperature is 150–220°C; preferably 160–190°C; and / or,

[0045] The esterification reaction time is 1–5 h; preferably 2–3 h; and / or,

[0046] After esterification, the system temperature is lowered to 50–120°C before adding the catalyst; preferably, the temperature is lowered to 50–80°C.

[0047] In a preferred embodiment of the present invention,

[0048] The prepolymerization temperature is 190–260°C; preferably 220–230°C; and / or,

[0049] The pre-polymerization pressure is 3–10 kPa; and / or,

[0050] The prepolymerization time is 0.5–5 h; preferably 0.5–1.5 h; and / or,

[0051] The final polycondensation temperature is 190–260°C; preferably 220–230°C; and / or,

[0052] The final polycondensation vacuum degree is below 300 Pa; and / or,

[0053] The final polycondensation time is 2 to 8 hours; preferably 4 to 8 hours.

[0054] A third objective of this invention is to provide a bio-based polyester elastomer prepared by the above method.

[0055] The fourth objective of this invention is to provide an application of a bio-based polyester elastomer in elastomeric nanocomposite materials.

[0056] The bio-based polyester elastomer can be blended with crosslinking agents, fillers and other raw materials, and molded at 140-180°C to prepare elastomer nanocomposite materials; preferably, melt blending is carried out in a Hacker internal mixer.

[0057] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0058] In existing technologies, polyester elastomers are prepared using two or more glycols as monomers. To ensure the production of esterified products with high esterification rates during the esterification stage, the alkyd-acid ratio is generally greater than 1.5:1 in actual industrial production. This leads to a series of problems:

[0059] (1) When removing excess diols during the polycondensation stage, it is impossible to control the removal ratio of two or more diols. Therefore, the molecular structure of polyester elastomer products synthesized in different batches will have certain differences.

[0060] (2) In the process of polyester production in industry, due to the addition of excessive diols, in order to control production costs, it is necessary to recycle and reuse the diols extracted in the polycondensation stage. It is difficult to fractionate and recycle two or more diols with similar boiling points, and the cost and energy consumption are high.

[0061] This invention uses a single diol as a monomer to prepare polyester elastomers, overcoming the above-mentioned defects. It can make different batches of products have a stable chemical structure, and excess alcohol is easy to recover, resulting in lower production costs.

[0062] This invention utilizes the "odd-even effect" in polyesters, namely, the characteristic that polyesters synthesized using monomers with an odd number of carbon atoms generally have weaker crystallization ability than those synthesized using monomers with an even number of carbon atoms. By using diacid and diol monomers with an odd number of carbon atoms for copolymerization, most structural units of the resulting bio-based polyester elastomer contain segments with an odd number of carbon atoms (derived from diols or diacids with an odd number of carbon atoms), thereby disrupting polyester crystallization. This solves the problem of overcoming the crystallization behavior of polyesters with a single diol at the molecular structure design level, and the resulting bio-based polyester elastomer has excellent elastomer properties.

[0063] The bio-based polyester elastomer prepared by this invention produces an elastomer nanocomposite material with good mechanical properties. Attached Figure Description

[0064] Figure 1 The Fourier transform infrared spectrum of the bio-based polyester elastomer prepared in Example 1;

[0065] Figure 2 Bio-based polyester elastomer prepared in Example 1 1 H NMR spectrum;

[0066] Figure 3 The second segment of the DSC temperature rise curves for the bio-based polyester elastomers prepared in Examples 1-3 are shown.

[0067] Figure 4 The stress-strain curve of the elastomeric nanocomposite material prepared from the bio-based polyester elastomer obtained in Example 3 is shown.

[0068] Figure 5 Thermogravimetric (TG) curve of the bio-based polyester elastomer prepared in Example 1;

[0069] Figure 6 Thermogravimetric (DTG) curve of the bio-based polyester elastomer prepared in Example 1;

[0070] Figure 7 Bio-based polyester elastomer prepared in Example 4 1 H NMR spectrum. Detailed Implementation

[0071] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention are still within the scope of protection of the present invention.

[0072] All raw materials used in the examples are commercially available.

[0073] Test method:

[0074] Fourier Transform Infrared Spectroscopy (FT-IR): Measurements were performed using a Bruker INVENIO S spectrometer manufactured by Bruker Corporation, employing the infrared transmission (TR) method at a wavenumber of 600 cm⁻¹. -1 Up to 4000cm -1 Performed at a resolution of 4cm -1 The scans were performed, with each sample being scanned 32 times;

[0075] 1H NMR spectrum 1 ¹H NMR: The test was performed at room temperature using a Bruker AVANCE AV600 spectrometer at a test frequency of 600 MHz, with deuterated chloroform (CDCl3) as the test solvent and tetramethylsilane (TMS) as the internal standard.

[0076] Differential scanning calorimetry (DSC) test: This test was performed under a nitrogen atmosphere using a Mettler-Toledo DSC1 manufactured by Mettler. Weigh 5-8 mg of sample, first heat the sample from room temperature to 100 °C and hold it for 5 min to eliminate the influence of the sample’s thermal history on the measurement, then cool the sample from 100 °C to -100 °C and hold it at -100 °C for 5 min, and finally heat the sample from -100 °C to 100 °C. The temperature change rate during both heating and cooling processes was 10 °C / min.

[0077] Thermogravimetric analysis (TGA) test: This test is conducted under a nitrogen atmosphere at a heating rate of 10℃ / min using a NETZSCHTG209C instrument to measure the mass change of the sample from 30℃ to 800℃.

[0078] Tensile testing: The tensile properties of the specimens were tested using an AI-7000S1 testing machine from High-speed Rail Corporation, according to ASTM D412. The dumbbell-shaped specimens were measured at 200 mm / min using a 500N sensor.

[0079] Example 1

[0080] 1,5-Pentanediol (36.45 g, 0.350 mol), 1,4-succinic acid (16.91 g, 0.143 mol), 1,6-adipic acid (20.92 g, 0.143 mol), itaconic acid (4.14 g, 0.032 mol), antioxidant phosphorous acid (0.0078 g, 0.01 wt% of total monomers), and polymerization inhibitor hydroquinone (0.031 g, 0.04 wt% of total monomers) were added to a reactor equipped with a mechanical stirrer. Under a nitrogen atmosphere, the system was heated to 160 °C for esterification reaction for 3 h. The system was then cooled to 50 °C, and tetrabutyl titanate (0.078 g, 0.1 wt% of total monomers) was added. The temperature was then raised to 220 °C, and the pressure was reduced to 10 kPa. Pre-polymerization was carried out at this temperature for 1.5 h, followed by final polymerization at 300 Pa for 8 h to obtain the bio-based polyester elastomer product.

[0081] The structural formula of the prepared bio-based polyester elastomer is as follows:

[0082]

[0083] a: (a+b) is 0.5; b: (a+b) is 0.5; c: (a+b+c) is 0.1.

[0084] Example 2

[0085] 1,5-Pentanediol (36.45 g, 0.350 mol), 1,4-succinic acid (23.67 g, 0.200 mol), 1,6-adipic acid (12.55 g, 0.086 mol), itaconic acid (4.14 g, 0.032 mol), antioxidant triphenyl phosphate (0.077 g, 0.1 wt% of total monomers), and polymerization inhibitor p-hydroxyanisole (0.077 g, 0.1 wt% of total monomers) were added to a reactor equipped with a mechanical stirrer. Under a nitrogen atmosphere, the system was heated to 190 °C for esterification reaction for 2 h. Then, the temperature was lowered to 80 °C, aluminum acetylacetonate (0.154 g, 0.2 wt% of total monomers) was added, and the temperature was raised to 230 °C. The pressure was reduced to 3 kPa, and pre-polymerization was carried out at this temperature for 0.5 h. Then, the temperature was maintained, and the pressure was reduced to 300 Pa for final polycondensation for 4 h to obtain the bio-based polyester elastomer product.

[0086] The structural formula of the bio-based polyester elastomer is the same as that in Example 1;

[0087] a: (a+b) is 0.7; b: (a+b) is 0.3; c: (a+b+c) is 0.1.

[0088] Example 3

[0089] 1,5-Pentanediol (36.45 g, 0.350 mol), 1,4-succinic acid (30.44 g, 0.258 mol), 1,6-adipic acid (4.18 g, 0.029 mol), itaconic acid (4.14 g, 0.032 mol), antioxidant phosphorous acid (0.0075 g, 0.01 wt% of total monomers), and polymerization inhibitor hydroquinone (0.030 g, 0.04 wt% of total monomers) were added to a reactor equipped with a mechanical stirrer. Under a nitrogen atmosphere, the system was heated to 180 °C for esterification reaction for 2 h. Then, the temperature was lowered to 80 °C, tetrabutyl titanate (0.075 g, 0.1 wt% of total monomers) was added, and the temperature was raised to 220 °C. The pressure was reduced to 3 kPa, and pre-polymerization was carried out at this temperature for 1 h. Then, the temperature was maintained, and the pressure was reduced to 300 Pa for final polycondensation for 6 h to obtain the bio-based polyester elastomer product.

[0090] The structural formula of the bio-based polyester elastomer is the same as that in Example 1;

[0091] a: (a+b) is 0.9; b: (a+b) is 0.1; c: (a+b+c) is 0.1.

[0092] Example 4

[0093] 1,5-Pentanediol (36.45 g, 0.350 mol), 1,4-succinic acid (16.91 g, 0.143 mol), 1,5-pentanediol (18.92 g, 0.143 mol), itaconic acid (4.14 g, 0.032 mol), antioxidant phosphorous acid (0.0076 g, 0.01 wt% of total monomers), and polymerization inhibitor hydroquinone (0.031 g, 0.04 wt% of total monomers) were added to a reactor equipped with a mechanical stirrer. Under a nitrogen atmosphere, the system was heated to 180 °C for esterification reaction for 2 h. Then, the temperature was lowered to 80 °C, tetrabutyl titanate (0.076 g, 0.1 wt% of total monomers) was added, and the temperature was raised to 220 °C. The pressure was reduced to 3 kPa, and pre-polymerization was carried out at this temperature for 1 h. Then, the temperature was maintained, and the pressure was reduced to 300 Pa for final polycondensation for 6 h to obtain the bio-based polyester elastomer product.

[0094] The structural formula of the prepared bio-based polyester elastomer is as follows:

[0095]

[0096] a: (a+b) is 0.5; b: (a+b) is 0.5; c: (a+b+c) is 0.1.

[0097] Example 5

[0098] 1,5-Pentanediol (36.45 g, 0.350 mol), 1,4-succinic acid (23.67 g, 0.200 mol), 1,5-pentanediol (11.35 g, 0.086 mol), itaconic acid (4.14 g, 0.032 mol), antioxidant phosphorous acid (0.0076 g, 0.01 wt% of total monomers), and polymerization inhibitor hydroquinone (0.030 g, 0.04 wt% of total monomers) were added to a reactor equipped with a mechanical stirrer. Under a nitrogen atmosphere, the system was heated to 180 °C for esterification reaction for 2 h. Then, the temperature was lowered to 80 °C, tetrabutyl titanate (0.076 g, 0.1 wt% of total monomers) was added, and the temperature was raised to 220 °C. The pressure was reduced to 3 kPa, and pre-polymerization was carried out at this temperature for 1 h. Then, the temperature was maintained, and the pressure was reduced to 300 Pa for final polycondensation for 6 h to obtain the bio-based polyester elastomer product.

[0099] The structural formula of the bio-based polyester elastomer is the same as that in Example 4;

[0100] a: (a+b) is 0.7; b: (a+b) is 0.3; c: (a+b+c) is 0.1.

[0101] Example 6

[0102] 1,2-Ethylene glycol (20.46 g, 0.330 mol), 1,5-pentanoic acid (17.82 g, 0.135 mol), 1,7-heptanediol (21.60 g, 0.135 mol), itaconic acid (3.90 g, 0.030 mol), antioxidant phosphorous acid (0.0064 g, 0.01 wt% of total monomers), and polymerization inhibitor hydroquinone (0.026 g, 0.04 wt% of total monomers) were added to a reactor equipped with a mechanical stirrer. Under a nitrogen atmosphere, the system was heated to 180 °C for esterification reaction for 2 h. Then, the temperature was lowered to 80 °C, tetrabutyl titanate (0.076 g, 0.1 wt% of total monomers) was added, and the temperature was raised to 220 °C. The pressure was reduced to 3 kPa, and pre-polymerization was carried out at this temperature for 1 h. Then, the temperature was maintained, and the pressure was reduced to 300 Pa for final polycondensation for 6 h to obtain the bio-based polyester elastomer product.

[0103] The structural formula of the prepared bio-based polyester elastomer is as follows:

[0104]

[0105] a: (a+b) is 0.5; b: (a+b) is 0.5; c: (a+b+c) is 0.1.

[0106] Example 7

[0107] 1,4-Butanediol (29.70 g, 0.330 mol), 1,5-pentanoic acid (14.52 g, 0.110 mol), 1,7-heptanediol (17.60 g, 0.110 mol), itaconic acid (7.15 g, 0.055 mol), antioxidant phosphorous acid (0.0069 g, 0.01 wt% of total monomers), and polymerization inhibitor hydroquinone (0.027 g, 0.04 wt% of total monomers) were added to a reactor equipped with a mechanical stirrer. Under a nitrogen atmosphere, the system was heated to 180 °C for esterification reaction for 2 h. Then, the temperature was lowered to 80 °C, tetrabutyl titanate (0.069 g, 0.1 wt% of total monomers) was added, and the temperature was raised to 220 °C. The pressure was reduced to 3 kPa, and pre-polymerization was carried out at this temperature for 1 h. Then, the temperature was maintained, and the pressure was reduced to 300 Pa for final polycondensation for 6 h to obtain the bio-based polyester elastomer product.

[0108] The structural formula of the prepared bio-based polyester elastomer is as follows:

[0109]

[0110] a: (a+b) is 0.5; b: (a+b) is 0.5; c: (a+b+c) is 0.2.

[0111] Comparative Example 1

[0112] 1,4-Butanediol (29.70 g, 0.330 mol), 1,4-succinic acid (15.93 g, 0.135 mol), 1,6-adipic acid (19.71 g, 0.135 mol), itaconic acid (3.90 g, 0.030 mol), antioxidant phosphorous acid (0.0069 g, 0.01 wt% of total monomers), and polymerization inhibitor hydroquinone (0.027 g, 0.04 wt% of total monomers) were added to a reactor equipped with a mechanical stirrer. Under a nitrogen atmosphere, the system was heated to 180 °C for esterification reaction for 2 h. Then, the temperature was lowered to 80 °C, tetrabutyl titanate (0.069 g, 0.1 wt% of total monomers) was added, and the temperature was raised to 220 °C. The pressure was reduced to 3 kPa, and pre-polymerization was carried out at this temperature for 1 h. Then, the temperature was maintained, and the pressure was reduced to 300 Pa for final polycondensation for 6 h to obtain the bio-based polyester elastomer product.

[0113] The structural formula of the prepared product is as follows:

[0114]

[0115] a: (a+b) is 0.5; b: (a+b) is 0.5; c: (a+b+c) is 0.1.

[0116] Comparative Example 2

[0117] 1,4-Butanediol (29.70 g, 0.330 mol), 1,4-succinic acid (15.93 g, 0.135 mol), 1,5-glutaric acid (17.82 g, 0.135 mol), itaconic acid (3.90 g, 0.030 mol), antioxidant phosphorous acid (0.0069 g, 0.01 wt% of total monomers), and polymerization inhibitor hydroquinone (0.027 g, 0.04 wt% of total monomers) were added to a reactor equipped with a mechanical stirrer. Under a nitrogen atmosphere, the system was heated to 180 °C for esterification reaction for 2 h. Then, the temperature was lowered to 80 °C, tetrabutyl titanate (0.069 g, 0.1 wt% of total monomers) was added, and the temperature was raised to 220 °C. The pressure was reduced to 3 kPa, and pre-polymerization was carried out at this temperature for 1 h. Then, the temperature was maintained, and the pressure was reduced to 300 Pa for final polycondensation for 6 h to obtain the bio-based polyester elastomer product.

[0118] The structural formula of the prepared product is as follows:

[0119]

[0120] a: (a+b) is 0.5; b: (a+b) is 0.5; c: (a+b+c) is 0.1.

[0121] Comparative Example 3

[0122] 1,3-Propanediol (10.26 g, 0.135 mol), 1,5-Pentanediol (14.04 g, 0.135 mol), 1,4-Succinic acid (26.07 g, 0.221 mol), itaconic acid (3.19 g, 0.025 mol), antioxidant phosphorous acid (0.0054 g, 0.01 wt% of total monomers), and polymerization inhibitor hydroquinone (0.021 g, 0.04 wt% of total monomers) were added to a reactor equipped with a mechanical stirrer. Under a nitrogen atmosphere, the system was heated to 180 °C for esterification reaction for 2 h. Then, the temperature was lowered to 80 °C, tetrabutyl titanate (0.054 g, 0.1 wt% of total monomers) was added, and the temperature was raised to 220 °C. The pressure was reduced to 3 kPa, and pre-polymerization was carried out at this temperature for 1 h. Then, the temperature was maintained, and the pressure was reduced to 300 Pa for final polycondensation for 6 h to obtain the bio-based polyester elastomer product.

[0123] The structural formula of the prepared product is as follows:

[0124]

[0125] (a+b)≈(c+d), a:b≈c:d≈9:1.

[0126] Elastomer nanocomposites were prepared from the bio-based polyester elastomers obtained in Examples 1-7 with dicumyl peroxide and silica.

[0127] Based on 100 parts by weight of bio-based polyester elastomer,

[0128] 100 parts by weight of bio-based polyester elastomer;

[0129] 0.1 to 1 part by weight of dicumyl peroxide;

[0130] 20-50 parts by weight of silica;

[0131] The raw materials were melt-blended in a Hacker internal mixer according to the specified dosage at a mixing temperature of 60°C for 30 minutes. The mixture was then molded at 160°C to obtain an elastomer nanocomposite material. The mechanical properties were tested, and a rubber composite material product with a tensile strength of 12 MPa and an elongation at break of 300% was prepared, which can meet most engineering applications.

[0132] Table 1 Performance test results of Examples 1-6 and Comparative Examples 1-2

[0133]

[0134]

[0135] a: Examples 1-3 were 1,4-succinic acid / 1,6-adipic acid; Examples 4-5 were 1,4-succinic acid / 1,5-glutaric acid; Examples 6-7 were 1,5-glutaric acid / 1,7-heptanenic acid; Comparative Example 1 was 1,4-succinic acid / 1,6-adipic acid; Comparative Example 2 was 1,4-succinic acid / 1,5-glutaric acid; Comparative Example 3 was 1,3-propanediol / 1,5-pentanediol.

[0136] b: This data is obtained through... 1 The results were obtained by quantitative integration from H NMR;

[0137] c: According to the parity of the number of carbon atoms in the diol, the even-even segment is defined as the combination of a diol with an even number of carbon atoms and a diacid with an even number of carbon atoms. The segment here excludes the itaconic acid ester unit, which is the cross-linking point.

[0138] Comparative Example 1 and Comparative Example 2 both used a single diol to prepare quaternary copolyesters with "even-even" segments. Compared with Examples 1 to 7, the introduction of even-even segments resulted in the crystallization ability of the polyester segments. They did not exhibit the state of an elastomer at room temperature and therefore could not be used as an elastomer matrix material.

[0139] Compared to Examples 1-7, Comparative Example 3 used two diols to prepare an amorphous polyester elastomer with odd and even chain segments, through core... 1The quantitative integration data from the H NMR results show that when the molar ratio of the two monomers is 0.50 / 0.50, the molar ratio of the two monomer segments is 0.41 / 0.59, with an error of about 10%. Examples 1-7 were all synthesized using a single diol. As can be seen from Table 1, the composition ratio of the final molecular segments is very close to the initial feed ratio, with an error of less than 1%, which is much greater than that of Examples 1-7 using a single diol. This is because two diols were used. Because an excess of diol was added during the feed stage (to prepare hydroxyl-terminated esters, which is beneficial to the transesterification molecular weight increase of the polycondensation segment), it was removed in an uncontrollable proportion during the polycondensation stage. Therefore, the molecular segment structure of Examples 1-7 using a single diol is more consistent with the feed ratio, and a structurally stable polyester elastomer product can be prepared.

[0140] Figure 1 Middle, 2591cm -1 With 2868cm -1 The peak at 1736 cm⁻¹ represents the stretching symmetry of the methylene structure (-CH₂-), the peak at 1465 cm⁻¹ represents the stretching vibration of the carbonyl group (-C=O), and the peak at 1256 cm⁻¹ represents the bending vibration of the methylene group (-CH₂-). -1 With 1164cm -1 The peak represents the stretching vibration of the ester group, at 1061 cm⁻¹. -1 The peak is (-CO-) vibration. Figure 2 In the figure, the proton chemical shifts at 4.09 ppm (a1), 3.65 ppm (a2), 1.66 ppm (b), and 1.41 ppm (c) correspond to the pentanediol structural unit (-C). H 2-C H 2-C H The characteristic absorption peak of 2-O-) and the proton chemical shift at 2.62 ppm(d) are due to the succinic acid structural unit (-(C)). H 2) Characteristic absorption peaks of 2-COO-). The proton chemical shifts at 2.33 ppm (h) and 1.66 ppm (i) correspond to the adipic acid structural unit (-(C)). H 2)2-C H The characteristic absorption peak of 2-COO-). The structural unit of itaconic acid is (-C(=C)). H 2) The proton chemical shifts on -CH2-COO-) appear at three positions: 6.32 ppm (e), 5.71 ppm (f), and 3.33 ppm (g).

[0141] Figure 1 , Figure 2 The structure of the bio-based polyester elastomer prepared in Example 1 was confirmed.

[0142] Figure 7 Example 41 In the 1H NMR spectrum, the proton chemical shifts at 4.09 ppm (a1), 3.65 ppm (a2), 1.66 ppm (b), and 1.41 ppm (c) correspond to the pentanediol structural unit (-C). H 2-C H 2-C H The characteristic absorption peak of 2-O-). The proton chemical shift at 2.62 ppm (d) corresponds to the succinic acid structural unit (-(C)). H 2) Characteristic absorption peak of 2-COO-). Glutaric acid structural unit (-C H 2-C H The proton chemical shifts on 2-COO-) appear at 2.37 ppm (h) and 1.94 ppm (i). The structural unit of itaconic acid is -C(=C) H 2) The proton chemical shifts on -CH2-COO-) appear at three positions: 6.32 ppm (e), 5.71 ppm (f), and 3.33 ppm (g).

[0143] Figure 7 The structure of the bio-based polyester elastomer prepared in Example 4 was confirmed.

[0144] from Figure 3 As can be seen, the Tg values ​​of Examples 1 to 3 are -54.9℃, -52.8℃, and -47.9℃, respectively, all of which are lower than -40℃.

[0145] Figure 4 The stress-strain curve of the bio-based polyester elastomer prepared in Example 3 shows that the tensile strength of the elastomer nanocomposite material after reinforcement with silica and crosslinking with DCP is greater than 12 MPa and the elongation at break is greater than 300%.

[0146] Figure 5 , Figure 6 The TG and DTG curves of Example 1 show that the initial decomposition temperature is above 300℃, indicating good thermal stability.

[0147] The bio-based polyester elastomers prepared in Examples 1-7 have good elastomer properties, proving that the "odd-even effect" of polyester can be used to disrupt polyester crystallization. This invention uses only a single unbranched diol monomer, and the resulting bio-based polyester elastomer has a more stable chemical structure. Furthermore, the diol is easy to recycle and has a lower cost.

Claims

1. A bio-based polyester elastomer, characterized in that: The structural formula of the bio-based polyester elastomer is: a, b, and c are all non-zero integers; a: (a+b) is 0.1~0.9; b: (a+b) is 0.1~0.9; c: (a+b+c) is 0.05~0.3; R1 is an unbranched chain alkyl group with 2 to 6 carbon atoms; R2 is an unbranched chain alkyl group with 2 to 8 carbon atoms; R3 is an unbranched chain alkyl group with 2 to 8 carbon atoms; If the number of carbon atoms in R1 is even, then the number of carbon atoms in R2 and R3 is odd. The bio-based polyester elastomer is prepared from raw materials including diols, diacid A, diacid B, itaconic acid, catalysts, antioxidants, and polymerization inhibitors; the diol is one of 1,2-ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, and 1,6-hexanediol; diacid A and diacid B are different. When the diol is 1,3-propanediol or 1,5-pentanediol, the dicarboxylic acid A and dicarboxylic acid B are each one of 1,4-succinic acid, 1,5-pentanenic acid, 1,6-adipic acid, 1,7-heptanenic acid, 1,8-octanoic acid, 1,9-azelaic acid, and 1,10-sebacic acid; when the diol is 1,2-ethylenediol, 1,4-butanediol or 1,6-hexanediol, the dicarboxylic acid A and dicarboxylic acid B are each one of 1,5-pentanenic acid, 1,7-heptanenic acid, and 1,9-azelaic acid.

2. The bio-based polyester elastomer as described in claim 1, characterized in that: c: (a+b+c) is 0.1~0.2; and / or, R2 is an unbranched chain alkyl group having 2 to 3 carbon atoms; and / or, R3 is an unbranched chain alkyl group with 3 to 5 carbon atoms.

3. The bio-based polyester elastomer as described in claim 1 or 2, characterized in that: The ratio of the molar number of the diol to the total molar number of diacid A, diacid B, and itaconic acid is (1.05~1.5):1; and / or, Itaconic acid accounts for 5-30% of the total molar fraction of dicarboxylic acid A, dicarboxylic acid B, and itaconic acid; and / or, The molar ratio of dicarboxylic acid A to dicarboxylic acid B is 1:(0.11~9); and / or, The amount of catalyst used is 0.05~0.5% of the total monomer mass in the reaction; and / or, The amount of antioxidant used is 0.01~0.2% of the total monomer mass in the reaction; and / or, The amount of polymerization inhibitor used is 0.01~0.2% of the total monomer mass in the reaction.

4. The bio-based polyester elastomer as described in claim 3, characterized in that: The ratio of the molar number of the diol to the total molar number of diacids A, B, and itaconic acid is (1.1~1.2):1; and / or, Itaconic acid accounts for 10-20% of the total molar fraction of dicarboxylic acid A, dicarboxylic acid B, and itaconic acid; and / or, The amount of catalyst used is 0.1~0.2% of the total monomer mass in the reaction; and / or, The amount of antioxidant used is 0.01~0.1% of the total monomer mass in the reaction; and / or, The amount of polymerization inhibitor used is 0.04~0.1% of the total monomer mass in the reaction.

5. The bio-based polyester elastomer as described in claim 1 or 2, characterized in that: The catalyst is at least one selected from alkylaluminum, organotin compounds, and titanates having 1 to 12 carbon atoms; and / or, The antioxidant is at least one selected from phosphoric acid, triphenyl phosphate, trimethyl phosphate, phosphorous acid, trimethyl phosphite, and triphenyl phosphite; and / or, The polymerization inhibitor is at least one of phenolic polymerization inhibitors, ether polymerization inhibitors, quinone polymerization inhibitors, and aromatic amine polymerization inhibitors.

6. The bio-based polyester elastomer as described in claim 5, characterized in that: The polymerization inhibitor is at least one of hydroquinone, p-tert-butylcatechol, p-hydroxyanisole, benzoquinone, diphenylamine, and p-phenylenediamine.

7. A method for preparing a bio-based polyester elastomer as described in any one of claims 1 to 6, characterized in that... The method includes: Under the protection of an inert gas, the raw materials are mixed according to the specified amounts and subjected to an esterification reaction. After the reaction is completed, the temperature is lowered and a catalyst is added. After pre-condensation and final condensation, the bio-based polyester elastomer is obtained.

8. The method for preparing the bio-based polyester elastomer as described in claim 7, characterized in that: The inert gas is nitrogen or argon; and / or, The esterification reaction temperature is 150~220℃; and / or, The esterification reaction time is 1-5 hours; and / or, After esterification, the system temperature is cooled to 50~120℃ before adding the catalyst.

9. The method for preparing the bio-based polyester elastomer as described in claim 8, characterized in that: The esterification reaction temperature is 160~190℃; and / or, The esterification reaction time is 2-3 hours; and / or, After esterification, the system temperature is lowered to 50-80℃ before adding the catalyst.

10. The method for preparing the bio-based polyester elastomer as described in claim 7, characterized in that: The pre-polymerization temperature is 190~260℃; and / or, The pre-polymerization pressure is 3~10 kPa; and / or, The prepolymerization time is 0.5~5h; and / or, The final polycondensation temperature is 190~260℃; and / or, The final polycondensation vacuum degree is below 300 Pa; and / or, The final polycondensation time is 2-8 hours.

11. The method for preparing the bio-based polyester elastomer as described in claim 10, characterized in that: The pre-polymerization temperature is 220~230℃; and / or, The prepolymerization time is 0.5~1.5h; and / or, The final polycondensation temperature is 220~230℃; and / or, The final polymerization time is 4~8 hours.

12. A bio-based polyester elastomer prepared by the preparation method according to any one of claims 7 to 11.

13. The application of a bio-based polyester elastomer as described in any one of claims 1 to 6 or a bio-based polyester elastomer prepared by the method described in any one of claims 7 to 11 in elastomer nanocomposites.

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