Degradable polyesters, methods for their preparation and degradable plastic articles

Abstract

The present application relates to a kind of preparation methods of degradable polyester, the preparation method includes the following steps: the first mixed reaction system comprising cyclohexane dicarboxylic acid or its ester, 2,3,5,6-tetrafluoro-1,4-p-xylyleneglycol, aliphatic dihydric alcohol and esterification or ester exchange catalyst is reacted under protective atmosphere, obtain intermediate product;Second mixed reaction system comprising the intermediate product and stabilizer is reacted under vacuum condition, obtain degradable polyester.The present application also relates to the degradable polyester prepared by the preparation method and the degradable plastic product made of the degradable polyester.The degradable polyester of the present application has high glass transition temperature, transparency, solvent resistance and degradable performance, etc., therefore, can be better applied to packaging material, film, plastic container and other products with high requirements of heat resistance, solvent resistance, transparency and degradability, and the degradable plastic product made of it has excellent comprehensive performance.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, and in particular to biodegradable polyesters, their preparation methods, and biodegradable plastic products. Background Technology

[0002] Currently, polymers such as polylactic acid (PLA), polyhydroxy fatty acid (PHA), polyhydroxyacetic acid (PGA), polybutylene succinate (PBS), and polybutylene terephthalate (PBAT) widely used in the market have good biodegradability. However, products made from these polymers have the following shortcomings: (1) poor heat resistance, which makes them very easy to deform under conditions higher than room temperature, thus affecting their use; (2) poor solvent resistance, which makes them very easy to be damaged in environments containing organic matter; and (3) poor transparency, which affects the use of products such as films and containers. Summary of the Invention

[0003] Therefore, it is necessary to address the above problems by providing a biodegradable polyester, its preparation method, and biodegradable plastic products. The biodegradable polyester has high glass transition temperature, transparency, solvent resistance, and biodegradability, and the biodegradable plastic products made from it have excellent overall performance.

[0004] To achieve the above objectives, the technical solution adopted by this invention is: a method for preparing biodegradable polyester, comprising the following steps:

[0005] A first mixed reaction system comprising cyclohexanedicarboxylic acid or its esterified form, 2,3,5,6-tetrafluoro-1,4-terephthalic acid, an aliphatic diol, and an esterification or transesterification catalyst is reacted under a protective atmosphere to obtain an intermediate product.

[0006] The second mixed reaction system, containing the intermediate product and the stabilizer, is reacted under vacuum conditions to obtain a biodegradable polyester.

[0007] In one embodiment, the molar ratio of 2,3,5,6-tetrafluoro-1,4-terephthalic acid to cyclohexanedicarboxylic acid or its esterified form is 5:100-60:100.

[0008] In one embodiment, the molar ratio of the sum of the molar amounts of 2,3,5,6-tetrafluoro-1,4-terephthalic acid and the aliphatic diol to the molar ratio of cyclohexanedicarboxylic acid or its esterified form is 120:100-300:100.

[0009] In one embodiment, the aliphatic diol is selected from at least one of propylene glycol, butanediol, and hexanediol.

[0010] In one embodiment, in the step of the first mixed reaction system reacting under a protective atmosphere, the temperature is 180°C-240°C and the time is 1.5h-6h.

[0011] And / or, in the step of the second mixed reaction system reacting under vacuum conditions, the vacuum degree is within 200 Pa, the temperature is 220℃-280℃, and the time is 1h-8h.

[0012] In one embodiment, the esterification or transesterification catalyst is selected from at least one of zinc-based catalysts, manganese-based catalysts, titanium-based catalysts, and antimony-based catalysts, and the molar ratio of the esterification or transesterification catalyst to the cyclohexanedicarboxylic acid or its esterified form is 0.2:1000-2.0:1000.

[0013] In one embodiment, the stabilizer is selected from phosphorus-based stabilizers, and the molar ratio of the stabilizer to the cyclohexanedicarboxylic acid or its esterified form is 0.2:1000-3.0:1000.

[0014] In one embodiment, the second mixed reaction system further includes a polycondensation catalyst selected from at least one of titanium-based catalysts, tin-based catalysts, antimony-based catalysts, and germanium-based catalysts, wherein the molar ratio of the polycondensation catalyst to the cyclohexanedicarboxylic acid or its esterified form is 0.2:1000-2.0:1000.

[0015] A biodegradable polyester, prepared by the aforementioned method for preparing biodegradable polyester.

[0016] A biodegradable plastic article, said biodegradable plastic article being made of said biodegradable polyester.

[0017] In this invention, 2,3,5,6-tetrafluoro-1,4-terephthalic acid and cyclohexanedicarboxylic acid or their esters are used as copolymerizing units, which can simultaneously improve the glass transition temperature and solvent resistance of the polyester. Furthermore, 2,3,5,6-tetrafluoro-1,4-terephthalic acid can break the ordered structure of the polyester during copolymerization, thereby effectively improving the transparency of the polyester. Therefore, the biodegradable polyester of this invention exhibits high glass transition temperature, transparency, solvent resistance, and biodegradability, demonstrating excellent overall performance. Thus, the biodegradable polyester of this invention can be better applied to packaging materials, films, plastic containers, and other products requiring high heat resistance, solvent resistance, transparency, and biodegradability. Biodegradable plastic products made from it exhibit excellent overall performance.

[0018] In addition, the preparation method of the present invention adopts an esterification-polymerization process, which is simple, easy to operate, highly controllable, easy to implement, and suitable for large-scale industrial production. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 It is the biodegradable polyester obtained in Example 1. 1 H-NMR spectrum;

[0021] Figure 2 This is the DCS pattern of the biodegradable polyester obtained in Example 1;

[0022] Figure 3 This is the TGA spectrum of the biodegradable polyester obtained in Example 1. Detailed Implementation

[0023] To facilitate understanding of the present invention, it will be described in more detail below. However, it should be understood that the present invention can be implemented in many different forms and is not limited to the embodiments or examples described herein. Rather, these embodiments or examples are provided to make the disclosure of the present invention more thorough and complete.

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments or examples only and is not intended to limit the invention. The optional scope of the term "and / or" as used herein includes any one of two or more of the related listed items, as well as any and all combinations of the related listed items, including any two related listed items, any more related listed items, or a combination of all related listed items.

[0025] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0026] The method for preparing biodegradable polyester provided by the present invention includes the following steps:

[0027] S1, a first mixed reaction system containing cyclohexanedicarboxylic acid or its esterified form, 2,3,5,6-tetrafluoro-1,4-terephthalic acid, aliphatic diol and an esterification or transesterification catalyst is reacted under a protective atmosphere to obtain an intermediate product.

[0028] S2, the second mixed reaction system containing the intermediate product and the stabilizer is reacted under vacuum conditions to obtain a biodegradable polyester.

[0029] To achieve higher glass transition temperature, transparency, solvent resistance, and biodegradability in the biodegradable polyester, in step S1, the molar ratio of 2,3,5,6-tetrafluoro-1,4-terephthalic acid to cyclohexanedicarboxylic acid or its esterified form is preferably 5:100-60:100, including but not limited to 5:100, 8:100, 10:100, 12:100, 15:100, 18:100, 20:100, 23:100, and 25:100. 18:100, 30:100, 33:100, 35:100, 38:100, 40:100, 42:100, 45:100, 48:100, 50:100, 52:100, 55:100, 58:100, 60:100, more preferably 10:100-50:100; and, the sum of the molar amounts of the 2,3,5,6-tetrafluoro-1,4-terephthalic acid and the aliphatic diol, and the cyclohexanedicarboxylic acid The preferred molar ratio of the esterified form of the esterified form is 120:100-300:100, including but not limited to 120:100, 125:100, 130:100, 135:100, 140:100, 145:100, 150:100, 155:100, 160:100, 165:100, 170:100, 175:100, 180:100, 185:100, 190:100, 195:100, and 200:100. 0, 205:100, 210:100, 220:100, 225:100, 230:100, 240:100, 245:100, 250:100, 255:100, 260:100, 265:100, 270:100, 275:100, 280:100, 285:100, 290:100, 295:100, 300:100, and further preferably 120:100-200:100.

[0030] Optionally, the esterified form of cyclohexanedicarboxylic acid is selected from dimethyl cyclohexanedicarboxylate, etc. In this invention, it is preferred to react cyclohexanedicarboxylic acid with 2,3,5,6-tetrafluoro-1,4-terephthalic acid and an aliphatic diol.

[0031] Optionally, the aliphatic diol is selected from propylene glycol, butanediol, pentanediol, hexanediol, octanediol, etc., preferably at least one of propylene glycol, butanediol, and hexanediol, so as to better control the degradation performance of the biodegradable polyester.

[0032] Optionally, the esterification or transesterification catalyst is selected from at least one of zinc-based, manganese-based, titanium-based, and antimony-based catalysts, specifically including at least one of anhydrous zinc acetate, anhydrous manganese acetate, tetrabutyl titanate, isopropyl titanate, antimony trioxide, antimony glycolate, antimony acetate, or antimony polyethylene glycol. The molar ratio of the esterification or transesterification catalyst to the cyclohexanedicarboxylic acid or its esterified form is preferably 0.2:1000-2.0:1000, including but not limited to 0.2:10. 00, 0.3:1000, 0.4:1000, 0.5:1000, 0.6:1000, 0.7:1000, 0.8:1000, 0.9:1000, 1.0:1000, 1.1:1000, 1.2:1000, 1.3:1000, 1.4:1000, 1.5:1000, 1.6:1000, 1.7:1000, 1.8:1000, 1.9:1000, 2.0:1000.

[0033] Optionally, in the step of reacting the first mixed reaction system under a protective atmosphere, the temperature is preferably 180℃-240℃, including but not limited to 180℃, 185℃, 190℃, 200℃, 205℃, 210℃, 215℃, 220℃, 225℃, 230℃, 235℃, and 240℃, and the time is 1.5h-6h. The protective atmosphere is selected from nitrogen, argon, etc., and nitrogen is preferred.

[0034] In step S2, where the second mixed reaction system reacts under vacuum conditions, the vacuum level is preferably below 200 Pa, the temperature is preferably between 220℃ and 280℃, including but not limited to 220℃, 225℃, 230℃, 235℃, 240℃, 245℃, 250℃, 255℃, 260℃, 265℃, 270℃, 275℃, and 280℃, and the time is preferably between 1h and 8h.

[0035] Specifically, the second mixed reaction system can be heated to 220℃-280℃ first, and then pre-polymerization can be carried out by slowly drawing a vacuum. Then, the vacuum degree can be controlled to below 200Pa to carry out the reaction to obtain biodegradable polyester.

[0036] Optionally, the stabilizer is selected from phosphorus-based stabilizers, specifically including at least one of phosphorous acid, hypophosphite, pyrophosphate, ammonium phosphate, trimethyl phosphate, dimethyl phosphate, triphenyl phosphate, diphenyl phosphate, triphenyl phosphite, diphenyl phosphite, ammonium phosphite, and ammonium dihydrogen phosphate. The molar ratio of the stabilizer to the cyclohexanedicarboxylic acid or its esterified form is 0.2:1000-3.0:1000, including but not limited to 0.2:1000, 0.3:1000, 0.4:1000, 0.5:1000, 0.6:1000, 0.7:1000, and 0.8:10. 00, 0.9:1000, 1.0:1000, 1.1:1000, 1.2:1000, 1.3:1000, 1.4:1000, 1.5:1000, 1.6:1000, 1.7:1000, 1.8:1000, 1.9:1000, 2.0:1000, 2.1:1000, 2.2:1000, 2.3:1000, 2.4:1000, 2.5:1000, 2.6:1000, 2.7:1000, 2.8:1000, 2.9:1000, 3.0:1000.

[0037] Optionally, the second mixed reaction system further includes a polycondensation catalyst selected from at least one of titanium-based catalysts, tin-based catalysts, antimony-based catalysts, and germanium-based catalysts. In particular, when the esterification or transesterification catalyst is selected from a zinc-based catalyst, a polycondensation catalyst is also added to the second mixed reaction system.

[0038] Specifically, the polycondensation catalyst includes at least one of tetrabutyl titanate, isopropyl titanate, antimony trioxide, antimony glycolate, antimony acetate, polyethylene glycol antimony, dibutyltin oxide, stannous isooctanoate, monobutyltriisooctanoate, dioctyltin oxide, germanium dioxide, and germanium oxide. The molar ratio of the polycondensation catalyst to the cyclohexanedicarboxylic acid or its esterified form is 0.2:1000-2.0:1000, including but not limited to 0.2:1000 and 0.3:10. 00, 0.4:1000, 0.5:1000, 0.6:1000, 0.7:1000, 0.8:1000, 0.9:1000, 1.0:1000, 1.1:1000, 1.2:1000, 1.3:1000, 1.4:1000, 1.5:1000, 1.6:1000, 1.7:1000, 1.8:1000, 1.9:1000, 2.0:1000.

[0039] In the preparation method of this invention, 2,3,5,6-tetrafluoro-1,4-terephthalic acid and cyclohexanedicarboxylic acid or their esters are used as copolymerizing units, which can simultaneously improve the glass transition temperature and solvent resistance of the polyester. Furthermore, 2,3,5,6-tetrafluoro-1,4-terephthalic acid can break the ordered structure of the polyester during copolymerization, thereby effectively improving the transparency of the polyester. In addition, the preparation method of this invention uses an esterification-polymerization process, which is simple, easy to operate, highly controllable, easy to implement, and suitable for large-scale industrial production.

[0040] Therefore, the present invention also provides a biodegradable polyester prepared by the aforementioned method, wherein the biodegradable polyester has high glass transition temperature, transparency, solvent resistance and biodegradability, and other excellent comprehensive properties.

[0041] Furthermore, the biodegradable polyester of the present invention can be better applied to products such as packaging materials, films, and plastic containers that have high requirements for heat resistance, solvent resistance, transparency, and biodegradability, and the biodegradable plastic products made from it have excellent comprehensive performance.

[0042] Therefore, the present invention also provides a biodegradable plastic product made of the biodegradable polyester, such as packaging materials, films, plastic containers, etc.

[0043] The following specific examples will further illustrate the biodegradable polyester, its preparation method, and biodegradable plastic products.

[0044] In the following examples, the proton nuclear magnetic resonance spectrum... 1 H-NMR was measured on a Bruker 400AVANCE III Spectrometer instrument at 400 MHz, CDCl3.

[0045] In the following embodiments, thermal analysis was performed using a differential scanning calorimeter (Mettler Toledo DSC) at a heating rate of 10 °C / min in an N2 atmosphere, with a temperature range of -70 °C to 250 °C.

[0046] In the following examples, thermogravimetric analysis (TGA) was performed on a Perkin-Elmer Diamond TG / DTA at a heating rate of 20 °C / min and a temperature range of 50 °C–800 °C.

[0047] Example 1

[0048] 0.1 mol of cyclohexanedicarboxylic acid, 0.02 mol of 2,3,5,6-tetrafluoro-1,4-terephthalic acid, 0.2 mol of 1,4-butanediol, and 0.12% anhydrous zinc acetate based on cyclohexanedicarboxylic acid were added to a reaction vessel to obtain the first mixed reaction system. Then, the system was evacuated and purged with nitrogen twice. The stirring was started, and the temperature was gradually increased to 180°C. The reaction was carried out for 4 hours to obtain the intermediate product.

[0049] Antimony trioxide (0.1% based on the molar amount of cyclohexanedicarboxylic acid) and triphenyl phosphate (0.15% based on the molar amount of cyclohexanedicarboxylic acid) were added to the intermediate product to obtain a second mixed reaction system. The second mixed reaction system was heated to 220°C and pre-polymerized under vacuum for 1 hour. Then, the reaction was carried out under vacuum of less than 200 Pa for 4 hours to obtain a biodegradable polyester.

[0050] The biodegradable polyester obtained in this embodiment 1 H-NMR such as Figure 1 As shown, the DSC spectrum is as follows Figure 2 As shown, its glass transition temperature is 12.4℃, and the TGA spectrum is as follows. Figure 3 As shown, its T d,5％ It has a thermal decomposition temperature of 399℃, a visible light transmittance of 88% up to 700nm wavelength, and is sparingly soluble in methanol, ethanol, acetone, and cyclohexane.

[0051] Example 2

[0052] 0.1 mol of cyclohexanedicarboxylic acid, 0.005 mol of 2,3,5,6-tetrafluoro-1,4-terephthalic acid, 0.115 mol of 1,4-butanediol, and 0.08% anhydrous manganese acetate based on cyclohexanedicarboxylic acid were added to a reaction vessel to obtain the first mixed reaction system. Then, the system was evacuated and purged with nitrogen twice. The stirring was started, and the temperature was gradually increased to 220°C. The reaction was carried out for 1.5 h to obtain the intermediate product.

[0053] Add 0.02% antimony trioxide and 0.05% methyl phosphate based on the molar amount of cyclohexanedicarboxylic acid to the intermediate product to obtain a second mixed reaction system. Heat the second mixed reaction system to 230°C, slowly pre-condense under vacuum for 0.6 h, and then react for 3 h with the vacuum degree controlled below 150 Pa to obtain a biodegradable polyester.

[0054] Testing showed that the glass transition temperature of the biodegradable polyester obtained in this embodiment was 9.3℃. d,5％ It has a thermal decomposition temperature of 395℃, a visible light transmittance of 90% up to 700nm wavelength, and is sparingly soluble in methanol, ethanol, acetone, and cyclohexane.

[0055] Example 3

[0056] 0.1 mol of cyclohexanedicarboxylic acid, 0.03 mol of 2,3,5,6-tetrafluoro-1,4-terephthalic acid, 0.22 mol of 1,3-propanediol, and 0.02% tetrabutyl titanate based on cyclohexanedicarboxylic acid were added to a reaction vessel to obtain the first mixed reaction system. Then, the system was evacuated and purged with nitrogen twice. The stirring was started, and the temperature was gradually increased to 180°C. The reaction was carried out for 3.5 h to obtain the intermediate product.

[0057] Add 0.1% triphenyl phosphate based on the molar amount of cyclohexanedicarboxylic acid to the intermediate product to obtain a second mixed reaction system. Heat the second mixed reaction system to 220°C, slowly evacuate the vacuum for pre-condensation for 1 hour, and then control the vacuum degree to below 50 Pa for 2 hours to obtain a biodegradable polyester.

[0058] The glass transition temperature of the biodegradable polyester obtained in this embodiment was tested to be 44.8℃. d,5％ It has a thermal decomposition temperature of 383℃, a visible light transmittance of 90% up to 700nm wavelength, and is sparingly soluble in methanol, ethanol, acetone, and cyclohexane.

[0059] Example 4

[0060] 0.1 mol of cyclohexanedicarboxylic acid, 0.04 mol of 2,3,5,6-tetrafluoro-1,4-terephthalic acid, 0.26 mol of 1,3-propanediol, and 0.2% ethylene glycol antimony based on cyclohexanedicarboxylic acid were added to a reaction vessel to obtain the first mixed reaction system. Then, the system was evacuated and purged with nitrogen twice. Stirring was started, and the temperature was gradually increased to 190°C. The reaction was carried out for 3.5 h to obtain the intermediate product.

[0061] Add 0.2% dibutyltin oxide and 0.02% diphenyl phosphate based on the molar amount of cyclohexanedicarboxylic acid to the intermediate product to obtain a second mixed reaction system. Heat the second mixed reaction system to 220°C, slowly evacuate the vacuum for pre-condensation for 0.8 h, and then control the vacuum degree below 70 Pa to react for 2 h to obtain a biodegradable polyester.

[0062] The glass transition temperature of the biodegradable polyester obtained in this embodiment was tested to be 52.6℃. d,5％ The thermal decomposition temperature is 388℃.

[0063] Example 5

[0064] 0.1 mol of cyclohexanedicarboxylic acid, 0.05 mol of 2,3,5,6-tetrafluoro-1,4-terephthalic acid, 0.11 mol of 1,6-hexanediol, and 0.15% ethylene glycol antimony based on cyclohexanedicarboxylic acid were added to a reaction vessel to obtain the first mixed reaction system. Then, the system was evacuated and purged with nitrogen twice. Stirring was started, and the temperature was gradually increased to 230°C. The reaction was carried out for 3.5 h to obtain the intermediate product.

[0065] Add 0.15% isopropyl titanate and 0.08% methyl phosphate based on the molar amount of cyclohexanedicarboxylic acid to the intermediate product to obtain a second mixed reaction system. Heat the second mixed reaction system to 260°C, slowly vacuum pre-polymerize for 0.5 h, and then control the vacuum degree below 70 Pa to react for 8 h to obtain a biodegradable polyester.

[0066] Testing showed that the glass transition temperature of the biodegradable polyester obtained in this embodiment was 3.2℃. d,5％ The thermal decomposition temperature is 401℃.

[0067] Example 6

[0068] 0.1 mol of cyclohexanedicarboxylic acid, 0.06 mol of 2,3,5,6-tetrafluoro-1,4-terephthalic acid, 0.24 mol of 1,6-hexanediol, and 0.1% tetrabutyl titanate based on cyclohexanedicarboxylic acid were added to a reaction vessel to obtain the first mixed reaction system. Then, the system was evacuated and purged with nitrogen twice. The mixture was stirred and gradually heated to 240°C. The reaction was carried out for 6 hours to obtain the intermediate product.

[0069] Add 0.18% germanium dioxide and 0.15% diphenyl phosphate based on the molar amount of cyclohexanedicarboxylic acid to the intermediate product to obtain a second mixed reaction system. Heat the second mixed reaction system to 280°C, slowly evacuate the vacuum for 1 hour for pre-condensation, and then control the vacuum degree to below 20 Pa for 1 hour to obtain a biodegradable polyester.

[0070] Testing showed that the glass transition temperature of the biodegradable polyester obtained in this embodiment was 13.8℃. d,5％ The thermal decomposition temperature is 406℃.

[0071] Comparative Example 1

[0072] 0.045 mol of terephthalic acid, 0.055 mol of adipic acid, and 0.16 mol of butanediol, along with 0.12% anhydrous zinc acetate based on the sum of the molar amounts of terephthalic acid and adipic acid, were added to a reaction vessel to obtain the first mixed reaction system. The system was then evacuated and purged with nitrogen twice, stirred, and gradually heated to 180°C. The reaction was carried out for 4 hours to obtain the intermediate product.

[0073] Add 0.1% antimony trioxide and 0.15% triphenyl phosphate based on the sum of the molar amounts of terephthalic acid and adipic acid to the intermediate product to obtain a second mixed reaction system. Heat the second mixed reaction system to 220°C, slowly evacuate the vacuum for 1 hour to pre-condense, and then control the vacuum degree to below 200 Pa for 4 hours to obtain polybutylene adipate terephthalate (PBAT).

[0074] The glass transition temperature of the polybutylene adipate obtained in this comparative example was tested to be -29.3℃. d,5％ The thermal decomposition temperature is 375℃.

[0075] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0076] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for preparing a biodegradable polyester, characterized in that, Includes the following steps: A first mixed reaction system comprising cyclohexanedicarboxylic acid or its esterified form, 2,3,5,6-tetrafluoro-1,4-terephthalic acid, an aliphatic diol, and an esterification or transesterification catalyst is reacted under a protective atmosphere to obtain an intermediate product, wherein the molar ratio of 2,3,5,6-tetrafluoro-1,4-terephthalic acid to cyclohexanedicarboxylic acid or its esterified form is 5:100-20:100, and the aliphatic diol is selected from at least one of propylene glycol, butanediol, and hexanediol; The second mixed reaction system containing the intermediate product and the stabilizer is reacted under vacuum conditions to obtain a biodegradable polyester, wherein the temperature of the second mixed reaction system is 220℃-230℃.

2. The method for preparing biodegradable polyester according to claim 1, characterized in that, The molar ratio of the sum of the molar amounts of 2,3,5,6-tetrafluoro-1,4-terephthalic acid and the aliphatic diol to the molar ratio of cyclohexanedicarboxylic acid or its esterified form is 120:100-300:

100.

3. The method for preparing biodegradable polyester according to claim 1, characterized in that, In the step of the first mixed reaction system reacting under a protective atmosphere, the temperature is 180℃-240℃ and the time is 1.5h-6h. And / or, in the step of the second mixed reaction system being reacted under vacuum conditions, the vacuum degree is within 200 Pa and the time is 1h-8h.

4. The method for preparing the biodegradable polyester according to any one of claims 1-3, characterized in that, The esterification or transesterification catalyst is selected from at least one of zinc-based catalysts, manganese-based catalysts, titanium-based catalysts, and antimony-based catalysts, and the molar ratio of the esterification or transesterification catalyst to the cyclohexanedicarboxylic acid or its esterified form is 0.2:1000-2.0:1000.

5. The method for preparing the biodegradable polyester according to any one of claims 1-3, characterized in that, The stabilizer is selected from phosphorus-based stabilizers, and the molar ratio of the stabilizer to the cyclohexanedicarboxylic acid or its esterified form is 0.2:1000-3.0:1000.

6. The method for preparing the biodegradable polyester according to any one of claims 1-3, characterized in that, The second mixed reaction system also includes a polycondensation catalyst, which is selected from at least one of titanium-based catalysts, tin-based catalysts, antimony-based catalysts, and germanium-based catalysts. The molar ratio of the polycondensation catalyst to the cyclohexanedicarboxylic acid or its esterified form is 0.2:1000-2.0:1000.

7. A biodegradable polyester, characterized in that, It is prepared by the method for preparing the biodegradable polyester according to any one of claims 1-6.

8. A biodegradable plastic product, characterized in that, The biodegradable plastic article is made of the biodegradable polyester as described in claim 7.

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