Polyolefin-like long-carbon-chain polyester elastomer, and preparation method therefor and use thereof

Abstract

Disclosed in the present invention are a polyolefin-like long-carbon-chain polyester elastomer, and a preparation method therefor and a use thereof. The polyolefin-like long-carbon-chain polyester elastomer is formed by polymerizing a long-carbon-chain dicarboxylic acid or an esterified product of the long-carbon-chain dibasic acid with a dihydric alcohol. The long-carbon-chain polyester elastomer can be recycled in a closed loop manner. The preparation method comprises: under inert gas protection, placing a long-carbon-chain dicarboxylic acid or an esterified product thereof, a dihydric alcohol, and a catalyst into a three-necked flask in proportion, and controlling the reaction temperature and the stirring rotation speed to prepare an oligomer; and under vacuum conditions, carrying out a polycondensation reaction on the oligomer prepared in step S1 to obtain the long-carbon-chain polyester elastomer. In the present invention, the molecular weight and the thermodynamic properties can be effectively regulated by designing the ratio of soft and hard segments in a polymer; and the preparation process is simple, convenient and safe, and the equipment requirement and the catalytic cost are relatively low. Since the crystallization process can utilize the Van der Waals force between hydrocarbon chain segments, an ester bond is present in the structure, and chemical recycling is allowed by means of solvolysis, the long-carbon-chain polyester elastomer of the present invention is expected to become a potential substitute of high-density polyethylene.

Description

Polyolefin-like long carbon chain polyester elastomer, preparation method and application thereof Technical Field

[0001] The present invention relates to the technical field of polymer materials, and in particular to a polyolefin-like long carbon chain polyester elastomer, a preparation method and applications thereof. Background Art

[0002] In the context of low-carbon, green, and sustainable development, the degradation of synthetic polymers has become a global issue. Most polymer products are not environmentally friendly and are difficult to self-degrade through thermal degradation, causing serious environmental pollution. Polyolefin plastics, such as polyethylene, are the most important synthetic polymers used on a large scale. They are easy to process and have excellent mechanical properties, making them widely used in daily life. However, from the perspective of a circular economy, the production of polyethylene consumes a large amount of petroleum resources. However, due to the chemical inertness and hydrophobicity of the hydrocarbon chain, it is extremely difficult to degrade after use, causing serious environmental pollution and incompatible with the concept of sustainable development.

[0003] Aliphatic polyesters contain ester bonds in their main chains and are biodegradable in the environment after production and processing. However, common aliphatic polyesters have relatively short chain segments and often have deficiencies in mechanical or thermal properties. By utilizing longer-chain aliphatic repeating units similar to polyolefins, the overall performance of the material can be further improved or regulated, broadening its scope of application. Long-chain polyesters have a linear hydrocarbon chain structure similar to polyethylene, enabling crystallization and stacking, and exhibiting excellent material properties. At the same time, the low-density intrachain functional groups in long-chain polyesters serve as breaking points for chemical depolymerization into monomers for recycling, almost completely preserving the material's properties and enabling green, low-carbon, and sustainable development in the polymer materials industry.

[0004] Chinese patent CN117164979A discloses a polyolefin material, its preparation method, and application. The method comprises mixing a polyolefin resin, a brominated flame retardant, antimony trioxide, melamine cyanurate, ammonium polyphosphate, piperazine pyrophosphate, a laser marking agent, an antioxidant, and a processing aid. The mixture is processed through a twin-screw extruder to obtain a first-step feed, followed by a second-step mixing process to obtain the polyolefin material. The resulting polyolefin material exhibits excellent performance, but is difficult to degrade and recycle, requiring incineration or landfill disposal, which can be highly environmentally friendly.

[0005] Chinese patent CN117209639A discloses a method for preparing and using a polyolefin elastomer. The polyolefin elastomer exhibits both the characteristics of a polyolefin and an elastomer, with significantly improved material polarity and excellent overall performance. However, the polymerization process is solution polymerization, and the solvent used is an organic solvent such as toluene, which is highly toxic and environmentally hazardous. Furthermore, solvent recovery is difficult. Recycling of the polyolefin elastomer is hampered by deteriorating material properties, resulting in severe environmental pollution.

[0006] Chinese patent CN115286788A discloses a polyolefin-like bio-based linear polyesteramide and its preparation method. The method involves first reacting a bio-based diester with an amino group in a solvent to produce an amide diol monomer. The amide diol and the bio-based diacid are then esterified to produce a prepolymer. Finally, a short-chain diol is added, and the polyolefin-like bio-based linear polyesteramide is obtained after esterification and polycondensation. This synthesis method uses one or both of DMF and THF as toxic solvents, which have limited recycling potential. Furthermore, the preparation method is complex and requires high equipment operation requirements.

[0007] Existing (quasi) polyolefin material preparation technologies cannot achieve controllable molecular structure and molecular weight, have complex process flows, harsh reaction conditions, high equipment requirements, and poor thermodynamic properties. In addition, the products are difficult to degrade and reuse, and are highly harmful to the environment.

[0008] Therefore, the polyolefin-like long carbon chain polyester elastomer prepared by the present invention has a designable molecular structure, controllable molecular weight, simple preparation process operation, low equipment requirements, and can achieve closed-loop recycling, which obviously has important research significance.

[0009] Summary of the Invention

[0010] The purpose of the present invention is to provide a polyolefin-like long carbon chain polyester elastomer, a preparation method and its application. The preparation process is simple, the molecular structure is controllable, the product structure and performance are similar to polyolefins, but closed-loop recycling can be achieved, and it is expected to become a potential substitute for petroleum-based polyethylene.

[0011] To achieve the above-mentioned object, the present invention adopts the following technical solution: a polyolefin-like long carbon chain polyester elastomer is prepared by polymerization of a long carbon chain dibasic acid or an ester of a long carbon chain dibasic acid and a diol, and has the following structure:

[0012] Wherein, R1 is selected from C 11 -C 18 R2 is selected from C2-C 18 An alkyl group; R3 is selected from C 11 -C 36 A long carbon chain alkyl group containing a branch.

[0013] Preferably, the long carbon chain dibasic acid comprises a branched long carbon chain dibasic acid.

[0014] Preferably, the long carbon chain dibasic acid further comprises a linear dibasic acid with a general structural formula of HOOC(CH2)xCOOH, wherein x≥10.

[0015] Preferably, the long carbon chain dibasic acid ester comprises at least one of dimethyl dibasic acid ester and diethyl dibasic acid ester.

[0016] Preferably, the diol includes one or more combinations of ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 2-methyl-1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, and long carbon chain diols.

[0017] Preferably, the intrinsic viscosity of the long carbon chain polyester elastomer is 0.7 to 1.4 dL / g;

[0018] The number average molecular weight of the long carbon chain polyester elastomer is 4×104 to 1.3×105 g / mol;

[0019] The glass transition temperature of the long carbon chain polyester elastomer is -40 to 75°C;

[0020] The tensile strength of the long carbon chain polyester elastomer is 3 to 95 MPa.

[0021] Preferably, the long carbon chain polyester elastomer can be closed-loop recycled, and the closed-loop recycling method comprises the following steps:

[0022] 1) Depolymerization process: In a pressure vessel, a long carbon chain polyester elastomer, a solvent, and a catalyst are added in proportion, and the reaction temperature and stirring speed are controlled to carry out a depolymerization reaction to obtain a depolymerized monomer;

[0023] 2) Repolymerization process: The depolymerized monomers are subjected to transesterification and polycondensation to synthesize long carbon chain polyester elastomer again;

[0024] The depolymerization reaction temperature is 100-220° C., the reaction time is 2-7 hours, and the stirring speed is 350-650 rpm.

[0025] More preferably, the temperature of the depolymerization reaction is 120-200°C.

[0026] More preferably, the reaction time of the depolymerization reaction is 3 to 5 hours.

[0027] More preferably, the stirring speed of the depolymerization reaction is 450-550 rpm.

[0028] Preferably, the mass ratio of the polyester elastomer to the solvent is 1.0:9.0-15.0, more preferably 1.0:10.0-12.0; the amount of the catalyst is 0.2%-0.6% of the total mass of the polyester elastomer and the solvent, more preferably 0.3%-0.5%; the solvent includes at least one of methanol, ethanol, and ethylene glycol; and the catalyst includes zinc acetate.

[0029] The present application also claims a method for preparing a polyolefin-like long carbon chain polyester elastomer, which is used to prepare the polyolefin-like long carbon chain polyester elastomer as described above, comprising the following steps:

[0030] S1. Transesterification reaction to produce oligomers: Under inert gas protection, a long carbon chain dibasic acid or its esterified product, a diol, and a catalyst are placed in a three-necked flask in appropriate proportions, and the reaction temperature and stirring speed are controlled to produce oligomers;

[0031] S2. Polycondensation reaction to obtain a polymer: Under vacuum conditions, the oligomer prepared in step S1 is subjected to a polycondensation reaction to obtain a long carbon chain polyester elastomer.

[0032] Preferably, the molar ratio of the long-chain dicarboxylic acid or its ester to the diol is 1.0:1.0-2.0, more preferably 1.0:1.1-1.8; the molar ratio of the branched long-chain dicarboxylic acid or its ester structural unit is 10-90 mol%, more preferably 30-70 mol%; the amount of the catalyst is 0.2% of the total molar amount of the long-chain dicarboxylic acid.

[0033] Preferably, in step S1, the catalyst is selected from at least one of titanium-based catalysts, more preferably at least one of tetrabutyl titanate, tetraisopropyl titanate, titanium dioxide, and titanium glycol.

[0034] Preferably, in step S1, the reaction temperature is 160-240°C, more preferably 180-220°C; the reaction time is 2-4 hours, more preferably 2.5-3 hours.

[0035] Preferably, the reaction temperature in step S2 is 200-280° C., more preferably 220-260° C.; the reaction time is 2-4 h, more preferably 2.5-3.5 h.

[0036] Preferably, in step S2, the reaction vacuum degree is 80-250 Pa, more preferably, the reaction vacuum degree is 100-220 Pa.

[0037] Preferably, in step S1, performing the step under the protection of an inert gas means introducing nitrogen three times and then maintaining the introduction of nitrogen at a constant speed.

[0038] Preferably, in step S1, when the amount of water generated by the reaction collected at the condensation portion reaches more than 90 to 95% of the theoretical amount of water, the esterification reaction is completed.

[0039] In the above, the reaction conditions of the repolymerization process in step 2) are the same as the reaction conditions for preparing the long carbon chain polyester elastomer.

[0040] The present application also claims protection for the application of a polyolefin-like long carbon chain polyester elastomer, and the application of the above-mentioned polyolefin-like long carbon chain polyester elastomer in polymer modification, automotive parts, medical supplies, and cable systems.

[0041] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art:

[0042] 1. The long carbon chain polyester elastomer prepared by the present invention can effectively design the molecular structure and control the molecular weight, thereby optimizing the thermodynamic properties;

[0043] 2. The long-chain polyester elastomer prepared by the present invention has a crystal structure and mechanical properties similar to those of polyethylene. The crystallization process can be facilitated by van der Waals forces between hydrocarbon chain segments. However, due to the presence of ester groups in the molecular chain, closed-loop recycling via solvent decomposition is possible, making it environmentally friendly and promising as a potential alternative to high-density polyethylene.

[0044] 3. The catalyst used in the present invention can be used not only as a catalyst for esterification (transesterification) reaction, but also as a catalyst for polycondensation reaction. It can be added once during the reaction process, making the experimental operation simple and safe, and the synthesis efficiency high;

[0045] 4. The present invention adopts the melt polycondensation method, which does not require a solvent, has a high concentration of reactants, and the product after polymerization is in a molten state and can be directly processed. The operation is simple and easy to control, the energy consumption is significantly reduced, and the production efficiency is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the specific embodiments or the description of the prior art. Obviously, some of the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0047] FIG1 is a Fourier transform infrared spectroscopy FTIR curve of the long carbon chain polyester elastomer in Example 1, wherein the abscissa represents the wave number and the ordinate represents the transmittance.

[0048] FIG2 is a differential scanning calorimetry (DSC) curve of the long carbon chain polyester elastomer in Example 1, wherein the abscissa represents temperature and the ordinate represents heat flow.

[0049] FIG3 is an engineering stress-strain curve of the long carbon chain polyester elastomer in Example 1, wherein the abscissa represents the elongation at break and the ordinate represents the tensile strength.

[0050] FIG4 is a dynamic mechanical thermal analysis DMTA curve of the long carbon chain polyester elastomer in Example 1, wherein the abscissa represents temperature and the ordinate represents elastic modulus.

[0051] FIG5 is an XRD curve of the X-ray diffraction analysis of the long carbon chain polyester elastomer in Example 1, wherein the abscissa represents the diffraction angle and the ordinate represents the diffraction intensity.

[0052] FIG6 is an engineering stress-strain curve of the long carbon chain polyester elastomer and its recycled analogues in Example 7, where the abscissa is the elongation at break and the ordinate is the tensile strength. DETAILED DESCRIPTION

[0053] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0054] Unless otherwise specified, the raw materials and catalysts in the examples of this application were purchased from commercial sources. The long carbon chain dibasic acid or its ester and diol raw materials used were from MacLean Biochemical Technology Co., Ltd., and the catalyst was purchased from Titan Technology Co., Ltd.

[0055] Example 1

[0056] First, 0.1 mol of 1,12-dodecanedioic acid and 0.1 mol of dimer acid were added to a three-necked flask equipped with a mechanical stirrer, a nitrogen inlet, and a condenser. 0.22 mol of 1,12-dodecanediol was then added, and 0.0004 mol of tetrabutyl titanate was used as a catalyst. The flask was placed in an oil bath and, under a nitrogen atmosphere, gradually heated to 160°C to initiate the reaction. The reaction continued at 160°C for 1 hour, 180°C for 0.5 hour, and 200°C for 1 hour. When the amount of water generated by the reaction, collected by condensation, reached over 90% of the theoretical amount, the reaction system was switched to a vacuum environment and continued. In the second stage, polycondensation was carried out under reduced pressure and vacuum at 180 Pa for 1 hour. The temperature was then raised to 220°C for 1 hour, and finally to 240°C for 1 hour. The product exhibited spooling, at which point the reaction was stopped and discharged. The product was then dried under vacuum at 30°C for 12 hours to obtain the final product.

[0057] As shown in Figures 1 to 5 , the final product prepared in Example 1 had an intrinsic viscosity of 0.92 dL / g, and its number average molecular weight, as measured by gel permeation chromatography, was 6.57×10⁴. Its glass transition temperature was -25°C, its crystallization temperature was 27.48°C, its melting point was 48.28°C, its tensile strength was 18.07 MPa, its tensile modulus was 1.29 MPa, and its elongation at break was 1743.04%.

[0058] Example 2

[0059] First, 0.18 mol of 1,12-dodecanedioic acid and 0.02 mol of dimer acid were added to a three-necked flask equipped with a mechanical stirrer, a nitrogen inlet, and a condenser. 0.22 mol of 1,12-dodecanediol was then added, and 0.0004 mol of tetrabutyl titanate was used as a catalyst. The flask was placed in an oil bath and, under a nitrogen atmosphere, gradually heated to 180°C to initiate the reaction. The reaction continued at 180°C for 1 hour, 200°C for 1 hour, and 220°C for 1 hour. When the amount of water generated by the reaction, collected from the condensate, reached over 90% of the theoretical amount, the reaction system was switched to a vacuum environment and continued. In the second stage, polycondensation was carried out under reduced pressure and vacuum at 200 Pa for 1 hour. The temperature was then raised to 240°C for 1 hour, and finally to 260°C for 1.5 hours. The product exhibited spherical spinning, at which point the reaction was stopped and discharged. The product was then dried under vacuum at 50°C for 12 hours to obtain the final product.

[0060] The final product prepared in Example 2 had an intrinsic viscosity of 1.33 dL / g, and a number average molecular weight of 8.78×10⁴ as measured by gel permeation chromatography. It also had a glass transition temperature of -9.30°C, a crystallization temperature of 60.81°C, a melting point of 76.87°C, a tensile strength of 29.44 MPa, a tensile modulus of 241.46 MPa, and an elongation at break of 1487.97%.

[0061] Example 3

[0062] First, 0.12 mol of 1,12-dodecanedioic acid and 0.08 mol of dimer acid were added to a three-necked flask equipped with a mechanical stirrer, a nitrogen inlet, and a condenser. 0.22 mol of 1,12-dodecanediol was then added, and 0.0004 mol of tetrabutyl titanate was used as a catalyst. The flask was placed in an oil bath and, under a nitrogen atmosphere, gradually heated to 180°C to initiate the reaction. The reaction continued at 180°C for 1 hour, 200°C for 0.5 hour, and 220°C for 1 hour. When the amount of water generated by the reaction, collected from the condensate, reached over 90% of the theoretical amount, the reaction system was switched to a vacuum environment and continued. In the second stage, polycondensation was carried out under reduced pressure at 220 Pa for 1 hour. The temperature was then raised to 240°C for 1 hour, and finally to 260°C for 1.5 hours. The product exhibited spherical propellers, at which point the reaction was stopped and discharged. The product was then dried under vacuum at 50°C for 12 hours to obtain the final product.

[0063] The final product prepared in Example 3 had an intrinsic viscosity of 1.01 dL / g, and a number average molecular weight of 6.94×10⁴ as measured by gel permeation chromatography. It also had a glass transition temperature of -22.3°C, a crystallization temperature of 36.29°C, a melting point of 55.5°C, a tensile strength of 17.19 MPa, a tensile modulus of 6.9 MPa, and an elongation at break of 1429.79%.

[0064] Example 4

[0065] First, 0.14 mol of 1,12-dodecanediolacid and 0.06 mol of dimer acid were added to a three-necked flask equipped with a mechanical stirrer, a nitrogen inlet, and a condenser. 0.22 mol of 1,12-dodecanediol was then added, and 0.0004 mol of tetrabutyl titanate was used as a catalyst. The flask was placed in an oil bath and, under a nitrogen atmosphere, gradually heated to 180°C to initiate the reaction. The reaction continued at 180°C for 1 hour, 200°C for 0.5 hour, and 220°C for 1 hour. When the amount of water generated by the reaction, collected from the condensate, reached over 90% of the theoretical amount, the reaction system was switched to a vacuum environment and continued. In the second stage, polycondensation was carried out under reduced pressure and vacuum at 220 Pa for 1 hour. The temperature was then raised to 240°C for 1 hour, and finally to 260°C for 1.5 hours. The product exhibited spherical propellers, at which point the reaction was stopped and discharged. The product was then dried under vacuum at 50°C for 12 hours to obtain the final product.

[0066] The final product prepared in Example 4 had an intrinsic viscosity of 0.97 dL / g, and a number average molecular weight of 5.74×10⁴ as measured by gel permeation chromatography. It also had a glass transition temperature of -20.04°C, a crystallization temperature of 45.4°C, a melting point of 64.73°C, a tensile strength of 19.89 MPa, a tensile modulus of 113.66 MPa, and an elongation at break of 1559.23%.

[0067] Example 5

[0068] First, 0.06 mol of 1,12-dodecanedioic acid and 0.14 mol of dimer acid were added to a three-necked flask equipped with a mechanical stirrer, a nitrogen inlet, and a condenser. 0.22 mol of 1,12-dodecanediol was then added, and 0.0004 mol of tetrabutyl titanate was used as a catalyst. The flask was placed in an oil bath and, under a nitrogen atmosphere, gradually heated to 180°C to initiate the reaction. The reaction continued at 180°C for 1 hour, 200°C for 0.5 hour, and 220°C for 1 hour. When the amount of water generated by the reaction, collected from the condensate, reached over 90% of the theoretical amount, the reaction system was switched to a vacuum environment and continued. In the second stage, polycondensation was carried out under reduced pressure at 220 Pa for 1 hour. The temperature was then raised to 240°C for 1 hour, and finally to 260°C for 1.5 hours. The product exhibited spherical spinning, at which point the reaction was stopped and discharged. The product was then dried under vacuum at 50°C for 12 hours to obtain the final product.

[0069] The final product prepared in Example 5 had an intrinsic viscosity of 0.8 dL / g, and its number average molecular weight, as measured by gel permeation chromatography, was 6.36×10⁴. It also had a glass transition temperature of -29.14°C, a crystallization temperature of 7.66°C, a melting point of 32.12°C, a tensile strength of 5.84 MPa, a tensile modulus of 1.25 MPa, and an elongation at break of 1183.31%.

[0070] Example 6

[0071] First, 0.1 mol of 1,12-dodecanedioic acid and 0.1 mol of dimer acid were added to a three-necked flask equipped with a mechanical stirrer, a nitrogen inlet, and a condenser. 0.36 mol of 1,4-butanediol was then added, and 0.0004 mol of tetrabutyl titanate was used as a catalyst. The flask was placed in an oil bath and, under a nitrogen atmosphere, gradually heated to 180°C to initiate the reaction. The reaction continued at 180°C for 1 hour, 200°C for 0.5 hour, and 220°C for 1 hour. When the amount of water generated by the reaction, collected from the condensate, reached over 90% of the theoretical amount, the reaction system was switched to a vacuum environment and continued. In the second stage, polycondensation was carried out under reduced pressure at 220 Pa for 1 hour. The temperature was then raised to 240°C for 1 hour, and finally to 260°C for 1.5 hours. The product exhibited spherical propellers, at which point the reaction was stopped and discharged. The product was then dried under vacuum at 50°C for 12 hours to obtain the final product.

[0072] The final product prepared in Example 6 had an intrinsic viscosity of 0.85 dL / g, and a number average molecular weight of 4.78×10⁴ as measured by gel permeation chromatography. It also had a glass transition temperature of -18.1°C, a crystallization temperature of 38.12°C, a melting point of 65.63°C, a tensile strength of 27.89 MPa, a tensile modulus of 137.46 MPa, and an elongation at break of 1057.2%.

[0073] Example 7

[0074] First, 0.1 mol of 1,12-dodecanedioic acid and 0.1 mol of dimer acid were added to a three-necked flask equipped with a mechanical stirrer, a nitrogen inlet, and a condenser. 0.22 mol of 1,10-decanediol was then added, and 0.0004 mol of tetrabutyl titanate was used as a catalyst. The flask was placed in an oil bath and, under a nitrogen atmosphere, gradually heated to 180°C to initiate the reaction. The reaction continued at 180°C for 1 hour, 200°C for 1 hour, and 220°C for 1 hour. When the amount of water generated by the reaction, collected from the condensate, reached over 90% of the theoretical amount, the reaction system was switched to a vacuum environment and continued. In the second stage, polycondensation was carried out under reduced pressure and vacuum at 200 Pa for 1 hour. The temperature was then raised to 240°C for 1 hour, then to 240°C for 0.5 hour, and finally at 260°C for 1 hour. If the product exhibited spooling, the reaction was stopped and discharged. The product was then dried under vacuum at 50°C for 12 hours to obtain the final product.

[0075] As shown in Figure 6, the final product prepared in Example 7 had an intrinsic viscosity of 0.97 dL / g, and its number average molecular weight, as measured by gel permeation chromatography, was 5.36×10⁴. Its glass transition temperature was -20.04°C, melting point was 54.73°C, crystallization temperature was 35.4°C, tensile strength of the strip was 19.89 MPa, tensile modulus was 53.66 MPa, and elongation at break was 1559.23%.

[0076] Example 8

[0077] First, 0.1 mol of 1,18-octadecanediolacid and 0.1 mol of dimer acid were added to a three-necked flask equipped with a mechanical stirrer, a nitrogen inlet, and a condenser. 0.22 mol of 1,12-dodecanediol was then added, and 0.0004 mol of tetrabutyl titanate was used as a catalyst. The flask was placed in an oil bath and, under a nitrogen atmosphere, gradually heated to 160°C to initiate the reaction. The reaction continued at 160°C for 1 hour, 180°C for 1 hour, and 200°C for 1 hour. When the amount of water generated by the reaction, collected by condensation, reached more than 90% of the theoretical amount, the reaction system was switched to a vacuum environment and continued. In the second stage, polycondensation was carried out under reduced pressure and vacuum at 160 Pa for 1 hour. The temperature was then raised to 220°C for 1 hour, then to 240°C for 1 hour, and finally at 260°C for 0.5 hour. If the product exhibited spooling, the reaction was stopped and discharged. The product was then dried under vacuum at 50°C for 12 hours to obtain the final product.

[0078] The final product prepared in Example 8 had an intrinsic viscosity of 0.78 dL / g, and a number average molecular weight of 6.42×10⁴, as measured by gel permeation chromatography. It also had a glass transition temperature of -27.38°C, a crystallization temperature of 19.56°C, a melting point of 31.72°C, a tensile strength of 12.78 MPa, a tensile modulus of 1.63 MPa, and an elongation at break of 1206.43%.

[0079] Example 9

[0080] First, 0.1 mol of 1,18-octadecanediol and 0.1 mol of dimer acid were added to a 250ml three-necked flask equipped with a mechanical stirrer, a nitrogen inlet, and a condenser. 0.22 mol of 1,18-octadecanediol was then added, and 0.0004 mol of tetrabutyl titanate was used as a catalyst. The flask was placed in an oil bath and, under a nitrogen atmosphere, gradually heated to 160°C to initiate the reaction. The reaction continued at 160°C for 1 hour, 180°C for 1 hour, and 200°C for 1 hour. When the amount of water generated by the reaction, collected in the condensate, reached more than 90% of the theoretical amount, the reaction system was switched to a vacuum environment and continued. In the second stage, polycondensation was carried out under reduced pressure and vacuum at 120 Pa for 1 hour. The temperature was then raised to 220°C for 1 hour, then to 240°C for 0.5 hour, and finally at 260°C for 0.5 hour. If the product exhibited swirl, the reaction was stopped and discharged. The product was then dried at 20°C under vacuum for 12 h to obtain the final product.

[0081] The final product prepared in Example 9 had an intrinsic viscosity of 0.76 dL / g, and a number average molecular weight of 4.86×10⁴ as measured by gel permeation chromatography. It also had a glass transition temperature of -39.36°C, a crystallization temperature of 2.66°C, a melting point of 30.28°C, a tensile strength of 3.64 MPa, a tensile modulus of 1.27 MPa, and an elongation at break of 708.57%.

[0082] Example 10

[0083] First, 0.1 mol of 1,12-dodecanedioic acid and 0.1 mol of dimer acid were added to a three-necked flask equipped with a mechanical stirrer, a nitrogen inlet, and a condenser. 0.22 mol of 1,12-dodecanediol was then added, and 0.0004 mol of titanium dioxide was used as a catalyst. The flask was placed in an oil bath and, under a nitrogen atmosphere, gradually heated to 160°C to initiate the reaction. The reaction continued at 160°C for 1 hour, 180°C for 1 hour, and 200°C for 2 hours. When the amount of water generated by the reaction, collected by condensation, reached over 90% of the theoretical amount, the reaction system was switched to a vacuum environment and continued. In the second stage, an appropriate amount of titanium dioxide catalyst was added. Polycondensation was then carried out under reduced pressure and vacuum at 180 Pa for 1 hour. The temperature was then raised to 220°C for 1 hour, and finally to 240°C for 1.5 hours. The product began to spin, at which point the reaction was stopped and discharged. The product was then dried under vacuum at 30°C for 12 hours to obtain the final product.

[0084] The final product prepared in Example 10 had an intrinsic viscosity of 0.72 dL / g, and a number average molecular weight of 4.21×10⁴ as measured by gel permeation chromatography. It also had a glass transition temperature of -25°C, a crystallization temperature of 15.48°C, a melting point of 27.28°C, a tensile strength of 12.07 MPa, a tensile modulus of 1.09 MPa, and an elongation at break of 973.04%.

[0085] Example 11

[0086] First, 0.14 mol of 1,12-dodecanediolacid and 0.06 mol of dimer acid were added to a three-necked flask equipped with a mechanical stirrer, a nitrogen inlet, and a condenser. Then, 0.22 mol of 1,12-dodecanediol was added, and 0.0004 mol of tetrabutyl titanate was used as a catalyst. Esterification was carried out at 180°C-220°C for 3 hours, followed by polycondensation at 220-260°C for 3-3.5 hours. The product began to spin, at which point the reaction was stopped and discharged. The product was then dried under vacuum at 40°C for 12 hours to obtain the final product.

[0087] The tensile strength of the final product prepared in Example 11 was 16.77 MPa, and the elongation at break was 1477.20%.

[0088] Depolymerization and Repolymerization Process: 20.0 g of the aforementioned PE-12,12 and 300 ml of methanol were placed in a 500 ml steel pressure vessel. 0.771 g of zinc acetate catalyst was then added and methanolyzed at 200°C with stirring (500 rpm) for 3 hours. Repolymerization of these depolymerized products, following the reaction conditions described in the "Polymerization Process," yielded 17.25 g of high-molecular-weight PE-12,12, corresponding to an 86.25% chemical polymer-to-polymer recycling rate. The recovered PE-12,12 exhibited a tensile strength of 16.83 MPa and an elongation at break of 1424.90%. As expected, this recycled PE-12,12 retained its excellent mechanical properties.

[0089] Example 12

[0090] First, 0.1 mol of 1,12-dodecanedioic acid and 0.1 mol of dimer acid were added to a three-necked flask equipped with a mechanical stirrer, a nitrogen inlet, and a condenser. Then, 0.22 mol of 1,12-dodecanediol was added, and 0.0004 mol of tetrabutyl titanate was used as a catalyst. Esterification was carried out at 180°C-220°C for 3 hours, followed by polycondensation at 220-260°C for 3-3.5 hours. The product began to spin, at which point the reaction was stopped and discharged. The product was then dried under vacuum at 30°C for 12 hours to obtain the final product.

[0091] The final product prepared in Example 12 had a tensile strength of 18.07 MPa and an elongation at break of 1743.04%.

[0092] Depolymerization and Repolymerization Process: 20.0 g of the aforementioned PE-12,12 and 300 ml of methanol were placed in a 500 ml steel pressure vessel. 0.771 g of zinc acetate catalyst was then added and methanolyzed at 200°C with stirring (500 rpm) for 3 hours. Repolymerization of these depolymerized products, following the reaction conditions described in the "Polymerization Process," yielded 15.72 g of high-molecular-weight PE-12,12, corresponding to a 78.6% chemical polymer-to-polymer recycling rate. The recovered PE-12,12 exhibited a tensile strength of 16.43 MPa and an elongation at break of 1628.62%. As expected, this recycled PE-12,12 retained its excellent mechanical properties.

[0093] Example 13

[0094] First, 0.1 mol of 1,12-dodecanedioic acid and 0.1 mol of dimer acid were added to a three-necked flask equipped with a mechanical stirrer, a nitrogen inlet, and a condenser. Then, 0.36 mol of 1,4-butanediol was added, and 0.0004 mol of tetrabutyl titanate was used as a catalyst. Esterification was carried out at 180°C-220°C for 3 hours, followed by polycondensation at 220-260°C for 3-3.5 hours. The product began to spin, at which point the reaction was stopped and discharged. The product was then dried under vacuum at 50°C for 12 hours to obtain the final product.

[0095] The final product prepared in Example 13 had a tensile strength of 27.89 MPa and an elongation at break of 1057.2%.

[0096] Depolymerization and Repolymerization Process: 20.0 g of the aforementioned PE-12,4 and 300 ml of methanol were placed in a 500 ml steel pressure vessel. 0.771 g of zinc acetate catalyst was then added and methanolyzed at 200°C with stirring (500 rpm) for 3 hours. These depolymerization products were repolymerized according to the reaction conditions described in the "Polymerization Process" to obtain 13.83 g of high-molecular-weight PE-12,4, equivalent to a 69.2% chemical polymer-to-polymer recycling rate. As expected, this recycled PE-12,4 retained its excellent mechanical properties. The tensile strength of the specimen was 26.53 MPa, and the elongation at break was 828.12%.

[0097] Comparative Example 1

[0098] 0.2 mol of 1,12-dodecanediolacid and 0.2 mol of 1,12-dodecanediol were added to a three-necked flask equipped with a mechanical stirrer, a nitrogen inlet, and a condenser. 0.0004 mol of tetrabutyl titanate catalyst was then added. The flask was placed in an oil bath and, under a nitrogen atmosphere, gradually heated to 180°C to initiate the reaction. The reaction continued at 180°C for 1 hour, then at 200°C for 1 hour, and then at 220°C for 1 hour. When the amount of water generated by the reaction, collected by condensation, reached over 90% of the theoretical amount, the reaction system was switched to a vacuum environment and continued. In the second stage, polycondensation was carried out under reduced pressure and vacuum at 200 Pa for 1 hour. The temperature was then raised to 220°C for 1 hour, and finally to 240°C for 0.5 hour. The product exhibited spherical ...

[0099] The final product prepared in Comparative Example 1 had an intrinsic viscosity of 0.98 dL / g, a number average molecular weight of 5.01×104 as measured by gel permeation chromatography, a glass transition temperature of -18°C, a crystallization temperature of 71.01°C, a melting point of 124.30°C, a strip tensile strength of 33.51 MPa, a tensile modulus of 380.12 MPa, and an elongation at break of 585.10%.

[0100] Comparative Example 2

[0101] First, 0.1 mol of 1,4-butanediol and 0.1 mol of sebacic acid were added to a three-necked flask equipped with a mechanical stirrer, a nitrogen inlet, and a condenser. 0.36 mol of 1,4-butanediol was then added, and 0.0004 mol of tetrabutyl titanate was used as a catalyst. The flask was placed in an oil bath and, under a nitrogen atmosphere, gradually heated to 180°C to initiate the reaction. The reaction continued at 180°C for 1 hour, 200°C for 1 hour, and 220°C for 1 hour. When the amount of water generated by the reaction, collected by condensation, reached over 90% of the theoretical amount, the reaction system was switched to a vacuum environment and continued. In the second stage, polycondensation was carried out under reduced pressure and vacuum at 190 Pa for 1 hour. The temperature was then raised to 240°C for 1 hour, and finally to 260°C for 1 hour. The product exhibited spherical ...

[0102] The final product prepared in Comparative Example 2 had an intrinsic viscosity of 0.79 dL / g and a number average molecular weight of 4.98×10⁴, as measured by gel permeation chromatography. It also had a glass transition temperature of -10.87°C, a crystallization temperature of 35.48°C, a melting point of 57.28°C, a tensile strength of 15.07 MPa, a tensile modulus of 18.09 MPa, and an elongation at break of 523.44%.

[0103] Comparative Example 3

[0104] The corresponding elastomer synthesized in Comparative Example 2 was subjected to depolymerization and then polymerization. The depolymerization and repolymerization process involved adding 20.0 g of the aforementioned PE-4,4 and 300 ml of methanol to a 500 ml steel pressure vessel. 0.771 g of zinc acetate catalyst was then added, and methanolyzed at 200°C with stirring (500 rpm) for 3 hours. The depolymerization product was then repolymerized according to the reaction conditions described in the "Polymerization Process" to obtain 6.93 g of PE-4,4. The tensile strength of the bars from Comparative Example 3 was 4.73 MPa, and the elongation at break was 79.81%.

[0105] As clearly demonstrated in Examples 1-5, by adjusting the ratio of the added linear long-chain diacid to the branched long-chain diacid, the ratio of the soft and hard segments in the elastomer can be adjusted, allowing the preparation of a polyester elastomer with a high molecular weight. These elastomers exhibit excellent, controllable mechanical properties, with tensile strengths ranging from 5.84 to 29.44 MPa and elongations at break ranging from 1183.31 to 1743.04%.

[0106] It can be concluded from Examples 1-5 and Comparative Examples 1 and 2 that copolymerization with dimer acid can improve the toughness and ductility of polyester, and there is an optimal dimer acid addition amount. Among them, when the ratio of soft and hard segments is 1:1, the elongation at break is as high as 1743.04%. Too high a dimer acid content will reduce the strength and elongation of the copolyester.

[0107] Examples 1, 6, 7, 8, and 9 demonstrate that by varying the types of linear long carbon chain dibasic acid monomers and diol monomers, different types of branched long carbon chain polyester elastomers can be obtained. Examples 1 and 10 demonstrate that by varying the type of polymerization catalyst, thermoplastic polyester elastomers with varying molecular weights can be obtained, thereby affecting the tensile strength, elongation at break, thermal properties, and other properties of the elastomers. Comparison of the performance test results of the examples with those of the comparative examples demonstrates that the mechanical and thermal properties of the thermoplastic polyester elastomers prepared by the present invention can be controlled by designing the molecular structure, adjusting the molecular weight, and the ratio of soft and hard segments, thereby meeting application requirements.

[0108] As can be seen from Examples 11-13 and Comparative Example 3, long-chain polyesters with low-density intrachain functional groups as breaking points can be chemically recovered by solvent decomposition with a high recovery rate. At the same time, the breaking points do not interfere with the crystalline structure, and the desired material properties are almost completely retained during recycling. The inertness of polyethylene hinders chemical recovery, requiring temperatures above 600 degrees Celsius, and the yield of recovered ethylene is less than 10%. Long-chain aliphatic condensation polymers have macroscopic properties comparable to traditional polyolefin materials, unique chemical recyclability, and a wide range of application scenarios.

[0109] In the above, the product testing and characterization methods used in Examples 1-13 and Comparative Examples 1-3 of the present invention are as follows:

[0110] Intrinsic viscosity test method: The intrinsic viscosity of polyester elastomers was measured using an NCY-4 automatic viscometer from Shanghai Starda Co., Ltd. The solvent used was a 1:1 phenol / 1,1,2,2-tetrachloroethane mixture, and an Ubbelohde viscometer with an inner diameter of 0.84 mm. The test was conducted in a constant temperature water bath at (25±0.05)°C.

[0111] Molecular weight test method: The molecular weight of the sample was determined by a Waters 1515 gel permeation chromatograph, using an Agilent PLgel 5 μm MIXED-C column, tetrahydrofuran as the mobile phase, a flow rate of 1 mL / min, and polystyrene as the standard.

[0112] Melting and Crystallization Temperature Testing Method: The thermal properties of the copolyester were studied using a TA Q2000 differential scanning calorimeter (DSC). Under a nitrogen atmosphere, a 5-10 mg sample was heated to 130°C at a rate of 10°C / min and held at that temperature for 10 minutes. The sample was then cooled to -50°C at a rate of 10°C / min. The crystallization exotherm was recorded, and the corresponding crystallization temperature (Tc) was read. Finally, the sample was heated to 130°C at a rate of 10°C / min, and the melting curve was recorded, and the corresponding melting point (Tm) was read.

[0113] Mechanical properties testing method: The tensile properties of the material were tested using a universal testing machine. The copolymer was hot-pressed into a 1mm thick film, which was then cut into dumbbell-shaped strips. The samples were allowed to stand at room temperature for a period of time and then subjected to tensile testing at a speed of 50mm / min. Each sample was tested at least five times.

[0114] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A polyolefin-like long carbon chain polyester elastomer, characterized in that: It is formed by the polymerization of long-chain dibasic acid or ester of long-chain dibasic acid and diol, and its structure is as follows: Wherein, R1 is selected from C 11 -C 18 R2 is selected from C2-C 18 An alkyl group; R3 is selected from C 11 -C 36 A long carbon chain alkyl group containing a branch.

2. The polyolefin-like long carbon chain polyester elastomer according to claim 1, characterized in that: The long carbon chain dibasic acid includes a branched long carbon chain dibasic acid.

3. The polyolefin-like long carbon chain polyester elastomer according to claim 1, characterized in that: The long carbon chain dibasic acid ester comprises at least one of dimethyl dibasic acid ester and diethyl dibasic acid ester.

4. The polyolefin-like long carbon chain polyester elastomer according to claim 3, characterized in that: The diols include one or more combinations of ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 2-methyl-1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, and long carbon chain diols.

5. The polyolefin-like long carbon chain polyester elastomer according to claim 1, characterized in that: The intrinsic viscosity of the long carbon chain polyester elastomer is 0.7 to 1.4 dL / g; The number average molecular weight of the long carbon chain polyester elastomer is 4×104 to 1.3×105 g / mol; The glass transition temperature of the long carbon chain polyester elastomer is -40 to 75°C; The tensile strength of the long carbon chain polyester elastomer is 3 to 95 MPa.

6. The polyolefin-like long carbon chain polyester elastomer according to claim 1, characterized in that: The long carbon chain polyester elastomer can be recycled in a closed loop, and the closed loop recycling method comprises the following steps: 1) Depolymerization process: In a pressure vessel, a long carbon chain polyester elastomer, a solvent, and a catalyst are added in proportion, and the reaction temperature and stirring speed are controlled to carry out a depolymerization reaction to obtain a depolymerized monomer; 2) Repolymerization process: The depolymerized monomers are subjected to transesterification and polycondensation to synthesize long carbon chain polyester elastomer again; The depolymerization reaction temperature is 100-220° C., the reaction time is 2-7 hours, and the stirring speed is 350-650 rpm.

7. The polyolefin-like long carbon chain polyester elastomer according to claim 6, characterized in that: In step 1), the mass ratio of the polyester elastomer to the solvent is 1.0:9.0-15.0; the amount of the catalyst is 0.2%-0.6% of the total mass of the polyester elastomer and the solvent; the solvent includes at least one of methanol, ethanol, and ethylene glycol; and the catalyst includes zinc acetate.

8. A method for preparing a polyolefin-like long carbon chain polyester elastomer, characterized in that: The method for preparing the polyolefin-like long carbon chain polyester elastomer according to any one of claims 1 to 7 comprises the following steps: S1. Transesterification reaction to produce oligomers: Under inert gas protection, a long carbon chain dibasic acid or its esterified product, a diol, and a catalyst are placed in a three-necked flask in appropriate proportions, and the reaction temperature and stirring speed are controlled to produce oligomers; S2. Polycondensation reaction to obtain a polymer: Under vacuum conditions, the oligomer prepared in step S1 is subjected to a polycondensation reaction to obtain a long carbon chain polyester elastomer.

9. The method for preparing a polyolefin-like long carbon chain polyester elastomer according to claim 8, characterized in that: The molar ratio of the long-chain dibasic acid or its ester to the diol is 1.0:1.0-2.0; the molar ratio of the branched long-chain dibasic acid or its ester structural unit is 10-90 mol%; and the amount of the catalyst is 0.2% of the total molar amount of the long-chain dibasic acid.

10. An application of a polyolefin-like long carbon chain polyester elastomer, characterized in that: Use of the polyolefin-like long carbon chain polyester elastomer according to any one of claims 1 to 7 in polymer modification, automotive parts, medical supplies, and cable systems.

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