A highly compatible and creep-resistant biodegradable polyester blend, its preparation method and application

Abstract

The present invention discloses a highly compatible, creep-resistant biodegradable polyester blend, its preparation method, and application. The highly compatible, creep-resistant biodegradable polyester blend comprises the following components, measured by weight: 100 parts of two or more biodegradable polyester compositions, 1 to 3 parts of a nitrogen-containing polyhydroxy compound, 0.2 to 0.6 parts of an antioxidant, and a multifunctional isocyanate or anhydride crosslinking agent; the molar ratio of the hydroxyl functional groups in the nitrogen-containing polyhydroxy compound to the isocyanate or anhydride functional groups in the multifunctional isocyanate or anhydride crosslinking agent is 1:1.2 to 1:0.8. The present invention exhibits excellent compatibility, significantly improved mechanical properties and high-temperature dimensional stability compared to uncrosslinked blends, and good thermoplastic processability, overcoming the problems of poor compatibility and high-temperature dimensional stability often encountered in biodegradable polyester blends.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer material blending, and in particular to a highly compatible creep-resistant biodegradable polyester blend, a preparation method and application thereof. Background Art

[0002] The development of plastics has brought great convenience to people's production and life. At the same time, the white pollution caused by the extensive use and disposal of traditional plastics has posed a serious threat to human survival. According to statistics, more than 300 million tons of plastic waste enters the environment every year, and it is predicted that by 2050, plastic waste will reach about 12 billion tons. The pandemic of the new coronavirus infection has sharply increased the consumption of disposable plastic products (about 130 billion masks and about 65 billion gloves are produced each month), exacerbating the growth of plastic waste. Faced with the increasingly prominent "white pollution" problem, countries around the world have begun to enact laws and regulations to restrict disposable plastic products. my country has also successively issued "plastic restrictions" and "plastic bans", while vigorously encouraging the development of biodegradable plastics.

[0003] However, single biodegradable plastics have more or less shortcomings such as insufficient toughness or heat resistance, which limits their application range. For example, polylactic acid has high mechanical strength and modulus, but its performance is brittle and heat resistance is poor; while polybutylene terephthalate-adipate has good ductility and heat resistance, but its mechanical strength is low. Blending two or more biodegradable polyester materials can obtain the advantageous properties of each blending component, which has become one of the commonly used modification methods for biodegradable polyester materials (Polymer Reviews, 2017, 57 (4), 557-593). However, this method has the problem of poor compatibility between different biodegradable polyesters. In addition, the resulting blended material is usually a linear polymer material, the blended material has poor heat resistance, and creep is prone to occur at high temperatures.

[0004] Although the crystallinity of biodegradable polyester materials can be improved by annealing and other means, thereby improving the creep resistance of the materials, it will increase the complexity of the process and increase the defective rate. By constructing dynamic covalent crosslinking in thermoplastics, the creep resistance of the material can be improved and the thermoplasticity of the material can be maintained (Green Chem., 2021, 23, 2931; Science, 2017, 356(6333), 62-65; Macromolecules, 2017, 50(16), 6117-6127). Bao et al. obtained polylactic acid glass polymer by adding glycerol and zinc acetate ester exchange catalyst to polylactic acid and then adding diphenylmethane diisocyanate, which improved the melt strength of polylactic acid and was used to prepare polylactic acid foam materials. However, the mechanical properties of the obtained material are relatively brittle, with an elongation at break of only 1% and a tensile strength of about 29MPa (ACS Applied Materials & Interfaces 2022, 14, 45966-4597).

[0005] Currently, there is a lack of a highly compatible creep-resistant biodegradable polyester blend and a preparation method and application thereof. Summary of the Invention

[0006] In order to solve the defects of the prior art, the present invention provides a highly compatible creep-resistant biodegradable polyester blend and a preparation method and application thereof.

[0007] In order to solve the problems of the prior art, the present invention provides the following technical solution: a highly compatible creep-resistant biodegradable polyester blend of the present invention, wherein the highly compatible creep-resistant biodegradable polyester blend comprises the following components in parts by weight:

[0008] 100 parts of two or more biodegradable polyester compositions,

[0009] 1 to 3 parts of nitrogen-containing polyhydroxy compounds,

[0010] 0.2-0.6 parts of antioxidant,

[0011] and a multifunctional isocyanate or anhydride crosslinking agent; the molar ratio of the hydroxyl functional group in the nitrogen-containing polyhydroxy compound to the isocyanate or anhydride functional group in the multifunctional isocyanate or anhydride crosslinking agent is 1:1.2 to 1:0.8;

[0012] Furthermore, the biodegradable polyester composition is one or a combination of brittle polyester or tough polyester; the multifunctional isocyanate or acid anhydride crosslinking agent is one or a combination of diphenylmethane diisocyanate, triphenylmethane triisocyanate or pyromellitic dianhydride.

[0013] Furthermore, the brittle polyester is one or a combination of polylactic acid PLA, polyhydroxyalkanoate PHA or polyglycolic acid PGA; the tough polyester is one or a combination of polybutylene terephthalate-adipate PBAT, polybutylene succinate PBS, polypropylene carbonate PPC or polycaprolactone PCL.

[0014] Furthermore, the nitrogen-containing polyhydroxy compound is one or a combination of diethanolamine, triethanolamine or bis(2-hydroxyethyl)amino(trihydroxymethyl)methane BTM.

[0015] Furthermore, the antioxidant is one or a combination of hindered phenol, p-phenylenediamine or phosphite antioxidants.

[0016] Furthermore, the highly compatible creep-resistant biodegradable polyester blend has a cross-linked network structure and a gel fraction of 50% to 100%.

[0017] The method for preparing the highly compatible creep-resistant biodegradable polyester blend of the present invention comprises the following steps: (1) the highly compatible creep-resistant biodegradable polyester blend is prepared by reactive blending, wherein the biodegradable polyester composition and the nitrogen-containing polyhydroxy compound are dried in a vacuum oven;

[0018] (2) weighing a biodegradable polyester composition, an antioxidant, and a nitrogen-containing polyhydroxy compound according to a proportion, premixing, and adding the mixture into a twin-screw extruder or an internal mixer for reactive blending;

[0019] (3) adding a multifunctional isocyanate or anhydride crosslinking agent and continuing to blend;

[0020] (4) The blended samples were hot pressed in a flat plate vulcanizer to obtain highly compatible, creep-resistant biodegradable polyester blends.

[0021] Furthermore, in step (2), the reactive blending temperature is 170-230° C., and the blending time is 5-10 minutes.

[0022] Furthermore, in step (4), the hot pressing temperature is 170-230° C., and the hot pressing time is 5-10 minutes.

[0023] The highly compatible creep-resistant biodegradable polyester blend of the present invention is used in food packaging, logistics packaging, biological tissue engineering, and automobile manufacturing.

[0024] Beneficial Effects: Based on the excellent compatibility and crosslinking network of the biodegradable polyester blend, the present invention significantly improves the dimensional stability and mechanical properties of the biodegradable polyester blend prepared by the present invention compared to uncrosslinked blends, overcoming the problems of poor compatibility and high-temperature dimensional stability of biodegradable polyester blends. Furthermore, because the hydroxyl and ester groups in the system can undergo an exchange reaction at high temperatures and under internal catalytic conditions, the material's thermoplastic processing properties are maintained. This overcomes the difficulty of thermoplastic processing of materials after crosslinking using traditional crosslinking methods such as peroxides or radiation. The result is a biodegradable polyester blend material that is high in strength, toughness, dimensional stability, and thermoplastic processability.

[0025] Compared with the prior art, the present invention has the following advantages:

[0026] (1) The present invention utilizes an internal catalytic transesterification reaction between nitrogen-containing polyhydroxy compounds and biodegradable polyesters. On the one hand, the transesterification reaction between biodegradable polyesters is promoted, which is beneficial to the compatibility between different biodegradable polyesters at the molecular level, thereby overcoming the problem of poor compatibility between different biodegradable polyesters. On the other hand, more hydroxyl functional groups are introduced into the chain ends or in the biodegradable polyester chains, and crosslinking agents such as multifunctional isocyanates are used to react with the hydroxyl groups to construct a crosslinked network structure, thereby improving the high-temperature creep resistance and dimensional stability of the biodegradable polyester blends.

[0027] (2) The highly compatible, creep-resistant biodegradable polyester blend provided by the present invention is prepared by reactive blending, which is simple and adaptable to industrial production. The tertiary amine structure of the nitrogen-containing polyhydroxy compound in the highly compatible, creep-resistant biodegradable polyester blend provided by the present invention can serve as an internal catalyst for the transesterification reaction, overcoming the problems of catalyst incompatibility and easy migration caused by the addition of external catalysts. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The preferred embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0029] Figure 1 This is a thermoplastic processing diagram of Test Example 1 of the present invention after reactive blending and cross-linking.

[0030] Figure 2 These are the creep curves of Comparative Example 1, Comparative Example 2 and Test Example 1 of the present invention at 80°C. The illustrations are photographs of the samples after thermal deformation curve testing (a) and scanning electron microscope images of the cross-sectional morphology of Comparative Example 1 and Test Example 1 of the present invention (b). DETAILED DESCRIPTION

[0031] The present invention will be described in detail below with reference to specific test examples. It is necessary to point out that the following test examples are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art to the present invention based on the contents of the present invention still fall within the scope of protection of the present invention.

[0032] Example 1

[0033] The present invention provides a highly compatible creep-resistant biodegradable polyester blend, which comprises the following components in parts by weight:

[0034] 100 parts of two or more biodegradable polyester compositions,

[0035] 2 parts of nitrogen-containing polyhydroxy compounds,

[0036] 0.4 parts antioxidant

[0037] and multifunctional isocyanate or anhydride crosslinking agents;

[0038] The molar ratio of the hydroxyl functional groups in the nitrogen-containing polyhydroxy compound to the isocyanate or anhydride functional groups in the multifunctional isocyanate or anhydride crosslinking agent is 1:1;

[0039] The method for preparing the highly compatible creep-resistant biodegradable polyester blend of the present invention comprises the following steps: (1) the highly compatible creep-resistant biodegradable polyester blend is prepared by reactive blending, wherein the biodegradable polyester composition and the nitrogen-containing polyhydroxy compound are dried in a vacuum oven;

[0040] (2) weighing a biodegradable polyester composition, an antioxidant, and a nitrogen-containing polyhydroxy compound according to a proportion, premixing, and adding the mixture into a twin-screw extruder or an internal mixer for reactive blending;

[0041] (3) adding a multifunctional isocyanate or anhydride crosslinking agent and continuing to blend;

[0042] (4) The blended samples were hot pressed in a flat plate vulcanizer to obtain highly compatible, creep-resistant biodegradable polyester blends.

[0043] Example 2

[0044] The difference between Example 2 and Example 1 is that the highly compatible creep-resistant biodegradable polyester blend of the present invention comprises the following components in parts by weight:

[0045] 100 parts of two or more biodegradable polyester compositions,

[0046] 1 part of nitrogen-containing polyhydroxy compound,

[0047] 0.6 parts of antioxidant and

[0048] Multifunctional isocyanate or anhydride crosslinking agents;

[0049] The molar ratio of the hydroxyl functional group in the nitrogen-containing polyhydroxy compound to the isocyanate or anhydride functional group in the multifunctional isocyanate or anhydride crosslinking agent is 1:0.8;

[0050] Example 3

[0051] The difference between Example 3 and Example 1 is that the highly compatible creep-resistant biodegradable polyester blend of the present invention comprises the following components in parts by weight:

[0052] 100 parts of two or more biodegradable polyester compositions,

[0053] 3 parts of nitrogen-containing polyhydroxy compounds,

[0054] 0.2 parts of antioxidant and

[0055] Multifunctional isocyanate or anhydride crosslinking agents;

[0056] The molar ratio of the hydroxyl functional group in the nitrogen-containing polyhydroxy compound to the isocyanate or anhydride functional group in the multifunctional isocyanate or anhydride crosslinking agent is 1:1.2.

[0057] Test Example 1

[0058] like Figure 1 As shown, the preparation method of the highly compatible creep-resistant biodegradable polyester blend of the present invention comprises the following steps:

[0059] (1) Dry appropriate amounts of polylactic acid (PLA), polybutylene terephthalate (PBAT), and bis(2-hydroxyethyl)amine tris(hydroxymethyl)methane (BTM) in a vacuum oven at 80°C for 4 h;

[0060] (2) 85 parts of polylactic acid (PLA), 15 parts of polybutylene terephthalate (PBAT), 1680.2 parts of antioxidant, and 2 parts of bis(2-hydroxyethyl)amine tris(hydroxymethyl)methane (BTM) were premixed and added to an internal mixer, and reactively blended at 180°C for 7 minutes.

[0061] (3) Add 6 parts of the crosslinking agent diphenylmethane diisocyanate (MDI) (the molar ratio of hydroxyl group to isocyanate group is 1:1) and continue reactive blending for 8 minutes.

[0062] (4) The sample blended in step (3) was hot-pressed at 180° C. for 8 minutes using a flat-plate vulcanizer to obtain a highly compatible creep-resistant biodegradable polyester blend.

[0063] Comparative Example 1

[0064] Without the addition of nitrogen-containing polyols and multifunctional isocyanates or anhydrides crosslinking agents:

[0065] like Figure 2 As shown, 85 parts of polylactic acid PLA, 15 parts of polybutylene terephthalate-adipate PBAT, and 0.2 parts of antioxidant 168 were premixed and added into an internal mixer, and reactive blending was performed at 180°C for 7 minutes;

[0066] In step (3), reactive blending was continued for 8 min.

[0067] In step (4), the sample blended in step (3) is hot-pressed at 180° C. for 8 minutes using a flat-plate vulcanizer to obtain a final sample.

[0068] Comparative Example 2

[0069] No nitrogen-containing polyols added:

[0070] In step (1), appropriate amounts of polylactic acid (PLA) and polybutylene terephthalate (PBAT) are dried in a vacuum oven at 80° C. for 4 h;

[0071] In step (2), 85 parts of polylactic acid PLA, 15 parts of polybutylene terephthalate adipate PBAT, and 0.2 parts of antioxidant 168 were pre-mixed and added to an internal mixer, and reactively blended at 180° C. for 7 minutes;

[0072] In step (3), 6 parts of diphenylmethane diisocyanate MDI (the molar ratio of hydroxyl group to isocyanate group is 1:1) as a crosslinking agent are added and reactive blending is continued for 8 minutes.

[0073] In step (4), the sample blended in step (3) is hot-pressed at 180° C. for 8 minutes using a flat-plate vulcanizer to obtain a final sample.

[0074] Comparative Example 3

[0075] No multifunctional isocyanate or anhydride crosslinking agent added:

[0076] In step (1), appropriate amounts of polylactic acid (PLA), polybutylene terephthalate (PBAT), and bis(2-hydroxyethyl)amine tris(hydroxymethyl)methane (BTM) are dried in a vacuum oven at 80° C. for 4 h.

[0077] In step (2), 85 parts of polylactic acid PLA, 15 parts of polybutylene terephthalate-adipate PBAT, 2 parts of bis(2-hydroxyethyl)amine tris(hydroxymethyl)methane BTM, and 0.2 parts of antioxidant 168 were pre-mixed and added to an internal mixer, and reactively blended at 180° C. for 7 minutes;

[0078] In step (3), reactive blending was continued for 8 min.

[0079] In step (4), the sample blended in step (3) is hot-pressed at 180° C. for 8 minutes using a flat-plate vulcanizer to obtain a final sample.

[0080] Test Example 2

[0081] The method for preparing the highly compatible creep-resistant biodegradable polyester blend of the present invention comprises the following steps:

[0082] In step (1), appropriate amounts of polyhydroxybutyrate valerate (PHBV), polybutylene terephthalate-adipate (PBAT), and diethanolamine are dried in a vacuum oven at 80° C. for 4 h;

[0083] In step (2), 60 parts of polyhydroxybutyrate valerate (PHBV), 40 parts of polybutylene terephthalate-adipate (PBAT), 0.2 parts of antioxidant 168, 0.2 parts of antioxidant 1010, and 3 parts of diethanolamine were pre-mixed and added to a twin-screw extruder, and reactive blending was performed at 180° C. for 7 minutes;

[0084] In step (3), 5.6 parts of triphenylmethane triisocyanate crosslinking agent (molar ratio of hydroxyl group to isocyanate group is 1:0.8) was added and reactive blending was continued for 8 minutes.

[0085] In step (4), the sample blended in step (3) is hot-pressed at 180° C. for 8 minutes using a flat-plate vulcanizer to obtain a highly compatible, creep-resistant, biodegradable polyester blend.

[0086] Comparative Example 4

[0087] Without the addition of nitrogen-containing polyols and multifunctional isocyanates or anhydrides crosslinking agents:

[0088] In step (1), appropriate amounts of polyhydroxybutyrate valerate (PHBV) and polybutylene terephthalate adipate (PBAT) are dried in a vacuum oven at 80° C. for 4 h;

[0089] In step (2), 60 parts of polyhydroxybutyrate valerate (PHBV), 40 parts of polybutylene terephthalate-adipate (PBAT), 0.2 parts of antioxidant 168, and 0.2 parts of antioxidant 1010 were added to a twin-screw extruder and reactively blended at 180° C. for 7 minutes.

[0090] In step (3), reactive blending was continued for 8 min.

[0091] In step (4), the sample blended in step (3) is hot-pressed at 180° C. for 8 minutes using a flat-plate vulcanizer to obtain a final sample.

[0092] Test Example 3

[0093] The method for preparing the highly compatible creep-resistant biodegradable polyester blend of the present invention comprises the following steps:

[0094] In step (1), polylactic acid PLA, polypropylene carbonate PPC, and triethanolamine are dried in a vacuum oven at 80° C. for 4 h;

[0095] In step (2), 70 parts of polylactic acid PLA, 30 parts of polypropylene carbonate PPC, 1680.2 parts of antioxidant, 0.2 parts of antioxidant AO 80, and 1 part of triethanolamine were pre-mixed and added to an internal mixer, and reactively blended at 170° C. for 10 minutes;

[0096] In step (3), 2 parts of a cross-linking agent, pyromellitic dianhydride (the molar ratio of hydroxyl group to anhydride being 1:0.9), were added and reactive blending was continued for 10 minutes.

[0097] In step (4), the sample blended in step (3) is hot-pressed at 170° C. for 10 minutes using a flat-plate vulcanizer to obtain a highly compatible, creep-resistant, biodegradable polyester blend.

[0098] Comparative Example 5

[0099] Without the addition of nitrogen-containing polyols and multifunctional isocyanates or anhydrides crosslinking agents:

[0100] In step (1), polylactic acid PLA and polypropylene carbonate PPC are dried in a vacuum oven at 80° C. for 4 h;

[0101] In step (2), 70 parts of polylactic acid PLA, 30 parts of polypropylene carbonate PPC, 1680.2 parts of antioxidant, and 0.2 parts of antioxidant AO80 were pre-mixed and added into a twin-screw extruder, and reactively blended at 170° C. for 10 minutes;

[0102] In step (3), reactive blending was continued for 10 min.

[0103] In step (4), the sample blended in step (3) is hot-pressed at 170° C. for 10 minutes using a flat-plate vulcanizer to obtain a final sample.

[0104] Test Example 4

[0105] The method for preparing the highly compatible creep-resistant biodegradable polyester blend of the present invention comprises the following steps:

[0106] In step (1), polyglycolic acid PGA, polybutylene succinate PBS, polycaprolactone PCL, and bis(2-hydroxyethyl)amine tris(hydroxymethyl)methane BTM were dried in a vacuum oven at 80° C. for 4 h;

[0107] In step (2), 50 parts of PGA, 30 parts of polybutylene succinate PBS, 20 parts of polycaprolactone PCL, 0.3 parts of antioxidant 168, 0.3 parts of antioxidant AO80, and 1.5 parts of BTM were pre-mixed and added to an internal mixer, and reactively blended at 230° C. for 5 minutes;

[0108] In step (3), 4.7 parts of pyromellitic dianhydride (with a molar ratio of hydroxyl group to anhydride of 1:1.2) as a cross-linking agent were added and reactive blending was continued for 5 minutes.

[0109] In step (4), the sample blended in step (3) is hot-pressed at 230° C. for 5 minutes in a flat-plate vulcanizer to obtain a highly compatible creep-resistant biodegradable polyester blend.

[0110] Comparative Example 6

[0111] Without the addition of nitrogen-containing polyols and multifunctional isocyanates or anhydrides crosslinking agents:

[0112] In step (1), polyglycolic acid PGA, polybutylene succinate PBS, and polycaprolactone PCL were dried in a vacuum oven at 80° C. for 4 h;

[0113] In step (2), 50 parts of polyglycolic acid PGA, 30 parts of polybutylene succinate PBS, 20 parts of polycaprolactone PCL, 0.3 parts of antioxidant 168, and 0.3 parts of antioxidant AO80 were premixed and added to an internal mixer, and reactively blended at 230° C. for 5 minutes;

[0114] In step (3), reactive blending was continued for 5 min.

[0115] In step (4), the sample blended in step (3) was hot-pressed at 230° C. for 5 minutes in a flat-plate vulcanizer to obtain a final sample. The typical properties of Test Examples 1 to 4 and Comparative Examples 1 to 6 are shown in Table 1:

[0116] Table 1

[0117]

[0118] a The samples of Comparative Example 6 and Test Example 4 used phenol as the solvent, while the other samples used tetrahydrofuran as the solvent and were measured by Soxhlet extraction for 24 h.

[0119] b Measured by dynamic thermal mechanical analyzer, stress 0.05MPa, heating rate 5℃ / min.

[0120] Figure 1 This is a diagram of thermoplastic processing after reactive crosslinking in Experimental Example 1 of the present invention. It can be seen that because the crosslinking system in the present invention is a dynamic covalent crosslinking system, the crosslinked polyester blend can still be thermoplastically processed even with a gel fraction of approximately 84%. Figure 2 Figure a shows the creep curves of Comparative Examples 1, 2, and Test Example 1 of the present invention at 80°C. The inset shows a photograph of the samples after heat deformation curve testing. The figure shows that creep is suppressed after crosslinking, indicating improved creep resistance and dimensional stability. Adding a crosslinker alone does not effectively improve the creep resistance and dimensional stability of the biodegradable polyester blend. Furthermore, the photographs show that the shape of the comparative example samples changes significantly due to melting, while the dimensions of the crosslinked biodegradable polyester blend are maintained, indicating significantly improved dimensional stability. Figure 2 b is a scanning electron microscope image of the cross-sectional morphology of comparative example 1 and test example 1 of the present invention. It can be seen that the compatibility of the cross-linked biodegradable polyester blend is significantly improved compared with the uncross-linked biodegradable polyester blend. Table 1 lists the mechanical data, gel fraction and temperature (°C) at 10% tensile strain of each test example and comparative example. It can be seen from the mechanical data in Table 1 that the yield strength and breaking strength of the cross-linked biodegradable polyester blend are significantly improved compared with the uncross-linked biodegradable polyester blend. When the cross-linking density is low, the elongation at break is also improved. This is due to the good compatibility between the biodegradable polyesters and the existence of the cross-linked structure.

[0121] Comparing the data from Comparative Example 2 and Test Example 1, we can see that when only a crosslinking agent is added, the elongation at break and mechanical strength of the material are improved compared to the biodegradable polyester without the crosslinking agent, because the small molecule crosslinking agent acts as a chain extender and plasticizer. However, the improvement in mechanical strength is limited, and the dimensional stability of the material is not improved. This fully demonstrates the necessity of adding nitrogen-containing polyols to construct a crosslinked network. Comparing the data from Comparative Example 3 and Test Example 1, adding only nitrogen-containing polyols does not produce an effective crosslinked network, and it causes material degradation, resulting in a decrease in various performance properties. In addition, the temperature data at 10% tensile strain in Table 1 show that the heat deformation temperature of the crosslinked biodegradable polyester blend is significantly increased, indicating that the dimensional stability and creep resistance of the material are significantly improved.

[0122] The highly compatible creep-resistant biodegradable polyester blend material prepared by the present invention can be applied to multiple fields such as food packaging, logistics packaging, biological tissue engineering, and automobiles, and has high market value and good application prospects.

[0123] The above-mentioned experimental examples are intended only to illustrate the technical concepts and features of the present invention. Their purpose is to enable those skilled in the art to understand the contents of the present invention and implement them accordingly. They are not intended to limit the scope of protection of the present invention. Any equivalent changes or modifications made based on the essence of the present invention are intended to be covered by the scope of protection of the present invention.

Claims

1. A highly compatible creep-resistant biodegradable polyester blend, characterized by: The highly compatible creep-resistant biodegradable polyester blend is composed of the following components in parts by weight: 100 parts of two or more biodegradable polyester compositions, 1 to 3 parts of nitrogen-containing polyhydroxy compounds, 0.2~0.6 parts of antioxidant, and multifunctional isocyanate or anhydride crosslinking agents; The molar ratio of the hydroxyl functional group in the nitrogen-containing polyhydroxy compound to the isocyanate or anhydride functional group in the multifunctional isocyanate or anhydride crosslinking agent is 1:1.2 to 1:0.8; The blend has a dynamic covalent cross-linked network structure with a gel fraction of 50% to 100%, and the dynamic covalent cross-linked network is formed by the reaction of hydroxyl groups of the nitrogen-containing polyhydroxy compound with functional groups of the cross-linking agent; The nitrogen-containing polyhydroxy compound is one or a combination of diethanolamine, triethanolamine or bis(2-hydroxyethyl)amino(trihydroxymethyl)methane BTM.

2. The highly compatible creep-resistant biodegradable polyester blend according to claim 1, characterized in that: The biodegradable polyester composition is one or a combination of brittle polyester or tough polyester; The multifunctional isocyanate or anhydride crosslinking agent is one or a combination of diphenylmethane diisocyanate, triphenylmethane triisocyanate or pyromellitic dianhydride.

3. The highly compatible creep-resistant biodegradable polyester blend according to claim 2, characterized in that: The brittle polyester is one or a combination of polylactic acid PLA, polyhydroxyalkanoate PHA or polyglycolic acid PGA; The tough polyester is one or a combination of polybutylene terephthalate-adipate (PBAT), polybutylene succinate (PBS), polypropylene carbonate (PPC) or polycaprolactone (PCL).

4. The highly compatible creep-resistant biodegradable polyester blend according to claim 1, characterized in that: The antioxidant is one or a combination of hindered phenol, p-phenylenediamine or phosphite antioxidants.

5. The method for preparing the highly compatible creep-resistant biodegradable polyester blend according to any one of claims 1 to 4, characterized in that The steps include: (1) The highly compatible and creep-resistant biodegradable polyester blend is prepared by reactive blending, wherein the biodegradable polyester composition and the nitrogen-containing polyhydroxy compound are dried in a vacuum oven; (2) weighing the biodegradable polyester composition, antioxidant and nitrogen-containing polyhydroxy compound according to a proportion, premixing and adding them into a twin-screw extruder or internal mixer for reactive blending; (3) Add a multifunctional isocyanate or anhydride crosslinking agent and continue blending; (4) The blended samples were hot pressed in a flat plate vulcanizer to obtain highly compatible, creep-resistant biodegradable polyester blends.

6. The method for preparing the highly compatible creep-resistant biodegradable polyester blend according to claim 5, characterized in that: In step (2), the reactive blending temperature is 170-230°C, and the blending time is 5-10 min.

7. The method for preparing the highly compatible creep-resistant biodegradable polyester blend according to claim 6, characterized in that: In step (4), the hot pressing temperature is 170-230°C, and the hot pressing time is 5-10 minutes.

8. Use of the highly compatible creep-resistant biodegradable polyester blend according to claim 1 in food packaging, logistics packaging, biological tissue engineering, and automobile manufacturing.

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